Abstract LB419: Dose escalation and expansion of nivolumab plus relatlimab (NIVO + RELA) in solid tumors in RELATIVITY 020 Parts A-C

Abstract Background: NIVO + RELA is approved for unresectable or metastatic melanoma at 480 mg NIVO + 160 mg RELA Q4W based on results from RELATIVITY-047. RELATIVITY-020 (NCT01968109) was a phase 1/2a, dose escalation and cohort expansion open-label study investigating RELA +/− NIVO in advanced solid tumors. Parts A-C investigated dose escalation and expansion into solid tumor types. Methods: See Table for tumor types and abbreviations. Part A was a dose escalation analysis in patients (pts) with immuno-oncology (IO) treatment-naive solid tumors with RELA monotherapy at 20-800 mg with dose expansion studies in IO RF NSCLC and RCC (A1). Part B was NIVO + RELA doseescalation across tumor types plus cervical, ovarian, and colorectal cancer from Q2W 80 + 20 to 240 + 240 mg or Q4W 480 + 160 to 480 + 1440 mg. Primary endpoint in Parts A and B was safety. Part C was expansion at NIVO + RELA 240 + 80 Q2W (with bladder at 480 + 160 Q4W). Endpoints were safety and BICRassessed ORR, disease control rate, and duration of response. Results: Baseline LAG3 expression ≥ 1% was comparable across cohorts (24-41%). Minimum follow-up in mo was: 87-110 (Part A), 44 (B), and 61-84 (C). NIVO + RELA dose escalation demonstrated an acceptable safety profile, with no maximum tolerated dose (MTD) identified. Grade 3-4 treatment-related adverse events occurred in approximately 16% of pts across all Parts, leading to discontinuation in 4-11% of pts. Efficacy was noted across all tumor types tested in Part C (Table). RELA exposure increased doseproportionally as combination or monotherapy. No pharmacokinetic interaction between NIVO and RELA was identified and there was a low incidence of antidrug and neutralizing antibodies for both RELA and NIVO. Conclusions: NIVO + RELA demonstrated preliminary efficacy across several different tumor types. Clinical activity was observed in both IO naive and IO RF pts, with tolerable toxicity observed. Although no MTD was reached, PK data supported the NIVO 480 + RELA 160 mg dose. Citation Format: Paolo A. Ascierto, Carlo Gomez-Roca, Ignacio Melero, Katriina Jalkanen, Rachel E. Sanborn, Juan Martin-Liberal, James Larkin, Rastilav Bahleda, F. Stephen Hodi, Margaret Callahan, Marta Nykas, Giuseppe Curigliano, Sebastian Bauer, Solange Peters, Takekazu Aoyama, Mark Semaan, Sourav Mukherjee, Sonia Dolfi, Satyendra Suryawanshi, Evan Lipson. Dose escalation and expansion of nivolumab plus relatlimab (NIVO + RELA) in solid tumors in RELATIVITY 020 Parts A-C abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts) ; 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86 (8Suppl): Abstract nr LB419.