# PENELOPE-B

Source: https://onco.cc/trials/penelope-b/  
OnCo record `penelope-b` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

PENELOPE-B tested whether a year of the CDK4/6 inhibitor palbociclib after chemotherapy and surgery would prevent recurrence in women at high risk; it did not, one of two trials to show that palbociclib does not work in early breast cancer even though later drugs in the class do.

## Summary

PENELOPE-B randomised 1250 women with hormone receptor-positive, HER2-negative breast cancer who still had invasive disease at surgery after neoadjuvant chemotherapy, and a high clinical-pathological risk score, to 13 cycles of palbociclib or placebo alongside standard endocrine therapy. The primary endpoint was invasive disease-free survival.

Palbociclib did not improve invasive disease-free survival; an early separation of the curves disappeared with longer follow-up. Together with PALLAS, which tested two years of palbociclib in a broader population, it showed that palbociclib has no role in early breast cancer, while abemaciclib (monarchE) and ribociclib (NATALEE) proved effective, a reminder that the class does not behave as one drug.

## Fields

- Kind: Trial
- Status: negative
- Last checked: 2026-09-17
- Tags: subtype-trials
- Registry id: NCT01864746
- Phase: 3
- Setting: Hormone receptor-positive, HER2-negative early breast cancer with residual disease and high risk of relapse after neoadjuvant chemotherapy: one year of palbociclib or placebo added to endocrine therapy
- Sponsor: German Breast Group (GBG Forschungs GmbH)
- Enrolled: 1250
- Result: One year of palbociclib added to endocrine therapy did not improve invasive disease-free survival.

## Sources

- ClinicalTrials.gov NCT01864746: https://clinicaltrials.gov/study/NCT01864746

## Connected records

- cancers: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/), [High-risk early HR-positive breast cancer](https://onco.cc/cancers/hr-positive-early-high-risk/), [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/)
- drugs: [Palbociclib](https://onco.cc/drugs/palbociclib/)
- companies: [Pfizer (incl. Seagen)](https://onco.cc/companies/pfizer/)
- people: [Sibylle Loibl](https://onco.cc/people/sibylle-loibl/)

---
JSON: https://onco.cc/api/v1/entities/penelope-b.json