The main purpose of this study is to determine the highest dose of STK-012 that can be given safely alone and in combination with a standard dose of pembrolizumab in subjects with advanced solid tumors, this will be assessed in the dose escalation phase of the study. In the dose expansion phase of the study, the highest dose of STK-012 that can be safely given in combination with pembrolizumab, as determined in the dose escalation phase, will be given to more people for further study.STK-012 is a modified (changed in the laboratory) form of a cytokine (protein) called interleukin-2 (IL-2)...