LAUSR

4509Background: Pegilodecakin (PEGylated hIL-10, AM0010) alone produced 25% partial responses (PR) in heavily pre-treated (median prior therapies 3) RCC pts. IL-10 receptors and PD1 are expressed on activated and exhausted CD8+ T cells. IL-10 stimulates the cytotoxicity and proliferation of CD8+ T cells. This provides a rationale for combining pegilodecakin with anti-PD-1. Methods: Between 2/20/2015 and 11/18/16, 38 pts with metastatic RCC (87% clear cell) were enrolled in a phase Ib trial and received pegilodecakin at 10 (n = 6) or 20 ug/kg (n = 32, QD SC) and nivo (n = 29; 3mg/kg, q2wk IV) or pembro (n = 9; 2mg/kg, q3wk IV). Pts had intermediate- or poor-risk disease by IMDC criteria (94%) and a median of 1 prior therapy (range: 1-3), including at least one VEGFR-TKI. Results: Pegilodecakin + nivo or pembro was well tolerated. TrAEs were reversible and transient. G3/4 TrAE in pts who received pegilodecakin (20 ug/kg) + nivo or pembro included anemia (10), thrombocytopenia (7), and hypertriglyceridemia (...