AstraZeneca is preparing to talk to the FDA about a potential new use of its immunotherapy Imfinzi after a pivotal study in early-stage stomach cancer met its main goal.
When added to a chemotherapy combination called FLOT, Imfinzi significantly reduced the risk of disease recurrence, worsening or death in patients with resectable, early-stage gastric and gastroesophageal junction cancers who got the regimen before and after surgery, the company said Friday.
The event-free survival readout vaults the phase 3 Matterhorn trial to the positive category, following a previous interim analysis that showed Imfinzi could help more patients achieve no detectable cancer cells in resected tumors, known as a pathological complete response (pCR).
Matterhorn is now the first phase 3 trial of an immunotherapy to show a statistically significant improvement in event-free survival in this cancer setting, Cristian Massacesi, M.D., chief medical officer and oncology chief development officer at AstraZeneca, said in a statement.
Event-free survival is the primary endpoint of Matterhorn, while pCR is a secondary endpoint. On another important secondary endpoint, overall survival, AZ flagged “a strong trend” suggesting a potential life extension benefit for the Imfinzi-based regimen. The trial is progressing toward its final analysis, when overall survival will be formally assessed.
AZ said it will share detailed results with global regulatory authorities and at a medical meeting.
“We are eager to bring this regimen with the potential to transform the standard of care to patients as soon as possible,” a spokesperson told Fierce Pharma.
With Matterhorn, AZ is angling Imfinzi as a perioperative treatment. The PD-L1 inhibitor would be given together with chemotherapy both before and after surgery, then by itself for several additional cycles.
Following presurgical neoadjuvant treatment, Imfinzi and chemo achieved a pCR of 19% at the time of surgery, versus 7% for the chemo-only regimen, according to an interim analysis published in 2023.
Perioperative trial designs have raised some eyebrows as doctors worry about overtreating patients, given the lack of separate efficacy data for each phase of treatment. The concern culminated in a high-profile FDA advisory committee meeting last year on Imfinzi’s perioperative use in early-stage non-small cell lung cancer. In a unanimous vote, a panel of experts called for future trials in resectable NSCLC to include assessments of the contributions of each treatment phase.
“This perioperative approach with Imfinzi underscores our commitment to moving into earlier stages of cancer where novel therapies can have the biggest impact on patients’ lives,” Massacesi said in a Friday statement.