Pembrolizumab
Pembrolizumab is a PD-1 blocking antibody approved in more than 40 settings, from melanoma and lung cancer to the first tumour-agnostic approval for mismatch-repair-deficient tumours in 2017, and before and after surgery in triple-negative breast cancer. A subcutaneous form arrived in 2025, and it is the backbone partner for ADCs and personalised neoantigen vaccines.
Overview
Approvals span melanoma, NSCLC, head and neck, Hodgkin, urothelial, MSI-H/dMMR tumours (first tumour-agnostic approval, 2017), gastric, oesophageal, cervical, HCC, RCC, endometrial, TNBC (KEYNOTE-355 metastatic CPS ≥10; KEYNOTE-522 neoadjuvant/adjuvant with 7-year OS benefit), TMB-high, and more. 2026 additions include platinum-resistant PD-L1+ ovarian cancer, adjuvant RCC with belzutifan, and combination labels with sacituzumab govitecan (ASCENT-04) and enfortumab vedotin. Subcutaneous Keytruda Qlex approved 2025. Backbone for neoantigen vaccines (intismeran).
Humanised IgG4 blocking PD-1; restores T-cell effector function.
1.Antibody binds PD-1 on T cells
- Route
- IV infusion over 30 min (subcutaneous Keytruda Qlex available)
- Schedule
- 200 mg every 3 weeks or 400 mg every 6 weeks; paediatric 2 mg/kg (max 200 mg) every 3 weeks; up to 24 months in most metastatic settings
- Dose modifications
- Hold for grade 2 immune-mediated events; permanently discontinue for grade 4 or recurrent grade 3
- Monitoring
- Thyroid function, LFTs, creatinine, glucose at baseline and periodically; patient education on immune-related symptoms
Source: US prescribing information (DailyMed). Doses are for orientation; the current label governs.
- PD-L1 IHC 22C3 pharmDx · TPS at least 1% or at least 50% (NSCLC); CPS at least 1 (head and neck, oesophageal, gastric); CPS at least 10 (TNBC, gastric first line); CPS at least 1 (cervical)
- VENTANA PD-L1 (SP263) Assay · TC at least 1% (durvalumab after chemoradiotherapy, NSCLC; PACIFIC-derived)
- FoundationOne CDx · Per companion claim: EGFR, ALK, BRAF V600, ERBB2 amplification, KRAS wild-type, BRCA1/2 and HRR genes, PIK3CA, MET exon 14, RET, FGFR2 fusions, IDH1, NTRK fusions; MSI-high; TMB at least 10 mutations per megabase
- VENTANA MMR RxDx Panel · Loss of nuclear expression of any mismatch-repair protein in tumour cells (dostarlimab, endometrial cancer)
- MSI by PCR (Promega MSI Analysis System and equivalents) · Instability at two or more of five markers (MSI-high); NGS panels report MSI from hundreds of loci
- Tumour mutational burden (FoundationOne CDx and equivalents) · At least 10 mutations per megabase (pembrolizumab, tumour-agnostic, KEYNOTE-158)
- Medicare
- Part B (clinician-administered)
Given by infusion or injection in a clinic or hospital outpatient department, so it is a Part B drug: Medicare pays 80% after the Part B deductible and the patient owes 20% coinsurance, uncapped in Original Medicare unless a Medigap policy applies. HCPCS J9271. The subcutaneous Keytruda Qlex is also clinician-administered and stays in Part B.
- Commercial insurance
- covered with prior authorisation
Covered under the medical benefit with prior authorisation confirming diagnosis, biomarker status and line of therapy; site-of-care policies may steer infusions away from hospital outpatient departments. The largest-selling cancer drug in the US; nearly every plan has a Keytruda policy tied to indication and PD-L1 status where the label requires it.
- List price
- $11,115.20 per 200 mg dose every 3 weeks (manufacturer list price)
Merck, KEYTRUDA cost and financial support page (2024). Net prices after rebates are usually lower.
- Assistance programmes
- Merck Access Program
- Merck Patient Assistance Program: Free medicine for eligible uninsured or underinsured patients.
- PAN Foundation: Disease-specific co-pay and premium funds; open and closed funds change monthly.
- HealthWell Foundation
- CancerCare Co-Payment Assistance Foundation
- Patient Advocate Foundation Co-Pay Relief
20% Part B coinsurance on a high-cost infusion adds up quickly: Medigap Plan G or N, Medicare Advantage maximum out-of-pocket, Medicaid dual eligibility, or a charity fund are the usual buffers.
Sources: Medicare.gov: Chemotherapy · Medicare.gov: Prescription drugs (outpatient, Part B). Not medical or financial advice; verify with your plan.
- Appraised for
- Untreated PD-L1 ≥50% metastatic NSCLC (2-year stopping rule)
- Notes
- One of NICE's most-appraised medicines: melanoma (TA357, TA366, adjuvant TA766), NSCLC (TA428, TA531, TA557, TA600), classical Hodgkin lymphoma (TA540), urothelial (TA522), head and neck (TA661), RCC with axitinib (TA692), TNBC (TA801, TA851), MSI-H colorectal (TA709), oesophageal (TA737) and more. Most are optimised with a 2-year treatment stop. With chemoradiotherapy for untreated FIGO 2014 stage 3 to 4A locally advanced cervical cancer (KEYNOTE-A18): TA1177 (July 2026), within the licence. Relapsed or refractory classical Hodgkin lymphoma from age 3 after 2 or more treatments when a transplant is not possible: TA967 (May 2024). Adjuvant treatment of high-risk resected NSCLC after platinum chemotherapy (KEYNOTE-091): TA1037 (February 2025), within the licence. With gemcitabine and cisplatin for untreated advanced biliary tract indication: TA966 (April 2024), terminated appraisal. Adjuvant renal cell carcinoma at increased risk of recurrence after nephrectomy (KEYNOTE-564): TA830 (October 2022), within the licence. Adjuvant completely resected stage 2B or 2C melanoma from age 12 (KEYNOTE-716): TA837 (October 2022).
- NHS England
- Routinely funded for the appraised indication (or via managed access)
Sources: NICE TA531 · SMC advice: pembrolizumab. Funding decisions are indication-specific and change monthly; verify with NICE and your treating team.
Catalysts
Catalyst calendar- 2027expectedHARMONi-3: ivonescimab plus chemotherapy versus pembrolizumab plus chemotherapy, first-line NSCLC
The first head-to-head test of the PD-1 x VEGF bispecific against pembrolizumab in a Western population. Timing is our estimate from the registry record; the sponsor has not given a date. Source
- 2027expectedSUNRAY-01: olomorasib plus pembrolizumab, first-line KRAS G12C NSCLC
Phase 3 in first-line KRAS G12C-mutant NSCLC. Timing is a registry-based estimate. Source
- 2027expectedRegulatory filings for intismeran autogene plus pembrolizumab in adjuvant melanoma (INTerpath-001)
The sponsors said filings would follow the positive topline result of August 2026 and the full data presentation. Timing is our estimate. Source
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- 4 Sept 2014ApprovalUS
Accelerated approval, advanced melanoma after ipilimumab; first PD-1 inhibitor in the US source
- 2 Oct 2015ApprovalUS
PD-L1+ NSCLC after platinum source
- 23 May 2017ApprovalUS
MSI-H/dMMR solid tumours: first tumour-agnostic approval source
- 16 Jun 2020ApprovalUS
TMB-high solid tumours (tumour-agnostic) source
- 13 Nov 2020ApprovalUS
Metastatic TNBC, PD-L1 CPS ≥10, with chemotherapy (KEYNOTE-355) source
- 26 Jul 2021ApprovalUS
High-risk early TNBC, neoadjuvant and adjuvant (KEYNOTE-522) source
- 16 Oct 2023ApprovalUS
Perioperative NSCLC (KEYNOTE-671) source
- Sept 2025ApprovalUS
Subcutaneous pembrolizumab (Keytruda Qlex) source
- Q1 2026ApprovalUS
Platinum-resistant PD-L1+ ovarian cancer source
- 12 Jun 2026ApprovalUS
Adjuvant RCC with belzutifan (LITESPARK-022) source
- 24 Jun 2026ApprovalUS
First-line PD-L1+ TNBC with sacituzumab govitecan (ASCENT-04) source
- 10 Jul 2026ApprovalUS
Muscle-invasive bladder cancer with enfortumab vedotin, as pembrolizumab or pembrolizumab with berahyaluronidase alfa source
Approvals
| Region | Year | Indication |
|---|---|---|
| US | 2014 | Melanoma (first of >40 indications) |
| US | 2017 | MSI-H/dMMR solid tumours (tumour-agnostic) |
| US | 2020 | Metastatic TNBC, PD-L1 CPS ≥10, with chemotherapy |
| US | 2021 | High-risk early TNBC, neoadjuvant + adjuvant (KEYNOTE-522) |
| US | 2026 | Platinum-resistant PD-L1+ ovarian cancer; adjuvant RCC with belzutifan; with sacituzumab govitecan in 1L TNBC |
| Adverse event | Any grade | Grade 3+ |
|---|---|---|
| Hypothyroidism (immune-mediated) | 8% | - |
| Pneumonitis (immune-mediated) | 3.4% | - |
| Colitis (immune-mediated) | 1.7% | - |
| Hepatitis (immune-mediated) | 0.7% | - |
| Fatigue | - | - |
| Musculoskeletal pain | - | - |
| Rash | - | - |
| Diarrhoea | - | - |
| Pyrexia | - | - |
Pooled monotherapy data, >2,800 patients. Rates read from the US prescribing information. Blank cells mean the figure was not sourced, not that it is zero.
| Country | Reimbursement | List price | Assistance |
|---|---|---|---|
| United States | Medicare Part B (physician-administered); commercial plans per formulary | $11,564 per 200 mg dose (WAC, Merck price disclosure 2024) | merckaccessprogram-keytruda.com |
| United Kingdom | NICE: recommended across many indications (melanoma, NSCLC, TNBC KEYNOTE-522/355, RCC, HNSCC, cervical, oesophageal and others) | not disclosed | - |
| European Union | EMA approved; reimbursed in all member states for core indications | not disclosed | - |
List prices are manufacturer or Medicare figures where publicly disclosed; net prices after rebates are usually lower. Reimbursement changes; check the payer.
Trials
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Latest papers
topQuery for this drug: (TITLE:"Pembrolizumab" OR ABSTRACT:"Pembrolizumab" OR TITLE:"Keytruda" OR ABSTRACT:"Keytruda" OR TITLE:"Keytruda Qlex" OR ABSTRACT:"Keytruda Qlex") AND (radiopharmaceutical OR radioligand OR radionuclide OR theranostic OR "nuclear medicine" OR "molecular imaging" OR radiotracer OR scintigraphy OR cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about Pembrolizumab, not a curated reading list.
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