Abstract 2746: Preclinical activity and manufacturing feasibility of genetically modified PDCD-1 knockout (KO) tumor-infiltrating lymphocyte (TIL) cell therapy (2022)

Abstract Background: Adoptive cell therapy with autologous TIL has demonstrated an objective response rate (ORR) of 36% in the post-immune checkpoint inhibitor (ICI) setting in patients (pts) with advanced/unresectable melanoma (Sarnaik JCO 2021), while in ICI-naïve pts who received early-line combination of TIL and pembrolizumab, the ORR was 60%, with a 30% CR rate (O’Malley SITC 2021). Although effective, anti-PD-1 therapy is limited by poor penetration into the tumor, internalization, and endocytic clearance, in contrast with TIL, which overcome this inherent limitation. PDCD-1 gene inactivation (PD-1 KO) may enhance TIL cell therapy efficacy in the post-ICI setting and abrogate the need for systemic anti-PD-1 therapy in ICI-naïve pts. In preclinical studies, PD-1 KO TIL maintain robust effector function and phenotypic markers indicative of functional TIL (Ritthipichai ESMO 2020). We describe preclinical activity, clinical-scale manufacturing process development, and characterization of IOV-4001, an autologous PD-1 KO TIL cell product. Methods: hIL-2 NOG mice engrafted with melanoma tumor cells received adoptive transfer of autologous PD-1 KO TIL (developed with TALEN® gene editing technology in collaboration with Cellectis), mock TIL (electroporation without TALEN), mock TIL + anti-PD-1 antibody, or no adoptive transfer (n=14 each). Tumor size was measured 2×/wk for 39 days. A 22-day clinical-scale manufacturing process was established, including pre-rapid expansion protocol (pre-REP), activation, electroporation, resting, and REP, for the generation of PD-1 KO TIL. Final PD-1 KO TIL product was characterized for total viable cells (TVC), purity (% viability), identity (% CD45+CD3+), and function (PD-1 KO efficiency). Results: Day 39 mean ± SEM tumor size (mm2) for mice treated with PD-1 KO TIL (6 ± 2.8) showed superior tumor control relative to mock TIL (26 ± 8.5, P&amp;lt;0.05), mock TIL + anti-PD-1 (33 ± 8.8, P&amp;lt;0.01), and no adoptive TIL transfer (112 ± 8.4, P&amp;lt;0.0001). Product attributes from 6 clinical-scale manufacturing runs for PD-1 KO TIL were acceptable, with a median (range) TVC, purity, and identity of 8.3 × 109 (0.9×109-35.7×109), 94% (91%-99%), and 99% (98%-99%), respectively. Median (range) PD-1 KO efficiency was 48% (31%-84%). PD-1 KO TIL function and phenotype (differentiation, memory, activation, and exhaustion) were comparable to mock TIL. Conclusions: Anti-tumor activity of PD-1 KO TIL was superior to mock TIL suggesting that endogenous PD-1 inhibition may confer a functional advantage to the TIL over an antibody combination. PD-1 KO TIL clinical manufacturing was feasible and the TIL product quality attributes and phenotype were acceptable; importantly, lack of complete PD-1 KO may spare other PD-1-dependent in vivo cellular functions. Together, these data support clinical investigation of IOV-4001, an autologous PD-1 KO TIL cell therapy. Citation Format: Arvind Natarajan, Anand Veerapathran, Adrian Wells, Kenneth Onimus, Marcus Machin, Seth Wardell, Jamie L. Blauvelt, Madan Jagasia, Rafael Cubas. Preclinical activity and manufacturing feasibility of genetically modified PDCD-1 knockout (KO) tumor-infiltrating lymphocyte (TIL) cell therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2746.