Pembrolizumab

• Non-Small Cell Lung Cancer (NSCLC):
• First-line treatment of metastatic NSCLC with PD-L1 expression ≥1% (without EGFR or ALK mutations).
• In combination with chemotherapy regardless of PD-L1 status.
• For patients with recurrent or metastatic disease after prior chemotherapy.
• Melanoma:
• Treatment of unresectable or metastatic melanoma.
• Adjuvant therapy for high-risk melanoma after surgical resection.
• Head and Neck Squamous Cell Carcinoma (HNSCC):
• Recurrent or metastatic disease refractory to platinum-based chemotherapy.
• First-line with chemotherapy in PD-L1 expressing tumors.
• Classical Hodgkin Lymphoma (cHL):
• Relapsed or refractory disease after three or more prior therapies.
• Urothelial Carcinoma:
• Locally advanced or metastatic disease after platinum-containing chemotherapy.
• First-line treatment for cisplatin-ineligible patients with high PD-L1 expression.
• Microsatellite Instability-High (MSI-H) or Mismatch Repair Deficient (dMMR) Cancers:
• Solid tumors with MSI-H/dMMR that are unresectable or metastatic, and have progressed following prior treatment.
• Other Cancers:
• Gastric or gastroesophageal junction adenocarcinoma.
• Cervical cancer, endometrial carcinoma, and others with FDA approval.

• Route: Intravenous infusion.
• Adult dose:
• 200 mg IV every 3 weeks OR 400 mg IV every 6 weeks.
• Infusion duration: Approximately 30 minutes.
• Pediatrics: Safety and efficacy not established.
• Elderly: No dose adjustment required; monitor closely for toxicity.
• Renal impairment: No dosage adjustment recommended.
• Hepatic impairment: No dosage adjustment required for mild or moderate impairment; use caution in severe impairment.
• Duration: Until disease progression, unacceptable toxicity, or up to 2 years in responders.

Pembrolizumab is a humanized monoclonal antibody that selectively binds to the programmed cell death protein 1 (PD-1) receptor on T-cells. By blocking PD-1 interaction with its ligands PD-L1 and PD-L2, pembrolizumab releases PD-1–mediated inhibition of the immune response, thereby enhancing T-cell-mediated immune activity against tumor cells. This immune checkpoint inhibition restores anti-tumor immune surveillance and promotes tumor cell destruction.

• Absorption: Administered intravenously; bioavailability is 100%.
• Distribution: Volume of distribution ~6 L.
• Metabolism: Catabolized into small peptides and amino acids via proteolytic degradation.
• Half-life: Approximately 22 days.
• Clearance: Non-linear; decreases with repeated dosing due to target-mediated drug disposition.
• Steady-state: Achieved after approximately 18 weeks with repeated dosing.

• Pregnancy: No adequate data in humans; animal studies show potential risks. Use only if benefits outweigh risks. Consider contraception during and after treatment (at least 4 months for females, 7 months for males).
• Lactation: Unknown if excreted in human milk; breastfeeding not recommended during therapy and for 4 months after last dose.

• Immune checkpoint inhibitor
• Programmed cell death protein 1 (PD-1) receptor antagonist
• Monoclonal antibody, immunotherapy

• Known hypersensitivity to pembrolizumab or any excipients.
• Active autoimmune disease requiring systemic treatment (caution advised).
• Organ transplant recipients (risk of rejection).

• Immune-mediated adverse reactions: Pneumonitis, colitis, hepatitis, endocrinopathies (thyroiditis, adrenal insufficiency, diabetes), nephritis. Monitor and treat promptly.
• Infusion-related reactions: May occur; monitor during and post-infusion.
• Risk of severe or fatal immune reactions: Discontinue treatment if severe adverse effects develop.
• Use in patients with pre-existing autoimmune conditions: Caution advised.
• Live vaccines: Avoid concurrent administration.
• Monitor liver function, thyroid function, and other organ systems during treatment.

• Common: Fatigue, rash, pruritus, diarrhea, nausea, decreased appetite, cough, dyspnea, arthralgia.
• Serious: Immune-mediated pneumonitis, colitis, hepatitis, endocrinopathies, nephritis, severe infusion reactions.
• Onset: Variable; immune-related events can occur weeks to months after initiation.

• No significant CYP450 enzyme interactions.
• Immunosuppressants may reduce efficacy.
• Avoid live vaccines during and following treatment.

• Expanded approvals for multiple tumor types including MSI-H/dMMR cancers.
• FDA updated dosing schedule to allow 6-weekly administration.
• Guidelines emphasize early recognition and management of immune-related adverse events.
• Ongoing trials for combination therapies with chemotherapy, targeted agents, and other immunotherapies.

• Store refrigerated at 2°C to 8°C (36°F to 46°F).
• Do not freeze.
• Protect from light; keep in original carton until use.
• Do not shake.
• Use within recommended time after vial puncture.