FDA Greenlights AstraZeneca's Imfinzi for Early-Stage Stomach and GEJ Cancers

The U.S. Food and Drug Administration has given the nod to AstraZeneca (LON: AZN) for using its cancer immunotherapy drug Imfinzi (durvalumab) to treat adults with specific early-stage stomach and gastroesophageal junction (GEJ) cancers amenable to surgery. This marks a notable development in the management of these typically challenging cancer types.

Imfinzi's treatment regimen involves pairing the drug with chemotherapy before surgery, continuing the combo immediately after surgery, and then administering Imfinzi alone for a series of cycles. This approach was examined in the extensive Phase III MATTERHORN study, which included 948 patients across 176 centers in 20 countries.

Results from the MATTERHORN trial demonstrated that patients receiving Imfinzi along with chemotherapy reduced their risk of cancer recurrence, progression, or death by 29% compared to those treated with chemotherapy alone. Death risk was cut by 22%. Three years after treatment, approximately 69% of patients on the Imfinzi-based protocol were still alive, versus 62% with chemotherapy only.

One of the more encouraging data points is that roughly 72% of patients in both treatment arms experienced serious side effects at similar rates, indicating that adding Imfinzi does not markedly increase toxicity. Surgery plans largely stayed intact despite the dual treatment.

Stomach cancer is pernicious, ranking as the fifth leading cause of cancer-related deaths globally, with close to a million new cases diagnosed annually. Even after surgery and chemotherapy, the cancer is notorious for returning, with fewer than 50% of patients surviving five years post-diagnosis. The FDA's approval comes as around 6,500 U.S. patients received drugs targeting early-stage stomach or GEJ cancer in 2024.

The FDA fast-tracked Imfinzi's review through Project Orbis, an initiative that coordinates cancer drug assessments among various countries simultaneously. Beyond the U.S., drugs regulators in Australia, Canada, Switzerland, the European Union, and Japan are also evaluating the treatment.

Imfinzi acts by ramping up the immune system's ability to detect and attack cancer cells. It already holds approvals across several other tough-to-treat cancers, including those affecting the lungs, liver, bile ducts, and bladder. This expanded indication could increase its footprint in oncology therapeutics.

With positive survival data and manageable side effects from a large global trial behind it, Imfinzi's new approval might reshape standard treatment protocols for stomach and GEJ cancers. Whether this translates into noticeable shifts in AstraZeneca's market presence remains to be seen, but it's a milestone in the company's oncology portfolio.

Could this spark further momentum for immunotherapies in the early stages of gastrointestinal cancers? Time and trial follow-ups will tell.