Trastuzumab Deruxtecan Improves PFS in HER2-Mutant Lung Cancer

Treatment with trastuzumab deruxtecan (T-DXd), marketed as Enhertu, resulted in improved progression-free survival (PFS) for patients with advanced HER2-mutant non-small cell lung cancer (NSCLC) when initiated as a first-line therapy, compared to the standard regimen of pembrolizumab (Keytruda) combined with chemotherapy. This finding emerged from a large clinical trial, the results of which were presented at the American Society of Clinical Oncology (ASCO) 2024 Annual Meeting. The study, which enrolled 225 patients, showed a median PFS of 16.8 months for those receiving T-DXd, significantly outperforming the 10.4 months observed in the control arm. The hazard ratio for disease progression or death was 0.50, indicating a 50% reduction in the risk of progression or death for patients treated with T-DXd. Objective response rates (ORR) were also higher in the T-DXd arm, at 49.6%, compared to 29.5% in the standard treatment group. Furthermore, the median duration of response (DoR) was 17.4 months for T-DXd versus 8.3 months for the control arm. The study also reported preliminary overall survival (OS) data, with a median OS of 23.7 months for T-DXd compared to 17.9 months for the control arm, though these data are still maturing. The safety profile of T-DXd was generally consistent with previous studies, with the most common adverse events being nausea, fatigue, and decreased appetite. However, the study did note a higher incidence of interstitial lung disease (ILD) in the T-DXd arm, with Grade 3 or higher ILD occurring in 4.4% of patients, compared to 0.9% in the control arm. One patient in the T-DXd arm died due to ILD. This trial, known as DESTINY-Lung04, builds upon previous research highlighting the efficacy of T-DXd in HER2-expressing solid tumors. HER2 mutations are found in approximately 2-4% of NSCLC cases, and historically, these patients have had limited treatment options with poorer prognoses. The development of targeted therapies like T-DXd represents a significant advancement in personalized medicine for this specific subset of lung cancer patients. The trial's design and the subsequent presentation at ASCO underscore the growing importance of molecular profiling in guiding treatment decisions for lung cancer. The controversy, as alluded to in the headline, likely stems from the observed increase in ILD events, a known risk associated with antibody-drug conjugates, and the need for careful patient selection and monitoring. The data suggest that T-DXd is a promising new standard of care for first-line HER2-mutant NSCLC, but the management of its associated toxicities remains a critical consideration for clinicians.