In this study, people will first have tests to see if they can join. If they qualify, they will be placed by chance into one of two groups. One group will receive a medicine called JNJ 79635322, and the other group will receive a medicine called teclistamab.

Both medicines are given as shots under the skin. At the start, people will receive smaller doses that slowly increase, followed by regular treatment given in cycles that last 28 days. During the study, participants will have clinic visits for checkups, blood tests, urine tests, scans, and sometimes bone marrow tests. After the first doses, people may need to stay near the clinic for a short time and have someone with them to help. The study may last for several years, including time for treatment and follow up visits to check health.

Multiple myeloma that has come back or did not respond to treatment after 1 to 3 prior therapies.

People can join this study if they are adults who have a blood cancer called multiple myeloma that has come back or did not improve with treatment. They must have already received between one and three treatments for their cancer.

This study is testing a new medicine called JNJ 79635322 and comparing it to another medicine called teclistamab. Both medicines are used to help the body fight a blood cancer called multiple myeloma. Researchers want to learn which medicine works better and which one is safer for patients.