Abstract 5702: Characterization of circulating tumor cells during immune checkpoint inhibition in metastatic renal cell carcinoma and malignant melanoma
Zhang, T; Park, S; Runyambo, D; Poellmann, MJ; Reyes-Martinez, M; Mahbooba, Z; Green, R; Lee, C; George, DJ; Armstrong, AJ; Hong, S; Wang, AZ
Published in: Cancer Research
Background: Although immune checkpoint inhibitors (ICIs) have shown efficacy in a range of solid tumors, there are no established circulating biomarkers able to identify early responders to treatment. Circulating tumor cells (CTCs) allow a non-invasive peripheral assessment of disease burden over time. We evaluated the prevalence of CTCs before and during treatment with ICIs.Methods: Patients were enrolled prospectively at Duke Cancer Center and UNC Lineberger Cancer Center and selected for metastatic renal cell carcinoma (mRCC) and metastatic malignant melanoma (mMM) receiving standard of care immunotherapy. Using E-selectin for slowing cell rolling and a nanoparticle dendrimer based technology for cell capture with EpCAM, HER2, and EGFR, the CapioCyte platform was used for CTC capture at baseline, during treatment, and upon disease progression.Results: We enrolled 5 subjects with mRCC and 4 subjects with mMM. Prior to treatment, subjects had a median of 293 CTCs/mL (all healthy volunteers (HVs, n=10) had <8 CTCs/mL). All subjects had more CTCs at baseline than HVs. One subject had CTCs rise within the first 4 weeks on ICI treatment, which corresponded to clinical disease progression. Several other subjects showed a rapid decrease in CTCs within 4 weeks but increased at the time of disease progression. In most cases of disease control, CTCs decreased by at least 50% at the 4-week timepoint and increased at time of disease progression.Conclusions: CapioCyte is a sensitive platform to detect CTCs in mRCC and mMM. Based on CTC detection, many patients had early response to ICI treatment, but rapid progression corresponding to clinical progression. This pilot data suggest that CTCs can be a valuable biomarker for monitoring the clinical benefit of cancer immunotherapies.Citation Format: Tian Zhang, SinJung Park, Daniella Runyambo, Michael J. Poellmann, Marco Reyes-Martinez, Zahra Mahbooba, Rebecca Green, Carrie Lee, Daniel J. George, Andrew J. Armstrong, Seungpyo Hong, Andrew Z. Wang. Characterization of circulating tumor cells during immune checkpoint inhibition in metastatic renal cell carcinoma and malignant melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5702.
