A phase II trial of nivolumab plus axitinib in patients with anti-PD1 refractory advanced melanoma.

TPS9600 Background: A significant portion of patients (pts) with advanced melanoma (mel) either do not respond or become refractory to immune checkpoint inhibitor (ICI) therapy, with no established second line treatment regimen. A key ICI resistance mechanism includes formation of an immunosuppressive tumor microenvironment (TME). We have shown that high oxidative metabolism (OXPHOS) of mel tumor cells is associated with a hostile TME (1). Furthermore, this is associated with high intra-tumoral hypoxia (ITH). In mel tumor cells with high OXPHOS, CD8+ tumor infiltrating lymphocytes (TIL) display increased exhaustion and decreased functionality (decreased IFN-γ and TNF-α production). Pts with metastatic mel who progressed on ICI had tumor cells with high OXPHOS and ITH. Axitinib is a VEGFR small molecule tyrosine kinase inhibitor with high inhibitory activity for VEGFR 1-3. We previously showed that low dose axitinib reduces ITH in B16 murine mel, and our pre-clinical data show that axitinib synergizes with ICI to produce an improved tumor response (2). We hypothesize that axitinib will re-sensitize mel to ICI by modulating angiogenesis and reducing ITH and resultant T cell dysfunction. Methods: This is an investigator-initiated, single arm phase II trial of nivolumab plus axitinib for pts with unresectable stage III or IV cutaneous, acral, or mucosal mel who have progressed on prior anti-PD1 based therapy in the adjuvant or metastatic setting (NCT04493203). Pts previously treated with concomitant anti-CTLA4, anti-LAG3, BRAF/MEK inhibitors, and/or pts with brain metastases (asymptomatic or stable treated disease x 2 weeks) are eligible. Pts will receive nivolumab 480 mg IV every 4 wks with axitinib PO 5 mg twice daily for up to 2 years, or until progression or unacceptable toxicity. Pts will undergo biopsy at baseline and at 12 wks, with optional biopsy at progression. Pts will receive an oral dose of pimonidazole 0.5 mg/m 2 prior to each biopsy to permit in-vivo evaluation of ITH. Staging scans (full body PET-CT or CT and MRI brain) will be obtained at baseline, with restaging scans at 12 week intervals. Primary endpoint: overall response rate (ORR) by RECIST 1.1. Responses are determined by Blinded Independent Central Review (BICR). Secondary endpoints: safety analysis, progression-free survival (PFS) and overall survival (OS). Extensive correlative translational analyses will focus on immunophenotypic changes in the TME, ITH, profiling of tumor cell metabolism, and TIL function. The null hypothesis that the true ORR is 10% will be tested versus a one-sided alternative hypothesis of ≥25%, using Simon’s minimax two-stage design. This design has a type I error rate 0.08 and power 0.81 when the true response rate is 0.25. PFS and OS will be estimated via Kaplan-Meier method. 31 of planned 31 pts have been enrolled in January 2024, with no data analysis yet available. 1. Najjar et al., JCI Insight 2019. 2. Scharping et al., Nat Immunol 2021. Clinical trial information: NCT04493203 .