MSD has achieved a regulatory milestone with the US Food and Drug Administration's approval of Keytruda QLEX, marking the first subcutaneous programmed cell death protein 1 (PD-1) blocker to receive FDA authorization. The subcutaneous formulation combines pembrolizumab with berahyaluronidase alfa-pmph, offering an alternative delivery method for the world's best-selling cancer drug.
Enhanced Patient Convenience and Access
The approval grants patients with 38 different solid tumor indications access to Keytruda QLEX, including those with non-small cell lung cancer (NSCLC), triple-negative breast cancer, and melanoma. Dr. Joseph Thaddeus Beck, oncologist and medical director of the Highlands Clinical Trials Office, emphasized that the administration process will be faster while offering patients "more choices" regarding where they receive their therapy.
The subcutaneous formulation represents a significant convenience improvement, allowing patients to "receive their dose in minutes rather than having to sit for an hour or more in the clinic," according to Jack Cuthbertson, senior healthcare analyst at GlobalData. This efficiency gain could particularly benefit patients receiving Keytruda as monotherapy or in combination with oral medications.
Commercial Projections and Market Expansion
MSD projects that 30% to 40% of patients will be prescribed the subcutaneous formulation instead of the intravenous counterpart within two years of commercialization, which is set to occur in the US by late September 2025. The company is also exploring expansion into hematological indications through a Phase II trial (NCT06504394) investigating the drug's potential in two types of relapsed or refractory B-cell lymphomas.
Israel Stern, oncology healthcare consultant at GlobalData, forecasts that subcutaneous Keytruda's sales will eclipse $1 billion by 2026 in NSCLC alone. However, he notes that after multiple IV biosimilars enter the market, QLEX sales "will mirror the total sales coming from biosimilars."
Patent Cliff Challenges Persist
Despite the regulatory success, Keytruda faces a significant patent cliff in 2028 when MSD will lose exclusive US market rights. This timeline poses substantial risks given that Keytruda generated $29.5 billion for MSD in 2024 alone, accounting for nearly half of the company's total sales and cementing its position as the best-selling drug of all time.
Analysts express skepticism about the subcutaneous formulation's ability to significantly mitigate patent cliff impacts. Stern noted that the market edge may be dulled by "combination agents such as chemotherapies, antibody-drug conjugates (ADCs) and immunotherapies, which require intravenous administration." Cuthbertson echoed this concern, stating that "a SC formulation is unlikely to be chosen in a combination setting as it would not increase convenience."
Market Impact Assessment
While acknowledging the enhanced convenience for appropriate patient populations, analysts maintain cautious projections for long-term market protection. Cuthbertson explained that "though Merck will be able to maintain higher sales for longer with Keytruda QLEX, the company will likely still see a drop off after loss of IV Keytruda's patent exclusivity. This will be seen as not all patients will switch to the SC format, and biosimilars will still gain some market share."
The approval represents a strategic move for MSD to extend Keytruda's market dominance, though the ultimate commercial impact will depend on physician and patient adoption patterns, particularly in the context of evolving combination therapy landscapes and impending biosimilar competition.
