The designation was 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,
It signals the agency’s belief that the drug might offer a substantial improvement over existing therapies on one or more clinically significant endpoints.
Merck Research Laboratories president Roger Perlmutter said: "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."
It is the fourth designation for Keytruda and follows breakthrough status in advanced melanoma, non-small cell lung cancer, and colorectal cancer.
The FDA recently accepted Merck’s supplemental biologics license application for Keytruda in recurrent or metastatic head and neck cancer.
The agency granted Keytruda priority review status with a target action date of 9 August 2016.
Keytruda helps the immune system fight tumor cells by blocking the interaction between PD-1, a cell surface receptor on T cells and pro-B cells, and its ligands PD-L1 and PD-L2.
Merck said the drug is administered at a dose of 2 mg/kg as an intravenous infusion over 30 minutes every three weeks for the approved indications.
The clinical development program of Keytruda includes patients with over 30 tumor types in more than 250 studies, including in excess of 100 trials that combine the drug with other cancer treatments.
Image: Keytruda was approved in 2014 to treat melanoma. Photo: courtesy of Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, N.J., U.S.A.