Pembrolizumab, RT Combo Is Option for Multiple Myeloma After CAR T  

Combination treatment with the anti-PD-1 therapy pembrolizumab and single-fraction, low-dose radiotherapy may be a safe treatment option for patients with relapsed or refractory multiple myeloma (MM) who progressed after CAR T-cell therapy, according to results of a small study presented at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting.

Mohammad Khan, MD, of Emory University in Atlanta, Georgia, and colleagues tested this approach in 25 patients aged 18 or older who had relapsed or refractory disease and one or more osseous or extra-osseous lesion that could undergo radiotherapy. The majority of patients were White (76%) and had an Eastern Cooperative Oncology Group performance status of 1 (64%). Median number of prior lines of therapy was five.

One fraction of 8 Gy radiotherapy was given on day 0, cycle 1 followed by pembrolizumab for two years or until progression. The primary endpoint was toxicity.

No grade 2 or higher radiation-related toxicity occurred within the irradiated volume. One case of grade 3 or worse pembrolizumab-related toxicity was noted (fevers).

Improvement of nontarget lesions was noted in five of 25 patients (20%). Eight patients showed response to treatment.

The six-month progression-free survival (PFS) for the entire cohort was 31.8%; the 12-month PFS was 22.7%. The six- and 12-months overall survival (OS) was 68% and 64%, respectively.

Of the patients that responded to treatment, five were post CAR T-cell therapy, “suggesting that the most benefit may be in post CAR T-cell patients,” the researchers wrote. In post-CAR T-cell therapy patients, survival was increased compared with the entire cohort. The six-month PFS was 50% and the six-month OS was 71.4%.

According to the researchers, larger trials are needed to further test this combination in patients with relapsed or refractory MM.

Reference

Khan MK, Nasti T, Kleber T, al. Final results of pilot trial to evaluate anti-PD1 and 8 Gy in 1 fx for relapsed refractory multiple myeloma. Abstract #8017. Presented at the 2023 American Society of Clinical Oncology Annual Meeting; June 2-6, 2023; Chicago, Illinois.