US regulators have again expanded the list of approved uses of MSD’s immunotherapy Keytruda, issuing a green light for the treatment of primary mediastinal large B-cell lymphoma (PMBCL).

Marking the drug’s second approval for a haematologic malignancy, Keytruda (pembrolizumab) can now be prescribed for patients with refractory primary forms of PMBCL, a type of non-Hodgkin lymphoma, or those who have relapsed after two or more prior lines of therapy.

The decision gives PMBCL patients access to the first anti-PD-1 therapy for their condition.

Keytruda was cleared via the US Food and Drug Administration’s accelerated pathyway on the back of data from the KEYNOTE-170 trial involving 53 patients with relapsed or refractory PMBCL.

The data showed an objective response rate (ORR) of 45 percent, with a complete response rate (CRR) of 11 percent and a partial response rate of 34 percent.

Median duration of response, based on 24 patients who responded, was not reached, while median time to first objective response was 2.8 months.

"Relapsed or refractory PMBCL is often a challenging disease to treat, and many affected patients are young adults,” said Philippe Armand, medical oncologist in the Hematologic Oncology Treatment Center at Dana-Farber Cancer Institute.

“In the clinical trial that supported this approval, treatment with Keytruda resulted in meaningful responses, including complete disease remission in some patients. This approval therefore provides another therapeutic option for patients with PMBCL who have progressed on or after prior therapies."

In the US, Keytruda is already approved for various indications for melanoma, lung cancer, head and neck cancer, classical hodgkin lymphoma, urothelial carcinoma, microsatellite instability-high cancer, gastric cancer, and cervical cancer.