AstraZeneca’s Imfinzi Secures US Approval for Early Gastric Cancer Treatment

AstraZeneca PLC (LON: AZN) announced that Imfinzi (durvalumab) has been approved in the US for the treatment of adult patients with resectable, early-stage and locally advanced gastric and gastroesophageal junction (GEJ) cancers.

This marks a significant milestone as the first and only perioperative immunotherapy approved for these cancers.

The approval, granted by the Food and Drug Administration (FDA) under Priority Review, is based on the MATTERHORN Phase III trial results. These results demonstrated a 29% reduction in the risk of progression, recurrence, or death and a 22% reduction in the risk of death for the Imfinzi regimen compared to chemotherapy alone.

The approved regimen includes neoadjuvant Imfinzi in combination with chemotherapy before surgery, followed by adjuvant Imfinzi in combination with chemotherapy, then Imfinzi monotherapy.

The MATTERHORN trial data revealed compelling event-free survival (EFS) and overall survival (OS) benefits. Estimated median EFS was not yet reached for the Imfinzi arm versus 32.8 months for the comparator arm.

The final OS analysis showed a 22% reduction in the risk of death with the Imfinzi and FLOT perioperative regimen compared to chemotherapy alone (HR of 0.78; 95% CI 0.63-0.96; p=0.021).

This approval addresses a critical unmet need in gastric cancer treatment. Gastric cancer is the fifth leading cause of cancer death globally, with nearly one million people diagnosed each year. In 2024, there were roughly 6,500 drug-treated patients in the US in early-stage and locally advanced gastric or GEJ cancer.

Dave Fredrickson, Executive Vice President, Oncology Haematology Business Unit, AstraZeneca, stated: “This approval ushers in a new clinical paradigm for patients with early gastric and gastroesophageal junction cancers, with Imfinzi plus FLOT delivering a durable survival benefit that increases over time.”

The FDA approval of Imfinzi for early gastric cancer is likely to have a positive impact on AstraZeneca's stock. The significant clinical benefits demonstrated in the MATTERHORN trial, combined with the substantial market opportunity, could drive increased revenue and shareholder value. Markets will likely react favorably to this news, potentially leading to a short-term rally and increased investor confidence.

The safety profile for Imfinzi and FLOT chemotherapy was consistent with the known profiles of each medicine, and the percentage of patients that completed surgery was similar compared to chemotherapy alone. Grade 3 or higher adverse events due to any cause were similar between the two arms (71.6% for Imfinzi and FLOT arm; 71.2% for FLOT-only arm), which should reassure markets.

Regulatory applications are also under review in the European Union (EU), Japan and several other countries, in addition to Australia, Canada, and Switzerland, signaling potential for global expansion of Imfinzi's use in gastric cancer treatment.