Talquetamab in Relapsed/Refractory Multiple Myeloma: A First Gulf Experience and Case Series Following BCMA CAR-T Therapy and Relapsed Refractory Extramedullary Disease

Multiple myeloma is a cancer that begins in the plasma cells, the white blood cells responsible for making antibodies to fight infection. When these cells grow out of control, they crowd out healthy blood cells and damage bones. For many years, doctors treated this disease with drugs that target specific proteins on the surface of these cancer cells. One such protein, called BCMA, has been a major focus of modern treatment. Therapies designed to hunt down BCMA, including powerful cell-based treatments known as CAR-T therapy, have helped many patients. However, the cancer sometimes learns to hide by stopping the production of BCMA, allowing it to return even after these advanced treatments have worked. When the cancer comes back, especially in a form that spreads outside the bone marrow into soft tissues, it becomes extremely difficult to control.

Researchers in the Gulf region recently explored a new strategy for these difficult cases. They turned their attention to a different protein on the surface of myeloma cells called GPRC5D. Unlike BCMA, this protein remains present even after the cancer has learned to evade BCMA-targeting drugs. The team treated two patients with a new medicine called talquetamab, which acts like a guided missile. It has two ends: one grabs onto the GPRC5D protein on the cancer cell, and the other grabs onto a soldier cell in the patient's own immune system, the T-cell. By linking the two, the medicine forces the patient's immune system to recognize and destroy the cancer. This approach offered a fresh path for patients who had run out of other options.

The first patient was a 70-year-old man who had fought myeloma for a decade. He had undergone many treatments, including a CAR-T therapy that had successfully kept the disease away for three years. When the cancer returned in 2025, it had become resistant to the previous treatments. Doctors began administering talquetamab using a careful, step-up schedule to ensure his body could handle the new therapy. Over the course of six treatment cycles, the man's blood tests showed a steady and deepening decline in the cancer markers. The amount of abnormal protein in his blood dropped significantly, and his immune system remained stable. He experienced some side effects common to this type of drug, such as a change in taste, dry skin, and changes to his fingernails, but these were mild and managed with simple care. He did not suffer from the severe immune reactions that can sometimes occur with these powerful treatments, and he was able to continue the therapy without interruption.

The second case involved a 58-year-old man facing a more immediate crisis. He arrived at the hospital with severe back pain and paralysis caused by a large tumor pressing on his spinal cord. This tumor was an aggressive form of the disease that had spread outside the bones into soft tissue. After surgery to relieve the pressure on his spine, the cancer continued to spread rapidly to his liver and other areas, despite several rounds of standard chemotherapy. The medical team planned to send him abroad for a new CAR-T therapy, but they needed a way to stop the cancer from growing while he waited. They started him on talquetamab as a bridge to hold the disease in check. Remarkably, after just one cycle of the treatment, scans showed that all the active tumors had disappeared. The cancer that had been spreading through his body was completely gone, allowing him to travel safely for his next treatment.

These two stories highlight how targeting a different protein can succeed where other methods have failed. In the first case, the medicine provided a long-lasting response for a patient who had relapsed after a previous cell therapy. In the second, it acted quickly to clear aggressive, life-threatening disease, buying time for a patient to receive further care. The researchers noted that the side effects were predictable and manageable, mostly affecting the skin and sense of taste, which are areas where the GPRC5D protein is naturally found. This suggests that the medicine is safe enough to use even in patients who have been through many other treatments.

This report represents the first documented experience with this specific medicine in the Gulf Cooperation Council region. It shows that when cancer evolves to escape one type of attack, doctors can switch targets to a different protein that the cancer has not yet learned to hide. By using talquetamab, the medical team was able to control the disease in two very different, high-risk situations. The findings suggest that this approach is a valuable tool for patients who have exhausted other options, offering a way to regain control of the cancer and, in some cases, to prepare the body for even more advanced therapies.