US regulators have awarded Merck’s immunotherapy Keytruda another breakthrough badge, this time for the treatment of relapsed or refractory classical Hodgkin lymphoma, potentially further speeding up the regulatory pathway for the drug in this indication.

Keytruda’s (pembrolizumab) Breakthrough Therapy Designation in cHL is based on data from the ongoing Phase Ib KEYNOTE-013 and Phase II KEYNOTE-087 studies evaluating the drug as a single agent in patients with cHL, and signals the agency’s belief that it might offer a substantial improvement over existing therapies on one or more clinically significant endpoints.

The first showed that, of 31 evaluable patients, 65 percent responded, with five achieving a complete response (16 percent), 15 (48 percent) a partial response and seven (23 percent) exhibiting stabilisation of disease. 

Safety analysis also showed the drug to be generally well tolerated, with the most common treatment-related adverse events to be hypothyroidism (16 percent), diarrhoea (13 percent), nausea (13 percent) and pneumonitis (10 percent). 

Data from KEYNOTE-087 are to be presented at an upcoming medical conference, the firm noted.

Keytruda - a humanised monoclonal antibody that works by increasing the ability of the body’s immune system to help detect and fight tumour cells by blocking the interaction between PD-1 and its ligands - is already approved in the US for unresectable or metastatic melanoma as well as for some patients with non-small cell lung cancer.

“Merck has launched an ambitious clinical development program examining the efficacy of Keytruda in a broad range of solid and blood cancers, and our studies of relapsed or refractory classical Hodgkin lymphoma are quite promising,” said Dr Roger Perlmutter, president of Merck Research Laboratories. “The FDA’s Breakthrough Designation for this blood cancer provides an important mechanism to assist us in bringing this immunotherapy to patients who could benefit from its use.”

News comes of Keytruda’s new breakthrough status comes just days after the US Food and Drug Administration said it would undertake a priority review of Bristol-Myers Squibb’s rival Opdivo (nivolumab) in the cHL setting.