FDA Approves AstraZeneca's Imfinzi for Limited-Stage Small Cell Lung Cancer

AstraZeneca's (AZ) Imfinzi (durvalumab) has recently gained approval from the US Food and Drug Administration (FDA) for the treatment of adults with a particularly aggressive type of lung cancer. This approval specifically targets patients diagnosed with limited-stage small cell lung cancer (SCLC) whose condition has not worsened following a regimen of platinum-based chemotherapy combined with radiation therapy.

Small cell lung cancer represents about 15% of all lung cancer cases and is known for its rapid progression. Within this category, approximately 30% of patients have what is described as limited-stage disease, characterized by the cancer being confined to one lung or a single side of the chest. These patients generally have a bleak outlook, even when treated with the standard approach of concurrent chemoradiotherapy that aims for a cure.

Imfinzi works by inhibiting the interaction between the PD-L1 protein and the PD-1 and CD80 proteins. This mechanism helps to prevent tumors from evading the immune system, thereby facilitating a more robust immune response. Imfinzi is not entirely new to the market, as it is already approved in the United States and various other countries for addressing extensive-stage SCLC. In this more advanced stage, the cancer has typically spread to the opposite lung, lymph nodes on the other side of the chest, or even distant organs.

The FDA's recent approval was influenced by encouraging outcomes from the ADRIATIC trial, a late-stage study which demonstrated that Imfinzi reduced the risk of death by 27% in comparison to a placebo. The estimated median overall survival for patients treated with Imfinzi was 55.9 months, significantly higher than the 33.4 months observed in the placebo group. Furthermore, 57% of patients receiving Imfinzi were still alive after three years, as opposed to 48% of those given a placebo.

In addition to enhancing overall survival, Imfinzi was also effective in delaying disease progression or death by 24% compared to the placebo. The median progression-free survival was 16.6 months for those on Imfinzi, versus just 9.2 months for the placebo group. Notably, 46% of patients treated with Imfinzi had not experienced disease progression after two years, compared to 34% for those on placebo.

Dave Fredrickson, the executive vice president of AstraZeneca's oncology business unit, highlighted the significance of this approval, describing it as a landmark moment for patients with limited-stage SCLC. He emphasized that the ADRIATIC trial set a new standard by showcasing an improvement in median overall survival by 22.5 months. Fredrickson also noted that Imfinzi is now the only immunotherapy sanctioned for both limited- and extensive-stage SCLC.

Beyond the United States, Imfinzi has also received approval in Switzerland for treating limited-stage SCLC. Additionally, regulatory applications for this indication are currently under evaluation in the European Union and several other countries, according to AstraZeneca.