Merck’s immunotherapy Keytruda has been approved by US regulators to treat both adult and paediatric patients with refractory classical Hodgkin lymphoma (cHL), or those who have relapsed after three or more prior lines of therapy.

The US Food and Drug Administration issued an accelerated appraisal for the drug in this setting based on tumour response rate and duration of response; continued clearance for this indication may be contingent upon confirmation of this clinical benefit further trials.

Keytruda’s (pembrolizumab) clearance is based on data from the 210-patient Keynote-087 trial, which showed an overall response rate (ORR) with the drug of 69 percent with a complete remission rate (CRR) of 22 percent and a partial remission rate (PRR) of 47 percent. Also, among the 145 responding patients, the median duration of response was 11.1 months.

Approval of the anti-PD1 therapy, the first for the drug in a blood cancer, “reinforces the hope that immunotherapy will prove useful in a wide variety of cancers,” noted Dr Roger M. Perlmutter, president of Merck Research Laboratories.

“For the patients with classical Hodgkin lymphoma who are not cured with existing treatments, there are limited options, and treating their disease becomes more challenging,” added Dr Craig Moskowitz, clinical director, division of haematologic oncology, Memorial Sloan Kettering Cancer Center. “This approval is an important step forward in treating these patients, who are generally young and have a particularly poor prognosis, and gives us the opportunity to help patients in their fight against this devastating disease.”

Keytruda, a humanised monoclonal antibody that blocks the interaction between PD-1 and its ligands, thereby activating T lymphocytes which may affect both tumour cells and healthy cells, is already approved in the US for indications within melanoma, lung cancer and head and neck cancer.

MSI-H review delay
Meanwhile, the firm, which is known as MSD outside of North America and Canada, said US regulators have extended the review time for the drug for previously treated patients with advanced microsatellite instability-high (MSI-H) cancer.

The company recently submitted additional data and analyses to the FDA related to the pending application, which the regulators considers as a major amendment to the submission.

Thus, the target action date has been extended by three months to June 9, 2017.