This research is testing a new medicine, JNJ-1761981, on people with solid tumors, which are lumps of cancer cells. *Part 1* focuses on finding a safe dose that can be injected directly into the tumor. *Part 2* aims to find the best amount to treat the tumor effectively. Participants need to have a certain type of cancer that has not responded to usual treatments. They should have a good ECOG status, which means they can carry out daily activities with little or no assistance. People who can have children must use contraception during and after the study to prevent pregnancy.

• The study is divided into two parts, each focusing on different goals.
• Participants must have tried other treatments first.
• People joining will need to follow specific health and safety guidelines.

If you have any known allergies to the study drug or if your cancer is too close to important body parts, you may not be able to participate. This study is a chance to try a new treatment when other options have not worked.