Innovative combinatory approaches with dendritic cell-based vaccines: bridging preclinical insights and clinical challenges

Abstract

Dendritic cell (DC)-based vaccines have emerged as a promising and innovative approach in the immunotherapy of both solid tumors and hematologic malignancies. Owing to their unique capacity to present antigens and activate tumor-specific T cell responses, DC vaccines play a pivotal role in counteracting tumor immune evasion. Despite significant advances in vaccine development, several challenges — including the immunosuppressive tumor microenvironment, the complexities of designing optimal vaccines, and the difficulty of translating preclinical successes into consistent clinical outcomes — have limited their widespread effectiveness. This review highlights recent combinatory strategies aimed at enhancing the design and application of DC-based vaccines. These include the incorporation of neoantigens, tumor lysates, mRNA platforms, DC-tumor fusion constructs, and combination therapies involving immune checkpoint inhibitors and CAR-T cells. Furthermore, we examine the translational barriers that hinder the clinical implementation of these approaches and explore future directions for improving efficacy, safety, and personalization of DC vaccines. DC-based vaccines may be more effectively positioned to yield substantial and durable clinical advantages in standard oncology practice when these combinatorial strategies are integrated with rational clinical trial design, biomarker-informed patient selection, and rigorous compliance with manufacturing and regulatory standards. Ultimately, individualized and multifaceted strategies are expected to hold the greatest promise for improving therapeutic outcomes while minimizing adverse effects.

Introduction

Despite substantial progress in the management of neoplastic diseases, invasive surgical procedures, chemotherapy, radiotherapy, and allogeneic hematopoietic stem cell transplantation (HSCT) remain the primary therapeutic modalities. However, these conventional treatments are frequently associated with a broad spectrum of adverse effects, ranging from mild to severe, such as mucositis, opportunistic infections, veno-occlusive disease, and interstitial pneumonitis [1]. In recent years, immunotherapy has emerged as a promising approach for eliciting immune responses against malignant cells [2–4]. Specifically, cancer vaccines function by presenting tumor-associated antigens (TAAs) to the immune system, thereby facilitating targeted immune activation and promoting tumor-specific immunity [5, 6].

Antigen-presenting cells (APCs), particularly DCs, play a central role in initiating adaptive immune responses by capturing, processing, and presenting antigens to naïve T cells. Through the activation of CD4⁺ helper T cells and CD8⁺ cytotoxic T cells, DCs serve as a vital connection between innate and adaptive immunity [7]. The upregulation of co-stimulatory molecules further enhances their capacity to stimulate both CD8⁺ cytotoxic and CD4⁺ helper T cells. Moreover, DCs possess the ability to “cross-prime,” presenting exogenous antigens through MHC class I to induce CD8⁺ cytotoxic T-cell responses [8]. Overall, DCs are essential for immune activation and cytotoxic response to foreign antigens (Fig. 1).

Fig. 1.

Schematic overview of autologous monocyte-derived dendritic cell (DC) preparation and activation for personalized cancer immunotherapy. Peripheral blood monocytes are isolated from the patient and cultured with cytokines such as IL-4 and GM-CSF to generate immature DCs. These cells are then loaded with tumor-associated antigens, including tumor lysate, peptides, or DNA/RNA. Following antigen loading, DCs undergo maturation, characterized by the upregulation of co-stimulatory molecules (e.g., CD40L, CD70, TLR-4). Mature DCs are subsequently administered back to the patient, where they present antigens to CD4 + helper and CD8 + cytotoxic T cells, eliciting a targeted adaptive immune response

Following Ralph Steinman’s discovery of DCs in 1973, DC-based vaccination was soon explored as a therapeutic strategy for patients with acute myeloid leukemia (AML). Initial clinical outcomes, however, were largely disappointing. In recent years, advances in immunological and biotechnological approaches have renewed interest in DC vaccination for cancer therapy [9]; including mRNA transfection, induction of immunogenic cell death, and the use of cell-penetrating peptides, all of which enhance peptide delivery to DCs in vivo (Fig. 1) [10]. Both preclinical and clinical investigations have evaluated the capacity of DC vaccines to stimulate anti-tumor T-cell responses [11, 12], as well as their safety and therapeutic efficacy [13, 14], as well as combining DC-based vaccination with ICIs, adoptive cell therapies, or activated T-cell infusions [15, 16].

A diverse range of TAAs and neoantigens can be delivered through DC/tumor cell fusion vaccines. Antigen selection remains a critical determinant of DC vaccine efficacy. Although some tumor cell types may lose antigens through immunoediting, a variety of antigen sources, such as synthetic peptides, recombinant proteins, whole tumor cells, and tumor cell lysates, have been employed in the design of therapeutic vaccines. In addition, radiation-exposed or apoptotic tumor cells have also been utilized as antigenic substrates [17, 18].

Hematological malignancies offer unique advantages, including direct accessibility through the bloodstream and inherent immunomodulatory properties, which may contribute to more favorable clinical outcomes. While DC vaccines are capable of inducing tumor-specific immune responses, prior clinical studies have also highlighted important limitations [19, 20]. Despite the undeniable promising outcomes of DC-based vaccines in both clinical and experimental oncology, several challenges persist, including immune suppression, tumor immune evasion, and technical limitations. The present review provides a translationally oriented synthesis of combinatory DC-based strategies and investigates how these approaches can be logically advanced from preclinical models into practical clinical applications, in contrast to earlier reviews that mostly concentrated on DC biology or single-platform vaccines. Moreover, the present review seeks to examine the therapeutic potential of various DC vaccine strategies while also providing integrative approaches designed to enhance their efficacy and mitigate associated adverse effects.

Diverse types of dendritic cell-based vaccines in cancer immunotherapy

Peptide-pulsed DC vaccines

The tumor antigen selected for pulsing into dendritic cells (DCs) is a critical component of DC vaccine efficacy. Among these, neoantigens represent the most tumor-specific class of antigens and possess a strong capacity to activate T lymphocytes against malignant cells [21]. Because they evade central immunological tolerance in the thymus, peptides harboring amino acid substitutions derived from cancer-associated genetic mutations function as potent antigens for tumor rejection. Recent advances have focused on identifying neoantigens based on gene expression alterations and the predicted binding affinity of mutated peptides to HLA class I molecules. This approach has enabled the development of personalized, patient-specific vaccines incorporating HLA-class-I-restricted neoantigen peptides [22], through genetic profiling of each patient’s tumor, loading these peptides onto DCs, and delivering them directly into lymph nodes [23, 24]. Multiple clinical trials, both as monotherapies and in combination with other immunotherapies, have been initiated, with phase I/Ib studies demonstrating the safety and efficacy of neoantigen-based vaccines [22, 25]. Multiple TAAs or neoantigens can be incorporated into a single mRNA construct, and recent studies have demonstrated that these vaccines induce robust CD4⁺ and CD8⁺ T-cell responses in both preclinical models and early-phase clinical trials. However, the transient expression profile of mRNA characteristic of mRNA platforms and the limited in vivo persistence of ex vivo–generated dendritic cells constrain the durability of vaccine-induced immunity, often necessitating repeated booster administrations to maintain therapeutic responses. These limitations have prompted the development of lipid nanoparticle (LNP) delivery systems and in vivo DC-targeted mRNA approaches, which seek to deliver antigens directly to endogenous dendritic-cell subsets while enhancing scalability, batch-to-batch consistency, GMP compliance, and overall clinical feasibility [26].​​

In Japan, this approach has been classified as a Class III regenerative medicine under the Act to Ensure the Safety of Regenerative Medicine. Clinical studies assessing both immunological and therapeutic outcomes have reported encouraging results [23]. Notably, vaccine efficacy has been correlated with increased neoantigen-specific T-cell responses, as measured by interferon-gamma (IFN-γ) ELISpot assays; while adverse effects were minimal, underscoring the safety of this therapeutic strategy [23].

Despite their favorable safety profiles, peptide-pulsed DC vaccines have not demonstrated substantial efficacy in randomized phase III trials due to HLA restriction (only 40–50% of patients eligible), rapid peptide dissociation, limited neoantigen load in immunologically “cold” tumors, and extremely high manufacturing cost [27]. These obstacles help account for the absence of regulatory approval after more than 25 years of clinical investigation. Achieving future clinical success will likely require integration with tumor microenvironment–modulating agents rather than reliance on monotherapy [28].

Tumor lysate-pulsed DC vaccines

In recent years, numerous preclinical and clinical efforts have been directed toward loading apoptotic tumor cells into DCs, rather than relying on a single or limited set of antigens or peptides [29, 30]. Tumor lysate–pulsed DC vaccines incorporate a broad spectrum of both characterized and uncharacterized immunogenic antigens, along with costimulatory and adhesion molecules essential for initiating immune responses, including the activation and proliferation of tumor-specific CD4⁺ and CD8⁺ T cells. Compared with peptide-pulsed vaccines, tumor lysate–pulsed DC vaccines have been associated with lower expression levels of IL-2 and IFN-γ in HLA-restricted T-cell responses. Notably, a study by Kokhaei et al. displayed decreased IL-4 expression and an absence of IL-10 production in DC-based immunotherapy [31]. Although several early‑phase trials have demonstrated acceptable safety profiles and measurable immunogenicity, consistent clinical efficacy has remained challenging to substantiate. Further investigation is required to refine antigen formulation, optimize DC maturation protocols, and improve criteria for patient selection[32].

The application of chemically fused DCs/ tumor cells as potent T-cell stimulants represents a strategy analogous to vaccines derived from whole apoptotic leukemia bodies. Vaccination with autologous DC/tumor cell fusions presents a spectrum of antigens to stimulate both helper and cytotoxic T-lymphocytes (CTLs). In a recent Phase I, dose-escalation clinical trial on multiple myeloma, Rosenblatt et al. demonstrated encouraging outcomes, including favorable tolerability, disease stabilization, and absence of autoimmunity [33]. Similarly, Mohamed et al. generated a novel APC line by fusing tumor cells from hematological malignancies with the B-lymphoblastoid cell line HMy2. This approach produced a panel of self-replicating, long-lived hybrid lymphoblastoid cell lines that expressed CD80, CD86, HLA class I and II molecules, and multiple tumor-associated antigens (TAAs) [34]. Their findings supported the feasibility of using this hybrid technique to activate functional CTLs against autologous TAAs in both leukemia patients and healthy donors, marking a significant step toward developing long-lived immunotherapeutic reagents for hematological malignancies. Nonetheless, the clinical utility of this approach remains to be fully established. In another study, 18 patients with chronic lymphocytic leukemia (CLL) received irradiated GM-CSF–secreting autologous tumor cells shortly after allo-HSCT. With a median follow-up of 2.9 years (range: 1–4 years), the study achieved overall survival (OS) and progression-free survival (PFS) rates of 88% and 82%, respectively (95% CI: 54–94 and 59–97) (see Table 1 for comparison with other trials) [29]. This extended follow-up provided valuable insight into long-term treatment outcomes and demonstrated that the vaccine selectively targeted autologous tumor cells while sparing alloantigen-bearing normal recipient cells and building upon earlier findings in acute myeloid leukemia (AML), where Bacillus Calmette–Guérin (BCG) vaccination more than doubled survival, a recent trial combined BCG with a DC-based vaccine using irradiated autologous CLL cells. However, no therapeutic advantage was observed over DC vaccination alone, and additional adverse effects were attributed to BCG administration [35]. According to recent studies, the whole leukemic cell vaccines are also being explored as an alternative to ex vivo DC pulsing, as they inherently contain a wide range of immunogenic antigens. Qin et al. reported that chronic-phase chronic myeloid leukemia (CML) patients with partial responses to imatinib developed strong IgG titers against multiple leukemia-associated antigens (LAAs) after receiving an irradiated K562-GM-CSF⁺ cell-based vaccine [36]. Importantly, no single antigen was consistently detected across all responders, emphasizing the necessity of targeting multiple antigens. According to earlier work by Laumbacher et al. proposed that while monocytes can effectively internalize tumor material in vivo, they lack the ability to prime T cells or mediate tumor cell killing. In contrast, mature DCs have superior T-cell priming and cytotoxic potential [37]. Based on these observations, the researchers developed the cascade priming (CAPRI) approach, in which autologous monocytes are first stimulated ex vivo with cytokines and subsequently restimulated using identical peripheral blood mononuclear cells (PBMCs) without exogenous tumor material. This method generated a synergistic antitumor effect by activating monocytes, DCs, and both cytotoxic and helper T lymphocytes against various solid tumors [37].

Table 1.

Representative studies on combinatorial strategies in dendritic cell vaccine development

Author/ year/ ref	Type of cancer	DC type and preparation method	Loaded antigen type	Combination strategy	Clinical outcome	Adverse event	DC dose and number of injections	Patient sample size	Special consideration or innovation
M DONG/ 2012 [256]	AML	moDCs, GM-CSF + 1IFN-α + 2FLT-3 ligan + 3SCF + 4TGF-β	NA	Chemotherapy/ 5CIK	found to be a promising candidate for treatment of AML in elderly patients	feeling cold, myalgia and noninfective fever	7.36 ± 0.48 × 107/ 5	21	NA
T Kitawaki/2011 [239]	AML	moDCs, GM-CSF + 6TNF + 7PGE2	8WT1& zoledrnate	NA	strengthening of vaccinations may result in an improved clinical outcome	NA	1 × 107cells/ 3–5	3	NA
L. ZAHRADOVA/ 2012 [257]	9MM	moDCs / IL-4 + GM-CSF	10ID-Protein	NA	safe and induce a specific immune response in multiple myeloma patients	NA	NA	11	NA
LE Franssen/ 2017 [258]	MM	moDCs / IL-4 + GM-CSF	11MiHA peptide	12DLI	safe, feasible, and capable of inducing objective MiHA-specific T-cell responses	Erythema/ Fever	45–90 × 106 / 3	9	NA
X Zhao/ 2015 [241]	MM	moDCs / IL-4 + GM-CSF	NA	13CIK/ chemotherapy	has an excellent clinical efficacy and potential for treating MM, reversing the Th1 to Th2 shift, and boosting the immune system’s ability to fight tumors	chills and fever	2–5 × 109 / 6	26	NA
Marzia Palma/ 2018 [259]	14CLL	moDCs / IL-4 + GM-CSF	apoptotic bodies derived from autologous leukemic cells	lenalidomide	Lenalidomide is a potent immune adjuvant in combination with anti-tumor vaccination in CLL	NA	20 × 106/ 5	10	NA
Sun Y/ 2010 [260]	15NHL	moDCs / IL-4 + GM-CSF	tumor cell lysate	CIK	show the ability to specifically kill the lymphoma cells	transient fever & Chill	NA	NA	NA
Youko Suehiro/ 2015 [261]	16ATL	moDCs / IL-4 + GM-CSF	Tax peptide	NA	safe and feasible treatment for ATL patients in stable condition	Mild	5 × 106 / NA	3	NA
M Di Nicola/ 2009 [238]	B-cell lymphoma	moDCs / IL-4 + GM-CSF	killed autologous tumor cells	NA	induce both T- and B-cell responses and produces clinical benefits in indolent NHL	injection site reactions	NA/ 4	16	NA
Rosa A van Amerongen/2022 [262]	AML	CD34 + hematopoietic precursor cells, CD14 + -derived immature and mature DCs, and B cells were tested for recognition by the TCR-T cells	WT1 peptide	WT1-17TCR engineered T cells	High WT1 expression	No on-target and off-target toxicity was observed	0.1 × 106 cells/mL for 3 days	11 18ALL samples, 15 AML, 1 19 (HCL)	Novel antigen-loading method
Jurjen M Ruben/2014 [263]	AML	moDCs: Apoptotic blebs bleb-loaded MoDC prime CD8 + T cells	bleb-loaded MoDC	T cell cytokine release and CD8 + T cell priming	superior ingestion efficiency and migration, combined with favorable T cell cytokine release and CD8 + T cell priming ability and avidity	NA	4 × 104 (loaded) MoDC	cell line HL60	Novel antigen-loading method
Staffan Holmberg-Thyden/2022 [264]	20MDS	regulatory T-cells, 21NK and NKT-cells, monocytes, dendritic cells (DC), myeloid-derived suppressor cells (MDSCs), and CD34 + hematopoietic stem cells	WT1 peptide	combined AZA with a therapeutic peptide vaccine targeting antigens encoded from NY-ESO-1, MAGE-A3, PRAME, and WT-1	The average time to progression (TTP) from inclusion was 5.2 months (range 2.8 to 7.6), while average survival was 11.3 months (range 4.3 to 22.2). The average survival from time of diagnosis was 18.1 months (range 10.9 to 30.6) in our patient cohort	NA	one dose of vaccine, corresponding to 50 µg of each of the four peptides	5	Novel antigen-loading method
Volker L Reichardt/1999 [265]	MM	PBMCs	Tumor idiotype	Ex vivo pulse	2/12 patients developed idiotype-specific immune response 2/12 patients maintained 22CR at 17 and 30 months	minor and transient side effects	1 and 11 × 10 6	12	NA
Martha Q Lacy/2009 [266]	MM	PBMCs	Tumor idiotype	Ex vivo pulse	Median 23OS in trial patients was 5.3 years compared to 3.4 years in the control group	feasible and safe	24NR	27	NA
Arcangelo Liso/2000 [267]	MM	PBMCs	Tumor idiotype	Ex vivo pulse	4/26 patients developed an idiotype-specific immune response 17/20 patients alive at median follow-up of 30 months	minor and transient side effect	DCs infused was 3.6 million (range, 3.0–19.1 million). Median purity was 15% (range, 3%-63%)	26	NA
Willemijn Hobo/2013 [268]	MM	PBMCs	mRNA from 25MAGE3, 26BCMA or survivin	Electropolated with mRNA	2/12 patients developed vaccine-specific immune response 5/12 patients had stable disease at a median follow-up of 55 months	fever, chills, malaise and muscular pain	intravenous (5–22 × 106 DCs) and intradermal vaccines (4–11 × 106 DCs)	12	Novel antigen-loading method
Jacalyn Rosenblatt/2011 [33]	MM	PBMCs	Whole tumor cell	Ex vivo DC/tumor cell fusion	11/15 evaluable patients had an expansion of myeloma-reactive T cells 11/16 evaluable patients had stable disease	erythema, itching Serious adverse event, possibly related Pulmonary embolus	1 × 106, 2 × 106, and 4 × 106	18	NA
Jacalyn Rosenblatt/2013 [269]	MM	PBMCs	Whole tumor cell	Ex vivo DC/tumor cell fusion	All evaluable patients developed a two-fold increase in myeloma-reactive T lymphocytes 78% of patients achieved CR or 27VGPR	transient pruritus, rash, fatigue, fever, and myalgias	3.6 × 106	36	NA
Sébastien Anguille/2017 [11]	AML	PBMCs	WT1 mRNA construct by in vitro transcription	DCs electropolated with WT − 1 mRNA	1.5-fold increase in WT1-specific tetramer CD8 + T cells in 50% of evaluable patients 30% of patients with molecular remission and 13% with disease stabilization	no local immunoreactivity	0.5 × 106 WT1/DCs	30	Novel antigen-loading method
John M. Timmerman/2002 [270]	Follicular Lymphoma	PBMCs	Tumor idiotype	Idiotype pulsed DCs	65% of patients are in remission with T cell or humoral response 70% of patients with 28PFS at 43 months	mild to moderate chills, rigors, or fevers	DCs administered over the 4 infusions were dictated by cell yield and ranged from 12 to 69 × 106	35	Novel antigen-loading method
M. Christina Cox/2019 [271]	Follicular Lymphoma	PBMCs	Antigen unloaded	Intranodal unloaded 29IFN-DC plus rituximab	All patients showed induction or enhancement of T cell responses 3/8 patients converted from active disease to CR, with 2/8 ongoing CR at 22 and 27 months	brief, localized	10 × 106 cells/cycle	8	NA
Felix S Lichtenegger/2018 [272]	AML	30TLR-3-DCs	WT1 peptide	combination of 31LAG-3 and 32PD-1	enhance T cell responses	NA	NA	NA	Combining DC vaccination with checkpoint inhibition
Prajakta Shinde/2019 [273]	MM	Mo-DCs	Peptide antigen	DC vaccine with a CTLA-4	33CTLs primed from 34HD-SC-DCs of apheresis samples from healthy donors exhibited efficient killing of cancer cell lines in vitro	NA	5.3 ± 1.7 × 106 and 4.5 ± 1.2 × 106	7 apheresis samples	Combining DC vaccination with checkpoint inhibition
MaartenVersteven/2022 [274]	Hematological Malignancies	moDC IL-15, pro-inflammatory cytokines and immunological danger signals	WT1 mRNA	MiHA-loaded PD-L-silenced DC Vaccination after 35allo-SCT	requiring further optimization	NA	NA	NA	Combining DC vaccination with checkpoint inhibition
Yasushi Akahori/2018 [275]	36CML	PBMCs	WT1	DCs present WT1 antigen to CAR-T cells engineered with scFv specifically recognizing WT1/37HLA-A*2402 complex	Vaccination with DCs loaded with WT1 antigen significantly augments in vivo expansion, tumor infiltration, and therapeutic efficacy of 38CAR-T cells	immune-related, but manageable	1 × 105 cells/5	26	Combining DC vaccination with CAR-T Therapy
Shuhong Han/2008 [276]	MM	PBMCs + IL-4 + 39GMCSF	DC/MM DC/PBMC DC/BCL	Post-CAR-TAg-presenting and immune modifying DC vaccine	modulate the number and/or the functions of Treg	NA	NA	MM patients gradu ally develop tolerance to their cancer cells with increased Treg activities	Combining DC vaccination with CAR-T Therapy
Sanfang Tu/2024 [161]	AML	PBMCs	WT1	CAR-T Cells Combined With Peptide-Specific Dendritic Cell in Relapsed/Refractory Leukemia/MDS	broad mechanistic	NA	2.26 106/kg- 5.44 106/kg	30	Combining DC vaccination with CAR-T Therapy
Antoni Ribas/2009 [133]	Melanoma	MART-1 antigen-pulsed DC	peptide–pulsed DC vaccine	Tremelimumab (anti-CTLA-4)	No benefit	NA	1 × 107- i.d-every 3 months	16	Combining DC vaccination with checkpoint inhibition
Theodore S. Nowicki/2019 [277]	Solid Tumours	40NY-ESO-1157–165 pulsed DC alone	peptide-pulsed DC vaccination	Ipilimumab (anti-CTLA-4)	Pending	NA	3/3- 2/3	NA	Combining DC vaccination with checkpoint inhibition
Jan Nesselhut/2016 [278]	pancreatic cancer	41MoDC	NA	PD-L1 blockade improved the efficacy of DC-based vaccination	improving the T-cell-specific response	NA	1–2 mg/kg body weight	7	Combining DC vaccination with checkpoint inhibition
Janos L. Tanyi /2018 [279]	ovarian cancer	autologous dendritic cells	DCs loaded with autologous tumor lysate	autologous dendritic cells (DCs) pulsed with oxidized autologous whole-tumor cell lysate combination with 42ICI	showed safety and broad antitumor immunity	NA	5 to 10 × 106- intranodally every 3 week	25	Combining DC vaccination with checkpoint inhibition
Marta Español-Rego/2023 [280]	Metastatic colorectal cancer	Autologous DC vaccine	tumor lysat	Therapy cycles of DC vaccination with anti-PD-L1 therapy	NA	fatigue, diarrhea and flu-like symptoms	10 × 10 6- intradermal-	33	Combining DC vaccination with checkpoint inhibition
Hyo S. Han/2023 [281]	Breast Cancer I/II	Autologous DCs loaded with recombinant TAAs or TAA-derived peptide(s)	TAAs or TAA-derived peptide(s)	dendritic cell (DC) vaccination, anti-43SEMA4D blocking antibody (pepinemab) and CD4 + T cell adoptive transfer + trastuzumab	increasing amounts of transferred CD4 + T cells	NA	NA	28	Peptide-Pulsed DC Vaccines
Kenichiro Iwami/2012 [282]	malignant gliomas	PBMC	Tumor antigens-stimulated DC vaccines	DC were generated from peripheral blood and pulsed with HLA-matched peptide	A positive T-cell response-	NA	1 × 10(7) DC were administered every 2 weeks	8	NA
Willem Buys/2024 [283]	Solid tumors or lymphomas	autologous dendritic cells	NA	Autologous EphA2-targeting 44CAR-DC vaccine loaded with TP53 mutant peptide (45TP53-46EphA-2-CAR-DC)	preclinical	NA	NA	10	Combining DC vaccination with checkpoint inhibition and CAR-T cell
Jolien Van den Bossche/2024 [284]	Pleural mesothelioma	PBMCs + IL-4 + GMCSF + TNFα + PGE2 + 47KLH	DC loaded with the mesothelioma-associated tumor antigen WT1	anti-PD-L1 antibody atezolizumab and WT1/ DC vaccination	The trial’s primary endpoints are safety and feasibility, secondary endpoints are clinical efficacy and immunogenicity	NA	8–10 × 106 cells/vaccination	15	Combining DC vaccination with checkpoint inhibition
Fabian Finkelmeier/2016 [285]	48HCC and liver metastases from colorectal carcinoma	Autologous dendritic cell	Autologous neoantigen	HCC-tumor neoantigen-pulsed mature-DC vaccine combined with ICI nivolumab and surgical resection	NA	NA	- 49ID	60	Novel antigen loading AND Combining DC vaccination with checkpoint inhibition
Changling Li/2018 [286]	high-grade gliomas	Autologous dendritic cell	TAAs	Autologous genetic modification-free DC cells will be loaded with multiple tumor neoantigen peptides	The primary outcomes were OS and PFS-Positive efficacy of dendritic vaccine	related adverse events (AEs)	dosages (,2 × 107), cycles(4), and route of injections (ID vs 50SC)	944	Novel antigen loading

¹IFN-α: Interferon-alpha, ²FLT3: Fms-like Tyrosine Kinase 3, ³SCF: Stem Cell Factor, ⁴TGF-β: Transforming Growth Factor-beta, ⁵CIK: Cytokine-Induced Killer cells, ⁶TNF: Tumor Necrosis Factor, ⁷PGE2: Prostaglandin E2, ⁸WT1: Wilms’ Tumor 1, ⁹MM: Multiple Myeloma, ¹⁰ID-Protein: Identity Protein, ¹¹MiHA: Minor Histocompatibility Antigen, ¹²DLI: Donor Lymphocyte Infusion, ¹³CIK: Cytokine-Induced Killer cells, ¹⁴CLL: Chronic Lymphocytic Leukemia, ¹⁵NHL: Non-Hodgkin Lymphoma, ¹⁶ATL: Adult T-cell Leukemia/Lymphoma, ¹⁷TCR: T-cell Receptor, ¹⁸ALL: Acute Lymphoblastic Leukemia, ¹⁹HCL: Hairy Cell Leukemia, ²⁰MDS: Myelodysplastic Syndromes, ²¹NK cells: Natural Killer cells, ²²CR: Complete Remission, ²³OS: Overall Survival, ²⁴NR: Not Reported, ²⁵MAGE-3: Melanoma Antigen Gene-3, ²⁶BCMA: B-cell Maturation Antigen, ²⁷VGPR: Very Good Partial Response, ²⁸PFS: Progression-Free Survival, ²⁹IFN-DC: Interferon-Induced Dendritic Cell, ³⁰TLR: Toll-Like Receptor, ³¹LAG-3: Lymphocyte-Activation Gene 3, ³²PD-1: Programmed Cell Death Protein 1, ³³CTLs: Cytotoxic T Lymphocytes, ³⁴HD-SC-DCs: High-Density Stem Cell-Derived Dendritic Cells, ³⁵allo-SCT: Allogeneic Stem Cell Transplantation, ³⁶CML: Chronic Myeloid Leukemia, ³⁶CML: Chronic Myeloid Leukemia, ³⁷HLA: Human Leukocyte Antigen, ³⁸CAR-T cells: Chimeric Antigen Receptor T cells, ³⁹GM-CSF: Granulocyte–Macrophage Colony-Stimulating Factor, ⁴⁰NY-ESO-1: New York Esophageal Squamous Cell Carcinoma-1, ⁴¹MoDC: Monocyte-derived Dendritic Cell, ⁴²ICI: Immune Checkpoint Inhibitor, ⁴³SEMA4D: Semaphorin 4D, ⁴⁴CAR-DC: Chimeric Antigen Receptor Dendritic Cell, ⁴⁵TP53: Tumor Protein p53, ⁴⁶EphA2: Ephrin Type-A Receptor 2, ⁴⁷KLH: Keyhole Limpet Hemocyanin, ⁴⁸HCC: Hepatocellular Carcinoma, ⁴⁹ID: Intradermal, ⁵⁰SC: Subcutaneous

RNA or DNA-based DC vaccines

DC vaccines can be generated by introducing DNA or RNA sequences encoding TAA epitopes into DCs. Compared with tumor cell–based approaches or peptide- and lysate-loaded DCs, nucleic acid–based strategies offer several benefits [38]. Transfection of DCs with DNA constructs enables prolonged antigen expression, allowing endogenous processing and presentation of peptides in association with MHC class I molecules, thereby eliciting potent cytotoxic T-cell responses. Importantly, the antigens are synthesized and expressed in their natural conformation, which facilitates recognition and processing by the immune system. Preclinical studies have reported favorable outcomes with DC vaccines engineered in this manner [39]. Although DCs are highly effective in priming T-cell responses, they do not always provide sufficient immunostimulatory signals to sustain durable immunity. Furthermore, the tumor microenvironment frequently exerts immunosuppressive effects that limit vaccine efficacy. Consequently, the development of effective vaccines based on dendritic cells that elicit a robust and long-lasting immune response is required [40]. To enhance therapeutic efficacy, combination immunotherapies are increasingly being explored, such as pairing immune checkpoint inhibitors (ICIs) with autologous antigen-loaded DC vaccination. Neoantigens, in particular, represent an attractive antigen source for DC-based vaccines, as they exhibit reduced tolerance and lower toxicity compared with conventional TAAs [41]. Future advancements in DC-based immunotherapy are therefore directed toward harnessing the strong immunostimulatory potential of DCs to optimize antigen capture, T-cell activation, and the induction of durable, antigen-specific antitumor immune responses [42].

Modern cancer immunotherapy increasingly relies on the combination of antigen-specific DC vaccination with the adoptive transfer of cytotoxic T cells primed by these antigen-specific DCs. T-cell receptor (TCR) technology is currently being applied to generate antigen-specific cytotoxic T lymphocytes ex vivo using antigen-loaded DCs [43]. Consequently, advances in molecular technologies have enabled the identification of such epitopes and the construction of DNA and RNA vectors encoding them, which can be introduced into DCs to generate genetically modified vaccines [44, 45]. Genetic material can be delivered into DCs using various techniques, including chemical or magnetic transfection, electroporation, and viral transduction. Electroporation has proven to be the most effective; this technique uses a brief electrical pulse to deliver mRNA directly into the cytosol [46, 47]. The most widely used method involves the introduction of plasmid-encoded DNA or RNA directly into cells, thereby bypassing endocytosis and targeted plasmid degradation. This strategy has allowed the incorporation of information encoding both TAA epitopes and immune “checkpoint” molecules, markedly enhancing the induction of cytotoxic immune responses. Preclinical studies have confirmed the ability of these approaches to elicit robust antitumor immunity. In both preclinical and clinical settings, multiple routes of administration have been employed for DC-based vaccines, including intravenous [48], intradermal [49] and, less commonly, intranodal [50] and intratumoral routes [51, 52], as well as in vivo dendritic cell induction [9]. Regardless of the delivery method, antigen-loaded dendritic cells can also promote T-cell immunity [51]. To streamline vaccine production, investigators have demonstrated that transfection of DCs with mRNAs encoding CD40L, CD70, and TLR4 can induce full maturation in a single step, eliminating the need for separate maturation cocktails. Compared with whole-tumor mRNA–based DC vaccines, synthetic mRNA-based formulations have shown reduced toxicity, greater potential for optimization, and suitability for large-scale manufacturing [53–55]. In clinical studies, these vaccines successfully stimulated antigen-specific CD8⁺ T lymphocytes [56, 57]. To further enhance vaccine potency, genetic constructs have incorporated transcription factors such as PU.1, Irf8, and Batf3, as well as migration factor genes such as SSR7, which provide DCs with enhanced maturation capacity and improved trafficking to draining lymph nodes [58, 59].

DCs transfected with DNA constructs encoding Her2/neu epitopes have been shown to generate both antigen-specific CD8⁺ T cells and long-lived memory T cells [60]. In addition, plasmids encoding receptors specific to selected TAAs have been employed to enhance the uptake of tumor-derived extracellular vesicles, thereby facilitating antigen delivery to DCs. Other plasmid-based strategies include the incorporation of small interfering RNAs to silence immunosuppressive genes such as PD-L1 and PD-L2 in DCs, alongside constructs designed to promote DC maturation and CTLs induction [61]. Engagement of PD-1 on T cells by its ligands results in apoptosis or antigen-specific anergy [58, 62]. Importantly, PD ligands (PD-L1) are expressed not only by mature DCs but also by a wide range of tumor cells [63]. These approaches reflect the highly personalized nature of DC-based immunotherapy, in which each patient receives an individualized treatment plan with tailored cell preparations. Typically, this requires the isolation of DCs from peripheral blood or their in vitro generation from hematopoietic progenitors, followed by transfection with tumor antigens using advanced delivery techniques, procedures that necessitate specialized laboratory expertise [64]. To overcome the limitations associated with conventional tumor antigen sources, mRNA has emerged as a promising alternative. Beyond serving as an efficient vehicle for antigen delivery, mRNA also provides intrinsic adjuvant activity, offering spatiotemporally controlled activation of both antigen presentation and innate immunity [65].

mRNA pulsing of DCs offers several distinct advantages. Exogenous mRNA activates multiple Toll-like receptors (TLRs), including TLR3, TLR7, and TLR8, thereby activating innate immune cells and conferring strong intrinsic adjuvanticity. Unlike DNA-based constructs, mRNA does not integrate into the host genome, eliminating the risk of insertional mutagenesis. Moreover, it can be produced efficiently in large quantities in vitro, engineered to enhance immunogenicity and reduce translational inhibition, and, being resistant to splicing events, avoids variability in protein expression caused by alternative splicing [66, 67]. A mild electric pulse is used to quickly integrate mRNA into the cytosol, preventing degradation by extracellular ribonucleases [53]. Furthermore, electroporation minimizes potential alterations in DC immunophenotype, maturation capacity, migratory ability, and T-cell stimulatory function [45, 68].

To enhance the efficiency of DC vaccines, strategies have been developed to co-transfect DCs with mRNAs encoding immunostimulatory ligands and receptors, thereby improving DC maturation and T-cell co-stimulation [69]. Preclinical studies have shown that co-transfection with mRNAs encoding CD83, OX40 ligand (OX40L/CD134), 4-1BB ligand (4-1BBL/CD137L), CD40 ligand (CD40L), and glucocorticoid-induced TNF receptor ligand (GITRL) enhances DC co-stimulation and T-cell priming [70, 71]. As an alternative strategy, the TriMix formulation, comprising mRNAs encoding CD70, CD40L, and constitutively active TLR4, was developed for electroporation in combination with antigenic mRNAs [72, 73]. Notably, electroporation of mature DCs with TriMix reprogrammed regulatory T cells (Tregs) into Th1-like cells with elevated IL-12 secretion, thereby alleviating Treg-mediated inhibition of CD8⁺ T cells in both in vitro and in vivo models [55, 73]. Additional efforts to improve DC maturation and T-cell priming in autologous antigen-loaded DC vaccines have employed co-transfection with mRNAs encoding stimulatory cytokines [74, 75]. A number of stimulatory cytokines were investigated, such as GM-CSF, IL-12, and IL-15. IL-12, in particular, plays a pivotal role in promoting Th1 differentiation and enhancing the cytotoxic activity of natural killer (NK) cells and CTLs [76, 77]. However, electroporation of IL-12 mRNA alone did not significantly influence DC survival or maturation status [78]. To address these limitations, Bcl-2 is an essential pro-survival factor that has anti-apoptotic effects, has been investigated [79, 80].

An ongoing Phase I clinical trial evaluating intratumoral injection of IL-12 mRNA in combination with the anti-PD-L1 monoclonal antibody durvalumab in patients with advanced solid tumors has confirmed the safety and tolerability of such combinatorial approach (NCT03946800) (NCT03946800) [81, 82]. Targeting antigen delivery directly to the site of T-cell activation eliminates the requirement for DC migration and selective antigen uptake, thereby enhancing prophylactic or therapeutic antitumor responses. This can be achieved through intranodal (i.n.) injection, which introduces mRNA directly into secondary lymphoid organs [83, 84]. In preclinical studies, simultaneous i.n. administration of TriMix and antigenic mRNA effectively recruited antigen-specific CD4⁺ and CD8⁺ T cells and induced CTL responses against multiple TAAs. Similarly, a Phase I clinical trial in patients with resected melanoma (NCT03394937) demonstrated the safety and tolerability of intravenous delivery of TriMix combined with melanoma-specific TAA mRNAs [85, 86]. Since many APCs are found in the skin [84, 87], intradermal (i.d.) administration has been considered the most effective method. Additionally, the effectiveness of i.d. distribution of self-adjuvanted mRNA-encoded TAAs has been demonstrated in a number of clinical trials and mice cancer models [88, 89]. However, intravenous administration of mRNA vaccines has been limited by rapid ribonuclease-mediated degradation of mRNAs and inefficient antigen expression in secondary lymphoid tissues [84, 90]. To overcome these limitations, an mRNA–liposome complex (mRNA-lipoplex) platform was developed. This approach stabilizes mRNA and directs it to lymph node–resident DCs following intravenous injection, with targeting efficiency determined by the net charge of the lipid particles [91, 92]. Despite encouraging preclinical and clinical findings, the optimal administration route for mRNA-pulsed DC vaccines remains a matter of debate, as different delivery strategies have shown variable prophylactic and therapeutic efficacy [53].

Ex vivo mRNA-electroporated moDCs circumvent HLA restriction and enable multi-epitope presentation; however, their clinical efficacy remains limited due to short DC persistence [48 h], high electroporation-induced cell death (20–30%), and labor-intensive GMP production [93, 94]. Recent studies indicate that in vivo DC-targeting platforms (LNP- or CLEC9A/CD11c-targeted mRNA) achieve superior lymph-node homing and persistence at dramatically lower cost and regulatory complexity, suggesting these approaches are far more translationally promising than traditional ex vivo moDCs [95].

Nucleic acid–transfected DCs can encode full-length antigens or defined epitopes, and multiple preclinical and early clinical investigations have demonstrated that such platforms elicit robust antigen-specific CD8⁺ and CD4⁺ T-cell responses. Although plasmid DNA can support more sustained antigen expression, it requires nuclear entry and raises theoretical safety considerations, none of which have been observed in current clinical trials [96].

DC-tumor cell fusions

Combining patient-derived DCs with autologous tumor cells represents a promising strategy for developing potent cell-based cancer vaccines [97, 98]. This approach maximizes antigen presentation through both class I and class II pathways by enabling the processing of newly synthesized and internalized antigens, respectively. As a result, it elicits a balanced CD4⁺ and CD8⁺ T-cell response, which is critical for generating durable antitumor immunity. Preclinical studies have demonstrated that DC–tumor cell fusions can activate tumor-specific helper and cytotoxic T-cell responses. In an animal model, syngeneic DCs were fused with MC38 tumor cells engineered to express the tumor-associated antigen MUC1. The resulting fusion cells co-expressed both MUC1 (from tumor cells) and costimulatory molecules (from DCs). Compared with irrelevant tumor cell fusions (e.g., bladder carcinoma), DC/MC38-MUC1 fusion vaccines conferred significant protection. Remarkably, vaccination eradicated established tumors in more than 90% of mice, an effect correlated with robust tumor-specific T-cell proliferation. Importantly, no evidence of autoimmunity or T-cell infiltration into healthy tissues was observed at sacrifice [99].

Preclinical research employing human cells shown that DC/tumor fusions successfully boost anti-tumor immunity [100, 101]. In one scenario, autologous DCs were utilized to fuse patient-derived breast cancer cells, and the fusion cells were found to co-express DC-derived costimulatory and maturation markers as well as tumor-associated MUC1. The therapeutic efficacy of DC/tumor fusion vaccines has been demonstrated across multiple animal and preclinical human tumor models, including multiple myeloma [102], osteosarcoma [103], glioma, ovarian cancer [101], hepatocellular carcinoma [104, 105], myeloid leukemia [106, 107], prostate cancer [108], renal cell carcinoma [109], colon cancer [110], esophageal cancer [111], and breast carcinoma [100, 112]. Notably, comparative preclinical studies revealed that DC/tumor fusions are superior to DCs pulsed with tumor lysates or apoptotic bodies in eliciting antitumor immune responses [113, 114].

Preclinical and early-phase clinical investigations have demonstrated that fusion-based vaccines are both immunogenic and generally well tolerated, capable of eliciting tumor-reactive T cell responses in patients with hematologic malignancies and solid tumors. Nevertheless, this platform remains technically complex, requiring access to viable autologous tumor material, efficient and reproducible cell-fusion procedures, and rigorous quality control of hybrid cells, all of which pose significant challenges for large-scale manufacturing and regulatory approval. Moreover, objective clinical responses have been variable, indicating that further optimization of fusion efficiency, DC maturation status, adjuvant use, and combination with other immunomodulatory agents will be necessary before DC–tumor fusion vaccines can be broadly implemented in routine clinical practice [115].

Neoantigen-loaded DC vaccines

Neoantigens are a distinct class of tumor-specific peptides that arise in malignant cells but are absent in normal tissues. Consequently, they differ from apart from TAAs, which are frequently expressed in both healthy and tumor tissues and may also include viral antigens [116, 117]. Neoantigens can originate from viral proteins, such as epitopes derived from open reading frames in viral genomes, or from tumor-specific somatic alterations, including frameshift mutations, gene fusions, insertions and deletions, transcriptomic and proteomic variants, and genomic variants such as single-nucleotide variants (SNVs) [118, 119]. Alterations in peptide sequence and conformation can increase binding affinity for major histocompatibility complex (MHC) molecules, thereby enhancing T-cell recognition and promoting antitumor immune responses [120]. Neoantigens are generally categorized into two subgroups: shared and personalized [121]. Shared neoantigens are expressed across multiple patients with the same tumor type and therefore have potential for broad therapeutic application. However, their clinical utility is limited by antigenic variations between patients and tumor types [122, 123].

By contrast, personalized neoantigens are unique to each patient’s tumor, reflecting the high mutational diversity even within cancers of the same histological type. Personalized neoantigen-based vaccination strategies therefore hold superior promise for inducing consistent and durable responses across diverse malignancies [121]. Accurate identification of neoantigens is a critical prerequisite for their therapeutic application. This process typically relies on high-throughput sequencing approaches, particularly next-generation sequencing (NGS), which enables rapid comparison of tumor DNA with matched normal tissue DNA [124]. Although one major challenge is that many tumor-specific mutations occur in noncoding regions or result in nonsense mutations that fail to yield functional peptides [124]. Whole-exome sequencing (WES), which focuses on protein-coding regions of the genome, has emerged as a widely adopted strategy for neoantigen discovery, offering higher efficiency and lower false-negative rates compared with conventional sequencing methods [125]. The exome is the protein-encoding portion of the genome; it must undergo translation and processing to convert the expressed mutant amino acid sequence into brief peptide fragments. To be properly identified by the immune system, they must also be expressed on the cell surface in combination with MHC molecules [116]. Several critical factors determine whether a mutation can generate an effective neoantigen: (i) whether the mutated DNA sequence can be translated and processed into peptides; (ii) the extent to which the peptides are presented and their binding affinity to MHC molecules; and (iii) the stability and strength of the interaction between the neoantigen–MHC complex and the T-cell receptor (TCR) [126].

Neoantigen-loaded DC vaccines are conceptually attractive because they target truly tumor-specific epitopes that are absent from normal tissues, thereby minimizing central tolerance and reducing the risk of on-target, off-tumor toxicity. Early clinical studies have shown that personalized neoantigen DC vaccines can induce robust T-cell responses and, in some cases, durable remissions. Enhancing the clinical feasibility of this strategy will require the optimization of bioinformatic pipelines, reduction of turnaround times, and integration of neoantigen DC vaccines into combination regimens with checkpoint inhibitors or other immunomodulatory agents to facilitate broader clinical translation [127].

Off-the-shelf allogeneic DC vaccines

The large-scale production of universal, off-the-shelf vaccines represents an ideal scenario for DC–based immunotherapy. One such candidate is DCOne, an allogeneic DC vaccine developed by DCPrime. Derived from an AML patient, DCOne is a DC-like cell line that expresses multiple shared TAAs, including WT-1, as well as a broad range of costimulatory molecules. In a phase I/II clinical trial involving patients with advanced-stage AML (NCT01373515), DCOne vaccination successfully elicited antigen-specific immune responses without inducing adverse effects. In vitro studies have further demonstrated that DCOne cells can transfer antigens such as MUC-1 and survivin to a patient’s endogenous APCs, thereby generating protective immunity against multiple myeloma cells [128]. Similarly, an allogeneic monocyte-derived DC (MoDC)–tumor fusion vaccine has been shown to be both safe and immunogenic in patients with renal cell carcinoma [129].

Integrative approaches in DC-based vaccines and immunotherapies

Combination with checkpoint inhibitors

A novel class of immunotherapeutic agents known as ICIs has been developed to improves the antitumor-specific T cell responses in a variety of cancer types, including Hodgkin and non-Hodgkin lymphoma, melanoma, bladder cancer, lung cancer, and head and neck squamous cell carcinoma [130, 131]. The most frequently studied and therapeutically targeted are included Cytotoxic T-lymphocyte antigen (CTLA)-4, programmed death 1 (PD-1), and its ligand programmed death ligand 1 (PD-L1) [132, 133]. The therapeutic diversity of this approach is illustrated by the fact that atezolizumab targets PD-L1, whereas pembrolizumab and nivolumab are monoclonal antibodies directed against PD-1 [134].

ICI therapy is generally more effective in tumors with a high frequency of somatic mutations and elevated mutational burdens, such as lung cancer and melanom [126, 135]. This correlation is largely attributed to the fact that a greater tumor mutational burden raises the load of neoantigens, thereby enhancing the likelihood of eliciting immunogenic neoantigens [120]. Moreover, tumors exhibiting an immune-inflamed phenotype, defined by the presence of immune cell infiltration either at the invasive margin or within the tumor stroma, indicative of an inflammatory microenvironment, tend to demonstrate improved responsiveness to checkpoint blockade. Conversely, patients with “non-inflamed” tumors, often associated with limited T cell infiltration and lower neoantigen loads, exhibit reduced clinical benefit [136, 137].

A. Clinical Evidence (Completed or Ongoing Human Trials)

Several phase I/II clinical trials have evaluated the combination of dendritic cell (DC) vaccination with immune checkpoint inhibitors (ICIs), particularly anti–PD-1/PD-L1 and anti–CTLA-4 antibodies. These studies indicate that DC vaccination can augment antigen-specific T-cell responses and may enhance clinical outcomes in selected cancers such as glioblastoma, melanoma, and other solid tumors[138].

B. Preclinical Evidence (Mouse or Ex Vivo Models)

In murine of hepatocellular carcinoma (HCC), the combination of DC vaccination with PD-1/PD-L1 blockade significantly enhances antitumor immunity, reduces tumor volume, and improves overall survival compared to monotherapies [139]. Similarly, in one study using B16 melanoma, DC-based vaccination plus anti-PD-1 led to improved expansion of antigen-specific CD8⁺ T cells, with memory phenotype and enhanced metabolic fitness, resulting in superior tumor control [140].

C. Mechanistic / Speculative Concepts

The rationale behind combining DC vaccination with ICIs lies in synergy: DC vaccines prime and expand tumor-specific T cells (increasing antigen presentation and T-cell activation), while ICIs relieve the immunosuppressive checkpoint-mediated inhibition — together potentially converting non-inflamed (“cold”) tumors into inflamed (“hot”) ones, more susceptible to immune attack[141]. However, many of these mechanistic hypotheses remain unproven in large-scale human trials; more data are needed to confirm whether the synergy seen in preclinical models translates into durable clinical responses.

DC vaccines combined with Oncolytic Viruses (OVs)

Oncolytic viruses (OVs) have emerged as particularly promising partners for dendritic cell (DC) vaccines due to their capacity to induce immunogenic cell death (ICD), release tumor-associated antigens (TAAs), and remodel the tumor microenvironment (TME) into an inflamed, DC-permissive state [142]. By lysing tumor cells and liberating neoantigens, OVs substantially expand the antigenic repertoire available for DC uptake, thereby enhancing cross-presentation and the priming of CD8⁺ cytotoxic T lymphocytes (CTLs) [143]. T-VEC (talimogene laherparepvec), the only FDA-approved OV, has shown the capacity to promote antigen spreading and systemic immune activation, providing a compelling rationale for its combination with patient-derived DC vaccines in early-phase clinical trials [142]. T-VEC (talimogene laherparepvec), the only FDA-approved OV, has shown the capacity to promote antigen spreading and systemic immune activation, providing a compelling rationale for its combination with patient-derived DC vaccines in early-phase clinical trials [144]. OV-induced TME “inflaming” enhances DC recruitment, facilitates migration to draining lymph nodes, and promotes more effective T-cell priming—mechanisms that are directly associated with improved outcomes in OV plus DC vaccine combinations [145].

DCs with CAR-T therapy

Since the discovery of DCs by Steinman and Cohn in 1973, immunotherapy has advanced considerably [146]. DCs are recognized as the most potent APCs, playing a pivotal role in the activation of naïve T cells. Within lymph nodes, T cells that are actively searching for their cognate peptides, which are presented by DCs through MHC molecules [146]. In cancer biology, tumor-infiltrated dendritic cells (TIDC) are essential for the recognition of TAA in the context of MHC class I molecules, thereby mediating T cell-dependent antitumor activity [147, 148]. Multiple studies have focused on strategies to directly stimulate DCs to efficiently express tumor-specific antigens, leading to the activation of naïve T cells with the potential to eradicate tumors in an antigen-dependent manner [91, 149]. Beyond antigen presentation, DCs also support cellular immunity by releasing immunostimulatory signals and proinflammatory cytokines upon TCR engagement. The most prominent cytokines secreted by DCs include interleukin-12 (IL-12) and type I interferons, which are critical for driving Th1 polarization and CTL responses. Furthermore, DCs secrete chemokines within the TME that facilitate the recruitment of T cells to tumor sites. Notably, CXC chemokine ligand 9 (CXCL9) and CXCL10 produced by DCs are key mediators in attracting CD8 + T cells into the TME [150, 151]. It is also important to distinguish between immature and mature DCs. Mature DCs have a decreased capacity to internalize antigens but may vigorously present antigens to T cells within lymph nodes, while immature DCs can quickly absorb tumor antigens but may have decreased motility [152]. Dysregulated DC function results in impaired T cell activation, thereby facilitating tumor progression. Moreover, DC dysregulation may compromise the efficacy of chimeric antigen receptor (CAR) T cell therapy by reducing antigen presentation [153].

To overcome these limitations, Because of this, adding combining ex vivo DC therapy to adoptive cell transfer (ACT) would be wise. Through an antigenic alteration of hiPSCs-derived DC, tumor antigens can be expressed, enabling their use as vaccines to prime CAR-T cells in vivo and promote the development of immunological memory cells. However, since tumor cells may be artificially altered to release immune-stimulating cytokines and to elicit a potent antitumor response, cancer cell-based vaccines can be used to activate CAR-T cells [154]. Shah et al. have more recently reused living tumor cells that have the ability to move to the location of their counterpart cancers and release factors that the immune system can recognize in addition to anticancer agents, therefore effectively promoted tumor eradication and promoting long-term immunity [155]. Generally speaking, a prerequisite for T cell activation, clonal proliferation, and tumor cytotoxicity is T cell or CAR-T cell specificity and binding to tumor-associated MHC molecule on the surface of DCs [156, 157]. A promising strategy to facilitate interaction between CAR-T cells and DCs involves the development of bispecific T cell engager (BiTE). In the conventional BiTE approach, the CD33-binding arm of the BiTE molecule directs T cells toward BiTE-associated tumor cells, leading to the formation of immunological synapses between tumor and T cells. Upon their activation, T cells release cytotoxic granules, resulting in targeted tumor cell to lysis [158]. Autologous T cells engineered with TCRs or CARs exhibit potent activation, specifically targeting malignant cells. This new strategy gives a compelling option for the treatment of different neoplasms. Clinical trials have already demonstrated the therapeutic efficacy of both TCR- and CAR-modified T cells across diverse cancer types [159, 160].

A. Clinical Evidence (Human Trials)

Only a very limited number of early-phase clinical studies have assessed the combination of DC vaccination with CAR-T cell therapy. A recent clinical report evaluating CD19-CAR-T in conjunction with autologous DC vaccination in adults with refractory/relapsed B-ALL patients demonstrated that DC vaccination can prolong CAR-T cell persistence, with a median duration of 336 days, and was not associated with any grade ≥ 3 CRS or neurotoxicity during DC vaccine infusions [161]. These findings provide the first human clinical evidence suggesting that DC + CAR-T therapy may be safe and enhance long-term CAR-T persistence.

B. Preclinical Evidence (Animal / In Vitro Models)

Preclinical data provide evidence for synergistic interactions between DC vaccination and CAR-T therapy in solid tumor models. In a 2023 murine study, the combination of a DC vaccine with mesothelin (MSLN) CAR-T cells significantly increased CAR-T proliferation, infiltration into tumors, and persistence in vivo, resulting in enhanced tumor regression compared with CAR-T alone [162]. Similarly, in a colorectal cancer–stem-cell (ALDH1⁺) model, monotherapy with either PD-L1–targeted CAR-T cells or DC vaccination produced only moderate antitumor effects, whereas the combination markedly increased cancer cell killing both in vitro and in vivo, demonstrating strong synergistic cytotoxicity [163].

C. Mechanistic / Speculative Concepts

The theoretical rationale for combining DC vaccines with CAR-T therapy is well described; DCs (or DC/tumor-fusion vaccines) can present a broader repertoire of tumor antigens, enhance antigen spreading, prime naïve and memory T cells, and improve CAR-T persistence and function. Review articles suggest that vaccine-boosted CAR-T (using DC-based or other vaccine platforms) could overcome common limitations of CAR-T in solid tumors (antigen heterogeneity, poor infiltration, limited persistence) [164]. However, these remain largely conceptual and demand rigorous clinical validation.

Currently, preclinical evidence strongly supports the potential synergy of DC vaccination and CAR-T therapy in both hematologic and solid tumors. Clinical data are minimal but encouraging, showing safety and improved CAR-T persistence in at least one trial. Mechanistic hypotheses are biologically plausible but require further verification. Therefore, DC + CAR-T remains a promising but early-stage combinatorial strategy, meriting additional clinical trials and careful design.

As summarized in Fig. 2, current and emerging strategies in dendritic cell-based cancer vaccines include integration with immune checkpoint inhibitors, CAR-T cell therapy, gene editing, and personalized neoantigen approaches, highlighting the translational potential of these combined modalities in oncology.

Fig. 2.

Current and future approaches in dendritic cell-based cancer vaccines, incorporating immune checkpoint inhibitors (ICIs), CAR-T cell therapy, oncolytic viruses, cytokine adjuvants, personalized neoantigens, gene editing, and DC–tumor cell fusion strategies

DC vaccines combined with cytokine or molecular adjuvants

Cytokine and molecular adjuvants have been extensively explored to enhance the immunogenicity of DC vaccines by promoting DC maturation, T-cell priming, and effector function through complementary mechanisms. Key cytokines include IL-2, IL-7, IL-12, IL-15, and IL-21, each of which differentially supports T-cell expansion and survival [165]. TLR agonists—such as poly I:C, CpG oligodeoxynucleotides, R848, and monophosphoryl lipid A (MPL A)—provide potent danger signals that induce DC maturation and type I interferon production [91]. STING agonists (e.g., cGAMP) activate cytosolic DNA-sensing pathways to enhance cross-presentation, whereas CD40 agonists directly license DCs for more effective CD8⁺ T-cell priming [166]. Among these, IL-12 plasmid constructs and CD40 agonists have achieved the most notable clinical translation. In a phase I/II trial (NCT00088685), autologous DC vaccination combined with intrapulmonary IL-12 plasmid delivery enhanced Th1 responses and induced disease stabilization in patients with non-small-cell lung cancer (NSCLC). Trials of CD40 agonists (e.g., CP-870,893 combined with DC vaccination) demonstrated robust T-cell activation but were constrained by hepatotoxicity [167]. While IL-2 promotes effector T-cell expansion, it can paradoxically stimulate regulatory T-cell (Treg) proliferation, diminishing antitumor efficacy in several models. In contrast, IL-15 and IL-21 selectively support the generation of memory CD8⁺ T cells without Treg bias [168]. Systemic administration of cytokines is frequently limited by dose-dependent toxicities, including vascular leak syndrome and cytokine release syndrome [169].

TME modulators combined with DC vaccines

The TME remains one critical barrier to the efficacy of dendritic cell (DC)–based vaccines. Clinical experience from skeletal metastases of unknown primary illustrates how the tumor microenvironment can dictate disease behavior and therapeutic urgency even before the primary tumor is identified. In these cases, interactions between metastatic cells and the bone microenvironment shape disease progression and clinical management, including the use of stabilizing therapies independent of tumor origin. This example underscores that microenvironmental cues can override tumor-specific biology, a concept directly relevant to dendritic cell-based vaccination, where an immunosuppressive TME can limit efficacy despite optimal antigen presentation [170]. Combining DC vaccination with TME-targeted therapies can enhance DC infiltration, improve antigen presentation, and restore cytotoxic T-cell activity [171]. IDO contributes to T-cell exhaustion and suppresses DC activation; preclinical studies have shown that co-administration of DC vaccines with IDO inhibitors, such as epacadostat, significantly increases CD8⁺ T-cell infiltration and strengthens antigen-specific immune responses [172]. Blockade of colony-stimulating factor 1 receptor (CSF1R) reduces tumor-associated macrophages (TAMs) and shifts the TME from an immunosuppressive to an immunostimulatory state, thereby facilitating improved DC migration and T-cell priming [173]. Additionally, abnormal VEGF-driven tumor vasculature impedes efficient DC trafficking; VEGF inhibitors, such as bevacizumab, can normalize tumor vessels, enhance DC infiltration, and promote T-cell priming when combined with DC vaccination [174].

TGF-β inhibits DC maturation and promotes Treg expansion. Combining TGF-β pathway inhibitors with DC vaccines significantly enhances CTL expansion and improves antitumor immunity in murine models of breast and pancreatic cancers [175]. Several TGF-β inhibitors are currently in phase I/II trials, providing a translational opportunity for integrating these molecules with DC-based vaccine regimens [176]. In addition, myeloid-specific PI3Kγ signaling contributes to immunosuppression by reprogramming macrophages toward an M2 phenotype [177]. The clinical translation of strategies combining DC vaccines with tumor microenvironment modulators will require careful optimization of treatment scheduling, management of potential toxicities, and implementation of standardized GMP-compliant manufacturing workflows[171].

Comparative translational potential of emerging DC combination strategies

Taken together, the available evidence suggests that DC vaccination in combination with ICIs has progressed furthest along the clinical translation pathway. Numerous early-phase trials have demonstrated acceptable safety profiles and immunological activity across multiple tumor types. While combinations with oncolytic viruses, cytokine or molecular adjuvants, and TME modulators remain more heterogeneous and largely confined to preclinical studies or small exploratory trials, they are supported by strong mechanistic rationales and may be particularly beneficial in tumors with highly suppressive microenvironments. From a practical standpoint, strategies that employ agents with established regulatory precedence and reduced manufacturing complexity—such as in vivo DC-targeting mRNA platforms or off-the-shelf DC products—are likely to offer the greatest near-term translational potential. Overall, DC plus ICI combinations currently represent the most clinically advanced approach, with multiple phase I/II studies demonstrating safety and immunogenicity across diverse tumor types [171].

Bridging the gap: translational challenges from preclinical to clinical success

Preclinical and clinical gaps

Advances in DC vaccines have demonstrated their capacity to induce tumor-specific immune responses to provide clinical benefits to patients [178]. Despite these promising results, several limitations continue to hinder their widespread and efficient use in inducing stable immune responses, thereby leading to maximal performance in vaccines. While some limitations are attributable to disease aggressiveness and systemic abnormalities in cancer patients, most limitations arise from tumor-induced immunosuppression and immune evasion, as well as from challenges in vaccine design. Such challenges relate to difficulties in generating sufficient quantities of high-quality DCs, the selection of appropriate antigens capable of stimulating both CD4 + and CD8 + T cells, compromised immune capacity in advanced stages of disease, and the limitations migratory capacity of DCs to lymph nodes [179–183].

Furthermore, the functionality of DC vaccine-induced T cells is often compromised by their limited migration or progressive exhaustion. Tumors extensively interfere with the immune system through their heterogeneous microenvironment, which is composed of cancer cells (e.g., stromal cells (fibroblasts, endothelial cells etc.,), immune cells (e.g., macrophages, NK cells, T and B lymphocytes) and a variety of soluble inhibitory mediators [184]. Among these factors are tumor-derived cytokines and metabolites including vascular endothelial growth factor (VEGF) [185], transforming growth factor-β (TGF-β) [186–188], prostaglandin E2 (PGE2) [189], indoleamine 2,3-dioxygenase (IDO) [190, 191], Arginase-1 [192] and IL-10 [193]. These molecules not only promote the expansion of myeloid-derived suppressor cells (MDSCs) [194], but also impair DC maturation and differentiation, ultimately suppressing their immunostimulatory capacity. Additionally, these factors induce accumulation of immature DCs, plasmacytoid DCs, and regulatory immunosuppressive DC subsets [195–198], which in turn induce T cells to assume an immune-tolerant phenotype to render anergic [156, 199, 200].

Vaccination can elicit T-cell responses; however, these responses often fail to persist. In the absence of sustained co-stimulation and within the suppressive milieu of the tumor, T-cell memory diminishes over time, and their functional capacity declines. This progressive attenuation impairs T-cell infiltration into tumors, providing a mechanistic explanation for the often-limited clinical efficacy of dendritic cell (DC)–based vaccines [201].

In leukemia, myeloid function is profoundly altered, resulting in deficiencies in both conventional DCs and monocyte-derived DCs. The non-leukemic hematopoietic stem cell pool is reduced, DC differentiation is impaired, and leukemic cells secrete immunosuppressive cytokines [182, 202]. Even following remission, when DC numbers may partially recover, intrinsic defects persist, diminishing the effectiveness of DC-based immunotherapies and underscoring the need for careful monitoring of circulating DCs using precise biomarkers [203]. MDSCs further inhibit immune responses by depleting essential amino acids such as L-arginine and L-cysteine, generating reactive species that degrade TCR ζ-chains, and slowing T-cell proliferation [204, 205]. Additionally, MDSCs secrete IL-10, TGF-β, and IDO, which suppress NK cell activity and recruit additional immunosuppressive cells, further undermining DC vaccine efficacy [206, 207]. Collectively, these factors create a tumor microenvironment that makes it difficult for DC vaccines to mount a strong antitumor response.

Tumor-infiltrating DCs also experience metabolic stress, which compromises maturation and immunogenicity. Hypoxia, nutrient deprivation, endoplasmic reticulum (ER) stress, and elevated reactive oxygen species (ROS) blunt co-stimulatory molecule expression and impede DC migration [208–210]. Altered amino acid and adenosine metabolism in mature DCs leads to upregulation of IL-10 and downregulation of IL-12, weakening pro-inflammatory signaling [211, 212]. Excess intracellular lipids, distinct from cytotoxic oxidized lipids, interfere with antigen processing and presentation by tumor-infiltrating DCs [213–215]. These metabolic constraints collectively limit the full therapeutic potential of DC vaccines.

Structural features of solid tumors further restrict DC vaccine efficacy. The ECM, composed of highly cross-linked collagen and elevated interstitial fluid, impedes immune cell migration and reduces the diffusion of therapeutic agents [216–218]. Hyaluronan contributes to nonspecific resistance by forming dense ECM networks that hinder immune cell penetration into tumor tissue [219].Tumor vasculature compounds these barriers: vessels are often irregular, poorly perfused, and deficient in adhesion molecules (e.g., CD31), resulting in hypoxic, immunosuppressive conditions that reduce immune cell infiltration [220, 221]. Together, the ECM and abnormal vasculature create an enclosed TME that restricts the ability of DC vaccines to access tumor cells and mount effective antitumor responses.

Defective lymphatic trafficking of DCs represents another major limitation. Under Good Manufacturing Practice (GMP) conditions, myeloid-derived DCs exhibit substantial variability in CCR7 expression, the chemokine receptor essential for migration to secondary lymphoid organs along CCL19/CCL21 gradients. Insufficient CCR7 expression diminishes the capacity of injected DCs to interact with naïve T cells, reducing vaccine efficacy [222]. Moreover, only a small fraction of ex vivo–generated DCs effectively traffic to lymph nodes, limiting T-cell activation. Strategies to enhance lymphatic homing—including CCR7 overexpression and co-administration of CCL19 or CCL21—have been explored to improve DC vaccine effectiveness [223].

Antigen selection also poses technical challenges. Personalized neoantigen vaccines require precise matching to HLA alleles and confirmation of stable tumor expression, complicating production. In contrast, TAAs are readily available for DC loading but are limited by HLA restriction and tumor heterogeneity, which constrains their effectiveness. Alternative antigen sources—including tumor RNA, apoptotic bodies, and tumor lysates—offer broader antigenic coverage and may enhance the efficacy of DC vaccines [221].

Protocol optimization

To overcome these limitations of DC-based vaccines, novel strategies that modulate the immune response have emerged as promising approaches. These strategies primarily focus on interfering with inhibitory pathways within the tumor’s microenvironment or inhibitory pathways that impair T lymphocyte functionality. One is the inhibition of the targeted suppression of regulatory T cell (Treg) activity and checkpoint pathways in the tumor microenvironment. One such pathway involves the PD-1/PD-L1 pathway, expressed on mature DCs and T lymphocyte cell surfaces. This pathway is known to be targeted to restore T-cell antitumor effectiveness to improve the efficacy of DC-based vaccines. For example, van der Waart et al. demonstrated that silencing PD-L1 and PD-L2 in monocyte-derived DCs using siRNA (PD-L1/PD-L2 mRNA-targeted) combined with pulsing with minor histocompatibility antigens (MiHAs) peptides, led to enhanced priming of naïve and memory CD8 + T cells. Upon adoptive transfer, mice vaccinated with PD-L silenced DCs displayed significantly increased frequencies of MiHA-specific CD8 + T cells in peripheral blood and spleen [60]. Clinical trials also showed promising safety and activity of anti-PD-L1 antibodies in patients with advanced solid cancers, including melanoma, non-small cell lung cancer, and renal cell carcinoma [224]. Furthermore, inhibitory factors against TGF-β have also been shown to enhance antitumor immunity. Yang et al. reported that soluble TGF-β receptor antagonist (SR2F)-transgenic mice exhibited substantially reduced metastasis without augmented growth in the primary tumor growth [225]. Beyond PD-1/PD-L1 and TGF-β pathways, other immunoregulatory pathways are under investigation. For instance‏, Trabanelli et al. employed monocyte-derived DCs from healthy donors and AML patients, matured them with different cytokines, such as PGE2, and employed IDO1 inhibitors. They showed that PGE2 activated IDO1, which is required for complete DC maturation, suppresses T cell responses, and augments Tregs. IDO1 inhibition reversed these effects, leading to improved antileukemic immune responses [226]. Furthermore, cytotoxic agents such as cyclophosphamide (CY) have been used to downregulate Treg populations and augment adaptive antitumor responses. Immunosuppressive chemicals support the overall effectiveness of DC-based vaccines by inhibiting immune response [227]. Rossowska et al. demonstrated that treatment with CY in combination with anti-IL-10 and bone marrow-derived dendritic cell (BMDC) pulsed with tumor antigens (TAg) strongly inhibited tumor growth by depleting MDSCs and activating NK cells. However, the addition of anti-IL-10 to CY + BMDC/TAg + BMDC/IL-12 downregulated the Th1 immune response, but did not improve therapeutic efficacy. Although Tregs were effectively depleted, MDSCs in tumors remained viable despite a reduction in inhibitory capacity [228]. In metastatic colorectal cancer patients, low-dose cyclophosphamide has induced antitumor T-cell responses correlating with improved survival, thereby emphasizing its immunomodulatory value in solid tumors [229].

Lowe et al. demonstrated that a combination of dasatinib with a DC vaccine inhibited tumor growth and increased survival compared to monotherapy. The combination therapy greater infiltration of CD11c + DCs and CD8 + T cells, fewer immunosuppressive cells such as MDSCs (CD11b + Gr1 +) and Tregs (CD4 + Foxp3 +) in the tumor microenvironment, and promoted the secretion of pro-inflammatory cytokines. The combination was diversified to expand T cell responses to non-vaccine antigens [14].

In a complementary study, Redin et al. investigated the effects of dasatinib in combination with anti-PD-1 therapy in both patient-derived data and murine models of non-small cell lung cancer (NSCLC). Their findings proved that dasatinib synergized with anti-PD-1 therapy, strongly augmenting antitumor response in NSCLC by hindering the activity of Tregs and their development. This dual intervention not only enhanced tumor regression but also promoted long-term immune protection and is valuable for enhancing NSCLC treatment [230].

Similarly, Larmonier et al. have shown Imatinib downregulated Treg cell number and suppressive capacity, thereby enhancing antitumor immune responses. Together with vaccination by DCs, it reduced liver metastasis and increased both CD4 + and CD8 + T cell production of IFN-γ [231]. Collectively, these findings highlight the promise of integration in combinational therapy has been shown to yield better results in DC vaccination by combining these immunomodulatory methods. Through concurrent engagement in various immunosuppressive pathways, these methods have immense potential to abrogate immune escape by tumors and to induce sustained antitumor immune responses [231].

Future directions: personalized DC vaccines and regulatory pathways

Personalized DC vaccines

Tumor cell lysate-derived, individualized cancer vaccines exploit the antigenic complexity of whole tumor cell lysate antigens, tumor-associated chaperone proteins, or apoptotic/necrotic tumor cell antigens. By incorporating both known and unidentified antigens, these vaccines are capable of eliciting broad polyclonal immune responses. Such an approach leverages antigenic heterogeneity and circumvents the selective targeting of predefined TAAs, thereby providing an advantage in late-stage cancers characterized by enhanced immune evasion [232, 233]. Generated ex vivo DC-based vaccine from patient and loaded with autologous tumor antigens, these DC vaccines are specifically tailored to the molecular profile of the tumor, enhances immune recognition of the heterogeneous tumor, while minimizing the risk of adaptive resistance [234, 235]. Clinical trials have further demonstrated the therapeutic potential of DC-based vaccination strategies. For instance, Chevallier et al. compared DC immunization in elderly patients with AML, where leukemic cells were collected prior to chemotherapy, apoptosis was induced, and immature DCs (iDCs) derived from peripheral monocytes were pulsed with autologous apoptotic leukemic cells. Vaccinated patients exhibited a superior median overall survival compared with those receiving standard therapy, highlighting the promise of this approach in an at-risk population [236].

Likewise, clinical trials in glioblastoma—a highly aggressive, and chemotherapy-resistant brain tumor—have also targeted DCs-based vaccines targeting tumor-specific antigens. One such trial investigated ICT-107, a multi-epitope-pulsed DC vaccine loaded with peptides derived from six TAA commonly expressed by glioblastoma and its cancer stem cells. This regimen was safe and well-tolerated, and also showed benefits that were most likely attributable to the broad antigen-specific immune responses and targeting of glioma stem-like cells, leading to prolonged progression-free and overall survival in a subset of patients [237]. Di Nicola et al. conducted a study in which patients with relapsed indolent non-Hodgkin lymphoma (NHL) were vaccinated with DC-based vaccines generated from apoptotic lymph node tumor cells or peripheral blood. The vaccine was well-tolerated and associated with a reduction in Tregs, elevated in cytotoxic CD56dimCD16 + natural killer (NK) cells, augmented tumor-specific T-cell responses (e.g., IFN-γ secretion), and tumor-restricted humoral immunity in responding patients [238]. Importantly, long-term clinical responses, particularly in patients with low tumor burden, confirm the therapeutic potential of DC vaccines for cancer immunotherapy.

Regulatory pathways

DC-based vaccines represent outstanding immunotherapeutic potential for the treatment of various malignancies, including hematologic cancers such as AML. Evidence from multiple clinical studies has demonstrated the therapeutic benefits of DC vaccination, including prolonged overall survival, improved disease control, and sustained antitumor immune response duration in vaccinated patients [186]. Furthermore, the planned study duration was significantly extended in vaccinated patients, reaching 509 days (16.9 months) compared to 147.5 days (4.9 months) in the non-vaccinated cohort [186].

A phase II trial by Anguille et al. investigated Wilms’ tumor 1 (WT1) messenger RNA (mRNA)-electroporated DCs as a post-remission therapy in 30 AML patients at high risk of relapse. The vaccine elicited clinical responses in 43% of patients (13/30), with 30% (9/30) achieving molecular remission, defined by normalization of WT1 transcript levels. Among 30 patients, five of them remained molecular remission for an average of one years. while disease stabilization was observed in 4 patients among the 13 patients who received treatment. Importantly, the response group exhibited superior five-year overall survival rates compared to non-response group (53.8% and 25%, respectively). This statistic shows that WT1-loaded DC vaccines are an effective strategy for prolonging survival among AML patients [11].

Studies by Kitawaki et al. and Van Tendeloo et al. showed DC vaccination in AML led to both complete remission and molecular remission because of vaccine-induced immune responses among patients receiving WT1-pulsed DC vaccines. These findings highlight that DC vaccination is capable of generating strong antitumor immune responses, ultimately contributing to improved clinical outcomes in AML patients [239, 240].

Additionally, favorable changes were observed in serum M protein, 24-h urinary light chains, and serum creatinine levels, indicating both reduced tumor load and preserved renal function. Significantly, the combined therapy enhanced antitumor immune responses by downregulating the immunosuppressive cytokines IL-4 and IL-10, thereby reinforcing the immunostimulatory potential of DC-based strategies in MM management [191].

Research has also demonstrated the therapeutic potential of DC-based immunotherapy in the treatment of MM patients, in addition to its proven success in AML cases. In a clinical study conducted by Zhao X et al. patients received a combination of DC immunotherapy, cytokine-induced killer (CIK) cell therapy, and chemotherapy against MM, while control group received chemotherapy alone. Compared with single-modality treatment, DC vaccination provided superior clinical outcomes, including a significant reduction in the tumor cell burden, a greater decline in β2-microglobulin (β2-MG) levels and improved disease response control. Additionally, favorable changes were observed in serum M protein, 24-h urinary light chains, and serum creatinine levels, indicating both reduced tumor load and preserved renal function. Significantly, the combined therapy enhanced antitumor immune responses by downregulating the immunosuppressive cytokines IL-4 and IL-10, thereby reinforcing the immunostimulatory potential of DC-based strategies in MM management [241]. Several clinical trials have been performed to examine the therapeutic potential of DC-based vaccines in the therapy of advanced solid tumors, including melanoma and glioblastoma. In a Phase II study, investigating a DC-based vaccine in patients with metastatic melanoma carrying the HLA-A24 genotype, demonstrated that the vaccine, composed of melanoma-associated peptides, was shown to be safe and capable of eliciting antigen-specific immune responses in 75% of participants. Interestingly, vaccinated patients demonstrated significantly prolonged survival compared with the non-vaccinated patients, and greater immune responses along with the presence of pre-existing antibodies, which was correlated with improved clinical outcome [242]. In a Phase I/II trial independent of the same trial, long-term follow-up indicated that DC vaccination can achieve long-term survival in melanoma patients. The 12-year survival rate among individuals with advanced disease reached 19%, with no significant adverse effects reposted. The vaccine, consisting of peptide-loaded monocyte-derived DCs, was shown to elicit robust immune responses. Although, overall survival was not significantly associated with the magnitude of such immune responses, it was significantly associated with local skin reactions at the injection site and increased eosinophil counts. Furthermore, vaccination augmented or induced high-affinity, interferon-γ-producing CD4 + T cells as well as polyfunctional, lytic CD8 + T cells in the majority of treated patients [243].

Furthermore, a Phase III clinical trial assessed the safety and efficacy of an autologous dendritic cell vaccine (DCVax®-L) administered as an adjuvant to standard therapy for newly diagnosed glioblastoma. The finding demonstrated that the vaccine was both safe and feasible, with serious vaccine-related adverse events at only 2.1% of subjects similar to that observed when on standard therapy alone. Efficacy analyses revealed a median overall survival (OS) for the entire cohort was 23.1, while patients with methylated MGMT promoter tumors achieved a significantly prolonged median OS of 34.7 months [32]. The primary advantages of vaccines developed using DC technology lies in their better safety profile compared with conventional treatment modalities. DC-based immunotherapy is increasingly utilized in oncology because it offers effective immune activation while minimizing treatment-associated toxicity. This reduced risk of severe adverse events highlights DC vaccination as a safer immunotherapeutic option for managing malignancies. Patients who received vaccinations in these studies experienced only mild and transient side effects, which primarily manifested as inflammation with itchiness and swelling at the injection site combined with exhaustion, headache, shivering, and mild fever [239, 240, 244]. The available clinical evidence consistently demonstrates that DC-based vaccination does not result in severe, life-threatening, or fatal adverse effects [11, 236, 239, 240]. The use of Wilms’ tumor 1 (WT1) peptide-pulsed DCs was associated with only mild adverse events, primarily injection-site reactions and fatigue, with no patients experiencing adverse events beyond grade 2 in severity and no reports of life-threatening complications [239]. Similarly, administration of WT1 mRNA-pulsed DC resulted in erythema and induration at the injection sites in all ten treated patients, while only one individual among ten reported mild fatigue symptoms. A single case of transient thrombocytopenia was observed, which resolved spontaneously without medical intervention. The trial reported no treatment-linked mortalities or grade ≥ 3 adverse events [240]. The human telomerase reverse transcriptase (hTERT)-DC vaccine treatment demonstrated an overall acceptable safety profile. Among twenty-one patients, nine reported adverse events, primarily injection-site reactions, thrombocytopenia, headache, and neutropenia. Notably, one patient developed grade 4 idiopathic thrombocytopenic purpura, which was determined to be vaccine-related and represented the sole treatment-associated mortality in this study. Despite this isolated event, evidence from multiple studies confirms that DC-based immunotherapies are generally well tolerated, with serious health risks remaining rare [244]. Collectively, the accumulated data underscore the favorable safety profile of DC vaccination, while careful monitoring and continued optimization of vaccine protocols are expected to enhance both safety and clinical utility further.

GMP and regulatory barriers in DC manufacturing

GMP manufacturing & cost challenges

The production of DC–based vaccines is inherently complex, encompassing multiple stages including cell harvesting, in vitro culture, antigen loading, and cell maturation. Each step introduces potential sources of technological variability, and adherence to Good Manufacturing Practice (GMP) standards further amplifies these challenges by increasing both procedural complexity and production costs, thereby limiting the feasibility of widespread clinical application [245, 246].

This issue is particularly pronounced for autologous therapies such as Sipuleucel-T, in which a dedicated production line is required for each individual patient. Such personalized manufacturing introduces variability, processing delays, and elevated costs [247]. GMP-compliant production necessitates a controlled cleanroom environment, qualified personnel, and extensive quality control testing, including assessments of sterility, endotoxin levels, mycoplasma contamination, cell viability, phenotypic characterization, and functional activity [248].

Patient-specific production timelines

The generation of monocyte-derived DCs typically requires 5–8 days for differentiation and maturation, followed by antigen loading. In the context of neoantigen-based vaccines, additional steps such as genomic sequencing, epitope prediction, and peptide synthesis further extend production timelines. These delays pose practical limitations for patients with rapidly progressing malignancies and hinder the routine implementation of DC-based vaccination in clinical practice [27].

Regulatory guidance (EMA/FDA) for DC-based therapies

Agencies such as the European Medicines Agency (EMA) and Food and Drug Administration (FDA) recommend that DC-based vaccines be developed based on established production principles, validated analyses, and robust biomarkers that accurately forecast their efficiency in humans. This is due to the complex nature of dendritic cell biology, which is the cornerstone of immune system regulation, thus finding its place within the broader group of Advanced Therapy Medicinal Product(ATMP). In the European Union, cell treatments, such as dendritic cell therapy, qualify as somatic cell therapy medicinal products, as defined by Regulation (European Commission, EC) 1394/2007. In the United States, dendritic cell treatments fall within the jurisdiction of the FDA’s Center for Biologics Evaluation and Research (CBER), as defined in Sect. 351, where one must submit an IND, adhere to current Good Manufacturing Practice (cGMP), and demonstrate potency [249].

Achieving product uniformity remains challenging due to the inherent diversity in DC processing. Variations in culture conditions, antigen loading, maturation protocols, and patient-derived cell populations can result in significant heterogeneity in the final product. In some cases, processing protocols may inadvertently expand immunosuppressive cell populations, potentially compromising therapeutic efficacy [250, 251]. Consequently, rigorous assessment of cell identity, sterility, endotoxin, viability, and overall product consistency is essential. Evaluating DC potency is particularly challenging. Conventional assays, such as mixed lymphocyte reactions (MLRs), remain the gold standard, but differences in assay preparation, cell types, and detection platforms limit reproducibility and broad applicability. Immunophenotypic profiling of markers such as CD11c, CD80, CD83, CD86, HLA-DR, and CD209 is commonly used as an indirect measure of potency [252–255]. However, there is insufficient evidence to establish a direct correlation between in vitro assay results and clinical efficacy, highlighting an ongoing need for standardized, predictive potency assessments. The different stages of dendritic cell vaccine development, from preclinical to clinical, and the challenges encountered in this process are illustrated in Fig. 3.

Fig. 3.

The stages of dendritic cell (DC) vaccine development, from preclinical research to commercial production and clinical translation. This diagram outlines critical processes, including the selection of clinically feasible platforms, adherence to GMP (Good Manufacturing Practice) standards in production, clinical trial phases (I and II), evaluation of safety and efficacy endpoints, and the regulatory pathways necessary for the successful development of DC-based vaccines

Conclusion and future prospects

DC-based vaccines constitute a promising and advancing strategy in the cancer immunotherapy of both solid tumors and hematologic malignancies. By harnessing the unique ability of DCs to process and present antigens, thereby activating robust tumor-specific T-cell responses, these vaccines offer substantial potential to counteract tumor immune evasion and enhance therapeutic outcomes.

Despite considerable progress in the development of DC-based vaccines, several challenges continue to hinder their clinical translation. These obstacles include the immunosuppressive characteristics of the tumor microenvironment, complexities in designing and producing effective vaccines, and the persistent difficulty in translating preclinical findings into consistent therapeutic benefits. To overcome these challenges, a variety of innovative strategies are currently being explored. These include the incorporation of patient-specific neoantigens, the development of mRNA-based vaccine platforms, the generation of dendritic cell–tumor cell fusion constructs, and the combination of DC vaccines with complementary immunotherapeutic approaches such as immune checkpoint inhibitors and CAR-T cell therapy. Overall, these approaches have demonstrated promising outcomes in preclinical studies and early-phase clinical trials, indicating that further refinement and optimization may substantially enhance their therapeutic efficacy.

Looking ahead, the future of DC-based cancer vaccines lies in the advancement of personalized immunotherapies tailored to patient-specific neoantigen landscapes, alongside the refinement of antigen presentation and delivery strategies. Integrating DC vaccines within broader therapeutic regimens that incorporate targeted therapies and next-generation immunotherapies will likely prove essential for maximizing efficacy. Finally, multifaceted and patient-specific combination strategies are expected to offer the greatest promise for improving clinical outcomes while minimizing adverse effects.

Abbreviations

ACT

Adoptive Cell Transfer

AML

Acute Myeloid Leukemia

APCs

Antigen-Presenting Cells

BiTE

Bispecific T cell Engager

BMDC

Bone Marrow-Derived Dendritic Cell

β2-MG

β2-Microglobulin

CAPRI

Cascade Priming

CAR

Chimeric Antigen Receptor

CLL

Chronic Lymphocytic Leukemia

CIK

Cytokine-Induced Killer

CXCL

CXC Chemokine Ligand

CY

Cyclophosphamide

CTL

Cytotoxic T-Lymphocyte

CTLA

Cytotoxic T-Lymphocyte Antigen

DCs

Dendritic Cells

HSCT

Hematopoietic Stem Cell Transplantation

hTERT

Human Telomerase Reverse Transcriptase

iDCs

Immature DCs

ICIs

Immune Checkpoint Inhibitors

IDO

Indoleamine 2,3-Dioxygenase

IFN-γ

Interferon-gamma

IL

Interleukin

MiHAs

Minor Histocompatibility Antigens

MoDC

Monocyte-Derived Dc

MDSCs

Myeloid-Derived Suppressor Cells

MDS

Myelodysplastic Syndromes

MM

Multiple Myeloma

NK

Natural Killer

NGS

Next-Generation Sequencing

NHL

Non-Hodgkin Lymphoma

NSCLC

Non-Small Cell Lung Cancer

OS

Overall Survival

PBMCs

Peripheral Blood Mononuclear Cells

PD-1

Programmed Death 1

PD-L1

Programmed Death Ligand 1

PFS

Progression-Free Survival

PGE2

Prostaglandin E2

Tregs

Regulatory T cells

R/R

Relapsed/Refractory

scFv

Single-chain Variable Fragment

SNVs

Single-Nucleotide Variants

TCR

T-Cell Receptor

TGF-β

Transforming Growth Factor-β

TAg

Tumor Antigens

TAAs

Tumor-Associated Antigens

TMEs

Tumor Microenvironments

TIDC

Tumor-Infiltrated Dendritic Cells’

VEGF

Vascular Endothelial Growth Factor

WES

Whole-Exome Sequencing

WT1

Wilms’ Tumor 1

Author contribution

Jamal Motallebzadeh Khanmiri and Behzad Baradaran contributed to the study conception and design, acquisition of data, analysis and interpretation of data, manuscript writing, and critical review and editing. Mohammad Khani-Eshratabadi, Fateme Seyedmoharrami, Mohammad Hossein Khazaee-Nasirabadi, Mehrad Dehdashti, Narjes Seddighi, Alireza Khiabani, and Alireza Khanahmad contributed to manuscript writing and critical review and editing. Fatemeh Peymaninezhad was responsible for figure design.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Competing Interests

The authors declare no competing interests.