# MATTERHORN

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

## TL;DR

Adding immunotherapy before and after surgery cut deaths in early stomach cancer; nearly seven in ten patients were alive at three years.

## Summary

MATTERHORN, trial NCT04592913 sponsored by AstraZeneca and reported in 2025, showed that adding durvalumab before and after surgery to perioperative FLOT chemotherapy cuts deaths in resectable stage II to IVA gastric and gastro-oesophageal junction adenocarcinoma. It randomised 948 patients, met its primary event-free survival endpoint, nearly tripled the pathologic complete response rate and showed an overall survival benefit at ESMO 2025, leading to FDA approval on 25 November 2025 as the first perioperative immunotherapy in gastric cancer, with benefit consistent across PD-L1 levels. OnCo links it to gastric cancer, PD-L1 as a target, durvalumab, FLOT, the perioperative, pCR and event-free survival terms and Florian Lordick. The trial had no chemotherapy-free arm, and whether FLOT can be de-escalated is the open question.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-07
- Registry id: NCT04592913
- Phase: 3
- Setting: Resectable stage II-IVA gastric/GEJ adenocarcinoma: perioperative FLOT + durvalumab vs FLOT + placebo
- Sponsor: AstraZeneca
- Enrolled: 957
- Result: EFS HR 0.71; OS HR 0.78; 3-year OS 68.6%.
- Outcomes: Event-free survival: FLOT + durvalumab vs FLOT + placebo, HR 0.71; Overall survival: FLOT + durvalumab vs FLOT + placebo, HR 0.78; Pathologic complete response: FLOT + durvalumab 19.2 percent vs FLOT + placebo 7.2 percent
- Replication: KEYNOTE-585 (pembrolizumab + chemotherapy) improved pCR but not EFS significantly; MATTERHORN is the only positive perioperative IO trial so far.

## Sources

- ClinicalTrials.gov NCT04592913: https://clinicaltrials.gov/study/NCT04592913

## Connected records

- cancers: [Gastric & gastro-oesophageal junction cancer](https://onco.cc/cancers/gastric/), [PD-L1-high gastric cancer](https://onco.cc/cancers/gastric-pdl1-high/)
- technologies: [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/)
- targets: [PD-L1](https://onco.cc/targets/pdl1/)
- drugs: [Durvalumab](https://onco.cc/drugs/durvalumab/), [FLOT (5-FU, leucovorin, oxaliplatin, docetaxel)](https://onco.cc/drugs/flot/)
- companies: [AstraZeneca](https://onco.cc/companies/astrazeneca/)
- terms: [Event-free / disease-free survival (EFS, DFS, iDFS, RFS)](https://onco.cc/terms/efs/), [Neoadjuvant / adjuvant / perioperative](https://onco.cc/terms/neoadjuvant-adjuvant/), [Pathologic complete response (pCR)](https://onco.cc/terms/pcr/)
- people: [Florian Lordick](https://onco.cc/people/florian-lordick/)
- key papers: [MATTERHORN: perioperative durvalumab with FLOT chemotherapy for resectable gastric and gastro-oesophageal junction cancer](https://onco.cc/key-papers/paper-matterhorn-nejm-2025/)
- roadmaps: [Surgery roadmap: radical operations → less surgery → no surgery when a drug has done the work](https://onco.cc/roadmaps/surgery-roadmap/)

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