AstraZeneca Korea said Imfinzi (ingredient: durvalumab) has won regulatory approval from the Ministry of Food and Drug Safety (MFDS) to treat limited-stage small cell lung cancer (LS-SCLC) as a monotherapy following platinum-based chemoradiotherapy (CRT).

With this new indication, Imfinzi becomes the first and only immune checkpoint inhibitor approved in Korea for the treatment of LS-SCLC patients whose disease has not progressed after CRT.

Small cell lung cancer (SCLC) is a fast-growing and aggressive form of lung cancer, accounting for 15–25 percent of all lung cancer cases. The prognosis remains poor, with only 15–30 percent of patients surviving five years after diagnosis. The limited stage is defined as cancer confined to one side of the chest, including the mediastinum, and about 30 percent of patients are diagnosed at this stage.

Despite CRT being the standard of care, more than 50 percent of patients experience disease recurrence within two years, and the median overall survival (OS) has remained between 16 and 24 months. Over the past decades, multiple clinical trials have failed to bring a meaningful paradigm shift to the treatment of LS-SCLC—until now.

The approval was based on data from the global phase 3 ADRIATIC trial, which evaluated Imfinzi monotherapy versus placebo following CRT in LS-SCLC patients. The co-primary endpoints of the study were overall survival (OS) and progression-free survival (PFS).

According to the study, Imfinzi demonstrated significant survival benefits across all pre-specified subgroups, regardless of age, sex, race, disease stage, or radiation treatment cycles.

The median OS in the Imfinzi arm reached 55.9 months, compared to 33.4 months in the placebo group—extending survival by over 22 months and reducing the risk of death by 27 percent.

The three-year OS rate was around 57 percent in the Imfinzi group versus 48 percent in the placebo group.

Imfinzi also reduced the risk of disease progression or death by 24 percent compared to the placebo. The median PFS was 16.6 months in the Imfinzi group and 9.2 months in the placebo group. At two years post-treatment, approximately 46 percent of patients receiving Imfinzi remained progression-free, compared to 34 percent in the placebo arm.

The safety profile of Imfinzi was consistent with previous studies. Grade 3 or 4 adverse events occurred in 24.4 percent of patients in the Imfinzi arm and 24.2 percent in the placebo arm.

“AstraZeneca Korea is committed to improving survival for lung cancer patients through innovative treatment options,” AstraZeneca Korea’s Oncology Business Unit Director Lee Hyun-ju said. “This latest approval for Imfinzi represents the first therapeutic advancement in LS-SCLC in over 30 years, marking a significant milestone in providing patients with access to immunotherapy for the first time.”

Following the success of the PACIFIC study in stage III non-small cell lung cancer, Imfinzi is now once again redefining the standard of care in SCLC through the ADRIATIC trial, Lee added.

Meanwhile, the U.S. FDA designated Imfinzi as a breakthrough therapy for this indication in August 2024 and granted full approval in December 2024 after a priority review. The American Society of Clinical Oncology (ASCO) also issued a rapid update to its treatment guidelines in November 2024, reflecting the positive outcomes of the ADRIATIC trial.