Immune cell profiling by spectral cytometry to predict response to avelumab in advanced bladder cancer patients.

Abstract

e14529 Background: Bladder urothelial cancer is a common neoplasm with a significant proportion of patients who progress to advanced disease despite optimal local and systemic therapy. Newly immune related therapies have improved patients’ outcome; however, only certain patients achieve durable responses. Hence, there is a need for non-invasive biomarkers for early response prediction. Methods: Peripheral Blood Mononuclear Cells (PBMCs) from advanced bladder cancer patients treated with avelumab (n=11) were obtained prior to immunotherapy administration. One year follow up revealed treatment response, which allowed a cohort division for immune cell signature comparison. A 40-plex spectral cytometry panel was applied, and further computational analysis performed. Results: Unsupervised spectral cytometry analysis revealed a highly heterogeneous circulating immunome landscape, capable of identifying 78 distinct immune clusters. Further analysis discriminated 10 clusters that significantly differed between responders and non-responders, 8 clusters from T, NK & innate lymphoid cells lineage and 2 clusters from Myeloids & antigen presenting cells lineage (Figure 2). Further hierarchical validation confirmed an expansion of effector CD4+ T cells and CD8+ TEMRA cells, an among non-responder patients before therapy. On the contrary, those with subsequent response displayed an overrepresentation of CD2⁻ innate lymphoid cells as well as CD25⁺ classical monocytes, supporting a blood-based immune signature associated with therapeutic benefit. Conclusions: We have demonstrated that spectral cytometry analysis is capable of revealing distinct immune fingerprint among bladder cancer patients in response to immunotherapy. The biomarkers found in this study could therefore be of use for anticipating clinical outcome in these patients, improving disease management.