On December 5, AstraZeneca announced that its PD-L1 monoclonal antibody, durvalumab (Imfinzi), has received FDA approval in the United States for a new indication. It is now approved for the treatment of adult patients with limited stage small cell lung cancer (LS-SCLC) whose disease has not progressed following concurrent platinum-based chemotherapy and radiation therapy. This marks the first and only immunotherapy option specifically for LS-SCLC.

This approval is based on the results from the ADRIATIC Phase III clinical trial. ADRIATIC is a randomized, double-blind, placebo-controlled, multicenter global Phase III trial designed to evaluate the efficacy of Imfinzi monotherapy and Imfinzi in combination with tremelimumab (a CTLA4 monoclonal antibody) versus placebo in 730 LS-SCLC patients who did not experience disease progression after concurrent chemoradiotherapy (cCRT).

The results showed that, based on overall survival (OS) comparisons, Imfinzi reduced the risk of death by 27% compared to placebo. The median OS for patients receiving Imfinzi was 55.9 months, compared to 33.4 months for the placebo group. It is estimated that 57% of patients treated with Imfinzi survived at three years, compared to 48% in the placebo group.

In terms of progression-free survival (PFS), Imfinzi reduced the risk of disease progression or death by 24% compared to placebo. The median PFS for patients receiving Imfinzi was 16.6 months, while the placebo group had a median PFS of 9.2 months. It is estimated that 46% of patients treated with Imfinzi did not experience disease progression within two years, compared to 34% in the placebo group.

Regarding safety, the overall safety profile of Imfinzi was manageable and consistent with its known safety profile, with no new safety signals observed.

Imfinzi was first approved by the FDA in May 2017 for previously treated patients with advanced bladder cancer. Since then, AstraZeneca has continually expanded its indications to include:

• Combination with tremelimumab and platinum-based chemotherapy for the treatment of metastatic non-small cell lung cancer (NSCLC) in adults without EGFR-sensitive mutations or ALK rearrangements.
• Treatment of unresectable Stage III NSCLC.
• Combination with standard treatment (SoC) chemotherapy, etoposide plus carboplatin or cisplatin, as a first-line treatment for extensive-stage small cell lung cancer (ES-SCLC) in adults.
• Combination with chemotherapy (gemcitabine plus cisplatin) for the treatment of locally advanced or metastatic biliary tract cancer (BTC) in adults.
• Combination with tremelimumab for the treatment of adults with unresectable hepatocellular carcinoma (HCC).
• Combination with carboplatin plus paclitaxel, followed by monotherapy for the treatment of primary advanced or recurrent endometrial cancer with mismatch repair deficiency (dMMR) in adults.

Since its initial approval, Imfinzi's sales have consistently increased. In 2023, global sales reached $4.237 billion. In the first nine months of 2024, global sales amounted to $3.463 billion, making it one of the top three revenue-generating products in AstraZeneca's pipeline.