This study focuses on individuals with Multiple Myeloma, a type of blood cancer, specifically those with the Relapsed/Refractory form, meaning the cancer has returned after previous treatment or has stopped responding to therapy. The purpose of the study is to evaluate the safety and early effectiveness of combining two specific medications. The experimental treatments being studied are linvoseltamab and REGN17372, which are both bispecific monoclonal antibodies. These are specialized proteins designed to attach to specific targets on cancer cells and immune cells at the same time to help the body fight the disease.

The research is conducted in two stages. The first stage focuses on finding the correct dosage by gradually increasing the amount of the drugs to see how well they are tolerated. The second stage looks more closely at how well the combination of linvoseltamab and REGN17372 works to reduce the cancer, or how well linvoseltamab works when used by itself. During the study, participants may also receive background medications such as paracetamol for pain, diphenhydramine hydrochloride to manage certain symptoms, or dexamethasone, which is a type of steroid used to reduce inflammation.