# PHERGain

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

## TL;DR

Using an early PET scan to spot responders let a third of women be cured of HER2-positive breast cancer without any chemotherapy.

## Summary

PET responders after 2 cycles continued antibodies alone; those achieving pCR (37.9% of the arm) skipped chemotherapy entirely. 3-year iDFS 95.4% in the PET-adapted arm, meeting its co-primary endpoint. Discussed at ESMO Breast 2026 as the model for imaging-guided de-escalation; a phase 3 (PHERGain-2) is underway.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-07
- Registry id: NCT03161353
- Phase: 2
- Setting: HER2+ early breast cancer: chemotherapy-free trastuzumab + pertuzumab with early 18F-FDG PET response assessment to decide whether chemotherapy is needed
- Sponsor: MEDSIR
- Enrolled: 377
- Result: 3-year iDFS 95.4% in the PET-adapted arm; ~1 in 3 spared chemotherapy.
- Outcomes: 3-year invasive disease-free survival (PET-adapted arm): PET-adapted HP ± chemotherapy 95.4%
- Replication: Consistent with WSG-ADAPT HER2+/HR- (pCR-guided de-escalation); phase 3 confirmation pending.

## Sources

- ClinicalTrials.gov NCT03161353: https://clinicaltrials.gov/study/NCT03161353

## Connected records

- cancers: [Early HER2-positive breast cancer](https://onco.cc/cancers/her2-positive-early-breast-cancer/), [HER2-positive breast cancer](https://onco.cc/cancers/breast-her2-positive/)
- technologies: [FDG PET](https://onco.cc/technologies/fdg-pet/)
- drugs: [Pertuzumab](https://onco.cc/drugs/pertuzumab/), [Trastuzumab](https://onco.cc/drugs/trastuzumab/)
- terms: [Pathologic complete response (pCR)](https://onco.cc/terms/pcr/)
- people: [Aleix Prat](https://onco.cc/people/aleix-prat/), [Javier Cortés](https://onco.cc/people/javier-cortes/)
- key papers: [3-year invasive disease-free survival with chemotherapy de-escalation using an 18 F-FDG-PET-based, pathological complete response-adapted strategy in HER2-positive early breast cancer (PHERGain): a randomised, open-label, phase 2 trial](https://onco.cc/key-papers/paper-phergain-lancet-2024-update/), [Chemotherapy de-escalation using an 18 F-FDG-PET-based pathological response-adapted strategy in patients with HER2-positive early breast cancer (PHERGain): a multicentre, randomised, open-label, non-comparative, phase 2 trial](https://onco.cc/key-papers/paper-phergain-lancet-oncol-2021/)
- pairings: [Early FDG-PET response → chemotherapy omission (HER2+)](https://onco.cc/pairings/pet-adapted-her2-deescalation/)
- ideas: [Can T-DXd alone cure early HER2-positive disease?](https://onco.cc/ideas/idea-tdxd-first-then-nothing/)
- roadmaps: [Trial modernisation roadmap: the randomised trial → platforms and adaptive designs → decentralised, pragmatic and always-on](https://onco.cc/roadmaps/trial-modernisation-roadmap/)

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