# Give exceptional responders less: pembrolizumab omission after complete response, anthracycline-free regimens and chemotherapy omission in lymphocyte-rich stage I disease

Source: https://onco.cc/ideas/idea-tnbc-de-escalation-for-exceptional-responders/  
OnCo record `idea-tnbc-de-escalation-for-exceptional-responders` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Two thirds of women treated on the KEYNOTE-522 regimen have no tumour left at surgery and about 92 percent of them are alive without relapse at five years, yet all receive nine more cycles of pembrolizumab. Trials are now testing whether the best responders can stop early, skip the anthracycline, or in lymphocyte-rich stage I tumours skip chemotherapy altogether.

## Summary

KEYNOTE-522 produced pathological complete response in 64.8 percent of patients and the CTNeoBC pooled analysis shows complete responders in triple-negative disease have an event-free survival hazard ratio of 0.24; Leon-Ferre's pooled cohort of 1,966 chemotherapy-untreated patients found five-year distant recurrence-free survival of 94 percent in stage I tumours with lymphocytes of 50 percent or more. Against this, the full regimen carries grade 3 or higher adverse events in 78 percent, permanent endocrine toxicity from pembrolizumab, and anthracycline cardiotoxicity and leukaemia risk. OptimICE-pCR (1,295 patients, primary completion May 2033) randomises complete responders to adjuvant pembrolizumab or observation; SCARLET (2,400, March 2033) tests an anthracycline-free regimen; St Gallen 2023 framed intensity and duration as the central problem. A prospective trial of chemotherapy omission in lymphocyte-rich stage I disease has not started.

## Fields

- Kind: Idea
- Last checked: 2026-09-24
- Tags: tnbc-evidence
- Hypothesis: In patients with pathological complete response after neoadjuvant chemotherapy plus pembrolizumab, omitting adjuvant pembrolizumab is non-inferior for three-year recurrence-free survival (margin 3 percentage points); in stage I tumours with stromal lymphocytes of 50 percent or more, surgery and radiotherapy without chemotherapy achieve five-year distant recurrence-free survival above 90 percent.
- Rationale: Complete response and high lymphocyte infiltration each identify a group whose outcome leaves little room for a drug to improve; the toxicity, cost and time saved are certain while the benefit forgone is small and measurable.
- Proposed test: OptimICE-pCR and SCARLET readouts (2033); a single-arm or registry-embedded trial of chemotherapy omission in stage I, lymphocyte-rich disease with a pre-specified five-year distant recurrence-free survival boundary and centrally scored, digitally assisted lymphocyte counts.
- Maturity: being-tested-at-scale
- Actor: research

## Sources

- Leon-Ferre et al.: tumour-infiltrating lymphocytes and outcome without chemotherapy (JAMA 2024): https://europepmc.org/article/MED/38563834
- ClinicalTrials.gov NCT05812807: https://clinicaltrials.gov/study/NCT05812807
- ClinicalTrials.gov NCT05929768: https://clinicaltrials.gov/study/NCT05929768

## Connected records

- cancers: [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- technologies: [Digital pathology & AI](https://onco.cc/technologies/digital-pathology-ai/), [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/)
- drugs: [Doxorubicin](https://onco.cc/drugs/doxorubicin/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/)
- terms: [Anthracyclines (doxorubicin, epirubicin)](https://onco.cc/terms/anthracycline/), [De-escalation, escalation and response-adapted therapy](https://onco.cc/terms/de-escalation/), [Pathologic complete response (pCR)](https://onco.cc/terms/pcr/), [Tumour-infiltrating lymphocytes (TILs)](https://onco.cc/terms/tils/)
- trials: [KEYNOTE-522](https://onco.cc/trials/keynote-522/), [OptimICE-pCR (A012103)](https://onco.cc/trials/optimice-pcr/), [SCARLET (SWOG S2212)](https://onco.cc/trials/scarlet-s2212/)
- bottlenecks: [Toxicity and quality of life are undervalued](https://onco.cc/bottlenecks/b-toxicity-qol/), [Trial design, endpoints and cost](https://onco.cc/bottlenecks/b-trial-design/), [Wrong doses](https://onco.cc/bottlenecks/b-dose-optimisation/)
- key papers: [Overall Survival with Pembrolizumab in Early-Stage Triple-Negative Breast Cancer](https://onco.cc/key-papers/paper-keynote-522-n-engl-j-med-2024-update/), [Pathological complete response and long-term clinical benefit in breast cancer: the CTNeoBC pooled analysis](https://onco.cc/key-papers/paper-cortazar-ctneobc-pcr-pooled-analysis-lancet-2014/), [Pembrolizumab for Early Triple-Negative Breast Cancer](https://onco.cc/key-papers/paper-keynote-522-n-engl-j-med-2020/), [Tumor-Infiltrating Lymphocytes in Triple-Negative Breast Cancer](https://onco.cc/key-papers/paper-leon-ferre-tils-tnbc-no-chemotherapy-jama-2024/), [Understanding breast cancer complexity to improve patient outcomes: The St Gallen International Consensus Conference for the Primary Therapy of Individuals with Early Breast Cancer 2023](https://onco.cc/key-papers/paper-st-gallen-2023-consensus-ann-oncol-2023/)
- roadmaps: [Triple-negative breast cancer roadmap: from a remainder defined by three negative tests to immunotherapy, antibody-drug conjugates and the residual disease problem](https://onco.cc/roadmaps/tnbc-roadmap/)

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