# PALOMA-2

Source: https://onco.cc/trials/paloma-2/  
OnCo record `paloma-2` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The trial that made palbociclib the first CDK4/6 inhibitor in routine use. It doubled progression-free time but did not extend life.

## Summary

PALOMA-2, trial NCT01740427 sponsored by Pfizer and reported in 2016, is the trial that made palbociclib the first CDK4/6 inhibitor in routine use: added to letrozole as first-line treatment for postmenopausal HR-positive, HER2-negative advanced breast cancer it doubled progression-free time but did not extend life. It randomised 666 women, met its primary progression-free survival endpoint, and at the final analysis showed no significant overall survival benefit, with substantial missing survival data; with PALOMA-3 this differentiates palbociclib from ribociclib and abemaciclib on survival. OnCo links it to CDK4/6 as a target, palbociclib, aromatase inhibitors and Richard S. Finn, and the absence of a survival benefit was replicated in PALOMA-3 and the adjuvant PALLAS and PENELOPE-B trials. Whether the three drugs truly differ or the trials did is the open question.

## Fields

- Kind: Trial
- Status: mixed
- Last checked: 2026-09-07
- Registry id: NCT01740427
- Phase: 3
- Setting: First-line postmenopausal HR+/HER2- advanced breast cancer: palbociclib + letrozole vs placebo + letrozole
- Sponsor: Pfizer
- Enrolled: 666
- Result: PFS HR 0.56; OS HR 0.96 (NS).
- Outcomes: Progression-free survival: Palbociclib + letrozole 27.6 months vs Placebo + letrozole 14.5 months, HR 0.56; Overall survival: Palbociclib + letrozole 53.9 months vs Placebo + letrozole 51.2 months, HR 0.96
- Replication: PFS effect replicated across all CDK4/6 trials; absence of OS benefit replicated in PALOMA-3 and the adjuvant PALLAS/PENELOPE-B trials.

## Sources

- ClinicalTrials.gov NCT01740427: https://clinicaltrials.gov/study/NCT01740427

## Connected records

- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/)
- technologies: [CDK4/6 inhibitors](https://onco.cc/technologies/cdk46-inhibitor/)
- targets: [CDK4/6](https://onco.cc/targets/cdk4-6/)
- drugs: [Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/), [Palbociclib](https://onco.cc/drugs/palbociclib/)
- companies: [Pfizer (incl. Seagen)](https://onco.cc/companies/pfizer/)
- people: [Richard S. Finn](https://onco.cc/people/richard-finn/)
- key papers: [Palbociclib and Letrozole in Advanced Breast Cancer](https://onco.cc/key-papers/paper-paloma-2-n-engl-j-med-2016/), [Palbociclib plus letrozole as first-line therapy in estrogen receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer with extended follow-up](https://onco.cc/key-papers/paper-paloma-2-breast-cancer-res-treat-2019-update/)
- roadmaps: [Hormonal therapy roadmap: removing the ovaries → tamoxifen → oral degraders switched by a blood test](https://onco.cc/roadmaps/hormonal-therapy-roadmap/)

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