Abstract LB418: RELATIVITY-104 Part 2: translational analyses in the programmed death ligand 1 (PD-L1) ≥ 1% and non-squamous (NSQ) non-small cell lung cancer (NSCLC) subgroup

Abstract Background: In Part 2 of the phase 2 RELATIVITY-104 study of first-line nivolumab (NIVO) plus relatlimab (RELA) with platinum-doublet chemotherapy (PDCT) vs NIVO + PDCT in patients with metastatic NSCLC, NIVO + RELA + PDCT demonstrated improved clinical benefit, including overall survival, in the prespecified subgroup of tumor PD-L1 expression ≥ 1%, which was further enriched in NSQ tumor histology. Baseline lymphocyte-activation gene 3 (LAG-3) expression was associated with enriched efficacy for both NIVO + RELA + PDCT and NIVO + PDCT. In a comparative transcriptomic analysis, NSQ and squamous tumors demonstrated distinct immune signatures, with NSQ tumors exhibiting higher expression of LAG-3 ligands and greater enrichment for combination therapy benefit by PD-L1 expression. To further elucidate the mechanism of action of NIVO + RELA + PDCT, we report additional exploratory translational data in the PD-L1 ≥ 1% NSQ subgroup for Part 2 of RELATIVITY-104. Methods: Patients with untreated metastatic NSCLC were randomized 1:1 to NIVO 360 mg + RELA 360 mg + PDCT or NIVO 360 mg + PDCT Q3W. Exploratory endpoints included translational analyses in the PD-L1 ≥ 1% NSQ subgroup. Gene expression data from pretreatment tumor RNA sequencing were normalized and analyzed for associations with clinical outcomes. Pre- and on-treatment peripheral blood samples were collected for high-dimensional flow cytometry immunophenotyping using a validated 24-marker LAG-3-specific panel that used drug-tolerant, noncompeting clones for LAG-3, PD-1, and CTLA-4. Statistical associations between biomarkers and clinical outcomes were assessed using logistic regression and Cox proportional hazards models. Data are from the May 2, 2025, database lock. Results: In the NIVO + RELA + PDCT arm, immune signatures demonstrated a significantly lower hazard ratio (HR) in the PD-L1 ≥ 1% NSQ subgroup, while stromal signatures demonstrated a significantly higher HR. T exhausted progenitor signature subsets, as well as ICOS+ CD4+ T cells, at baseline were shown to enrich for survival with NIVO + RELA + PDCT. Clinical benefit was observed across all baseline LAG-3 expression levels (< 1% and ≥ 1%); however, on-treatment increases in LAG-3+ T cells were associated with longer progression-free survival and a higher objective response rate with NIVO + RELA + PDCT. In the NIVO + PDCT arm, increases in LAG-3 cell populations were associated with lower response. Conclusions: In the RELATIVITY-104 study, the on-treatment immune dynamics of LAG-3+ T cells correlated with the benefit of NIVO + RELA + PDCT vs NIVO + PDCT in patients with PD-L1 expression ≥ 1% and NSQ NSCLC. Immune signatures including progenitor T exhausted signatures associated with improved outcomes with NIVO + RELA + PDCT. These data support the mechanistic rationale for adding anti-LAG-3 to anti-PD-1 + PDCT in PD-L1 ≥ 1% NSQ NSCLC. Citation Format: Jaclyn Neely, Annie Yu, Nicolas Girard, Manuel Cobo-Dols, Mauricio Burotto, Luis Paz-Ares, Vamsidhar Velcheti, Martin Reck, Srijata Samanta, Anila Qureshi, Priyanka Kasbekar, Charlie Garnett-Benson. RELATIVITY-104 Part 2: translational analyses in the programmed death ligand 1 (PD-L1) ≥ 1% and non-squamous (NSQ) non-small cell lung cancer (NSCLC) subgroup [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(8_Suppl):Abstract nr LB418.