Abstract 5619: First-in-class anaplastic lymphoma kinase (ALK)-specific TCR-T cells induce potent and selective antitumor immunity across ALK-driven human cancers

Abstract Introduction: Anaplastic Lymphoma Kinase (ALK) tyrosine kinase inhibitors (TKIs) have dramatically improved outcomes for patients with ALK-rearranged non-small cell lung cancer (NSCLC) and other ALK-positive (ALK+) cancer types. However, the near-universal emergence of resistance underscores an urgent need for new, durable therapeutic strategies. Leveraging our prior identification of the ALK-derived peptide RPRPSQPSSL presented by HLA-B*07:02 (PMID: 37430060), we aimed to develop ALK-specific TCR-engineered T cells (ALK.TCR-T) that can selectively recognize and eliminate ALK-driven tumors. Methods: HLA-B*07:02 transgenic mice were vaccinated with the RPRPSQPSSL peptide. After two priming and two booster injections, CD137+/CD8+ T cells were sorted and subjected to single-cell sequencing for TCR discovery. The most expanded TCR clonotypes were then cloned and retrovirally transduced into human T cells to generate ALK.TCR-T cells. The anti-tumor activity of ALK.TCR-T cells was evaluated against various models of ALK+ tumors both in vitro and in vivo. Results: From twelve dominant clonotypes, six ALK-specific TCRs were identified. Two (ALK.TCR-1 and ALK.TCR-2) demonstrated 95% ALK-dextramer binding. Notably, ALK.TCR-2 bound the ALK-dextramer also in CD4+ T cells, indicating co-receptor-independent peptide-MHC recognition. Both TCRs mediated robust, antigen-specific cytotoxicity against ALK+/HLA-B*07:02+ cell lines, with no activity against mismatched targets. Engineering either EML4;ALK variant 3 or HLA-B*07:02 into non-expressing cells restored potent killing, confirming strict peptide-MHC specificity. In vivo, a single infusion of ALK.TCR-1 or ALK.TCR-2 markedly suppressed tumor growth and extended survival in a metastatic ALK+/HLA-B*07:02+ NSCLC model. Treated animals exhibited near-complete tumor clearance by day 7 post-ALK.TCR-T infusion, while control mice experienced progressive disease. Remarkably, in a metastatic ALK+/HLA-B*07:02+ neuroblastoma model, 70% (7/10) of mice achieved complete, durable responses (100 days tumor-free) without evidence of on-target/off-tumor or off-target toxicity. Conclusion: We report the first generation of ALK-specific TCR-T cells targeting the naturally presented ALK peptide RPRPSQPSSL in the context of HLA-B*07:02. ALK.TCR-T cells display potency, selectivity, and safety across multiple ALK-driven tumor models, providing a strong rationale for advancing ALK.TCR-T cell therapy into clinical development. Citation Format: Carmen Mecca, Simone Piane, Nirmala Tilija Pun, Ana Azambuja, Luca Alessandrí, Rafael Blasco, Chi Nguyen Puc Bao, Elisa Bergaggio, Gabriele Saccu, Alessandro Gasparetto, Haley Ohlson, David A. Barbie, Ellis L. Reinherz, Marcos Simoes-Costa, Roberto Chiarle. First-in-class anaplastic lymphoma kinase (ALK)-specific TCR-T cells induce potent and selective antitumor immunity across ALK-driven human cancers abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5619.