The study uses several cancer medicines, depending on the specific change found in the tumor. These include olaparib, erlotinib, crizotinib, trametinib, pemigatinib, selpercatinib, axitinib, vismodegib, pembrolizumab, larotrectinib, dabrafenib, and the injection Phesgo (trastuzumab and pertuzumab). Standard care medicines in the study include oxaliplatin, capecitabine, irinotecan, fluorouracil, calcium folinate, gemcitabine, and paclitaxel albumin-bound. Some medicines are taken by mouth, while others are given by injection or infusion into a vein.

During the study, people are assigned to receive either the tailored treatment or standard care. Treatment is given in repeated cycles, with regular medical visits to check health, side effects, and how the cancer is doing. The study follows people over time to see how long the cancer stays under control and how the treatments compare in safety and overall benefit.

The study is divided into two parts. In the first part, participants will receive DS-3939a to assess its safety and how well it is tolerated by the body. In the second part, the study will continue to evaluate safety and also measure the treatment’s effectiveness at a recommended dose. This will involve looking at how the cancer responds to the treatment, which is known as the objective response rate. Participants may have different types of advanced cancers, including those of the lung, breast, ovary, and pancreas, among others.

Throughout the study, participants will be closely monitored for any side effects or changes in their health. This includes regular check-ups, laboratory tests, and imaging studies to track the progress of the treatment. The study aims to gather important information that could lead to new treatment options for people with advanced solid tumors. Some participants may receive a placebo, which is a substance with no active medication, to help compare the effects of DS-3939a.