Pembrolizumab (Keytruda): What It Is and How It Is Used
Pembrolizumab, sold as Keytruda, is a PD-1 immune checkpoint inhibitor given by intravenous infusion. It blocks a brake on T cells so the immune system can recognise cancer cells. It is approved in India for specific advanced cancers only, in patients whose tumour type, stage and biomarker results meet the approved criteria.
Medically reviewed by Dr. C. Raghavendra Reddy, Medical Oncologist, MBBS (Gold Medal) · DNB · DM (Medical Oncology, Gold Medal) · Last reviewed August 2026
What is pembrolizumab (Keytruda) and how does it work?
Pembrolizumab is a monoclonal antibody that binds the PD-1 receptor on T cells and blocks it from pairing with PD-L1 and PD-L2 on tumour cells. That pairing normally switches the T cell off. Blocking it aims to let the immune system recognise and attack the cancer itself.
Two things follow from that mechanism. First, pembrolizumab does not attack cancer cells directly the way chemotherapy does. It works only where a person still has T cells able to respond, which is why it helps in a proportion of patients rather than in everyone who receives it. Second, releasing a brake on the immune system can let it turn on healthy organs. That is the origin of immune-related adverse events, covered below.
Pembrolizumab is the generic name of the molecule; Keytruda is the brand it is sold under, made by MSD. They are the same medicine. It sits in the same class as nivolumab, and in the wider checkpoint-inhibitor family alongside the PD-L1 and CTLA-4 drugs.
Cited class and mechanism descriptions follow standard oncology references used by NCCN, ASCO and ESMO in their patient-facing material, and the manufacturer’s approved product information.
Which cancers is pembrolizumab approved for in India?
Pembrolizumab is not approved for cancer in general. It is approved in India for a defined list of specific cancers and settings, each cleared separately by the Drugs Controller General of India. Within each of those, only certain stages, biomarker results or prior-treatment histories qualify.
This is the part most searches skip. Because the brand name is famous, it is often assumed to be an option for any cancer at any stage. It is not. Pembrolizumab first received marketing permission in India in 2016, and its Indian indication list has been widened in steps since — cervical and oesophageal cancer in January 2023, triple-negative breast cancer and renal cell carcinoma in October 2023, with further combination indications reviewed by the CDSCO oncology expert committee since. Each addition is separate. A cancer type that is not on the list is not an off-label choice you can request.
Indicative summary of publicly reported regulatory decisions as of August 2026 — a starting point for the conversation with your oncologist, not the approved product label and not a suitability check. The label that applies to your exact diagnosis governs, and it changes over time.
How is pembrolizumab given?
Pembrolizumab is given as an intravenous infusion in a day-care oncology unit, usually over about 30 minutes. Most people go home the same day. Cycles are typically every three weeks, or every six weeks at a higher dose, with the interval set by the treating oncologist under the approved label.
It is not a tablet and it cannot be taken at home. At CION centres, immunotherapy of this kind is administered as day care; where a response-assessment PET-CT is needed between cycles, it is coordinated at partner imaging centres rather than performed in-house.
- Before the cycle — blood tests check thyroid, liver, kidney and blood-count values, and you are asked about new symptoms since the last cycle. Results can delay a cycle; that is routine, not a setback.
- Review — the oncologist confirms the dose and that it is safe to proceed today.
- The infusion — a cannula is placed and the drug runs in over roughly 30 minutes. No sedation, no hair loss expected from this drug itself.
- Short observation — a period of monitoring for infusion reactions before you leave.
- Between cycles — you watch for new symptoms and report them promptly. Immune side effects can appear weeks or months after a dose, and even after treatment has stopped.
How long treatment continues varies. In many advanced-disease settings it continues while it appears to be working and is tolerated, reviewed at each scan. In some approved settings the label specifies a maximum duration, commonly up to about two years. It stops earlier if the cancer progresses, if a serious immune-related event develops, or if the person chooses to stop.
Who pembrolizumab is not for
Most people who search this drug name are not candidates for it. That is the single most useful fact on this page, and it is better heard now than later. Pembrolizumab is generally not used, or is used only with specialist caution, in these situations:
- Cancers outside its approved list — if your diagnosis is not an approved indication, it is not an option you can request.
- Early, curable disease where standard treatment already works — where surgery, chemotherapy or radiotherapy is the established curative path, adding a checkpoint inhibitor is not standard.
- Tumours that do not meet the biomarker condition — several indications require a PD-L1 level, or MSI-High / dMMR status, confirmed on testing.
- Active autoimmune disease needing systemic immunosuppression — releasing an immune brake can worsen it.
- Solid-organ transplant recipients on anti-rejection medicines — there is a real risk of graft rejection.
- People already on high-dose steroids for another condition — this needs individual assessment before any decision.
- Significant existing lung inflammation or interstitial lung disease — specialist judgement is required.
- Pregnancy, and poor overall performance status — both are weighed carefully against any expected benefit.
It is also not an immunity booster, not a preventive, and not something to take alongside another plan without telling the treating team. Eligibility can only be decided by your own oncology team from your own reports and biomarker results.
What side effects can pembrolizumab cause?
The characteristic risks are immune-related adverse events, or irAEs — the immune system attacking a healthy organ. The commonest involve the thyroid, skin, gut, liver and lungs. Most are manageable when caught early. A few, such as inflammation of the lungs, bowel, heart muscle or adrenal glands, are medical emergencies.
irAEs are defined as much by when they appear as by what they are. Skin rash and thyroid changes tend to appear earliest. Colitis, hepatitis and pneumonitis often appear later in a course, and some events appear weeks or months after the last dose. That is why pre-cycle blood tests continue throughout treatment.
Symptoms that need urgent assessment, not home management: new or worsening breathlessness or a persistent dry cough; loose motions that increase in number or contain blood; chest pain or palpitations; severe unexplained fatigue with dizziness, vomiting or collapse; yellowing of the eyes or skin. For any of these, contact your treating oncology team immediately or go to the nearest emergency department. Do not self-medicate and do not wait for the next scheduled cycle. Tell any doctor who sees you, in any department, that you are on immunotherapy — it changes how these symptoms are investigated.
Detailed, symptom-by-symptom guidance sits on the dedicated side-effect pages rather than here; this page is an orientation to the medicine, not a triage tool.
Is there a pembrolizumab biosimilar in India, and what drives the cost?
There is no approved pembrolizumab biosimilar in India as of August 2026. The originator product, Keytruda from MSD Pharmaceuticals, is the only source. Its Indian patent protection is expected to begin lapsing around 2028-29, so lower-cost versions are not expected before then.
That is a meaningful difference from nivolumab, the other widely used PD-1 inhibitor: nivolumab’s Indian patent lapsed in May 2026, and a domestic biosimilar launched in January 2026 at roughly a quarter of the reference price (indicative, as of August 2026). The two drugs are in the same class but are not interchangeable, and the cost gap between them is not a reason to ask for a switch — which drug applies is set by your cancer type, biomarkers and the approved label.
What actually drives the total for pembrolizumab is dose, the number of cycles, the day-care and monitoring costs around each infusion, and any imaging between cycles. Published price reporting varies by source and date, so we do not attach a figure to this molecule here. For a worked breakdown, see the dedicated cost page linked below.
An authenticity note, not a sales one: counterfeit checkpoint inhibitors have been reported entering the Indian market. Insist that any vial is dispensed through a licensed hospital pharmacy with documented cold-chain handling, and keep the batch documentation. This is a patient-safety issue and should not be softened.
Pembrolizumab (Keytruda): Frequently Asked Questions
What is pembrolizumab (Keytruda) and how does it work?
Pembrolizumab is a monoclonal antibody known as a PD-1 immune checkpoint inhibitor. It binds the PD-1 receptor on T cells and blocks it from pairing with PD-L1 and PD-L2 on tumour cells. That pairing normally switches the T cell off, which is one way a cancer hides from the immune system. Blocking it aims to let the immune system recognise and attack the cancer itself. Pembrolizumab does not kill cancer cells directly the way chemotherapy does, and it is not a general immunity booster. It is sold internationally under the brand name Keytruda, made by MSD.
Which cancers is pembrolizumab approved for in India?
Pembrolizumab is not approved for cancer in general. It is approved for a defined list of specific cancers and settings, each cleared separately by the Indian regulator. Publicly reported approvals include advanced melanoma, non-small-cell lung cancer, head and neck squamous cell carcinoma, classical Hodgkin lymphoma, urothelial carcinoma, cervical and oesophageal cancer (approved January 2023), and triple-negative breast cancer and renal cell carcinoma (approved October 2023). Within each of those, only certain stages, biomarker results or prior-treatment histories qualify. The approved label for your exact diagnosis governs, and that list changes over time.
How is pembrolizumab given, and how long does an infusion take?
Pembrolizumab is given as an intravenous infusion in a day-care oncology unit, usually over about 30 minutes. Most people go home the same day and no hospital admission is needed for the infusion itself. Cycles are typically every three weeks, or every six weeks at a higher dose, with the interval set by the treating oncologist according to the approved label for that indication. Blood tests are done before each cycle to check thyroid, liver, kidney and blood-count values. It is not given as a tablet and it cannot be taken at home.
How long does pembrolizumab treatment usually continue?
There is no single answer, because it depends on the indication and on how the cancer and the person respond. In many advanced-disease settings, treatment continues while it appears to be working and is tolerated, and is reviewed at each scan. In some approved settings the label specifies a fixed maximum duration, commonly up to about two years. Treatment stops earlier if the cancer progresses, if a serious immune-related side effect develops, or if the person decides to stop. Stopping is a clinical decision made with your oncologist, reviewed scan by scan.
Who should not receive pembrolizumab?
Most people with cancer are not candidates. It is not used where surgery, chemotherapy or radiotherapy alone is the standard curative treatment, and it is not used for cancers outside its approved list. Extra caution or exclusion applies to people with an active autoimmune disease needing systemic immunosuppression, solid-organ transplant recipients on anti-rejection medicines, people already on high-dose steroids for another reason, and people with significant existing lung inflammation. Pregnancy and poor performance status are also considered. Only your treating oncology team can decide this from your own reports.
Is there a pembrolizumab biosimilar in India?
Not as of August 2026. Pembrolizumab is supplied in India only as the originator product, Keytruda, by MSD Pharmaceuticals, which received marketing permission from the Indian regulator in 2016. Its patent protection is expected to begin lapsing around 2028-29, so biosimilar versions are not expected before then. That differs from nivolumab, whose Indian patent lapsed in May 2026 with a domestic biosimilar launched in January 2026. Because counterfeit checkpoint inhibitors have been reported in India, sourcing only through a licensed hospital pharmacy with documented cold-chain handling matters.