Radiation Therapy May Boost Effectiveness of CAR T-Cell Treatment in Aggressive Multiple Myeloma

CAR T-cell therapy has revolutionized treatment options for patients with advanced multiple myeloma. This innovative therapy reprograms a patient’s immune cells to target and destroy cancer cells. However, new research from Moffitt Cancer Center reveals that patients with extramedullary disease (EMD), a more aggressive form of multiple myeloma in which tumors form outside the bone marrow, may not benefit from CAR T-cell therapy unless additional treatments are considered.

In a new study presented at the American Society for Radiation Oncology annual meeting, physician-scientists examined the outcomes of 116 relapsed or refractory multiple myeloma patients who received anti-B-cell maturation antigen CAR T-cell therapy, 30 of whom had EMD. The results showed that patients with EMD had significantly worse outcomes, with only a 15.6% 12-month progression-free survival rate compared to 60.2% in patients without EMD. Nearly all patients with EMD experienced disease progression shortly after treatment.

These findings have prompted physicians to consider new strategies for improving outcomes in this high-risk group. One approach is the use of targeted radiation therapy to treat EMD sites before administering CAR T-cell therapy. Radiation therapy, which uses high-energy rays to destroy cancer cells, could reduce the tumor burden, making CAR T-cell therapy more effective.

Justyn Nakashima, DO

Justyn Nakashima, DO, lead author of the study, emphasized the potential benefits of this combined approach. “Radiation therapy has been a fundamental part of cancer treatment, particularly for tumors that don't respond well to other therapies," he said. "By targeting the specific areas where extramedullary disease is present, we can shrink or even eliminate these tumors before CAR T-cell therapy is administered. This could give the CAR T cells a better chance to do their job effectively, leading to better outcomes for our patients."

In the study, although most EMD patients received some form of systemic therapy before CAR T-cell treatment, none received radiation therapy specifically directed at their EMD sites. The results suggested that patients with local EMD recurrences, where their disease returned at the original tumor sites, had particularly poor outcomes. Nakashima says this underscores the potential value of integrating radiation therapy into the treatment plan for EMD patients.

"For patients with EMD, a tailored approach that includes radiation therapy may be the key to overcoming the challenges posed by this aggressive disease. We're encouraged by the possibility that combining radiation with CAR T-cell therapy could offer these patients,” said Nakashima, a radiation oncology resident at Moffitt.