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KEYNOTE-826: What the Cervical Cancer Trial Found
KEYNOTE-826 added pembrolizumab to chemotherapy for advanced cervical cancer, the first real change in that setting for about a decade. Both of its main measures improved, in three populations tested one after another.
Original commentary from the Cancer Explained editorial team.
Please note: this page is educational only — it is not medical advice, and it does not speculate about anyone’s health beyond reliable public reporting. For questions about your own health, talk with your healthcare team.
A decade with nothing new
Cervical cancer that keeps coming back, or has spread, had been treated much the same way for around ten years: platinum chemotherapy, often with bevacizumab. KEYNOTE-826 asked whether adding an immune drug to that backbone would help.
It matters who this affects. Advanced cervical cancer falls hardest on women who never had reliable access to screening, so a change in this setting reaches a group that earlier advances mostly missed.
What a combined positive score means
Tumour samples were scored for PD-L1 using a combined positive score, or CPS. You count the cells staining for PD-L1, divide by the total number of live tumour cells, and multiply by 100. A CPS of 1 means one stained cell per hundred tumour cells.
The trial pre-specified three populations and tested them in a fixed order: CPS of 1 or more, then everyone randomised, then CPS of 10 or more.
How the trial was built
| Field | Detail |
|---|---|
| Trial | KEYNOTE-826 |
| Identifier | NCT03635567 |
| Phase | Phase 3 |
| Design | Randomised, double-blind, placebo-controlled |
| Cancer type | Persistent, recurrent or metastatic cervical cancer |
| Comparator | Pembrolizumab or placebo by infusion every three weeks, added to platinum chemotherapy, with bevacizumab at the doctor's discretion |
| Primary endpoints | Progression-free survival and overall survival |
617 people were randomised, half to each side, with pembrolizumab or placebo given for up to 35 cycles. 548 had a CPS of 1 or more and 317 had a CPS of 10 or more.
Bevacizumab was not assigned by the trial. Each investigator decided, which means background treatment varied between patients.
The progression-free survival numbers
Among the 548 with CPS of 1 or more, median progression-free survival was 10.4 months with pembrolizumab and 8.2 months with placebo (hazard ratio 0.62, 95% CI 0.50 to 0.77, p<0.001).
Across all 617, the medians were the same two figures — 10.4 and 8.2 months — with a hazard ratio of 0.65 (95% CI 0.53 to 0.79, p<0.001). Among the 317 with CPS of 10 or more, 10.4 against 8.1 months, hazard ratio 0.58 (95% CI 0.44 to 0.77, p<0.001).
The medians barely move between the groups. What that suggests is that the benefit is not concentrated in the highest-scoring tumours in the way it is for some other cancers.
Survival at two years
Survival was reported as a rate at 24 months, not as a median, because the medians were not yet reached.
- CPS of 1 or more: 53.0% alive against 41.7% (hazard ratio 0.64, 95% CI 0.50 to 0.81, p<0.001)
- All randomised: 50.4% against 40.4% (hazard ratio 0.67, 95% CI 0.54 to 0.84, p<0.001)
- CPS of 10 or more: 54.4% against 44.6% (hazard ratio 0.61, 95% CI 0.44 to 0.84, p=0.001)
The commonest severe side effects were anaemia (30.3% against 26.9%) and low neutrophils (12.4% against 9.7%) — differences small enough that the chemotherapy backbone, not the immune drug, accounts for most of the burden.
What this trial cannot tell you
- Anything much about PD-L1-negative disease. 548 of the 617 participants had a CPS of 1 or more, so the trial had few of the others.
- What bevacizumab contributes. It was given at the doctor's discretion, not randomised.
- The full size of the survival gain. These are first interim results, reported as two-year rates because median survival had not been reached.
- What happens beyond two years. Follow-up did not go that far.
Questions at an advanced cervical cancer diagnosis
- Was my tumour scored for PD-L1, and what was the number?
- Would bevacizumab be part of my plan, and why or why not?
- What does a two-year survival figure mean for how we plan the next year?
Sources
This article was written from the sources below, which were checked on the source-check date shown above.
- NEJM: Pembrolizumab for Persistent, Recurrent, or Metastatic Cervical Cancer (KEYNOTE-826) (primary)
How this article was prepared
Prepared by Cancer Explained's AI-assisted editorial system and checked against the sources listed below. This article has not been reviewed by a healthcare professional unless a named reviewer is specifically shown.
Cancer Explained is published by the National Cancer Information Foundation as a nonprofit-oriented public-interest education project. It is not a diagnostic service, does not recommend treatments, and is not for emergencies.
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Put the story in context
Prevention, possible warning signs, screening, and diagnosis
This story relates to Cervical cancer. The information below is general: it does not reveal anything else about a public person’s health, and not every point applies to every cancer. Personal advice depends on age, symptoms, family history, exposures, and medical history.
Prevention and risk reduction
Not every cancer can be prevented. Avoiding tobacco, protecting skin from ultraviolet radiation, limiting alcohol, staying active, and receiving recommended HPV or hepatitis B vaccination can lower the risk of certain cancers. A risk factor is not a prediction or a cause in one individual.
Symptoms and possible early signs
Possible signs vary and are often caused by conditions other than cancer. Changes worth discussing include a new lump, unexplained bleeding or weight loss, a persistent cough, lasting bowel or bladder changes, a changing skin spot, or symptoms that persist or worsen. Some early cancers cause no symptoms.
Screening and early detection
Screening looks for certain cancers before symptoms begin. Recommended tests exist only for some cancers and depend on age and risk. Screening can have benefits and harms; it is not the same as evaluating a new symptom, and there is no single routine scan or blood test that reliably screens for every cancer.
How cancer is diagnosed
Diagnosis may involve a history and exam, imaging, laboratory tests, and often a biopsy. Pathology can identify the cancer type and may test biomarkers that guide treatment. Symptoms, screening results, tumor markers, or online stories alone cannot confirm cancer.
Learn about this story’s cancer topic
A public story may encourage questions, but it should not be used to estimate your risk or choose testing. Contact a healthcare professional about a persistent or concerning change. Seek urgent care for severe or rapidly worsening symptoms.