Merck & Co Inc.’s (MRK) blockbuster cancer drug Keytruda (pembrolizumab) has secured another approval from the U.S. Food And Drug Administration (FDA) for treating classical Hodgkin's lymphoma, marking the drug’s first approval for treatment of a blood cancer. The multiple-indication drug is already approved for five other indications including lung, head and neck, and melanoma cancers.

Secured Accelerated Approval

The intravenous form of Keytruda is now approved for treating adults with a fixed dose of 200 mg and for treating children with a dose of 2 mg/kg for refractory classical Hodgkin lymphoma (cHL), a type of cancer that starts in white blood cells. Keytruda can now be administered to adult and pediatric patients having refractory cHL, or to those whose cancers have relapsed after three or more earlier lines of therapy.

The approval was granted based on tumor response rate and durability of response observed in the KEYNOTE-087 trial comprised of 210 patients. The trial demonstrated 69% overall response rate (ORR) with Keytruda. ORR is the portion of patients with a tumor size decrease of a predefined amount for a minimum time period. Results also indicate a complete remission rate (CRR) of 22%, and a partial remission rate (PRR) of 47%. 

As the approval was secured under FDA’s accelerated approval program, Merck is required to furnish further evidence of the drug's clinical benefit in confirmatory trials. If the company fails to provide the necessary verification and details in time, the approval may be revoked under accelerated-approval regulations. (See also, Merck's Keytruda Approved for Lung Cancer in EU.)

 “Today’s approval – the first for Keytruda in a hematologic malignancy – reinforces the hope that immunotherapy will prove useful in a wide variety of cancers,” said Dr. Roger M. Perlmutter, president of Merck Research Laboratories.

Keytruda faces stiff competition from a similar multiple-indication cancer drug, Opdivo (nivolumab), which was jointly developed by Bristol-Myers Squibb Co. (BMY) and Japan-based Ono Pharmaceutical Co. Ltd. Keytruda garnered $483 million in fourth-quarter sales compared to $1.31 billion by Opdivo. (See also, Bristol-Myers Hodgkin Lymphoma Drug OKed in EU.)

Keytruda ranks among the top cancer drugs with high sales potential. Peak sales are estimated to top $6.56 billion by 2022. (For more, see Top Cancer Drugs with High Future Sales Potential.)