Biopharmaceutical company AstraZeneca PLC (LSE: AZN) (STO: AZN) (Nasdaq: AZN) announced on Wednesday that it has secured US approval for Imfinzi as the first perioperative immunotherapy for adults with resectable early-stage and locally advanced gastric and gastroesophageal junction cancers. The regimen combines neoadjuvant Imfinzi with FLOT chemotherapy ahead of surgery, followed by adjuvant Imfinzi with chemotherapy and subsequent Imfinzi monotherapy.

Approval follows Priority Review by the US Food and Drug Administration and is supported by Phase III MATTERHORN data showing a 29% reduction in the risk of progression, recurrence or death, and a 22% reduction in the risk of death versus chemotherapy alone. Median event-free survival was not reached for the Imfinzi arm, compared with 32.8 months for the comparator. Overall survival data showed sustained benefit over time, independent of PD-L1 status.

Safety outcomes were consistent with known profiles, with similar rates of grade 3 or higher adverse events across treatment arms and comparable surgical completion rates. The US filing was assessed under Project Orbis, with parallel reviews ongoing in Australia, Canada and Switzerland. Additional submissions are under review in the EU, Japan and other markets.

Gastric cancer remains a major global health burden, with nearly one million new cases annually and poor long-term survival despite surgery and chemotherapy. In 2024, around 6,500 drug-treated patients were recorded in the US in early-stage and locally advanced gastric or GEJ cancer.

The MATTERHORN trial enrolled 948 patients across 20 countries and evaluated Imfinzi plus FLOT as perioperative therapy, with event-free survival as the primary endpoint and overall survival as a key secondary measure.

Imfinzi is already approved across multiple tumour types, including biliary tract cancer, hepatocellular carcinoma, non-small cell lung cancer and small cell lung cancer. More than 414,000 patients have been treated globally since its first approval in 2017.

AstraZeneca continues to expand its gastrointestinal oncology portfolio through Imfinzi, novel combinations, and targeted therapies including Enhertu, Lynparza and a broad early-stage pipeline focused on gastric, biliary, liver, oesophageal and pancreatic cancers.