Imfinzi Boosts Response Rate in Early-Stage Stomach Cancers

Positive results from a planned interim analysis of the MATTERHORN Phase III trial showed treatment with AstraZeneca's Imfinzi (durvalumab) in combination with standard-of-care FLOT neoadjuvant chemotherapy (fluorouracil, leucovorin, oxaliplatin, and docetaxel given before surgery) demonstrated a statistically significant and clinically meaningful improvement in the key secondary endpoint of pathologic complete response (pCR) versus neoadjuvant chemotherapy alone for patients with resectable, early-stage and locally advanced (Stages II, III, IVA) gastric and gastroesophageal junction (GEJ) cancers.

These results will be presented today at the European Society for Medical Oncology (ESMO) Congress 2023 in Madrid, Spain (abstract #LBA73).

Treatment with Imfinzi plus neoadjuvant FLOT chemotherapy resulted in a pCR rate of 19% versus 7% for patients treated with neoadjuvant chemotherapy alone as assessed by blinded independent central review (BICR) (difference in pCR rate 12%; odds ratio [OR] 3.08; pImfinzi combination and 14% with neoadjuvant chemotherapy alone.

The trial, which is assessing Imfinzi in combination with FLOT chemotherapy as a perioperative treatment (before and after surgery), will continue as planned to assess the primary endpoint of event-free survival (EFS) and the key secondary endpoint of overall survival (OS) to which the trial team, investigators and participants remain blinded.

Yelena Janjigian, MD, Chief Attending Physician of the Gastrointestinal Medical Oncology Service, Memorial Sloan Kettering Cancer Center, New York and principal investigator in the trial said: "Disease recurrence after curative-intent surgery is far too common for patients with resectable gastric and gastroesophageal junction cancers. These early MATTERHORN results showing encouraging pathologic complete responses give hope that adding durvalumab to FLOT chemotherapy in the future will offer a much-needed new treatment approach in the perioperative setting."

Susan Galbraith, Executive Vice President, Oncology R&D, AstraZeneca, said: "The results from MATTERHORN highlight the potential of early treatment for patients with gastric and gastroesophageal junction cancers using an immunotherapy and chemotherapy combination. These findings reinforce our commitment to improving outcomes in gastrointestinal cancers, where unmet need is high and treatment options are limited."

Imfinzi was generally well tolerated, and no new safety signals were observed in the neoadjuvant setting. Further, the safety and tolerability of adding Imfinzi to neoadjuvant chemotherapy was consistent with the known profile for this combination. Grade 3 or higher adverse events from all causes were similar between the two arms, occurring in 69% of patients treated with the Imfinzi-based regimen versus 68% for neoadjuvant chemotherapy alone.

Summary of results: MATTERHORN

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