ABSTRACT
In recent years the addition of the oral BCL2 inhibitor venetoclax to hypomethylating agents (HMAs) has emerged as the standard‐of‐care for patients with acute myeloid leukemia (AML) who are not fit for intensive chemotherapy, significantly improving survival and quality‐of‐life. Venetoclax is metabolized mainly by cytochrome P450 3A4 enzymes and serves as a P‐glycoprotein substrate, which make it largely affected by interactions with drugs. Dose reductions are needed to allow mold active antifungal prophylaxis, but there is no consensus on the exact venetoclax target dose concomitantly with posaconazole. We report on efficacy and safety of venetoclax combinations in 38 first‐line (FL) and 51 relapsed‐refractory (R/R) AML patients. Although complete remission (CR) rate was lower in R/R than in FL (49% vs. 68%; p = 0.08), achievement of this status was associated with comparable median overall survival (OS) in R/R and FL (13.67 vs. 13.72 months). Eighteen (20%) patients underwent allogenic hematopoietic stem cell transplantation (HSCT) with a 2‐year OS probability of 66.7%. Although antifungal prophylaxis was associated with a lower rate of grade 3–4 fungal infections (6% vs. 24%, p 0.044), patients treated with venetoclax daily dose of 50 mg with posaconazole had significantly shorter mOS in multivariate analysis (16.5 vs. 4.5 months; p 0.011). We conclude that AML patients in remission with venetoclax combinations may still be consolidated, and potentially cured, by HSCT, even after failure of intensive chemotherapy. Posaconazole prophylaxis effectively reduces risk of severe fungal infections, but a concomitant venetoclax dose of 50 mg may be sub‐optimal.
Keywords: acute myeloid leukemia, hypomethylating agents, interactions, posaconazole, venetoclax
1. Introduction
Acute myeloid leukemia (AML) is diagnosed mainly at older age and with standard chemotherapy regimens has an estimated 5‐year overall survival (OS) of 32% (up to 50% in young patients and less than 10% in patients older than 60) [1, 2, 3, 4].
Historically, treatment for AML has relied heavily on intensive cytotoxic chemotherapy, aiming to achieve complete remission (CR). However, a significant proportion of patients, particularly those considered unfit for intensive chemotherapy due to advanced age, comorbidities, or poor performance status, face limited treatment options and dismal prognoses. Furthermore, for patients who experience relapse or refractory (R/R) disease outcomes have traditionally been very poor, highlighting an urgent unmet medical need [1, 2, 3, 4].
In recent years, the therapeutic landscape for AML has undergone a significant transformation with the introduction of venetoclax (VEN), an oral selective inhibitor of the B‐cell lymphoma 2 (BCL‐2) anti‐apoptotic protein. BCL‐2 is often overexpressed in AML blast cells, promoting their survival and resistance to chemotherapy‐induced apoptosis. By selectively inhibiting BCL‐2, venetoclax restores the apoptotic pathway, leading to the programmed cell death of leukemic cells. This targeted mechanism of action has made VEN an attractive therapeutic agent [5, 6].
A pivotal advancement has been the combination of venetoclax with hypomethylating agents (HMAs), such as azacitidine or decitabine. The synergy between venetoclax and HMAs has been demonstrated in clinical trials, leading to remarkable improvements in response rates and survival outcomes. Initially, this combination received regulatory approval for AML patients deemed unfit for intensive chemotherapy, offering a much‐needed, less toxic, yet highly effective alternative. Building on this success, the indication for VEN‐HMAs was extended to include patients with relapsed/refractory AML [7, 8, 9, 10, 11, 12].
Recent data suggest that patients achieving remission with VEN‐HMAs can proceed to allogenic hematopoietic stem cell transplantation (HSCT) with comparable rates of long‐term remission to those who underwent salvage chemotherapy. Ongoing studies are investigating the combination of VEN‐HMAs as a frontline backbone to achieve remission in younger and fit patients who are candidates for HSCT [13, 14, 15, 16].
Effective management of venetoclax therapy necessitates a thorough understanding of its pharmacokinetics and potential drug‐drug interactions. Venetoclax is a substrate of cytochrome P450 3A4 (CYP3A4), a major enzyme involved in drug metabolism. Co‐administration with moderate or strong CYP3A inhibitors, such as the triazole antifungal agents, can substantially elevate venetoclax plasma concentrations and increase the risk of dose‐dependent toxicities [17, 18, 19, 20].
Primary prophylaxis with broad‐spectrum antifungal agents demonstrated efficacy in reducing the incidence of invasive fungal infection (IFIs) during neutropenia in AML patients. While VEN‐based treatments are considered less intensive induction therapies, they can still induce severe and prolonged neutropenia [21, 22]. Given posaconazole strong CYP3A4 inhibitory effect, a substantial reduction in the venetoclax dose, by at least 75%, is generally recommended when co‐administered to mitigate the risk of excessive VEN exposure and associated toxicities. However, despite these guidelines, a precise consensus on the exact target dose of venetoclax when co‐administered with strong CYP3A4 inhibitors remains a subject of ongoing discussion and variability in clinical practice, raising concerns about achieving optimal therapeutic drug levels [17, 18, 19, 20].
Here, we report the results of a retrospective analysis on 89 AML patients treated with venetoclax combinations at our center. This study aims to provide real‐world data on the efficacy and safety of VEN‐based regimens in both first‐line and relapsed/refractory AML. Furthermore, we aim to offer a valuable perspective on the impact of drug‐drug interactions, specifically with azole antifungals, on clinical outcomes, and the prognostic significance of minimal residual disease (MRD) monitoring in this patient population.
2. Patients and Methods
This was a single‐center retrospective study on adult patients receiving venetoclax in combination with HMAs for newly diagnosed or R/R AML. The study was conducted in accordance with Declaration of Helsinki, and was approved by our local Ethics Committee (number 711_2018). Written informed consent was obtained from each patients or by the legal representatives of deceased subjects. Due to its descriptive design, this study had no pre‐specified number of patients to be included. We obtained the list of venetoclax‐treated patients from our pharmacy registry.
All patients who received venetoclax for AML since November 2017 to September 2023, as by our hospital pharmacy registry, were included in the analysis. Data were censored at April 2024. All patients or their relatives provided informed consent for inclusion in this study. In patients who maintained CR at 2 and 4 months, MRD status was evaluated by quantitative real‐time polymerase chain reaction (RT‐qPCR) (maximum sensitivity: 10−6) or flow cytometry (FCM) as by Euroflow instructions. Venetoclax was administered at the dose of 400 mg daily after a short ramp‐up. The venetoclax dosage was reduced to 50 or 100 mg daily in case of concomitant strong CYP3A4 inhibitors (e.g., posaconazole) and 200 mg daily in case of moderate CYP3A4 inhibitors (e.g., isavuconazole). Azole prophylaxis, management of cytopenia and venetoclax/HMA reduction policies were performed as previously reported [23]. Particularly, by November 2020 our institution introduced a policy of routine azole use in all patients receiving venetoclax combinations since beginning of treatment until reaching of an absolute neutrophil count (ANC) stably > 1.0 × 109/L. Before that date, routine antifungal prophylaxis was not offered, such that two different cohorts (one with prophylaxis and one without) can be identified. Progression free survival (PFS; time from venetoclax start to AML progression, relapse or death) and OS were assessed using the Kaplan‐Meier method and compared between groups using the log‐rank test; p values < 0.05 were considered significant. Multivariate survival analysis was performed using Cox proportional hazards ratio (HR). Statistical analysis was performed using RStudio, R version 4.2.1.
3. Results
We included 89 consecutive patients, 38 (43%) first‐line (FL‐AML) and 51 (67%) R/R AML. Sixty‐three patients (71%) faced reductions of venetoclax dose due to interactions, mainly azoles during induction/neutropenia or after diagnosis of fungal infection, while one patient experienced dose reductions due to toxicity. Main clinical and demographic features of the study population are shown in Table 1.
TABLE 1.
Main features and outcomes of first‐line and relapsed/refractory AML patients treated with venetoclax regimens.
|
Whole cohort N = 89 |
First‐line N = 38 |
Relapsed/Refractory N = 51 |
|
|---|---|---|---|
| Age | |||
| Median (range), years | 69 (30–87) | 75 (56–87) | 65 (30–84) |
| > 65–no (%) | 60 (67) | 33 (87) | 26 (51) |
| Sex—n (%) | |||
| male | 54 (61) | 23 (61) | 27 (53) |
| AML type—n (%) | |||
| De novo | 58 (65) | 20 (53) | 38 (75) |
| Transformed | 31 (35) | 18 (47) | 13 (25) |
| Previous HMA—n (%) | 29 (33) | 8 (21) | 21 (41) |
| Relapsed status—n (%) | |||
| Salvage 1 | 30 (31) | 0 | 30 (59) |
| Salvage ≥ 2 | 21 (26) | 0 | 21 (41) |
| Prior allogenic HSCT—no. (%) | 13 (15) | 0 | 13 (25) |
| Risk ELN 2022–n (%) | |||
| Favorable | 11 (12) | 4 (11) | 7 (14) |
| Intermediate | 53 (60) | 22 (58) | 31 (61) |
| Adverse | 25 (28) | 12 (32) | 13 (25) |
| Cytogenetic risk category—n (%) | |||
| NA karyotype | 6 (7) | 3 (8) | 3 (6) |
| Intermediate | 59 (66) | 23 (60) | 36 (71) |
| Trisomy 8 | 12 (13) | 4 (11) | 8 (16) |
| Poor | 24 (27) | 12 (32) | 12 (24) |
| del (5q)/‐5 | 16 (18) | 8 (21) | 8 (16) |
| del (7q)/‐7 | 10 (11) | 4 (11) | 6 (12) |
| del (17p)/‐17 | 7 (8) | 4 (11) | 3 (6) |
| Complex karyotype | 15 (17) | 7 (18) | 8 (16) |
| Somatic mutations or translocations—n (%) | |||
| RUNX1‐RUNX1T1 | 1 (1) | 1 (3) | 0 |
| CBFB‐MYH11 | 0 | 0 | 0 |
| FLT3‐ITD | 8 (9) | 2 (5) | 6 (12) |
| FLT3‐TKD | 1 (1) | 0 | 1 (2) |
| NPM1 | 14 (16) | 5 (13) | 9 (18) |
| KMT2A rearrangement | 1 (1) | 1 (3) | 0 |
| CEBPA biallelic | 1 (1) | 0 | 1 (2) |
| IDH1 | 3 (3) | 2 (5) | 1 (2) |
| IDH2 | 6 (7) | 3 (8) | 3 (6) |
| Venetoclax combination regimen—n (%) | |||
| Azacitidine | 75 (84) | 35 (92) | 38 (75) |
| Decitabine | 11 (12) | 3 (8) | 8 (16) |
| ARA‐C | 4 (4) | 0 | 4 (8) |
| no | 3 (3) | 0 | 3 (6) |
| Dose of venetoclax—n (%) | |||
| 50 mg | 36 (40) | 21 (55) | 15 (29) |
| 70 mg | 1 (1) | 0 | 1 (2) |
| 100 mg | 12 (13) | 8 (21) | 4 (8) |
| 200 mg | 15 (17) | 4 (11) | 11 (22) |
| 300 mg | 0 | 0 | 0 |
| 400 mg | 27 (30) | 6 (16) | 21 (41) |
| Best response—no. (%) | |||
| CR | 31 (35) | 14 (37) | 17 (33) |
| CRi/MLFS | 20 (22) | 12 (32) | 8 (16) |
| PR | 5 (6) | 1 (3) | 4 (8) |
| NR or dead before evaluation | 32 (36) | 11 (29) | 21 (41) |
| SD | 1 (1) | 0 | 1 (2) |
| Number of cycles to composite CR—n (%) | |||
| 1 | 33 (37) | 14 (37) | 16 (64) |
| 2 | 10 (11) | 7 (18) | 3 (12) |
| > 2 | 12 (13) | 7 (18) | 6 (24) |
| Allogenic HSCT after venetoclax—n (%) | 18 (20) | 5 (13) | 13 (25) |
Abbreviations: AML: acute myeloid leukemia; CR: complete remission; ELN: european leukemia network; HMA: hypomethylating agents; HSCT: hematopoietic stem cell transplantation; MDS: myelodysplastic syndrome; MLFS: morphologic leukemia‐free state; MPN: myeloproliferative; NA: not available; NR: no response; PR: partial remission; SD: stable disease.
3.1. First‐Line AML Cohort
Median age was 75 years (range 56–87), with 87% over 65 years old. Four patients (11%) had favorable risk according to European Leukemia Net guidelines (ELN) 2022 [24], 22 (58%) had an intermediate risk and 12 (32%) had an adverse risk. Eighteen patients (47%) had secondary AML to myelodysplastic syndrome (MDS), myeloproliferative neoplasm (MPN) or MDS/MPN overlap. Twenty (34%) evaluable patients had poor cytogenetics: monosomic/deleted chromosomes 5/5q (23%), 7/7q (11%), 17/17p (11%) or complex karyotype (20%). We found NPM1 mutations in 5 (13%) patients, IDH1 in 2 (5%), IDH2 in 3 (8%), FLT3‐ITD in 2 (5%), and KMT2A‐ and RUNX1‐RUNXT1 rearrangement in 1 patient (3%) each. Eight (21%) patients had been exposed to HMA before AML diagnosis. Venetoclax was combined with azacitidine in 35 (92%) and decitabine in 3 cases (8%). Thirty‐two (84%) patients faced venetoclax dose reductions, mainly due to interaction with concomitant azoles therapy.
Best response was CR in 14 (37%) patients, and CR with incomplete hematological recovery (CRi) or morphological leukemia free state (MLFS) in 12 (32%) (composite CR rate of 68%), one patient had partial response (PR), while the remaining experienced progression, refractoriness or death during induction. Best response was achieved after 1 cycle in 14 patients (54%). When restricting to transformed AML, a composite CR rate of 10/18 (56%) was noted.
Composite CR was lower in patients previously exposed to HMAs for pre‐leukemic conditions, compared to unexposed (4/8, 50%, vs. 22/30, 73%; p 0.23), and in transformed AML compared to de novo (10/18, 56%, vs. 16/20, 80%; p 0.16). Patients with adverse cytogenetic profile had a lower rate of composite CR (6/12, 50%, vs. 19/23, 83%, p 0.0592). Five patients received an allogeneic HSCT (median age 64 years, range 59–74).
Median OS was 7.8 months (CI95% 5.2–16.4), median PFS was 6.06 months (CI95% 4.5–13.9). Transformed AML was associated with shorter median OS than de novo AML (4.8 months vs. 10.0; p 0.23). Previous HMA exposure was associated with lower OS (5.9 months vs. 9.0; p 0.67). Adverse cytogenetics was associated with lower OS (4.7 vs. 10.4 months; p 0.069) and PFS (3.9 vs. 7.2 months; p 0.077), as well as ELN 2022 adverse risk (median PFS 3.9 vs. 6.7 months; p 0.053; median OS: 4.7 vs. 10.0 months; p 0.054). Venetoclax dose reductions due to pharmacological interactions were associated with significantly lower median OS (7.0 vs. 22.4 months; p 0.028), and non‐significantly lower median PFS (5.0 vs. 22.7 months; p 0.1). When we focused on venetoclax reduction to 50 mg daily for concomitant posaconazole, mOS was significantly lower than in patients without reductions/with any other VEN reduction (16.5 vs. 4.5 months; p 0.011).
On multivariate analysis, besides response status, there were no factors significantly associated with different risk of death or progression.
3.2. Relapsed/Refractory AML Cohort
Median age was 65 years (range 30–84) with 51% over 65 years old. Thirty patients (59%) relapsed after first line treatment, while 21 (41%) had received 2 or more lines before venetoclax and 13 (25%) had relapsed after HSCT. Twelve (25%) patients had poor cytogenetics; we found mutations of NPM1 in 9 (18%) patients, IDH1 in 1 (2%), IDH2 in 3 (6%), FLT3‐ITD in 6 (12%) and FLT3‐TKD or CEBPA biallelic mutation in 1 patient (2%), respectively. Twenty‐one (41%) patients had been previously exposed to HMA. Venetoclax was combined with azacitidine in 38 cases (75%), decitabine in 8 (16%), cytarabine in 4 (8%), and used as single agent in other 3 patients (6%).
CR rate was 17/51 (33%) with a composite CR rate of 49%. Best response was achieved after 1 cycle in 16 (64%) patients. Composite CR was significantly lower only in patients with adverse cytogenetics (33% vs. 56%, p 0.031), while a trend to statistical significance was observed in patients previously exposed to HMAs, (33% vs. 60%; p 0.089), and in patients exposed to more of one line of treatment (33% vs. 60%; p 0.089). Thirteen patients (25%) received an allo‐HSCT as consolidation (median age 56 years, range 44–74).
Median OS was 8.1 months (CI95% 4.3–13.0) and median PFS was 6.1 (CI95% 4.0–10.6).
Survival was not significantly longer for patients in second line versus third or further line of treatment (mPFS 6.4 vs. 4.3 months; p 0.74; mOS 8.7 vs. 4.3 months, p 0.28, respectively). Previous HMA exposure was associated with lower survival than in HMA‐unexposed patients (mPFS 2.4 months vs. 9.3; p 0.0014; mOS 1.4 vs. 8.2 months, p < 0.001). Adverse cytogenetics or NPM1/FLT3 mutational status were not significantly associated to survival.
No significant differences in mPFS and mOS were also observed between patients who received venetoclax dose reductions or standard dose.
3.3. Whole Cohort Analysis
On whole‐cohort analysis (n = 89), we found a comparable OS among patients who achieved composite CR, whether they were in FL or R/R setting (14.5 vs. 13.7 months, respectively), which was significantly longer than in those who did not achieve composite CR (2.2 months in FL and 2.9 months in R/R); p < 0.001. When differentiating CR from CRi, the former state was associated with a statistically significant longer median PFS than the latter (12.9 vs. 6.0 months, respectively; p 0.049), as well a borderline‐significant longer OS (15.4 vs. 9.0 months, respectively; p 0.058) (Figure 1).
FIGURE 1.
Outcomes of patients treated with venetoclax combinations. Progression free survival (PFS) and overall survival (OS) from venetoclax start according to response status are shown in panel (A and B), respectively. PFS and OS from venetoclax start, comparing complete remission (CR) with CR with incomplete count recovery (CRi), are shown in panels (C and D), respectively. PFS and OS from venetoclax start in patients who underwent consolidation with HSCT are shown in panels (E and F), respectively.
Of 51 patients who achieved composite CR, 12 were not available for MRD at two months due to early progression (2 patients), necrosis/hypocellularity at BM sampling (2), lost in follow up (1), and absence of a suitable leukemia associated immunophenotype (LAIP) (7). The remaining 39 (76%) were evaluable for MRD at 2 months (8 by quantitative polymerase chain reaction of NPM1 transcript, 31 by multiparametric flow cytometry, FCM). Median PFS and OS were comparable between 2‐month MRD‐positive and ‐negative; in contrast, among 23 evaluable patients at 4 months, mPFS was 31.5 months in MRD‐negative versus 15.4 in MRD positive (p = 0.38). Eighteen (22%) patients underwent HSCT after venetoclax, 5 (22%) of which in first line, 10 (56%) in second line and 3 (17%) in third line of therapy. Median age at transplant was 58 years (range 44–74 years). Table 2 shows clinical features of these patients. The 24‐months OS rate of the 18 patients who underwent allo‐HSCT was 63%, median not reached, with no significant differences between first‐line and R/R AML.
TABLE 2.
Clinical features of patients undergoing allogeneic HSCT after venetoclax.
| alloHSCT after VEN (N = 18) | |
|---|---|
| Age at HSCT | 58 (44–74) |
| Sex (M) | 13 (72) |
| Treatment line | |
| 1 | 5 (28) |
| 2 | 10 (56) |
| 3 | 3 (17) |
| Secondary AML | 4 (22) |
| HMA before VEN | 3 (17) |
| ELN2022 category | |
| Favorable | 1 (5) |
| Intermediate | 12 (67) |
| poor | 5 (28) |
| VEN reduction due to interactions | |
| Yes | 11 (61) |
| no | 7 (39) |
| N of VEN cycles | 3 (1–18) |
| Best response before HSCT | |
| CR | 12 (67) |
| CRi | 5 (28) |
| MLFS | 0 |
| PR | 0 |
| NR | 1 (5) |
| Donor type | |
| HLA identical | 2 (11) |
| MUD | 5 (28) |
| MMUD | 2 (11) |
| Haplo | 9 (50) |
| Conditioning | |
| Bu‐flu | 4 (22) |
| TTF | 8 (44) |
| TF‐RIC | 4 (22) |
| Treo flu | 2 (11) |
| aGVHD | |
| No | 9 (50) |
| G1‐2 | 6 (33) |
| G3‐4 | 2 (11) |
| G5 | 1 (6) |
| cGVHD | |
| No | 13 (72) |
| G1‐2 | 5 (28) |
| G3‐4 | 0 |
| Relapse after HSCT | |
| No | 13 (72) |
| Yes, molecular | 1 (6) |
| Yes, overt | 4 (22) |
Abbreviations: aGVHD: acute graft versus host disease, alloHSCT: allogeneic hematopoietic stem cell transplant, AML: acute myeloid leukemia, ANC: absolute neutrophil count, Bu Flu: busulfan fludarabine, cGVHD: chronic graft versus host disease, Haplo: haploidentical, HMA: hypomethylating agent, MUD: matched unrelated donor, MMUD: mismatched unrelated donor, TF‐RIC: treosulfan fludarabine at a reduced intensity conditioning, Treo Flu: treosulfan fludarabine, TTF: thiotepa treosulfan fludarabine, VEN: venetoclax.
4. Safety
Concerning fungal infections, two patients in first line were ineligible for analysis due to concomitant/previous diagnosis fungal infection and AML in need of therapy, as well as other 7 R/R patients who had been diagnosed with IFI before venetoclax start. Eleven patients (14%) developed fungal infections after venetoclax, with a significantly lower rate for those who received prophylaxis in first venetoclax cycles: 3/47 (6%) in the prophylaxis group versus 8/33 (24%) in the group without prophylaxis (p = 0.044).
According to EORTC/MSG criteria, these infections included 6 cases of possible fungal pneumonia, 3 probable fungal pneumonia, 1 proven systemic mycosis by Acremonium spp and Fusarium spp., and one proven complicated urinary candidiasis. When excluding possible infections, focusing on probable/proven ones, the cumulative incidence was higher in patients who did not receive prophylaxis (4/33,12%) than in those who did (1/47, 2%; p 0.15). Table 3 shows clinical features of patients according to antifungal prophylaxis status, whereas Table 4 shows additional information about the three patients who developed fungal infections despite antifungal prophylaxis.
TABLE 3.
Clinical features of patients according to primary prophylaxis status.
| Variable | Level | No.prophylaxis | Prophylaxed | p (only if significant) |
|---|---|---|---|---|
| n | 33 | 47 | ||
| treatment_line_cat (%) | ≥ 2nd | 10 (30.3) | 26 (55.3) | 0.039 |
| 1st | 23 (69.7) | 21 (44.7) | ||
| Age (median [IQR]) | 70.95 [64.72, 76.36] | 72.95 [59.95, 77.03] | ||
| Sex (%) | Female | 12 (36.4) | 17 (36.2) | |
| Male | 21 (63.6) | 30 (63.8) | ||
| secondary_AML (%) | No | 22 (66.7) | 28 (59.6) | |
| Yes | 11 (33.3) | 19 (40.4) | ||
| HMA_before_VEN (%) | No | 18 (54.5) | 37 (78.7) | 0.028 |
| Yes | 15 (45.5) | 10 (21.3) | ||
| ANC (median [IQR]) | 2.88 [0.48, 8.75] | 3.35 [1.09, 7.83] | ||
| ELN2022 (%) | Favorable | 5 (15.2) | 5 (10.6) | |
| Intermediate | 20 (60.6) | 29 (61.7) | ||
| Poor | 8 (24.2) | 13 (27.7) | ||
| Cytogenetics (%) | Adverse | 8 (24.2) | 12 (25.5) | |
| NA | 3 (9.1) | 3 (6.4) | ||
| Not adverse | 22 (66.7) | 32 (68.1) | ||
| fungal_infection (%) | No | 25 (75.8) | 44 (93.6) | 0.044 |
| Yes | 8 (24.2) | 3 (6.4) | ||
| Year of treatment start (n, %) |
< 2021 ≥ 2021 |
29 (87.9) 4 (12.1) |
4 (8.51) 43 (91.5) |
< 0.01 |
TABLE 4.
Clinical features of patients who developed IFI despite azole prophylaxis in first cycles of Venetoclax‐HMA.
| Patient | Case 1 | Case 2 | Case 3 |
|---|---|---|---|
| Type of IFI | Possible pulmonary aspergillosis | Possible pulmonary aspergillosis | Probable pulmonary aspergillosis |
| Ongoing azole at IFI diagnosis | Yes (PCZ) | Yes (PCZ) | No (but prophylaxed first cycles) |
| If yes, TDM | NA | 1.9 | / |
| VEN cycle at IFI diagnosis | 2 | 1 (only few days) | PD after fourth cycle |
| ANC et IFI diagnosis | 0 | 0.04 | 0 |
| Treatment | L‐Amb 5 mg/kg x 12w | L‐Amb 5 mg/kg, then ISA due to AKI | Voriconazole |
| Outcome | IFI resolved, then resumed AZA‐ven, then septic shock, then PD, then palliation and death | Resolved, then rechallenge with aza‐ven, then septic shock, permanently stopped aza‐ven, then palliation and death | While treating IFI, further progression of AML, transferred to hospice |
Abbreviations: AKI: acute kidney injury, AML: acute myeloid leukemia, ANC: absolute neutrophil count, AZA: azacitidine, IFI: invasive fungal infection, ISA: isavuconazole, L‐Amb: Liposomal B‐Amphotericin, PCZ: posaconazole, PD: progressive disease, TDM: trough drug monitoring, Ven: venetoclax.
On multivariate analysis, besides response status, factors significantly associated with higher HR for a PFS event were previous exposure to HMAs (HR 2.01, p 0.025) and venetoclax dose reduction to 50 mg due to interaction with strong CYP3A4 inhibitors (2.26, p 0.031). The only factor significantly associated with a higher risk of death was previous exposure to HMAs (HR 3.30, p < 0.001).
Concerning safety, 69/89 patients (76%) experienced grade 3/4 adverse events (G3/4 AEs), with a cumulative incidence of hematological G3/4 AEs of 39/89 (44%), infectious G3/4A Es of 47/89 (53%), arrhythmia in 2/89 (2%), drug induced liver injury in 1/89 (1%), stroke in 1/89 (1%), tumor lysis syndrome in 1/89 (1%).
5. Discussion
Our single‐center retrospective study provides a real‐world evaluation of venetoclax combinations in both first‐line and relapsed/refractory AML. While our survival data (mOS 7.8 months in FL) are lower than those in phase III trials, they align with real‐world meta‐analyses, reflecting a cohort enriched with adverse prognostic features and prior HMA exposure. Importantly, we observed that achieving a composite CR yields comparable OS between FL and R/R settings (14.5 vs. 13.7 months) [9, 10, 11, 12].
This observation strongly suggests that VEN‐HMAs can effectively rescue a substantial proportion of R/R patients, offering a bridge to allo‐HSCT [13, 14, 15, 16]. In our R/R cohort 25% of the patients successfully proceeded to allo‐HSCT, demonstrating the regimen's capability to facilitate a potentially curative strategy in a population with dismal prognoses. The 24‐month OS rate of 63% in the 18 patients who underwent allo‐HSCT, with no significant differences between first‐line and R/R AML, further solidifies the critical role of transplantation as a consolidation strategy for those achieving deep remissions with VEN‐HMAs.
We observed a longer PFS and OS in patients achieving CR as compared to CRi. This remarks that the objectives of VEN‐HMA extend beyond blast clearance, aiming a rapid recovery of cytopenia. The use of granulocyte colony‐stimulating factor for persistent neutropenia after confirming blast clearance and a stepwise reduction of the venetoclax treatment interval might help the hematopoietic recovery.
When we focused on MRD evaluation, we found that the MRD assessment after 4 months of therapy might be more informative than at 2 months. Specifically, among 23 evaluable patients at 4 months, median PFS was 31.5 months in MRD‐negative patients versus 15.4 months in MRD‐positive patients (p = 0.38). This observation suggests that a later MRD assessment might be more predictive of sustained response in VEN‐HMA treated patients compared to traditional chemotherapy. Further prospective studies with larger cohorts are crucial to validate the optimal timing and prognostic significance of MRD assessment in this context, potentially guiding treatment duration or intensification [25, 26, 27].
The most actionable finding of this study concerns the complex interplay between antifungal prophylaxis and venetoclax pharmacokinetics. We confirmed that azole prophylaxis is indispensable, significantly reducing the rate of severe fungal infections (6% vs. 24%, p = 0.044).
However, this clinical benefit introduces a significant challenge due to strong CYP3A4 inhibition.
Our data reveal a concerning correlation between dose reductions and inferior outcomes. In the FL cohort, VEN dose reductions were significantly associated with shorter OS (7.0 vs. 22.4 months, p = 0.048). Furthermore, on multivariate analysis across the entire cohort, pharmacological interactions emerged as the sole factor significantly associated with a higher hazard ratio (HR) for both PFS events (HR 3.56; p = 0.0037) and OS events (HR 7.28; p = 0.006).
Patients receiving a daily VEN dose of 50 mg with concomitant posaconazole had a significantly lower mOS (4.5 months) compared to those without such reductions (16.5 months, p = 0.034).
While a 50 mg dose is permissible by European Medicine Agencies labeling and was utilized in pivotal trials, our real‐world evidence suggests this blanket approach may lead to sub‐therapeutic exposure in a significant subset of patients [7, 8, 17, 18, 19, 20, 28]. This suboptimal exposure likely compromises anti‐leukemic activity and shortens response duration.
Earlier pharmacokinetic studies demanded at least 75% reduction, which would allow for a 100 mg dose [7, 8, 17, 18, 19, 20, 28]. The Food and Drug Administration label for venetoclax recommended a 70 mg dose reduction, although reductions to 100 mg remained more practical according to some sources. More recently, De Gregori et al. demonstrated that dose reductions to 70 mg concomitantly with posaconazole may lead to therapeutic VEN concentrations, but highlighted that steady state was reached after a longer time and with significant inter‐individual variability [28].
The inherent difficulty lies in translating population‐level pharmacokinetic data, which often suggests 50–70 mg achieves target concentrations, into individualized strategies for patients with varying comorbidities and disease burdens. Without routine therapeutic drug monitoring, the risk of underpowering the treatment remains high.
As regards the safety aspects, the overall profile of VEN‐HMAs in our cohort was consistent with previously published reports. A cumulative incidence of grade 3/4 adverse events was observed in 76% of patients, with the most common severe adverse events being hematological (44%) and infectious (53%). These findings underscore the importance of meticulous supportive care and proactive management of potential toxicities to ensure patient safety and optimize treatment adherence. Given the potential severity of invasive fungal infection, especially in these severely immune compromised patients, we argue in favor of vigorous antifungal treatment, including proven and probable pulmonary aspergillosis. Antifungal therapy should also be considered empirically in possible pulmonary aspergillosis, when optimal wide spectrum antibacterial therapy is not followed by improvement, and bronchoalveolar lavage or pulmonary biopsies are not feasible [29, 30].
The retrospective nature and the single‐center design are inherent limitations of our study. Most notably, the absence of systematic therapeutic drug monitoring for venetoclax concentrations prevented us from definitively correlating specific drug levels with clinical outcomes in patients receiving dose reductions.
6. Conclusion
Venetoclax combinations are effective in both FL and R/R AML, also as a bridge to transplantation. However our data highlight a challenge: while posaconazole effectively prevents life‐threatening infections, a broad reduction of VEN to 50 mg daily may underpower its antileukemic efficacy. We therefore strongly advocate for the implementation of venetoclax drug monitoring and a careful selection of the right population for antifungal prophylaxis. This precision approach is essential to balancing efficacy and toxicity, thereby improving long‐term survival in AML patients.
Author Contributions
Mariarita Sciumè: conceptualization, methodology, validation, formal analysis, investigation, data curation, writing – original draft preparation, writing – review and editing. Alessandro Bosi: conceptualization, methodology, validation, formal analysis, investigation, data curation, writing – riginal draft preparation. Alfredo Marchetti: conceptualization, methodology, investigation, data curation, writing – original draft preparation. Fabio Serpenti: validation, investigation, data curation. Pasquale De Roberto: validation, data curation. Sonia Fabris: validation. Francesco Versino: methodology, investigation, data curation. Elena Tagliaferri: investigation, data curation. Francesco Passamonti: validation, writing – review and editing, supervision. Nicola Stefano Fracchiolla: conceptualization, methodology, validation, formal analysis, investigation, writing – review and editing, supervision. All authors have read and agreed to the published version of the manuscript.
Funding
This study was partially funded by Italian Ministry of Health, current research IRCCS.
Ethics Statement
The data were collected within studies approved by CET Lombardia 3.
Consent
Written informed consent was obtained from each patients or by the legal representatives of deceased subjects.
Conflicts of Interest
Dr. Fracchiolla has received travel or speaker honoraria from Abbvie.
Permission to Reproduce Material From Other Sources
The authors have nothing to report.
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.