Small cell lung cancer (SCLC) remains a highly lethal disease with limited targetable surface antigens beyond delta-like ligand 3 (DLL3). We sought to systematically identify and validate tumor-selective cell-surface targets in relapsed SCLC. To this end, we developed an integrated proteogenomic pipeline combining single-cell RNA sequencing, combinatorial optimization, mass spectrometry–based proteomics, and immunohistochemistry to systematically map the SCLC surfaceome of 49 tumors across 25 patients with relapsed SCLC. Using this approach we found claudin-3 (CLDN3) to be a consistently expressed and tumor-selective antigen, with broader coverage than DLL3, which is the current clinical benchmark. CLDN3 was highly expressed across various treatment states, while maintaining low expression in most nonmalignant tissues. Functional validation using a novel CLDN3-specific monoclonal antibody (ABN501) demonstrated NK cell–mediated cytotoxicity in vitro and tumor regression in vivo, as well as a favorable safety profile. These findings support clinical development of CLDN3-directed therapies and demonstrate the utility of integrated proteogenomic approaches for antigen discovery in solid tumors.
Brett Schroeder, Jaehyun Choi, Alejandro A Schaffer et al.· bioRxiv· 0 citations
Neoepitope-based therapies hold great promise for cancer immunotherapy because they target tumor-specific mutations and elicit potent anti-tumor T-cell responses. However, their clinical implementation remains limited by the complexity of neoepitope discovery and uncertainty regarding presentation by tumor cells. A potential alternative is the generation of immunogenic neoepitopes directly within cancer cells through programmable RNA editing. Here, we develop Short Precise-Encodable ADAR Recruiting (SPEAR) gRNAs that harness endogenous ADAR1 to direct precise adenosine-to-inosine (A-to-I) editing at selected transcript sites. Using these gRNAs, we demonstrate the generation of immunogenic neoepitopes through RNA editing at the transcript level, termed editopes. In a proof-of-concept model based on the melanoma antigen MART-1, SPEAR-mediated RNA editing restored antigen-specific T cell recognition and enabled tumor control in vivo. Finally, we developed a computational pipeline to identify candidate tumor-selective neoepitopes across multiple cancer types amenable to guided RNA editing. Our findings establish programmable RNA editing as a strategy for engineering immunogenic editopes and provide a framework for neoepitope-directed cancer immunotherapy.
R. Pecori, Beatrice Casati, Rona Merdler-Rabinowicz et al.· EMBO Journal· 0 citations