Lyell Immunopharma Reports Dose-dependent Clinical Activity from Phase 1 Trial of LYL797, a ROR1-targeted CAR-T Cell Product Candidate Enhanced with its Proprietary Anti-exhaustion Technology

SOUTH SAN FRANCISCO, Calif., June 26, 2024 (GLOBE NEWSWIRE) -- Lyell Immunopharma, Inc. (Nasdaq: LYEL), a clinical‑stage T-cell reprogramming company advancing a diverse pipeline of cell therapies for patients with solid tumors, today announced initial clinical and translational data from its Phase 1 trial of LYL797, its first-generation reprogrammed ROR1 CAR T‑cell product candidate enhanced with proprietary anti-exhaustion technology. The initial dataset consists primarily of patients with triple-negative breast cancer (TNBC) and demonstrated dose-dependent antitumor clinical activity and the ability of LYL797 CAR T cells to proliferate, infiltrate tumors and kill cancer cells in patients with relapsed/refractory disease. Patients with TNBC treated with LYL797 had an objective response rate (ORR) of 40% and clinical benefit rate (CBR) of 60% at the 150 x 10⁶ CAR T cell dose level, with a CBR of 38% across all dose levels evaluable to date. Common treatment-related adverse events in patients without lung metastases included Grade 1 and 2 cytokine release syndrome (CRS) and headache, and the expected cytopenia from lymphodepletion. There were no reports of immune effector cell-associated neurotoxicity syndrome (ICANS) attributed to LYL797. Pneumonitis occurred in patients with lung metastases and dose escalation is continuing separately and more gradually in those patients. No dose-limiting toxicities have been reported in patients without lung involvement. All patients are now receiving prophylactic steroids prior to LYL797 treatment.