# PADA-1

Source: https://onco.cc/trials/pada-1/  
OnCo record `pada-1` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A French trial that showed, for the first time in a randomised study, that changing hormone therapy when a resistance mutation appears in the blood, before scans change, keeps breast cancer controlled for longer.

## Summary

PADA-1 (NCT03079011, UNICANCER) enrolled 1,017 women at 83 French hospitals receiving an aromatase inhibitor with palbociclib as first-line treatment for ER-positive, HER2-negative advanced breast cancer and monitored circulating tumour DNA for a rising ESR1 mutation. 279 (27 per cent) developed one and 172 were randomised: switching to fulvestrant plus palbociclib gave a median progression-free survival of 11.9 months against 5.7 months for continuing, stratified hazard ratio 0.61 (Bidard et al., Lancet Oncology 2022). The abstract describes the target as ESR1-mutated subclones that may be sensitive to fulvestrant.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-11-04
- Also known as: PADA 1; UCBG3-05
- Registry id: NCT03079011
- Phase: 3
- Setting: First-line aromatase inhibitor plus palbociclib for ER-positive, HER2-negative metastatic breast cancer, monitored for a rising ESR1 mutation in blood; patients with a rising mutation and no progression randomised to switch to fulvestrant plus palbociclib or continue
- Sponsor: UNICANCER
- Enrolled: 1017
- Result: Median PFS 11.9 vs 5.7 months, HR 0.61 (0.43 to 0.86), p = 0.0040.
- Outcomes: Progression-free survival from randomisation: Switch to fulvestrant + palbociclib 11.9 months vs Continue aromatase inhibitor + palbociclib 5.7 months, HR 0.61
- Replication: SERENA-6 applied the same switch-at-ESR1-emergence strategy with camizestrant and was also positive.

## Sources

- ClinicalTrials.gov NCT03079011: https://clinicaltrials.gov/study/NCT03079011
- Bidard et al., Lancet Oncol 2022: https://doi.org/10.1016/S1470-2045(22)00555-1

## Connected records

- trials: [SERENA-6](https://onco.cc/trials/serena-6/)
- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/)
- technologies: [Liquid biopsy (ctDNA)](https://onco.cc/technologies/liquid-biopsy/)
- targets: [Estrogen receptor (ERα)](https://onco.cc/targets/estrogen-receptor/)
- drugs: [Fulvestrant](https://onco.cc/drugs/fulvestrant/), [Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/), [Palbociclib](https://onco.cc/drugs/palbociclib/)
- companies: [UNICANCER](https://onco.cc/companies/unicancer/)
- terms: [Circulating tumour DNA (ctDNA)](https://onco.cc/terms/ctdna/), [ESR1 mutation](https://onco.cc/terms/esr1-mutation/)
- people: [François-Clément Bidard](https://onco.cc/people/francois-clement-bidard/)
- key papers: [Switch to fulvestrant and palbociclib versus no switch in advanced breast cancer with rising ESR1 mutation during aromatase inhibitor and palbociclib therapy (PADA-1): a randomised, open-label, multicentre, phase 3 trial](https://onco.cc/key-papers/paper-bidard-pada-1-lancet-oncol-2022/)
- bottlenecks: [Naming which clone or phenotype is left after treatment](https://onco.cc/bottlenecks/b-subclone-attribution-residual-disease/)
- biomarkers: [ESR1 mutation (ligand-binding domain, usually in ctDNA)](https://onco.cc/biomarkers/esr1-mutation-ctdna/)

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