FDA Approves Subcutaneous Keytruda Qlex for solid tumors: A New Era for Immunotherapy Delivery

By Maria Poimenidou

10/16/2025

On September 19, 2025, the FDA approved pembrolizumab and berahyaluronidase alfa-pmph (brand name Keytruda Qlex™) for subcutaneous injection in patients 12 years and older with solid tumors already eligible for intravenous pembrolizumab (brand name Keytruda®). This milestone reflects both clinical innovation and patient-centered care, offering a new delivery route for one of oncology’s most widely used immunotherapies.

But what does this approval mean in practice for clinicians, patients, and the broader oncology community?

A Quick Primer: What is pembrolizumab or Keytruda?

Pembrolizumab, marketed by Merck under the brand name Keytruda, is a type of cancer immunotherapy called an immune checkpoint inhibitor. It belongs to a class of drugs known as anti–PD-1 monoclonal antibodies.

• How it works: Cancer cells are good at hiding. They use a signal called PD-1 (short for programmed death receptor-1) to tell T cells, the body’s defender cells, to stand down instead of fighting. Pembrolizumab blocks PD-1, lifting that stop sign so T cells can wake up, recognize the cancer cells, and attack them.

• FDA history: First approved in 2014 for melanoma, pembrolizumab has since gained approvals across a wide range of cancers including lung, head and neck, gastric, cervical, endometrial, triple-negative breast cancer, and any tumor with high microsatellite instability (MSI-H) or high tumor mutational burden (TMB-H). Both MSI-H and TMB-H make cancers more visible to the immune system and drugs like pembrolizumab work especially well when the immune system has more abnormal signals to target.

• Why it matters: Keytruda has become a cornerstone of modern oncology, dramatically improving survival in diseases where chemotherapy alone often fell short. In fact, pembrolizumab is now one of the most prescribed immunotherapies worldwide.

What’s New About Keytruda Qlex?

Until now, pembrolizumab has only been administered intravenously, typically as a 30-minute infusion. Keytruda Qlex changes the game by combining pembrolizumab with berahyaluronidase alfa, an enzyme that enhances absorption when injected under the skin. This allows oncologists to deliver the therapy subcutaneously in as little as 1–2 minutes, depending on the dose.

For patients, this means less time in the clinic, reduced need for infusion chairs, and potentially a more comfortable treatment experience.

Clinical Evidence Behind the Approval

The FDA’s decision was anchored by Study MK-3475A-D77 (NCT05722015), a randomized, open-label trial in patients with treatment-naïve metastatic non-small cell lung cancer without EGFR, ALK, or ROS1 mutations.

• Design: Patients received Keytruda Qlex administered subcutaneously every 6 weeks with platinum doublet chemotherapy, or Keytruda® administered intravenously every 6 weeks with platinum doublet chemotherapy.

• Findings: Keytruda Qlex met the pharmacokinetic comparability threshold, showing equivalent exposure to IV Keytruda®.

• Efficacy: The overall response rate for patients on Keytruda Qlex was 3% higher than Keytruda, at 45% versus 42% and survival outcomes were comparable. Patients on Keytruda Qlex spent nearly half as much time in the treatment room compared with those on IV Keytruda.

• Safety: Side effects were consistent with known pembrolizumab risks; injection-site reactions were rare and mild.

Potential Advantages

• Patient convenience: According to Merck, Keytruda Qlex can be given in 1 minute every 3 weeks or in 2 minutes every 6 weeks compared to the previous IV infusions of 30 minutes.

• Clinic efficiency and expanded access: Less strain on infusion resources and may be more feasible in outpatient or resource-limited settings as Keytruda Qlex may be administered in infusion centers, doctors’ office, and local community-based clinic.

Important Considerations

• Immune-related toxicities remain: Pneumonitis, colitis, endocrinopathies, and other known pembrolizumab side effects are still possible.

• Allergy risk: As with any hyaluronidase-containing product, hypersensitivity reactions are possible.

• Pediatric use: Approved down to age 12, but data in adolescents are extrapolated.

• Real-world adoption: Logistics (training, reimbursement, site of care) will shape how widely subcutaneous pembrolizumab is adopted.

Why This Matters

This approval is part of a broader shift in oncology toward patient-friendly delivery methods. Just as oral targeted therapies transformed cancer care in the 2000s, the move from infusion to injection could reshape the patient experience in immunotherapy.

Keytruda Qlex is not a new drug, it’s a new way of delivering a proven one. But that subtle shift could have an outsized impact: freeing up clinical capacity, reducing patient burden, and sustaining innovation in a crowded immunotherapy space.

Looking Ahead

As Keytruda Qlex rolls out, real-world evidence will be essential to confirm its benefits across different cancers, age groups, and practice settings. Will patients prefer it? Will clinics adopt it quickly? And how will it fit into combination strategies or future immuno-oncology regimens?

From a public health standpoint, the shift from IV to subcutaneous administration could also improve health system efficiency and equity of access. Shorter treatment times may free up infusion chairs, reduce staffing burdens, and allow more patients to be treated in busy cancer centers. Subcutaneous delivery could also expand access in community-based or resource-limited settings, where infusion infrastructure is scarce but the need for cancer care is high.

So, what does this approval mean in practice?

·       For patients, it means less time hooked up to an IV and more time living their lives, a small change that could make a big difference.

·       For clinicians, it offers faster administration, smoother clinic flow, and more flexibility in where care can be delivered.

·       For the broader oncology community, it represents a meaningful step forward in how we deliver cutting-edge cancer therapies, with the potential to reshape both patient experience and system-wide efficiency.

Glossary of Key Terms:

Immune checkpoint inhibitor: A type of drug that helps the immune system fight cancer by blocking “checkpoints” or signals that normally stop immune cells from attacking. Pembrolizumab is an example.

PD-1 (programmed death receptor-1): A protein on T cells that acts like a brake. Cancer cells use it to turn T cells off. Pembrolizumab blocks PD-1 to release that brake.

Platinum doublet chemotherapy: A common two-drug chemotherapy combination. It always includes a platinum-based drug (cisplatin or carboplatin) plus another drug (like pemetrexed or paclitaxel). Together, they work better than either drug alone.

Subcutaneous (SC) vs Intravenous (IV): SC injections are given under the skin, usually in the thigh or abdomen, often in just 1–2 minutes. IV delivery goes directly into a vein through a drip or infusion, often taking 30 minutes or more.

MSI-H (microsatellite instability–high): A condition where a tumor’s DNA repair system is broken, leading to lots of small DNA errors that make the cancer more visible to the immune system.

TMB-H (tumor mutational burden–high): A tumor with a very high number of DNA mutations overall, which also makes it easier for the immune system to recognize and attack.