Study to Assess the Effect of OCT-598 in Patients With Advanced Solid Tumors

This study tests a new experimental drug called OCT-598 in people with advanced solid tumors (cancers that have spread and no longer respond to standard treatments). It is an early-phase trial focused on safety, dosing, and early signs of effectiveness. **You may be eligible if...** - You are 18 or older (19 or older in some locations) - You have advanced cancer with at least one measurable tumor - You have no good remaining standard treatment options (Part A), OR you are a candidate for docetaxel chemotherapy for cancers such as breast cancer, head and neck cancer, lung cancer, prostate cancer, or gastric cancer (Part B) - Your liver, kidneys, blood, and heart function are within acceptable levels - Your expected survival is more than 12 weeks **You may NOT be eligible if...** - You have had chemotherapy, immunotherapy, or other anti-cancer treatment in the past 28 days (or 5 half-lives of the drug) - You have uncontrolled brain metastases - You have serious heart problems - You are pregnant or breastfeeding - You have active autoimmune disease requiring systemic treatment Talk to your doctor to see if this trial is right for you.