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The trial that added immunotherapy to pre-surgery chemotherapy for triple-negative breast cancer and, uniquely, improved survival.
1,174 patients. pCR 64.8% vs 51.2%; event-free survival at 5 years 81.2% vs 72.2%; 7-year EFS 78.3% vs 69.8% and OS 85.1% vs 77.2% (ASCO 2026 update). Defines the standard of care for stage II-III TNBC. Open questions: whether adjuvant pembrolizumab is needed after pCR (OptimICE-pCR) and how to escalate for residual disease.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
1,174 enrolled.
Step lines join published landmark estimates; the true curve between them is not shown.
Curves show the trial population; they are not a prediction for any one person.
36-month rates from the 2022 NEJM report, 60-month from the 2024 NEJM report, 84-month from the ASCO 2026 update.
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Pathologic complete response (ypT0/Tis ypN0)primary | Pembrolizumab + chemotherapy | 401 | 64.8% | - | 0.00055 | link |
| Placebo + chemotherapy | 201 | 51.2% | ||||
| Event-free survival at 5 yearsprimary | Pembrolizumab + chemotherapy | 784 | 81.2% | 0.65 (0.51 to 0.83) | - | link |
| Placebo + chemotherapy | 390 | 72.2% | ||||
| Overall survival at 5 years | Pembrolizumab + chemotherapy | - | 86.6% | 0.66 (0.5 to 0.87) | 0.002 | link |
| Placebo + chemotherapy | - | 81.7% | ||||
| Event-free survival at 7 years | Pembrolizumab + chemotherapy | - | 78.3% | - | - | link |
| Placebo + chemotherapy | - | 69.8% | ||||
| Overall survival at 7 years | Pembrolizumab + chemotherapy | - | 85.1% | - | - | link |
| Placebo + chemotherapy | - | 77.2% |
NCCN is the source of the category grades on the triple-negative breast cancer page and the first major guideline to place an antibody-drug conjugate first line for the disease.
Answers the two questions that hung over adjuvant olaparib, durability and late leukaemia, in its favour; the remaining question is whether carriers who also received pembrolizumab or capecitabine, whom the trial did not study, get the same benefit.
Platinum and immunotherapy are now consensus for early triple-negative disease; the open votes have moved to who can safely receive less.
This is the European standard the UK page for triple-negative breast cancer is compared against; NICE guidance covers the same ground with a narrower set of funded drugs.
A second publication from the KEYNOTE-522 trial, later than the first and described in its title as an update or longer-term analysis. Read it with the primary publication linked from the trial page; the record was linked automatically and its figures have not been checked by hand.
For stage II-III triple-negative breast cancer, chemotherapy plus pembrolizumab before surgery and pembrolizumab alone afterwards is now the standard approach worldwide, and the survival gain is real, not just a surrogate. It does not apply to stage I disease or to hormone-receptor-positive or HER2-positive cancers. The price is a year of immunotherapy with a meaningful chance of a permanent endocrine side effect such as hypothyroidism or adrenal insufficiency.
Shows how quickly the standard moved: the 2021 guideline and its reversal are 15 months apart.
This is the paper Europe PMC returns for registry id NCT03036488 with the most citations, so it is the natural first reading for anyone following the KEYNOTE-522 trial. Read the abstract above alongside the trial page and the registry entry; the record was linked automatically and its figures have not been checked by hand.
Shares A-BRAVE, Sherene Loi, Carcinoma with medullary pattern (medullary breast cancer), PD-L1 combined positive score 10 in triple-negative breast cancer.
Shares Rebecca Dent, PD-L1 combined positive score 10 in triple-negative breast cancer, NeoTRIP (NeoTRIPaPDL1), Peter Schmid.
Shares Invasive disease-free survival (iDFS), Early breast cancer: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up, Sustained benefit of adjuvant olaparib in women with germline BRCA1- and BRCA2-associated high-risk HER2-negative early breast cancer: updated results from the OlympiA phase III trial, TNBC roadmap: from 'nothing to target' to ADC + immunotherapy first line.
Shares ECOG-ACRIN EA1131, ASCENT-05 / OptimICE-RD (AFT-65, GBG 119, NSABP B-63), TROPION-Breast03, Residual disease after neoadjuvant therapy in triple-negative breast cancer: the decision point.
Shares ASCENT-05 / OptimICE-RD (AFT-65, GBG 119, NSABP B-63), TROPION-Breast03, ctDNA-guided adjuvant decisions after residual disease: escalate the positive, spare the negative, Residual cancer burden (RCB).
Shares NeoTRIP (NeoTRIPaPDL1), ALEXANDRA / IMpassion030, GeparDouze / NSABP B-59, Pathologic complete response (pCR).
Shares c-TRAK TN, ECOG-ACRIN EA1131, Residual disease after neoadjuvant therapy in triple-negative breast cancer: the decision point, Residual cancer burden (RCB).
Shares Mesenchymal stem-like triple-negative breast cancer (MSL), Carcinoma with medullary pattern (medullary breast cancer), PD-L1 combined positive score 10 in triple-negative breast cancer, Basal-like 1 triple-negative breast cancer (BL1).