Merck’s Subcutaneous Pembrolizumab Shows Noninferior Pharmacokinetics to IV KEYTRUDA

Merck, known as MSD outside of the United States and Canada, announced the first data presentation from the pivotal 3475A-D77 Phase 3 trial, evaluating the subcutaneous administration of pembrolizumab, together with berahyaluronidase alfa (MK-3475A; from now on referred to as “subcutaneous pembrolizumab”). Berahyaluronidase alfa is a variant of human hyaluronidase developed and manufactured by Alteogen Inc. These results are being presented today at the European Lung Cancer Congress (ELCC) 2025 (Abstract #8MO) and published simultaneously in Annals of Oncology.

The study met its primary endpoints, demonstrating noninferior pharmacokinetics (PK) for subcutaneous pembrolizumab administered with chemotherapy with a median injection time of two minutes, versus intravenous (IV) KEYTRUDA (pembrolizumab) administered with chemotherapy for the first-line treatment of adult patients with metastatic non-small cell lung cancer (NSCLC). The secondary endpoints of objective response rate (ORR), progression-free survival (PFS) and duration of response (DOR) and safety were consistent for subcutaneous pembrolizumab with chemotherapy compared to IV KEYTRUDA with chemotherapy. Median overall survival (OS) was not reached in either arm.

Based on these data, the U.S. Food and Drug Administration (FDA) has accepted for review a Biologics License Application (BLA) seeking approval of subcutaneous pembrolizumab across all previously approved solid tumor indications for KEYTRUDA. The FDA has set a Prescription Drug User Fee Act (PDUFA), or target action, date of Sept. 23, 2025. Additionally, the European Medicines Agency (EMA) has validated an extension application to introduce a new pharmaceutical form and new route of administration for KEYTRUDA.

In addition, results of a prospective, observational time and motion descriptive analysis conducted alongside study 3475A-D77 show that, compared to IV KEYTRUDA, subcutaneous pembrolizumab reduced time for patients spent in-chair and in the treatment room by 49.7% and 47.4%, respectively, and reduced the total active time spent by healthcare professionals (HCPs) on treatment preparation, administration process and patient monitoring by 45.7%. These results are being presented as a poster at ELCC (Poster #33P). Pharmacokinetic, efficacy, safety and time and motion results are described further below.

“These study findings demonstrate subcutaneous pembrolizumab reduces time demands for both the patient and the healthcare provider, all while providing a consistent efficacy and safety profile with IV pembrolizumab,” said Dr. Enriqueta Felip, head of Thoracic Tumors Group, Vall d’Hebron Institute of Oncology. “As a physician, I am thrilled to see these data for subcutaneous pembrolizumab, which, if approved, have the potential to give patients valuable time back in their treatment day with results that are consistent with IV pembrolizumab.”

In the 3475A-D77 trial, subcutaneous pembrolizumab, administered every six weeks with a median injection time of two minutes (4.8 mL) along with chemotherapy, demonstrated noninferiority of area under the curve (AUC) exposure of pembrolizumab during the first dosing cycle (geometric mean ratio of 1.14 [96% CI, 1.06-1.22]; p<0.0001) and model-based trough concentration (Ctrough) of pembrolizumab measured at steady state (geometric mean ratio of 1.67 [94% CI, 1.52-1.84]; p<0.0001), compared to IV KEYTRUDA administered every six weeks with chemotherapy.

“KEYTRUDA has helped transform the treatment of certain cancers, and we continue to pursue innovations that build on this breakthrough medicine to give patients and those who treat them better experiences,” said Dr. Marjorie Green, senior vice president and head of oncology, global clinical development, Merck Research Laboratories. “If approved, we are excited about the potential of subcutaneous pembrolizumab to become a new meaningful treatment option that may increase access and save time needed for administration compared to IV KEYTRUDA. We look forward to working with global regulatory authorities to bring the first subcutaneous checkpoint inhibitor that can be administered in approximately two minutes to patients and providers.”

In the prospective, observational time and motion study, patient time in chair during treatment with pembrolizumab was reduced by 49.7% (weighted means [WM]: 59.0 versus 117.2 minutes) for subcutaneous pembrolizumab with chemotherapy compared to IV KEYTRUDA with chemotherapy. Patients receiving subcutaneous pembrolizumab versus IV KEYTRUDA spent 47.4% less time in the treatment room (WM: 66.7 versus 126.9 minutes). Time associated with chemotherapy administration was removed from chair and treatment room duration. Results also show that subcutaneous pembrolizumab with chemotherapy reduced total active HCP time by 45.7% (WM: 14.0 versus 25.8 minutes;), including 44.6% less time on subcutaneous pembrolizumab preparation (WM: 5.1 versus 9.2 minutes) and 46.7% less time on subcutaneous pembrolizumab administration process and patient monitoring (WM: 8.9 versus 16.7 minutes) compared to IV KEYTRUDA with chemotherapy. The differences as measured by a linear mixed model were statistically significant (p<0.0001) for active HCP and patient time endpoints.

In addition to the 3475A-D77 trial, Merck’s subcutaneous pembrolizumab clinical development program includes the 3475A-F84 Phase 3 trial evaluating subcutaneous pembrolizumab administered alone compared to IV KEYTRUDA alone for the first-line treatment of patients with metastatic NSCLC whose tumors have high PD-L1 expression (tumor proportion score [TPS] ≥50%), as well as the 3475A-F65 Phase 2 trial evaluating subcutaneous pembrolizumab administered alone in relapsed or refractory classical Hodgkin lymphoma and relapsed or refractory primary mediastinal large B-cell lymphoma. Merck is also conducting a patient preference Phase 2 study, 3475A-F11, evaluating participant-reported preference for subcutaneous pembrolizumab compared to IV KEYTRUDA.