The US Food and Drug Administration (FDA) has granted two more approvals for US Merck’s Keytruda, an anti-PD-1 therapy.

In the first, the drug gained its first regulatory clearance as a gynaecological cancer treatment. It is the first anti-PD-1 therapy to be approved for patients with advanced cervical cancer and progression on or after chemotherapy.

Roy Baynes, senior vice president and head of global clinical development, chief medical officer, Merck Research Laboratories, said the drug can now provide an important new second-line option for certain patients with this disease.

US regulators also gave another approval for Keytruda to treat hematologic malignancy, this time for patients with refractory primary forms of primary mediastinal large B-cell lymphoma (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 anti-PD-1 therapy for the first time.

“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 the Boston, Massachusetts-based Dana-Farber Cancer Institute.

In both cases, the indications were approved under the FDA’s accelerated approval pathway based on tumor response rate and durability of response. As a result, said Merck, conversion to full approval may depend upon verification and description of clinical benefit in confirmatory trials.

Merck’s fortunes are now said to be heavily tied to Keytruda, which has gained approvals in the US for multiple oncology indications, including lung cancer, melanoma, head and neck cancer, classical Hodgkin lymphoma, urothelial carcinoma, and gastric cancer.

Sales of the drug rocketed in 2017 to surpass $3.8 billion, which was a 172% year-on-year increase, and analysts expect Keytruda to account for at least a quarter of Merck’s total sales and the vast majority of its sales growth by 2022. But analysts are also said to be concerned about Merck’s focus on oncology, and Keytruda in particular, believing that the US drugmaker is not sufficiently diversified.

However, chairman, CEO and president Kenneth Frazier has argued that Keytruda is “a pipeline within a product” and that Merck is diversified in many types of cancer. Last year, the Kenilworth, New Jersey-headquartered group agreed to pay up to $8.5 billion to AstraZeneca to develop and commercialize cancer drug Lynparza, which could work in combination with Keytruda. Merck also agreed last September to acquire immuno-oncology biotech firm Rigontec for $554 million.