ALK-specific TCR-T cells showed potent and specific activity in ALK-positive anaplastic large cell lymphoma

Introduction: Anaplastic Lymphoma Kinase (ALK)-positive Anaplastic Large Cell Lymphoma (ALCL) is a rare subtype of T-cell lymphoma driven by nucleophosmin 1 (NPM1)-ALK fusion protein. Treatment with standard chemotherapy or ALK tyrosine kinase inhibitor crizotinib is highly effective; however, a significant portion of patients still experience relapses or refractory disease, highlighting the need for innovative therapeutic options. Our group has recently identified two ALK-specific T cell receptors targeting the human ALK peptide RPRPSQPSSL presented by HLA-B*07:02 (B7) and demonstrated specific and robust anti-tumor activity of ALK.TCR-T cells (ALK.TCR-T) in ALK+ non-small cell lung cancer [Mecca et al, Cancer res, 2024]. In this work, we aimed to address the efficacy of ALK.TCR-T in multiple models of ALK+ ALCL. Methods: Two ALK-specific TCRs were retrovirally transduced into human CD3+ T cells to generate ALK.TCR-T1 and ALK.TCR-T2. The anti-tumor activity of ALK.TCR-T was tested both in vitro and in vivo against a panel of crizotinib-sensitive and crizotinib-resistant ALK+ ALCL models. The specificity of peptide-MHC recognition was evaluated by employing ALK+/B7+, ALK+/B7-, and ALK-/B7+ cells. For in vivo studies, NSG mice were injected intravenously with ALK+ ALCL cell lines, and, after engraftment, treated with ALK.TCR-T, alone or in combination with crizotinib. Mice received 50mg/kg crizotinib by oral gavage for 10 days. Tumor growth was evaluated weekly by bioluminescence imaging. Results: In vitro killing assays demonstrated that both ALK.TCR-T selectively recognize and eliminate 80-100% of ALK+/B7+ ALCL, while no killing occurred in ALK+/B7- or ALK-/B7+ models, confirming that ALK.TCR-T specifically target the ALK peptide RPRPSQPSSL presented by HLA-B*07:02. Moreover, ALK-TCR-T were equally effective in killing crizotinib-resistant ALCL cells, independently of the mechanism driving the resistance to crizotinib. Interestingly, the combination of ALK.TCR-T and crizotinib potentiated the killing of crizotinib-sensitive ALK+ ALCL even at unfavorable E:T ratios (1:5 and 1:10).A single treatment with ALK.TCR-T significantly slowed tumor growth in an ALK+/B7+ systemic tumor model and increased the survival of mice, compared to treatment with irrelevant TCR-T cells. The combined treatment with ALK.TCR-T and crizotinib resulted in a further enhancement of tumor regression and mouse survival, with 50% (5/10) mice with no evidence of tumor 40 days after ALK.TCR-T injection. Conclusions: We demonstrated that ALK.TCR-T show specific and potent anti-tumor activity against multiple ALK+ ALCL models both in vitro and in vivo. The combination of ALK.TCR-T and crizotinib further potentiate the ability of ALK.TCR-T to control tumor growth and extend the survival of mice. These results lay the basis for developing a novel immunotherapy strategy for patients with ALK+ ALCL.