Sapu003 in Advanced mTOR-sensitive Solid Tumors

This study is testing a new drug called Sapu003, which blocks a cellular signaling pathway called mTOR, in two groups of patients: postmenopausal women with hormone receptor-positive, HER2-negative advanced breast cancer (Cohort A), and adults with kidney cancer, neuroendocrine tumors, TSC-related tumors, or liver cancer (Cohort B). **You may be eligible if (Cohort A — breast cancer)...** - You are a postmenopausal woman with advanced ER+/HER2- breast cancer - Your cancer has progressed after prior hormone therapy (with or without a CDK4/6 inhibitor) - You have not previously received mTOR inhibitors **You may be eligible if (Cohort B — other cancers)...** - You are 18 or older with advanced kidney cancer, neuroendocrine tumors, TSC-associated tumors, or hepatocellular carcinoma - Your cancer has progressed on or after prior standard therapy **You may NOT be eligible if...** - You have received prior mTOR inhibitor therapy - Your organ function is too poor to tolerate treatment - You are pregnant or breastfeeding - You have uncontrolled infections or certain lung conditions Talk to your doctor to see if this trial is right for you.