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. 2026 Jul;67(7):1056–1061. doi: 10.2967/jnumed.125.271601

Assessment of CCR2 PET as a Biomarker for Head and Neck Squamous Cell Carcinoma

Alexandria Li 1, Deborah Sultan 1, Gyu Seong Heo 1,2, Lisa Detering 1, Divangana Lahad 1, Hannah Luehmann 1, Xiaohui Zhang 1, Rajiu Venkatesan 1, Jennifer Frye 1, Julie Belmar 3, Salma Ramadan 4, Robert Crowder 4, Ying-Hwey Nai 1, Joan Tao 5, Robert Gropler 1, Richard Laforest 1,2, Ryan S Jackson 4,6, Rebecca Chernock 4,7, Chieh-Yu Lin 2,7, Shunqiang Li 2,3, Sidharth Puram 4,6, Farrokh Dehdashti 1,2, Yongjian Liu 1,2,✉
PMCID: PMC13321978  PMID: 41819828

Visual Abstract

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Keywords: CCR2, HNSCC, tumor, macrophage, biomarker, propagermanium

Abstract

Because of the lack of prognostic biomarkers, most patients with head and neck squamous cell carcinoma (HNSCC) are diagnosed at an advanced stage of the disease, leading to poor overall survival. There is an unmet need to identify biomarkers for the assessment of HNSCC. The goal of this study was to assess C-C chemokine receptor type 2 (CCR2) as a new diagnostic biomarker for HNSCC. Methods: The sensitivity and specificity of the CCR2-targeting radiotracer 64Cu-DOTA-ECL1i for tumor detection was assessed in a mouse oral carcinoma 1 (MOC1) xenograft model and compared with 18F-FDG. The capability of 64Cu-DOTA-ECL1i for monitoring MOC1 tumor treatment response was evaluated for multiple treatment strategies. The CCR2 inhibitor propagermanium was used for targeted therapy in the MOC1 tumor model, followed by 64Cu-DOTA-ECL1i imaging. The translational potential of 64Cu-DOTA-ECL1i for HNSCC imaging was further investigated using patient-derived xenograft models. Proof-of-concept studies were performed using primary tumors and lymph node metastases of 11 patients with HNSCC. Histopathologic analyses of tumors in mice and humans were performed to characterize the expression of CCR2 and associated cell types. Results: 64Cu-DOTA-ECL1i PET imaged MOC1 tumors with high contrast, tracked the increase of tumor volume, and monitored the treatment responses. Propagermanium effectively inhibited MOC1 tumor growth and significantly improved survival. In the patient-derived xenograft model, 64Cu-DOTA-ECL1i accurately identified the tumors and sensitively tracked their progression. In patients with HNSCC, CCR2 PET revealed strong and heterogeneous uptake within primary tumors and metastatic lymph nodes. Tissue analyses demonstrated overexpression of CCR2 on both tumor cells and macrophages. Conclusion: 64Cu-DOTA-ECL1i PET accurately detected the expression of CCR2 in patients with HNSCC. The effectiveness of propagermanium in the inhibition of MOC1 tumor progression indicated its potential for HNSCC therapy.

The incidence and mortality rate of head and neck squamous cell carcinoma (HNSCC) have grown over the past decade, making it the sixth most common cancer worldwide (1). Because of the lack of effective approaches for early diagnosis, approximately two thirds of newly diagnosed patients present with advanced disease, often with locoregional lymph node (LN) metastases (2), leading to a 5-y progression-free survival rate of only 50%. Moreover, up to 60% of patients with advanced-stage HNSCC develop recurrence after standard treatment (surgery or chemoradiotherapy), with a median overall survival time of approximately 1 y (3–5). Thus, there is an unmet clinical need to identify biomarkers for HNSCC monitoring, as well as biomarkers that can better inform targeted therapeutic approaches to improve survival.

Currently, human papillomavirus and p16 testing are the clinical prognostic biomarkers for HNSCC. However, they are limited in their ability to identify biologically aggressive cases of HNSCC, and their prognostic role in nonoropharyngeal HNSCC remains underexplored (6). Clinical imaging modalities, including PET/CT, contrast-enhanced CT, and MRI, are complementary for assessing the extent of tissue invasion, involvement of locoregional LNs, and presence of distant metastases. Many radiotracers have been used for the diagnosis, staging, and restaging of HNSCC and monitoring of treatment response, including 18F-FDG, epidermal growth factor receptor–based molecular agents, and fibroblast activation protein–targeting agents, with promising results in preclinical and clinical imaging studies (7–11). However, limited data are available for the assessment of HNSCC (12,13). An effective biomarker for HNSCC monitoring remains an unmet clinical need (14).

The C-C motif chemokine ligand 2 and its cognate receptor, C-C chemokine receptor type 2 (CCR2), promote the recruitment of tumor-associated macrophages (TAMs) during tumor invasion and metastasis (15). CCR2 is highly expressed by both TAMs (16,17) and malignant cells (18–20), making it a unique target for both monitoring and treatment. Clinical studies have found that CCR2 inhibitors, through the inhibition of CCR2-positive malignant cells and TAMs, reduced tumor-initiating cells, relieved the immunosuppressive tumor microenvironment, and improved therapeutic response (21–23). These findings highlight the importance of CCR2 in mediating the infiltration and immunosuppressive polarization of macrophages and its potential for tumor management.

Our group has developed a targeted radiotracer, 64Cu-DOTA-ECL1i, that allosterically binds to CCR2 and validated its imaging performance in multiple animal models and humans with inflammatory diseases (24–27). Here, we assessed the capability of 64Cu-DOTA-ECL1i for early detection of CCR2 in mouse oral carcinoma 1 (MOC1) and patient-derived xenograft (PDX) models, as well as its potential to monitor treatment response. Moreover, we performed proof-of-concept CCR2 PET studies in patients with HNSCC and characterized the CCR2 expression in the resected tumors to support further investigation of the role of CCR2 in HNSCC.

MATERIALS AND METHODS

A detailed description of the materials and methods used in this study is provided in the supplemental materials, available at http://jnm.snmjournals.org.

Study Population

Patients age 18 y or older with a newly confirmed diagnosis of HNSCC undergoing evaluation for surgical resection, as well as those with confirmed or suspected recurrent HNSCC who were candidates for salvage surgery, were eligible to participate in this study. Patients with regional metastatic disease from unknown primary tumors were also eligible to participate. Additional inclusion criteria included lesion size of at least 1.0 cm (longest dimension) identified by imaging. Women were required to be surgically sterile (documented bilateral oophorectomy or documented hysterectomy), postmenopausal (cessation of menses for more than 1 y), nonlactating, or of childbearing potential with a negative urine pregnancy test performed within 24 h before administration of 64Cu-DOTA-ECL1i.

Patients were excluded if they had another invasive malignancy (except nonmelanoma skin cancer), a history of another malignancy within the previous 2 y, were unable to tolerate approximately 60 min of 64Cu-DOTA-ECL1i PET/CT imaging, or were pregnant or lactating.

PET/CT Imaging

64Cu-DOTA-ECL1i PET/CT imaging of patients with HNSCC was performed under the approvals from the Food and Drug Administration (IND 137620) and Washington University Institutional Review Board (201912003). Written consent was provided by all study participants. All patients with HNSCC were diagnosed and managed by clinicians at the Washington University Head and Neck Tumor Center, in accordance with consensus clinical criteria.

After intravenous administration of 64Cu-DOTA-ECL1i, patients underwent a 60-min dynamic scan centered over the site of the known tumor, laying in a supine position on the imaging table with arms secured comfortably by the side of the body. The CT consisted of a 5- to 20-s topogram for determining correct anatomic positioning, followed by a low-dose spiral CT scan for attenuation correction, centered on the primary tumor site. Standard CT acquisition settings were applied: 100 kVp, 200 mA, 0.5 s per rotation, and a pitch of 1, yielding an effective tube current of 100 mA. CARE Dose (Siemens Healthineers) was applied, with a preset maximum of 100 mAs. The imaging field of view was 26 cm, with 38.4-mm collimation. Immediately after the attenuation CT scan, patients were injected with 64Cu-DOTA-ECL1i (296–370 MBq). The dose was followed by a normal saline flush of 10–30 mL. A 60-min list-mode dynamic imaging acquisition was performed after the injection of 64Cu-DOTA-ECL1i. At the end of the imaging session, patients were encouraged to void. A delayed scan (30-min static scan) was also acquired 1–4 h after the injection of 64Cu-DOTA-ECL1i.

Statistical Analysis

Data are presented as mean ± SD. Group comparisons were performed using 1-way ANOVA with Tukey adjustment in Prism version 10.0.2 (GraphPad Software). Pairwise group comparisons were assessed using a 2-tailed Mann–Whitney U test. A P value of less than 0.05 was considered statistically significant.

RESULTS

64Cu-DOTA-ECL1i PET/CT for Early and Accurate Detection of HNSCC

To assess the potential of 64Cu-DOTA-ECL1i for the early and accurate detection of HNSCC, we performed 64Cu-DOTA-ECL1i PET/CT scans in a MOC1 xenograft model and compared these with 18F-FDG PET scans. At 5 or 6 d after tumor implantation, neither 18F-FDG PET nor CT identified the MOC1 tumor because of its small volume and low metabolic activity, whereas 64Cu-DOTA-ECL1i PET revealed a discrete uptake at the flank where MOC1 cells were injected in the same mice, suggesting early detection of tumor cells expressing CCR2 (Fig. 1A). At 2 wk, the tumors became palpable and could be identified by CT, 18F-FDG PET, and 64Cu-DOTA-ECL1i PET. Although the tumor uptake of 18F-FDG (1.35 ± 0.40 %ID/g, n = 7) was approximately 50% higher than that of 64Cu-DOTA-ECL1i (0.88 ± 0.17 %ID/g, P < 0.01, n = 12), the low background retention of 64Cu-DOTA-ECL1i led to a higher tumor-to-muscle (T/M) contrast ratio (5.25 ± 0.66, n = 12, P < 0.0001) than with 18F-FDG (2.35 ± 0.49, n = 7) (Fig. 1B). Hematoxylin and eosin and immunofluorescence staining of the MOC1 tumor revealed that CCR2 was expressed by both TP63-positive tumor cells and CD68-positive macrophages, supporting the CCR2 PET data (Fig. 1C). At 2 wk after implantation, 64Cu-DOTA-ECL1i identified all small tumors (≤5 mm3, n = 12), whereas 18F-FDG visualized 7 tumors, highlighting the potential of 64Cu-DOTA-ECL1i for the sensitive and accurate detection of MOC1 tumors. At 7 wk after tumor development, both radiotracers clearly identified the tumors in the same mice, further demonstrating the capability of 64Cu-DOTA-ECL1i for early and accurate detection of MOC1 tumors.

FIGURE 1.

FIGURE 1.

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Assessment of 64Cu-DOTA-ECL1i PET/CT for detecting CCR2 in MOC1 tumor model. (A) 18F-FDG vs. 64Cu-DOTA-ECL1i imaging initiation and progression of MOC1 tumor. (B) Quantification of tumor uptake and T/M ratio. (C) Hematoxylin and eosin (H&E) and immunofluorescence staining of CCR2 expression in MOC1 tumor. T = tumor. ****P < 0.0001.

Sensitivity of 64Cu-DOTA-ECL1i for Determining HNSCC Treatment Response

We next assessed the sensitivity and specificity of 64Cu-DOTA-ECL1i for HNSCC treatment response in MOC1 tumor–bearing mice after treatment with cisplatin, programmed cell death protein 1 (PD-1) blockade, or cisplatin plus PD-1 blockade (28). Compared with the untreated group, who showed rapid tumor growth, treatment with cisplatin or PD-1 blockade alone slowed tumor growth. Moreover, cisplatin plus PD-1 blockade demonstrated more effective tumor inhibition compared with other treatments (Supplemental Fig. 1). After treatment, 64Cu-DOTA-ECL1i revealed sensitive detection of tumor treatment responses at 4 and 7 wk after tumor implantation. Quantification demonstrated increased tumor uptake of 64Cu-DOTA-ECL1i over time in all groups (Supplemental Figs. 1B and 1C), consistent with the progression of tumor volumes. This indicated the importance of CCR2 in MOC1 tumor development and highlighted the sensitivity of 64Cu-DOTA-ECL1i in tracking treatment response.

Evaluation of CCR2 as a Target for HNSCC Treatment

Because HNSCC tumor cells exhibit elevated CCR2 expression, we evaluated the effectiveness of the CCR2 inhibitor propagermanium in the MOC1 model (29). MOC1 tumor growth was significantly inhibited after treatment with propagermanium, resulting in a 5-fold reduction in tumor volume compared with the untreated group at 7 wk (Supplemental Fig. 2A). At day 62, all untreated mice died, whereas 75% of propagermanium-treated mice survived (Supplemental Fig. 2B). CCR2 PET at 6 wk revealed significantly less tumor uptake of 64Cu-DOTA-ECL1i in the propagermanium-treated group compared with the untreated group (Supplemental Fig. 2C). Consistent with tumor volume variation, CCR2 PET showed a decrease of approximately 50% in tumor uptake in the propagermanium-treated mice relative to the untreated mice at 30 d, which further decreased by approximately 75% at 6 wk (Supplemental Fig. 2D). This effective tumor inhibition highlighted the effectiveness of propagermanium for the treatment of HNSCC and further validated the sensitivity of 64Cu-DOTA-ECL1i for monitoring the treatment response.

64Cu-DOTA-ECL1i Imaging of CCR2 in HNSCC PDX Models

To further explore the potential of CCR2 PET for HNSCC diagnosis, we performed CCR2 immunostaining of HNSCC PDX models (n = 15). CCR2 is expressed at higher levels on TP63-positive malignant cells (88% ± 11%, n = 15) than on CD68-positive macrophages (12% ± 6%, n = 5), supporting the role of CCR2 as a biomarker for HNSCC. PDX tumors were classified by the intensity of CCR2 expression as weak (n = 3), medium (n = 5), or strong (n = 7) (30). We then performed 64Cu-DOTA-ECL1i PET in a PDX model with moderate CCR2 expression. At 4 wk after tumor implantation, CCR2 PET revealed a significant uptake of 64Cu-DOTA-ECL1i in the tumor (∼30 mm3) and a high T/M ratio. With the progression of tumors (∼200 mm3) at 8 wk, 64Cu-DOTA-ECL1i uptake and T/M ratios further increased (Figs. 2A and 2B). Hematoxylin and eosin and immunofluorescence staining showed high expression of CCR2-positive cells throughout the tumors. CCR2 was largely colocalized with TP63-positive tumor cells and certain CD68-positive macrophages (Fig. 2C), consistent with the data acquired from MOC1 tumors.

FIGURE 2.

FIGURE 2.

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64Cu-DOTA-ECL1i PET/CT imaging of HNSCC PDX tumors. PET/CT images (A) and quantification (B) of tumor uptake and T/M ratio. (C) Whole-tissue and zoomed-in hematoxylin and eosin (H&E) and immunofluorescence images showing high expression of CCR2 on tumor cells and macrophages. T = tumor; Tx = treatment. **P < 0.01; ***P < 0.001.

CCR2 Imaging in HNSCC Patients

We performed 64Cu-DOTA-ECL1i PET/CT in 11 patients with HNSCC (Supplemental Table 1). As a proof of concept, patients recruited in this study were required to have a lesion size of at least 1.0 cm. As shown in Figure 3A, a patient (HN-4) with HNSCC (pT4aN3b with extranodal extension, lymphovascular invasion, and cortical bone invasion) had a primary tumor of 6.0 cm at the alveolar ridge within the oral cavity, involving cortical bone and metastatic LN (1.9 cm), which was identified by CT. 64Cu-DOTA-ECL1i PET images acquired from the 0- to 60-min dynamic and static scans at 1.5 h postinjection showed sensitive and specific detection of the primary tumor, bone invasion, and LN metastasis, which were also identified by 18F-FDG PET (Fig. 3B; Supplemental Fig. 3A). Quantification of SUVmax demonstrated significant uptake in the primary tumor (SUVmax, 3.13 ± 0.63; n = 11) and LN (SUVmax = 3.00 ± 0.94, n = 7) during the dynamic and static scans (tumor SUVmax, 2.41 ± 0.64 [n = 11]; LN SUVmax, 2.60 ± 1.17 [n = 7]) (Fig. 3C). The T/M ratios acquired from the 2 sets of scans demonstrated sufficient contrast for the accurate detection of primary tumors (6.51 ± 2.51 and 5.69 ± 1.62, respectively; n = 11) and LN metastasis (6.07 ± 2.85 and 5.79 ± 1.91, respectively; n = 7) (Supplemental Fig. 4). Next, we performed kinetic modeling of 64Cu-DOTA-ECL1i tumor uptake to better understand its targeting specificity. Initial kinetic modeling of CCR2 tracer tumor time–activity curves showed that the reversible 2-compartment model (4 parameters) fit the best, with a volume of distribution almost 4 times higher than that of muscle (Supplemental Fig. 5; Supplemental Table 2). The parametric volume-of-distribution image was comparable with 64Cu-DOTA-ECL1i PET/CT images (Supplemental Fig. 3B), supporting the targeting specificity.

FIGURE 3.

FIGURE 3.

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64Cu-DOTA-ECL1i PET/CT of a patient with HNSCC. (A) CT, PET, and PET/CT images after 0- to 60-min dynamic scan of patient with HNSCC (green arrow, primary tumor; red arrow, LN; cyan arrow, bone invasion) showing 64Cu-DOTA-ECL1i detection of primary tumors and metastatic LNs. (B) 18F-FDG PET/CT acquired at 1 h postinjection revealing tumors and LNs. (C) 64Cu-DOTA-ECL1i tumor and LN uptake and target-to-background ratios for all 11 patients with HNSCC at both time points.

Hematoxylin and eosin staining of the primary tumor and LN specimens from patient HN-4 showed that the tumor was a well-differentiated keratinizing squamous cell carcinoma with dense expression of TP63-positive tumor cells. Whole-tissue and zoomed-in immunofluorescence staining revealed high expression of CCR2 across the tumor and LN, supporting the CCR2 PET data (Figs. 4A and 4B). Consistent with preclinical data, significant colocalizations were observed between CCR2 and TP63 and between CCR2 and CD68 in these specimens. Quantification of CCR2-to-DAPI (4′,6-diamidino-2-phenylindole) ratios from immunofluorescence staining showed strong CCR2 positivity in both sets of specimens, although the ratio for the LN (34.7% ± 15.4%, n = 7) was significantly higher than that for the primary tumor (21.7% ± 12.1%, n = 10) (Fig. 4C; Supplemental Fig. 6), likely because of the involvement of CCR2-positive, CD68-positive macrophages in metastasis. Ex vivo autoradiography of the primary tumor revealed strong 64Cu-DOTA-ECL1i binding to the tissue, which was significantly blocked by the competitive blockade, indicating binding specificity. Quantification of immunofluorescence staining intensity and autoradiography signal showed positive linear correlation, indicating the specificity of 64Cu-DOTA-ECL1i binding to CCR2 on the tumor (Fig. 4D). Moreover, regression analyses showed linear correlations between tumor uptake (SUVmean and SUVmax) and graded CCR2 positivity, and the number of CCR2-positive cells quantified from tissue immunofluorescence staining (Fig. 4E), further confirming imaging specificity of 64Cu-DOTA-ECL1i in patients with HNSCC.

FIGURE 4.

FIGURE 4.

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Characterization of primary tumor and LN from patient with HNSCC. Hematoxylin and eosin (H&E) and immunofluorescence staining of primary tumor (A) and LN (B) showing significant expression of CCR2. (C) Quantification of CCR2-to-DAPI staining positivity in primary tumor and LN. (D) Ex vivo autoradiography of 64Cu-DOTA-ECL1i binding to tumor and correlation with CCR2 immunostaining. (E) Correlation analyses between 64Cu-DOTA-ECL1i tumor uptakes and graded CCR2 positivity and number of CCR2-positive cells quantified from immunofluorescence staining. IHC = immunohistochemistry. **P < 0.01; ****P < 0.0001.

DISCUSSION

Because of the overexpression of CCR2 in both macrophages and malignant cells, the inhibition or deletion of CCR2 reduces infiltration of immunosuppressive myeloid cells, elevates penetration of CD8-positive T cells, and decreases tumorigenesis (31), demonstrating the importance of CCR2 in mediating the tumor microenvironment and potential as a biomarker for HNSCC imaging and therapy. Here, we reported the sensitive and specific detection of CCR2-positive cells in MOC1 and HNSCC PDX models using 64Cu-DOTA-ECL1i, assessed the potential of CCR2 inhibition for MOC1 tumor treatment, and performed proof-of-concept imaging in patients with HNSCC to determine CCR2 expression in primary tumors and metastatic LNs.

Consistent with our previous data acquired in mouse models with inflammatory diseases (24–27), 64Cu-DOTA-ECL1i PET revealed sensitive and specific detection of CCR2-positive cells, leading to significant tumor uptake that gradually increased as the malignancy progressed. Specifically, uptake of 64Cu-DOTA-ECL1i at the early stage of tumor development due to the overexpression of CCR2 on MOC1 cells and recruitment of TAMs highlighted the tumor imaging specificity of 64Cu-DOTA-ECL1i. Although the tumor uptake of 18F-FDG was approximately 50% higher than that of 64Cu-DOTA-ECL1i, the higher T/M ratios of 64Cu-DOTA-ECL1i during MOC1 tumor progression support the radiotracer’s tumor imaging efficiency. Moreover, 64Cu-DOTA-ECL1i demonstrated sensitivity in the detection of tumor treatment responses and a close association between tumor volumes and tumor uptake under the 4 different settings, further highlighting the role of CCR2 in tumor development and confirming the efficiency of 64Cu-DOTA-ECL1i for HNSCC imaging.

We next assessed the potential of CCR2 as a target for HNSCC therapy by using the CCR2 inhibitor propagermanium in the MOC1 tumor model. Consistent with another report (29), propagermanium effectively inhibited tumor growth to a level similar to that of cisplatin plus PD-1 blockade, which led to significantly decreased tumor uptake and improved survival compared with the untreated mice, suggesting the potential of CCR2 as a therapeutic target for MOC1 tumors.

In the selected PDX model with moderate expression of CCR2, 64Cu-DOTA-ECL1i revealed significant and heterogeneous tumor uptake and high T/M ratios, which increased with the progression of the PDX tumors. Tissue characterization demonstrated the elevated expression of CCR2 on TP63-positive malignant cells throughout the tumor, as well as the substantial infiltration of CD68-positive macrophages (32,33), supporting the further investigation of CCR2 PET in patients with HNSCC.

On the basis of our previous human imaging work (24,25,34), we translated the CCR2 PET in patients with HNSCC with tumors at varying stages. Our unique ability to comparatively analyze tumor uptake and CCR2 content in surgically harvested malignant tissues provides evidence of tissue validation of the imaging result. Compared with the nonmalignant contralateral side, which showed low radiotracer retention, CCR2 PET demonstrated a significant and heterogeneous uptake in primary tumors and metastatic LNs in all patients with HNSCC. The low background retention resulted in high T/M ratios, enabling the accurate detection of all tumors. The comparable T/M ratios between tumor SUVs and volumes of distribution further validated the targeting efficiency of CCR2 PET. Moreover, the high binding capability of 64Cu-DOTA-ECL1i led to persistently increased uptake and T/M ratios at later time points, expanding the imaging applicability. Consistent with the tissue characterization data acquired from mice, substantial expression of CCR2 on tumor cells and macrophages were determined in all the surgical specimens, highlighting the significance of CCR2 in HNSCC pathogenesis. The significant correlation between tumor uptake and characterization of CCR2 expression on tumors (i.e., immunohistochemistry score and number of CCR2-positive cells) suggests the specificity of CCR2 PET for tumor targeting in patients with HNSCC. Moreover, the linear correlation between CCR2 immunostaining and autoradiography signals supports the in vivo tumor targeting specificity of CCR2 PET.

Our study had several limitations. The MOC1 tumor used in this study research is a murine cell line model and may not represent human HNSCC tumor biology. The function of macrophages in NSG mice used to establish PDX models is defective. This may lead to incomplete evaluation of the role of CCR2-positive macrophages in HNSCC tumor pathogenesis in PDX models. Further, all patients were imaged once, as this study was a proof-of-concept study. More studies are necessary to verify the imaging repeatability. Although human imaging data demonstrated the sensitive and specific detection of primary tumors and metastatic LNs, the PET signals came from both CCR2-positive tumor cells and macrophages. Further understanding of the role of CCR2 expression in HNSCC pathogenesis is warranted for next-phase clinical investigation. Moreover, 64Cu-DOTA-ECL1i gradually washed out from the tumors on binding, necessitating further optimization of the imaging protocol to fully realize the potential of 64Cu-DOTA-ECL1i in HNSCC imaging and therapy.

CONCLUSION

64Cu-DOTA-ECL1i demonstrated sensitivity and specificity for imaging CCR2 expression during tumor progression and for monitoring of treatment response in murine HNSCC models. The effective inhibition of MOC1 tumor growth and significant improvement in survival observed after treatment with propagermanium support further evaluation of this as a targeted therapeutic to treat patients with HNSCC. The accurate detection of primary tumors and metastatic LNs in patients with HNSCC highlights the potential of CCR2 PET for HNSCC diagnosis.

DISCLOSURE

The preclinical imaging facility that conducted the animal PET/CT scans is supported by NIH/NCI Support Grant P30CA091842, the Therapy and Response Assessment Core of the Siteman Cancer Center, and NIH instrumentation grants S10OD018515 and S10OD030403. Human imaging was performed in the Center for Clinical Imaging Research supported by Mallinckrodt Institute of Radiology. Yongjian Liu, Robert Gropler, and Farrokh Dehdashtiare are supported by a grant from the NIH (P41EB025815). Yongjian Liu and Robert Gropler have a patent entitled “Methods for Detecting CCR2 Receptors” (patent number 12016935). No other potential conflict of interest relevant to this article was reported.

ACKNOWLEDGMENT

We thank the preclinical imaging facility for conducting the animal PET/CT scans.

KEY POINTS

QUESTION: Can 64Cu-DOTA-ECL1i PET detect HNSCC tumors?

PERTINENT FINDINGS: 64Cu-DOTA-ECL1i showed sensitive and specific detection of CCR2-positive cells in multiple murine HNSCC models. The unique overexpression of CCR2 on tumor cells and macrophages was evidenced on both murine and human tissues. The effective tumor inhibition and improved survival observed with propagermanium treatment in the MOC1 model indicated the potential of CCR2 as a theranostic biomarker for HNSCC. The accurate detection of primary tumors and metastatic LNs in patients with HNSCC highlights the potential of CCR2 PET for HNSCC diagnosis.

IMPLICATIONS FOR PATIENT CARE: CCR2 is highly expressed in HNSCC tumors and may be an effective biomarker for HNSCC management. Targeted imaging using 64Cu-DOTA-ECL1i may provide new insights into the role of CCR2-positive cells in the pathogenesis of HNSCC and be a useful tool for the assessment of patients with HNSCC.

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