Study of HuL001 in Relapsed/Refractory Multiple Myeloma Patients

The goal of this clinical trial is to learn if the antibody drug HuL001, combined with Lenalidomide/Dexamethasone works to treat Multiple Myeloma patients. It will also learn about the safety and tolerability of the therapeutic combination. The objectives of this study are: 1. To evaluate the safety and tolerability of HuL001 (in combination with Len/Dex). 2. To evaluate the efficacy of HuL001 (in combination with Len/Dex). Researchers will use the antibody drug HuL001, combined with Len/Dex, to see if this works for Multiple Myeloma therapy. Participants will: * Receive HuL001 antibody injections every 2 weeks * Take Lenalidomide for 21 consecutive days each month * Take Dexamethasone every 1 week * Visit the clinic on scheduled days for checkups and tests * Keep a diary of their symptoms and Myeloma responses.