Merck’s KEYTRUDA QLEX™ (pembrolizumab and berahyaluronidase alfa-pmph) Approved in Japan for Subcutaneous Administration for All KEYTRUDA® (pembrolizumab) Indications Approved in Japan

KEYTRUDA QLEX is the first and only subcutaneous immune checkpoint inhibitor in Japan that can be administered by a healthcare provider in as little as one minute

RAHWAY, N.J., September 21, 2026--Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced the Ministry of Health, Labor and Welfare (MHLW) in Japan has approved KEYTRUDA QLEX™ (pembrolizumab and berahyaluronidase alfa-pmph) injection for subcutaneous use for all indications approved in Japan for KEYTRUDA® (pembrolizumab), Merck's anti-PD-1 therapy. In Japan, KEYJECT®, for subcutaneous injection is the planned trademark for KEYTRUDA QLEX. KEYJECT can be administered in one minute every three weeks or in two minutes every six weeks. Berahyaluronidase alfa is a variant of hyaluronidase developed and manufactured by Alteogen Inc. For a list of select indications for which KEYTRUDA and KEYTRUDA QLEX are approved in the United States, see Selected Indications in the U.S. below.

"KEYJECT is the first and only subcutaneous immune checkpoint inhibitor available in Japan that can be administered by a healthcare provider in as little as one minute," said Dr. Marjorie Green, senior vice president and head of oncology, global clinical development, Merck Research Laboratories. "This approval is a significant milestone for patients and healthcare providers in Japan and reflects our commitment to advancing new patient-centered care options like KEYJECT that offers patients two dosing options and more choices of health care settings where they can receive therapy."

The approval of KEYJECT is based on results from the pivotal Phase 3 MK-3475A-D77 trial which compared KEYJECT to KEYTRUDA, both administered every six weeks, each in combination with chemotherapy, in patients with treatment-naïve metastatic non-small cell lung cancer (NSCLC) with no EGFR, ALK or ROS1 genomic tumor aberrations. This trial demonstrated comparable pharmacokinetic exposure levels between KEYJECT and KEYTRUDA. In descriptive analyses, overall response rates (ORR) were consistent between KEYJECT and KEYTRUDA. The ORR in the KEYJECT with chemotherapy arm was 45% (95% CI, 39-52) and 42% (95% CI, 33-51) in the KEYTRUDA with chemotherapy arm. There were no notable differences in progression-free survival (PFS) and overall survival (OS) observed in patients who received KEYJECT compared to patients who received KEYTRUDA.

In September 2025, the U.S. Food and Drug Administration (FDA) approved KEYTRUDA QLEX and it is now approved for adults in all the same solid tumor indications as KEYTRUDA. The European Commission approved subcutaneous pembrolizumab [known as KEYTRUDA SC™ in the European Union (EU)] in November 2025, and it is now approved for all KEYTRUDA indications in Europe.