Additional Study Information: This study is an open-label, multicenter phase 1/2 study. The study is designed in two parts, the first is designed to evaluate the safety of the study drug ulocuplumab in combination with nivolumab in subjects with small cell lung cancer (SCLC) and pancreatic adenocarcinoma (PAC). Subjects will receive a low dose of ulocuplumab in combination with nivolumab which will be increased to determine the maximum tolerated dose (MTD). This dose level will then be used in a dose expansion phase to further determine the safety profile of the study drugs. The second part will evaluate how well the study drug works on the body when given in combination with nivolumab.