Keytruda (Pembrolizumab)

What it is and what it treats

Pembrolizumab is a humanised monoclonal antibody that binds the PD-1 receptor on T-lymphocytes, blocking the interaction with its ligands PD-L1 and PD-L2. This interaction normally dampens T-cell activity; by interrupting it, pembrolizumab restores anti-tumour immune responses. It is classified as an immune checkpoint inhibitor and is administered as an intravenous infusion under oncology specialist supervision.

Regulatory authorities including the FDA and EMA have approved pembrolizumab across a broad range of malignancies, including non-small cell lung cancer, melanoma, head and neck squamous cell carcinoma, classical Hodgkin lymphoma, urothelial carcinoma, renal cell carcinoma, and microsatellite instability-high or mismatch repair deficient tumours across multiple tumour sites. Approved use varies by country, line of therapy, biomarker status (such as PD-L1 expression) and whether it is used alone or in combination with chemotherapy or other targeted agents.

Because approved indications and reimbursement status differ by jurisdiction, prescribing decisions are made by treating oncologists with reference to the applicable national label and clinical guidelines. Pembrolizumab is not indicated for self-administration and is not a treatment decision that patients or non-specialist providers should initiate independently.

Presentations and dosage forms

• 50 mg powder for concentrate for solution for infusion (single-use vial, reconstituted before dilution)
• 100 mg/4 mL (25 mg/mL) concentrate for solution for infusion (single-use vial)
• Solution is clear to slightly opalescent, colourless to pale yellow
• Supplied for single use only; no antimicrobial preservative

How it is administered

The approved EU SmPC and FDA prescribing information describe pembrolizumab as an intravenous infusion administered over approximately 30 minutes, given every 3 weeks (200 mg) or every 6 weeks (400 mg), depending on indication and treating physician's choice, until disease progression, unacceptable toxicity, or completion of the approved treatment duration (which may be up to 24 months in certain indications).

The labelled information describes dose modification and interruption criteria for immune-related adverse reactions, such as pneumonitis, colitis, hepatitis, endocrinopathies, nephritis and skin reactions, graded by severity. The SmPC and prescribing information should be consulted directly by the treating clinician for the applicable modification schedule; this content is descriptive only and is not a treatment recommendation.

Pembrolizumab is prepared and diluted by trained personnel using aseptic technique, typically diluted in sodium chloride or dextrose solution as specified in the product information, and administered via an in-line filter. Premedication is not routinely required. Patients are typically monitored during and after infusion for hypersensitivity or infusion-related reactions.

Storage and handling

• Store refrigerated at 2°C to 8°C in the original carton to protect from light
• Do not freeze
• Do not shake the vial
• Diluted solution may be stored per the product information for a limited period under refrigeration or at room temperature prior to administration
• Any unused product or waste material should be disposed of in accordance with local requirements for cytotoxic/biological medicinal products

Side effects

The following reflects adverse reaction information described in the approved EU SmPC and FDA prescribing information for pembrolizumab. Because pembrolizumab acts on immune checkpoints, most clinically significant reactions are immune-related and can affect any organ system.

Commonly reported

Serious effects requiring medical attention

Patients and caregivers should report new or worsening symptoms to the treating oncology team promptly, as early recognition and management of immune-related reactions materially affects outcomes. Suspected adverse reactions should also be reported through the applicable national pharmacovigilance scheme (e.g. Yellow Card in the UK, MedWatch in the US).

Keytruda (pembrolizumab) vs Opdivo (nivolumab)

Keytruda and Opdivo are both PD-1 immune checkpoint inhibitors, sharing the same general mechanism of action, and both received initial regulatory approval in 2014. They differ in their approved indications, dosing regimens and typical combination strategies. Choice between the two agents for a given patient is a clinical decision made by the treating oncologist based on tumour type, biomarker status, prior therapy and the specific approved label in the relevant jurisdiction.

Pembrolizumab is most often used as monotherapy or combined with chemotherapy or targeted agents such as lenvatinib. Nivolumab is frequently paired with ipilimumab (a CTLA-4 inhibitor) for dual checkpoint blockade in indications including melanoma, renal cell carcinoma, hepatocellular carcinoma and mesothelioma; this combination is associated with a higher rate of immune-related adverse events than either agent used alone, reflecting the additive immune activation of blocking two distinct checkpoints.

Neither agent is interchangeable with the other once treatment has begun, since both target the same PD-1 pathway; if a patient does not respond to one, the other is not typically expected to succeed via the same mechanism. Selecting between them, or moving to an alternative therapeutic class, is a matter for the treating multidisciplinary oncology team with reference to the applicable regulatory label.

Availability and supply route

Registration and reimbursement status for pembrolizumab differ by country and depend on national health authority approval, local labelling and the specific indication. Clinicians and procurement teams should confirm current registration status and the approved label with the relevant national regulator before initiating or sourcing treatment.

Where a product is not locally registered for a given indication, some healthcare systems operate named-patient or compassionate supply frameworks that allow access to a medicine on a physician's request for an individual patient, subject to national import and pharmacovigilance rules. This route is distinct from routine retail supply and requires a valid prescription and documentation at every stage.

Pharmacy Remedy is a licensed Turkish pharmaceutical wholesaler operating in the B2B channel; it supplies hospitals, clinics and other licensed healthcare entities against valid prescriptions and appropriate import documentation, and does not sell medicines to members of the public. All supply of pembrolizumab is subject to verification of licensure, prescription validity, and compliance with the destination country's import and pharmacovigilance requirements.

Frequently asked questions

Primary sources

• EMA — Keytruda (pembrolizumab) product information
• FDA — Keytruda (pembrolizumab) prescribing information

Further reading and regulatory routes

• Which country Keytruda is sourced from, and why prices differ
• How to verify a medicine is genuine
• Why medicines cost less in Türkiye
• WHO falsified medicine alerts
• Named patient supply
• UAE import guide
• For healthcare professionals
• All medicine monographs

Related medicines

• Opdivo (nivolumab)
• Herceptin (trastuzumab)
• Abraxane (paclitaxel formulated as albumin-bound nanoparticles (nab-paclitaxel))