CheckMate 8KX: Phase 1/2 multitumor preliminary analyses of a subcutaneous formulation of nivolumab (± rHuPH20).

2575 Background: Immunotherapy has transformed cancer survival expectations. Nivolumab (NIVO), a programmed death-1 inhibitor, is approved for intravenous (IV) administration across multiple cancers. BMS is developing a subcutaneous (SC) NIVO formulation with a permeation enhancer, recombinant human hyaluronidase PH20 enzyme (rHuPH20), to allow for more rapid delivery and the potential to decrease treatment burden. We report the first data on pharmacokinetics (PK), pharmacodynamics, safety, and immunogenicity for SC NIVO + rHuPH20. Methods: CheckMate 8KX is a phase 1/2 study in checkpoint inhibitor-naïve patients (pts) who were ≥ 18 years of age, ECOG PS 0–1, with metastatic/unresectable solid tumors and measurable disease. The primary objective was to describe SC NIVO PK; secondary objectives were safety and immunogenicity. Additional analyses compared exposures to historical IV NIVO (Zhao X, et al. J Clin Oncol 2020;31:302–309). In cycle 1, pts in Part A received SC NIVO 720 mg + rHuPH20, and pts in Part B received SC NIVO 720 mg, SC NIVO 960 mg + rHuPH20, or SC NIVO 960 mg. For cycles 2+, pts in Parts A and B received IV NIVO 480 mg every 4 weeks (Q4W). Pts still on study switched to Part C, SC NIVO 1200 mg + rHuPH20 until end of therapy. In Part D, pts received de novo SC NIVO 1200 mg + rHuPH20 Q4W. Results: Patient characteristics varied by age, weight, tumor type, and prior treatment. NIVO exposures increased with increasing SC dose (Table). For 960 mg and 1200 mg NIVO + rHuPH20, Cavg and Ctau were above geometric mean exposures for IV NIVO 3 mg/kg every 2 weeks (Q2W), and Cmax was below IV NIVO 10 mg/kg Q2W. In Part C (n = 28), 13 (46.4%) pts experienced any-grade TRAEs with no new/worsening grade 3+ TRAEs or TRAEs leading to discontinuation/death; 7 (25.0%) reported grade 1 local site reactions. In Part D (n = 36), 27 (75.0%) pts experienced any-grade TRAEs, 4 (11.1%) grade 3/4 TRAEs, 2 (5.6%) serious grade 3/4 TRAEs with 1 leading to discontinuation, and no treatment-related deaths; 10 (27.8%) reported grade 1 local site reactions. Anti-NIVO antibodies (Ab) were observed with SC NIVO but not associated with altered PK/safety, or neutralizing Ab. Exploratory biomarker data found increased CD8+ tumor-infiltrating lymphocytes and PD-L1 tumor expression in post-treatment biopsies, similar to IV NIVO. Conclusions: Exposures associated with SC NIVO + rHuPH20 doses investigated in CheckMate 8KX were well tolerated, with a safety profile consistent with IV NIVO. Data support evaluation of SC NIVO + rHuPH20 in a phase 3 study. Clinical trial information: NCT03656718. [Table: see text]