Durvalumab vs Pembrolizumab in Stage 3 Lung Cancer
Durvalumab and pembrolizumab are both immune checkpoint inhibitors used in lung cancer, but they sit at different points in the treatment path. In unresectable stage 3 non-small cell lung cancer treated with chemoradiation, it is durvalumab that is given afterwards, not pembrolizumab. This page sets out which drug follows chemoradiation, why the two are not interchangeable there, and how long each is given. Which medicine applies to a specific patient, if any, is a decision for the treating oncology team.
Medically reviewed by Dr. C. Raghavendra Reddy, Medical Oncologist, MBBS (Gold Medal) · DNB · DM (Medical Oncology, Gold Medal) · Last reviewed August 2026
Which Drug Is Used After Chemoradiation in Stage 3 Lung Cancer?
Durvalumab. For unresectable stage 3 non-small cell lung cancer that has not progressed after concurrent chemoradiation, consolidation durvalumab is the guideline-supported option in NCCN, ASCO and ESMO guidance. Pembrolizumab is not approved or recommended in that specific post-chemoradiation setting. Its lung cancer role sits elsewhere in the pathway.
Most people land here because they were offered one drug and read about the other. The difference is not that one molecule is stronger. Each was tested in a different clinical situation, and an approval earned in one situation does not carry over to another. Here is how the two line up.
| Durvalumab | Pembrolizumab | |
|---|---|---|
| Drug target | PD-L1 (the ligand on the tumour side) | PD-1 (the receptor on the T-cell side) |
| Brand marketed in India | Imfinzi (AstraZeneca) | Keytruda (MSD) |
| Unresectable stage 3 NSCLC, after chemoradiation | This is its established consolidation role | Not an approved or guideline-supported role |
| Resectable disease, around surgery | Used in some perioperative regimens | Used before and after surgery, and as adjuvant treatment after complete resection |
| Metastatic (stage 4) NSCLC | Not the usual first-line choice | A common first-line option, alone or with chemotherapy, depending on PD-L1 |
| Typical infusion schedule | 10 mg/kg every 2 weeks, or 1500 mg flat every 4 weeks | 200 mg every 3 weeks, or 400 mg every 6 weeks |
| Typical maximum duration | Up to 12 months as consolidation | Up to 2 years in metastatic disease; about 1 year as adjuvant treatment |
| Where it is given | Intravenous infusion in a hospital or day-care unit, with observation afterwards. Neither is a tablet and neither is taken at home. | |
This table shows broad approved roles, not eligibility for any individual. Stage, resectability, PD-L1 status, molecular results and organ function all change the answer. Current CDSCO-approved labelling, read alongside NCCN, ASCO or ESMO guidance, is what the treating oncologist works from.
Did you know?
Consolidation durvalumab is normally expected to start within 42 days of the last radiation dose. That is why the decision is usually made while chemoradiation is still running — waiting until treatment is over to raise the question can close the window.
Why Durvalumab and Not Pembrolizumab?
Because that is where each drug's evidence and approved indication sit. Durvalumab was tested specifically as consolidation after chemoradiation in unresectable stage 3 NSCLC, in the PACIFIC trial, and that setting became its indication. Pembrolizumab has not been established there. Its NSCLC evidence is in metastatic disease and around surgery.
PACIFIC asked a narrow question: in unresectable stage 3 disease that had not progressed after concurrent chemoradiation, does adding a PD-L1 inhibitor afterwards change outcomes. Regulators and guideline bodies accepted the answer for that population, and consolidation durvalumab entered NCCN, ASCO and ESMO guidance on that basis.
Pembrolizumab's lung cancer trials asked different questions. Its established roles are first-line metastatic NSCLC and treatment around surgery for disease that can be removed. Some of that surgical territory includes stage 3 tumours, which is where the confusion starts. An operable stage 3 cancer and a stage 3 cancer treated with definitive chemoradiation are two different clinical problems with two different drug pathways.
This is not a statement that one medicine is better than the other. They are different molecules against different targets, tested in different situations, and neither has been shown to be the right choice in the other's setting. If you have been offered one and read about the other, the useful conversation is with your oncologist about which setting the cancer actually falls into.
Approval status: both molecules are approved in India and marketed under the brand names above. Indications differ by country and are revised periodically, so the wording that applies to a specific cancer and stage should be checked against current CDSCO-approved labelling, not assumed from an international approval.
How Long Is Each Drug Given?
Consolidation durvalumab has a fixed stopping point: up to 12 months. Pembrolizumab has no single answer, because its duration depends on the setting — up to 2 years in metastatic disease, about a year as adjuvant treatment after surgery, and a defined number of cycles in perioperative regimens.
| Setting | Drug | Usual schedule | Usual maximum duration |
|---|---|---|---|
| Unresectable stage 3 NSCLC, after chemoradiation | Durvalumab | 10 mg/kg every 2 weeks, or 1500 mg every 4 weeks | Up to 12 months |
| Metastatic NSCLC, first line | Pembrolizumab | 200 mg every 3 weeks, or 400 mg every 6 weeks | Up to 2 years |
| After complete surgical resection (adjuvant) | Pembrolizumab | 200 mg every 3 weeks | About 1 year |
| Around surgery (perioperative) | Pembrolizumab | With chemotherapy before surgery, then continued after | A defined number of cycles, set by the regimen |
| Any of the above | Treatment stops early if the cancer progresses, if a serious immune-related side effect develops, or if the oncology team judges the risk has outgrown the likely benefit. | ||
Doses and schedules here are the commonly published ones for adults and are given for orientation only. The actual dose, interval and stopping point are decided by the treating oncologist for the individual patient, and can differ from these figures.
Who Durvalumab and Pembrolizumab Are Not For
Most people reading this page are not candidates for either medicine, and in stage 3 lung cancer the list of people consolidation immunotherapy is not for is longer than the list it suits. As a class, PD-1 and PD-L1 inhibitors are generally not used for:
- Disease that progressed during chemoradiation. Consolidation durvalumab is for cancer that has not progressed. If the disease advanced during treatment, the plan changes entirely.
- Stage 3 tumours that are operable. A resectable stage 3 cancer follows a surgical pathway, where the immunotherapy questions are different ones.
- Sensitising EGFR mutations, and usually ALK rearrangements. The evidence for consolidation durvalumab here has never been convincing, and guidance points elsewhere — see below.
- Active autoimmune disease needing systemic immunosuppression. Checkpoint inhibition can trigger a serious flare, and the risk often outweighs the possible gain.
- Solid organ or stem-cell transplant recipients. Releasing an immune brake carries a meaningful risk of organ or graft rejection.
- Incomplete recovery from chemoradiation. Persistent radiation pneumonitis, poor lung function or a low performance status can make consolidation unsafe, whatever the stage says.
- Pregnancy and breastfeeding, and known hypersensitivity. Neither molecule is established as safe in pregnancy, and a documented reaction to the drug or an excipient rules it out.
Neither medicine is chosen because it is newer, more talked about, or the one a relative was given. Eligibility is a clinical judgement against the approved indication for that cancer, stage and molecular profile.
What If the Stage 3 Cancer Has an EGFR Mutation?
The plan usually changes. For unresectable stage 3 NSCLC with a sensitising EGFR mutation, the evidence now supports osimertinib, a targeted tablet, after chemoradiation rather than a checkpoint inhibitor. The LAURA trial reported in 2024 and international guidance moved accordingly. Molecular testing therefore has to happen before consolidation is planned.
This is the most consequential detail on the page. The benefit of durvalumab in EGFR-mutated tumours was never persuasive in the original subgroup analyses, and a targeted option now exists for exactly this situation. ALK-rearranged disease is approached with similar caution, and sequencing a checkpoint inhibitor close to certain targeted tablets can raise the risk of serious side effects.
The practical step is narrow and specific: ask the oncology team whether molecular testing has been done, what it showed, and whether the consolidation plan reflects it. If a report is still pending, ask when it is expected relative to the last radiation dose. Which markers matter, and what each one changes, is covered in Biomarkers Beyond PD-L1.
Does Any of This Apply to Small Cell Lung Cancer?
Partly. In limited-stage small cell lung cancer, which overlaps with what patients call stage 3, durvalumab after concurrent chemoradiation became an option following the ADRIATIC trial reported in 2024. Pembrolizumab is not used in that setting. The two lung cancer types are treated as separate diseases throughout.
Small cell disease is staged and managed differently, and drugs are not swapped between the two types casually. In extensive-stage small cell disease the checkpoint inhibitors used alongside chemotherapy are atezolizumab and durvalumab, not pembrolizumab. The same principle applies as in NSCLC: the indication follows the trial, and the trial defined a specific population.
So if the pathology report says small cell, most of what is written online about pembrolizumab and stage 3 lung cancer does not apply. The two checkpoint inhibitors that do feature there are compared in Atezolizumab vs Durvalumab in Small Cell Lung Cancer.
How Do the Two Compare on Cost and Access?
Both are originator biologics in India with no domestic biosimilar confirmed as marketed for either molecule as of August 2026. Total cost is driven less by the price of one vial than by dose, body weight and how many months the course runs — and those differ sharply between the two settings.
Durvalumab consolidation has a defined ceiling of 12 months, so the course length is predictable from the outset. Pembrolizumab in metastatic disease can run to 2 years, so the same per-vial price accumulates over a far longer period. Comparing a single vial price between the two tells you very little about what a course costs.
For pembrolizumab, published pharmacy and distributor listings in India have shown a 100 mg vial in the region of ₹1,50,000 to over ₹2,00,000 — indicative, as of August 2026, from published listings rather than any CION rate. Durvalumab's Indian listed price is not quoted here, because it could not be verified against a citable published source at the time of writing; the hospital pharmacy handling the prescription is the reliable place to confirm it.
On biosimilars, nivolumab is the checkpoint inhibitor where a domestic biosimilar has actually launched in India, in January 2026, after the Indian patent lapsed in May 2026. Pembrolizumab's patent protection is expected to begin lapsing only around 2028-29. For durvalumab, the current Indian biosimilar position is unconfirmed and should be checked against CDSCO listings rather than assumed either way.
Whatever the molecule, buy it only through the treating hospital's pharmacy or a licensed, verifiable source. Counterfeit checkpoint inhibitors have been reported entering the Indian market as high-value products approach patent expiry, and a fake vial cannot be identified by appearance alone. What actually differs between locally made and imported product is covered in Indian-Made vs Imported Immunotherapy: What Actually Differs, and indicative pricing across every approved molecule is collected in Immunotherapy Cost Comparison: All Approved Medicines in India.
Durvalumab vs Pembrolizumab: Your Questions Answered
Which drug is used after chemoradiation for stage 3 lung cancer?
Durvalumab. In unresectable stage 3 non-small cell lung cancer that has not progressed after concurrent chemoradiation, consolidation durvalumab is the guideline-supported option in NCCN, ASCO and ESMO guidance, and it is the setting durvalumab was specifically tested in. Pembrolizumab is not approved or recommended there. Durvalumab is normally started within 42 days of the last radiation dose, so the plan is usually made before chemoradiation finishes rather than afterwards. Whether it applies at all depends on cancer type, molecular testing, recovery from chemoradiation and organ function, which only the treating oncology team can assess.
Why is pembrolizumab not used after chemoradiation in stage 3 lung cancer?
Because that is not where its evidence or its approved indication sits, not because it is a weaker medicine. Pembrolizumab has been studied and approved mainly in metastatic non-small cell lung cancer and around surgery for resectable disease, either given before and after an operation or as adjuvant treatment following complete resection. Durvalumab is the molecule studied as consolidation after definitive chemoradiation in unresectable stage 3 disease. Checkpoint inhibitors are not interchangeable across settings. An approval earned in one situation does not transfer to another, and Indian labelling follows the same logic.
How long is durvalumab given after chemoradiation?
Consolidation durvalumab is given for up to 12 months. The two usual schedules are 10 mg per kg by intravenous infusion every 2 weeks, or a flat 1500 mg dose every 4 weeks, both delivered in a day-care setting. Treatment stops earlier if the cancer progresses, if a serious immune-related side effect develops, or if the oncology team judges the risk has outgrown the likely benefit. It is usually started within 42 days of the final radiation dose. The exact schedule and stopping point are set by the treating oncologist, not read off a page.
How long is pembrolizumab given in lung cancer?
It depends on the setting, and none of those settings is after chemoradiation for unresectable stage 3 disease. In metastatic non-small cell lung cancer, pembrolizumab is typically 200 mg every 3 weeks or 400 mg every 6 weeks, continued for up to 2 years if it is working and being tolerated. After complete surgical removal, adjuvant pembrolizumab runs for about a year. In the perioperative approach it is given with chemotherapy before surgery and then continued for a defined number of cycles afterwards. Duration is always shortened by progression or by significant immune-related toxicity.
Does a PD-L1 test decide between durvalumab and pembrolizumab?
Not in the way most people expect. The clinical setting decides first and the biomarker refines it second. After chemoradiation for unresectable stage 3 disease, the question is whether consolidation durvalumab is appropriate at all, and PD-L1 requirements for that indication differ between regulators, with some labels restricting it to tumours that express PD-L1 and others not. In metastatic disease, PD-L1 scoring matters a great deal for pembrolizumab and helps decide whether it is used alone or alongside chemotherapy. A PD-L1 result on its own never selects a drug.
What happens if the stage 3 lung cancer has an EGFR mutation?
The plan usually changes. For unresectable stage 3 non-small cell lung cancer with a sensitising EGFR mutation, the evidence now supports osimertinib, a targeted tablet, after chemoradiation rather than a checkpoint inhibitor. The benefit of consolidation durvalumab in EGFR-mutated disease has never been convincing, and international guidance has moved accordingly. This is why molecular testing matters before consolidation is planned, not after it has started. ALK-rearranged disease is approached with similar caution. Ask the oncology team what the molecular report showed before assuming immunotherapy is the next step.