Merck’s Injectable Version of Blockbuster Cancer Drug Keytruda Wins FDA Approval

A subcutaneously injected version of Merck cancer immunotherapy Keytruda is now FDA approved, a regulatory decision that gives patients a less burdensome dosing option and provides the pharmaceutical giant a way to retain some market share as the original intravenously infused formulation — its top-selling product — faces patent expirations.

The approval announced Friday covers use of the injectable product in adults and children age 12 and older for 38 solid tumor indications, which is most of the indications covered by the original infused version of the drug. The injectable formulation will be marketed under the brand name Keytruda Qlex. Merck said this new product will become available in late September.

Keytruda belongs to a class of drugs called checkpoint inhibitors, antibodies designed to block so-called checkpoint proteins that keep immune cells from recognizing and fighting cancer cells. While antibody drugs are typically administered as infusions — a Keytruda infusion takes about 30 minutes — Merck developed Keytruda Qlex with an enzyme technology that enables the drug to be dosed as an injection that takes minutes. This technology comes from South Korea-based biotech company Alteogen.

The FDA decision for Keytruda Qlex was based on based on the results of a six-week, open-label Phase 3 study that compared Keytruda Qlex to Keytruda head to head, both alongside chemotherapy. Results showed the 377-patient study met the main goal of showing Keytruda Qlex’s exposure in the body was comparable to that of infused Keytruda. The confirmed overall response rate was 45% for the Keytruda Qlex arm and 42% for the Keytruda arm. There were no notable differences between the arms on the measures of progression-free survival or overall survival. The most common adverse reactions reported for Keytruda Qlex and chemotherapy included nausea, fatigue, and muscle pain.

Keytruda Qlex may be administered in a one-minute injection every three weeks or a two-minute injection every six weeks. Patients won’t need to go to an infusion center but they’ll still need to visit a clinical care site as the injectable drug must be administered by a medical professional.

“As part of supporting patients and families through their cancer journeys, we are excited to see patient-focused developments in subcutaneous cancer treatment that shorten administration time and may allow for more patients to receive treatment in multiple health care settings,” Cancer Support Community CEO Sally Werner said in Merck’s approval announcement.

Keytruda is far and away Merck’s top revenue generator, accounting for $15.1 billion in sales in the first half of this year, a 6.6% increase compared to the same period in 2024. But Keytruda face patent expiration in 2028, after which lower-cost biosimilar competitors can enter the market. Keytruda Qlex is the latest injectable checkpoint inhibitor to win FDA approval. In the past year, the FDA has approved injectable versions of the Roche immunotherapy Tecentriq and the Bristol Myers Squibb drug Opdivo.