Study Overview: This research looks at a new drug, OPN-6602, to see if it's safe and how it works for people with a type of blood cancer called multiple myeloma (MM), which has come back or hasn’t responded to other treatments. Multiple myeloma affects plasma cells, a type of white blood cell. The study will test OPN-6602 alone and with another medicine called dexamethasone, which helps reduce inflammation.

Participation Requirements: To join, you must have been diagnosed with MM and tried at least three different treatments that haven't worked. You also need to have healthy blood, kidney, liver, and heart function. You cannot join if you have other specific blood disorders or if you have recently had certain therapies or transplants.

• The study is Phase 1b, which means it’s an early-stage trial mainly to test safety.
• Participants must have previously tried at least three types of MM treatments.
• This study is open-label, meaning everyone knows the treatment being given.