ASCO24: AstraZeneca's Imfinzi to become standard care for limited-stage SCLC

At the American Society of Clinical Oncology (ASCO) annual meeting on Sunday, AstraZeneca presented promising data for Imfinzi (durvalumab), a PD-L1 inhibitor, in the treatment of limited-stage small-cell lung cancer (SCLC). These results come from the Phase III ADRIATIC study, which had already shown positive outcomes earlier this year. Lead researcher David Spigel highlighted the stagnation in advancements for limited-stage SCLC treatment over the past decades, noting that the current standard of care—concurrent chemoradiotherapy—still results in relapse for most patients within two years.

The ADRIATIC trial aimed to examine Imfinzi's efficacy as a consolidation therapy following concurrent chemoradiation in patients with limited-stage SCLC. Patients were either given Imfinzi alone or in combination with AstraZeneca’s anti-CTLA-4 antibody, Imjudo (tremelimumab). The study’s primary goals were to compare overall survival (OS) and progression-free survival (PFS) between patients receiving Imfinzi monotherapy and those receiving a placebo.

An interim analysis revealed encouraging results: the median OS for the Imfinzi monotherapy group was 55.9 months compared to 33.4 months for the placebo group. Similarly, the median PFS was 16.6 months for the Imfinzi group versus 9.2 months for the placebo group. These differences were both statistically significant and clinically impactful. Spigel stated that Imfinzi achieved a “27% reduction in the risk of death,” and at the three-year mark, the OS rates were 56.5% for Imfinzi compared to 47.6% for placebo. Moreover, there was a “24% reduction in the risk of death or progression” with Imfinzi.

The study also reported a favorable safety profile for Imfinzi. Rates of severe adverse events (Grades 3 or 4) were comparable between the treatment groups, around 24%. Adverse events leading to discontinuation were slightly higher in the Imfinzi group at 16.4% versus 10.6% in the placebo group. When examining immune-mediated adverse events of any grade, the rates were 32.1% for Imfinzi and 10.2% for placebo. As for radiation pneumonitis or pneumonitis, the rates were 38.2% in the Imfinzi group, compared to 30.2% in the placebo group.

ASCO expert Lauren Byers commented on the findings, emphasizing the need to identify which subsets of patients benefit the most from adding Imfinzi to their treatment regimen. She pointed out that small-cell lung cancers are a diverse group, and understanding who stands to gain the most from this therapy is crucial.

Currently, Imfinzi is approved in several markets, including the US and Europe, for treating extensive-stage SCLC. The new data from the ADRIATIC study suggest that it could become a new standard of care for patients with limited-stage SCLC, giving hope for better long-term outcomes in a disease that has seen little progress in recent years.