The purpose of this Phase 1/2 master protocol study is to evaluate if DCC-3009 is safe, tolerable and works effectively in the treatment of GIST. The study will use a modular approach with each module being defined according to therapy: DCC-3009 alone or DCC-3009 in combination with other anticancer therapies. Each module will be conducted in 2 parts: Part 1 (Dose Escalation) and Part 2 (Dose Expansion). Participants will be treated in 28-day treatment cycles with an estimated duration of up to 2 years.

This phase IV trial evaluates how well giving standard of care (SOC) peptide receptor radionuclide therapy (PRRT) after SOC surgical removal of as much tumor as possible (debulking surgery) works in treating patients with grade 1 or 2, somatostatin receptor (SSTR) positive, gastroenteropancreatic neuroendocrine tumors (GEP-NETs) that have spread from where they first started (primary site) to the liver (hepatic metastasis). Lutetium Lu 177 dotatate is a radioactive drug that uses targeted radiation to kill tumor cells. Lutetium Lu 177 dotatate includes a radioactive form (an isotope) of the element called lutetium. This radioactive isotope (Lu-177) is attached to a molecule called dotatate. On the surface of GEP-NET tumor cells, a receptor called a somatostatin receptor binds to dotatate. When this binding occurs, the lutetium Lu 177 dotatate drug then enters somatostatin receptor-positive tumor cells, and radiation emitted by Lu-177 helps kill the cells. Giving lutetium Lu 177 dotatate after surgical debulking may better treat patients with grade 1/2 GEP-NETs

This Phase II/III trial will evaluate the what kind of chemotherapy to recommend to patients based on the presence or absences of circulating tumor DNA (ctDNA) after surgery for colon cancer.