Groundbreaking Drug Launches
Hyaluronidase/Pembrolizumab (KEYTRUDA QLEX)
Mechanism of Action: Antibody-dependent cell cytotoxicity; Programmed cell death 1 receptor antagonists; T lymphocyte stimulants Drug class: Monoclonal antibodies; Small molecules Originator: Merck Sharp & Dohme Indication: Solid tumours; Bladder cancer Approved date: 19 September 2025 and 21 November 2025 Trials: MK-3475A-D77 and KEYNOTE-905
Solid Tumours
Solid tumors are abnormal masses of tissue that arise in organs such as the lung, breast, colon, or prostate, and do not involve the blood or bone marrow. They account for the majority of cancer diagnoses worldwide and include both benign and malignant forms. Advances in targeted therapies, immuno-oncology, and precision medicine are steadily improving outcomes for patients with solid tumors.
Solid tumors represent approximatively 90% of adult human cancers. They can develop in many parts of the human body, including the breast, lung, prostate, colon, melanoma, bladder, and kidney.
Distribution of Solid tumors
Fig 2: Percentage Distribution of Solid Tumor Types
Why is Hyaluronidase/Pembrolizumab poised to make an impact in 2026?
Hyaluronidase/Pembrolizumab (KEYTRUDA QLEX) is a fixed-dose combination therapy developed by Merck that combines pembrolizumab, a programmed cell death-1 (PD-1) receptor antagonist, with recombinant human hyaluronidase (MK-5180). It is being developed for the treatment of multiple tumour types, including malignant melanoma, non-small cell lung cancer, renal cell carcinoma, Hodgkin lymphoma, primary mediastinal B-cell lymphoma, squamous cell carcinoma, and other solid tumours. FDA-approved in September 2025, Keytruda Qlex covers most solid tumour indications already approved for IV Keytruda. Consensus estimates project Qlex sales approaching $900 million in 2026, helping drive combined Keytruda revenues beyond $33.5 billion that year.
Benefits for Patients and Healthcare Systems: The subcutaneous formulation can be administered in just one to two minutes, compared with a 30-minute IV infusion. This time-saving approach improves patient convenience, supports broader use in mono- and oral combination therapies, and reduces chair time and strain on healthcare resources.
Strategic Edge for Merck: With IV Keytruda facing U.S. patent expiry in 2028, Keytruda Qlex offers extended patent protection beyond that milestone. Merck positions the launch as a key strategy to mitigate the patent cliff and sustain long-term market leadership.
Pipeline Expansion: In 2026, Merck anticipates continued growth through new indications and geographic expansion. The FDA has set an April 7, 2026, action date to review Keytruda and Keytruda Qlex in combination with Padcev for certain patients with muscle-invasive bladder cancer, addressing a significant unmet need.
Regulatory milestones for Hyaluronidase/Pembrolizumab
Registrational Trials
The regulatory approvals from the US FDA were based on the data from MK-3475A-D77 and KEYNOTE-905 trials.
MK-3475A-D77:
A Phase 3 Randomized, Open-label Clinical Study to Evaluate the Pharmacokinetics and Safety of Subcutaneous Pembrolizumab Coformulated With Hyaluronidase (MK-3475A) Versus Intravenous Pembrolizumab, Administered With Chemotherapy, in the First-line Treatment of Participants With Metastatic Non-small Cell Lung Cancer (NCT05722015).
“The MK-3475A-D77 study showed that subcutaneous KEYTRUDA QLEX delivers pharmacokinetic and clinical efficacy comparable to IV KEYTRUDA when combined with chemotherapy in treatment-naïve metastatic NSCLC, supporting its potential as a convenient alternative without compromising outcomes. ”
KEYNOTE-905:
A Randomized Phase 3 Study Evaluating Cystectomy With Perioperative Pembrolizumab and Cystectomy With Perioperative Enfortumab Vedotin and Pembrolizumab Versus Cystectomy Alone in Participants Who Are Cisplatin-Ineligible or Decline Cisplatin With Muscle-Invasive Bladder Cancer (NCT03924895).
“In the Phase 3 KEYNOTE-905 (EV-303) trial, perioperative KEYTRUDA plus Padcev significantly improved event-free survival compared with surgery alone in patients with muscle-invasive bladder cancer ineligible for cisplatin. ”
