3016 Background: The immune checkpoint receptor programmed death-1 (PD-1) negatively regulates T-cell activation. In a phase I study, nivolumab, a PD-1 receptor blocking antibody, demonstrated durable clinical activity. Evaluation of the expression of the PD-1 ligand, PD-L1, by IHC with the 5H1 Ab suggested a correlation between pretreatment tumor PD-L1 expression and clinical response (Topalian et al, NEJM 2012). Methods: 304 pts with non-small cell lung cancer (NSCLC, n=127), melanoma (MEL, n=107), renal cell (RCC, n=34), colorectal (n=19) or prostate cancer (n=17) received nivolumab between 2008-2012 (0.1−10 mg/kg IV Q2W) during dose escalation and/or cohort expansion. Formalin-fixed paraffin-embedded tumor tissue and peripheral blood mononuclear cells (PBMC) were analyzed to explore potential pharmacodynamic/ predictive biomarkers associated with nivolumab therapy. Tumor surface PD-L1 expression was evaluated by IHC using an automated assay based on a sensitive and specific PD-L1 mAb (28-8) distinct from 5H1. PD-L1 positivity (PD-L1+) was defined as ≥5% cell membrane staining of any intensity. Lymphocyte subsets in PBMC were measured using flow cytometry. Results: Tumor membrane PD-L1 was measured in 101 MEL and NSCLC pts. 17/38 (45%) of MEL and 31/63 (49%) of NSCLC biopsies were PD-L1+. A numerically higher objective response rate (ORR), longer progression-free survival (PFS), and overall survival (OS) was seen with PD-L1+ in MEL pts (Table).Analysis of the association of PD-L1 expression with ORR, PFS and OS in NSCLC is ongoing. A correlative analysis of pt response with pre-/post-dose levels of lymphocytes will be presented. Conclusions: These data, using a novel, automated PD-L1 IHC assay and mAb, support the hypothesis of tumor PDL1+ predicting activity of nivolumab in advanced cancer, which is being prospectively assessed in phase III trials. Clinical trial information: NCT00730639. [Table: see text]

BackgroundMatrix metalloproteinase-9 (MMP9) selectively cleaves extracellular matrix proteins contributing to tumor growth and an immunosuppressive microenvironment. This study evaluated andecaliximab (ADX), an inhibitor of MMP9, in combination with nivolumab (NIVO), for the treatment of advanced gastric cancer.MethodsPhase 2, open-label, randomized multicenter study evaluating the efficacy, safety, and pharmacodynamics of ADX+NIVO versus NIVO in patients with pretreated metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma. The primary endpoint was objective response rate (ORR). Secondary endpoints included progression-free survival (PFS), overall survival (OS), and adverse events (AEs). We explored the correlation of efficacy outcomes with biomarkers.Results144 patients were randomized; 141 were treated: 81% white, 69% male, median age was 61 years in the ADX+NIVO group and 62 years in the NIVO-alone group. The ORR was 10% (95% CI 4 to 19) in the ADX+NIVO group and 7% (95% CI 2 to 16) in the NIVO-alone group (OR: 1.5 (95% CI 0.4 to 6.1; p=0.8)). There was no response or survival benefit associated with adding ADX. AE rates were comparable in both treatment groups; the most common AEs were fatigue, decreased appetite, nausea, and vomiting. Programmed cell death ligand 1, interferon-γ (IFN), and intratumoral CD8+ cell density were not associated with treatment response or survival. The gene signature most correlated with shorter survival was the epithelial-to-mesenchymal gene signature; high transforming growth factor (TGF)-β fibrosis score was negatively associated with OS (p=0.036). Gene expression analysis of baseline tumors comparing long-(1+ years) and short-term (<1 year) survivors showed that GRB7 was associated with survival beyond 1 year. Human epidermal growth factor receptor 2 (HER2)-positive disease was associated with significantly longer survival (p=0.0077). Median tumor mutation burden (TMB) was 2.01; patients with TMB ≥median had longer survival (p=0.0025) and improved PFS (p=0.016). Based on a model accounting for TMB, TGF-β fibrosis, and HER2, TMB was the main driver of survival in this patient population.ConclusionCombination of ADX+NIVO had a favorable safety profile but did not improve efficacy compared with NIVO alone in patients with pretreated metastatic gastric or GEJ adenocarcinoma. HER2 positivity, higher TMB or GRB7, and lower TGF-β were associated with improved outcomes.Trial registration numberNCT02864381 or GS-US-296–-2013.

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Monoclonal antibodies (mAbs) are widely used in the treatment of lymphoma and autoimmune diseases. The activity of several mAbs depends on the binding of the Fcγ regions to low-affinity Fcγ receptors (FcγR) expressed on effector cells, chiefly mononuclear phagocytes, cells that express both activating and inhibitory FcγRs. FcγRIIB (CD32B), the inhibitory FcγR, is expressed by normal and malignant B lymphocytes and is itself an immunotherapeutic target. A recently characterized anti-human CD32B-specific mAb (2B6) was Fc engineered to customize the FcγR binding profile for increased binding to the activating receptor FcγRIIIA (CD16A), resulting in an improved activating-to-inhibitory binding ratio. Fc-optimized versions of 2B6 showed enhanced cytotoxicity in vitro and increased potency in animal tumor models, including transgenic mice harboring the human low-affinity allele of the activating receptor, CD16A-158phe. The enhancement in tumor depletion correlated with an increased binding to FcγRIV, a mouse functional homolog to human CD16A. The expression of FcγRIV is limited to monocyte and macrophages, consistent with the role of these cells in tumor cell killing in vivo. These data support CD32B as a target for immunotherapy of B cell lymphoproliferative disorders and Fc optimization to increase the activating-to-inhibitory FcγR-binding ratio as a means to designing improved antibodies.