Gilead's Trodelvy fails bladder cancer study goal

Gilead Sciences faces uncertainty regarding the accelerated approval of its cancer drug Trodelvy after a failed confirmatory trial. The trial, named TROPiCS-04, aimed to assess Trodelvy's efficacy in extending survival rates among patients with locally advanced or metastatic bladder cancer. Unfortunately, the drug did not show a significant improvement compared to standard chemotherapy.

Although the data showed a numerical advantage for Trodelvy and positive trends in smaller subgroups, the overall outcome was not favorable. Additionally, there were more deaths due to adverse events in the Trodelvy group than in the chemotherapy group. These deaths mainly occurred early in the treatment process and were linked to complications from low white blood cell counts, a condition known as neutropenia. Trodelvy already carries a safety warning for this risk.

Gilead plans to investigate the deaths further and will remind physicians to administer supportive treatments to prevent neutropenic complications. The company intends to present the full study data at an upcoming medical meeting. However, analysts are concerned that this outcome may jeopardize Trodelvy's conditional approval for bladder cancer. Daina Graybosch, an analyst at Leerink Partners, suggested that the drug might lose its FDA-labeled indication for metastatic urothelial carcinoma following the disappointing trial results. Michael Yee, an analyst at Jefferies, echoed this sentiment, indicating that the negative findings put the drug's bladder cancer indication in doubt.

Trodelvy received conditional FDA approval for bladder cancer in 2021 based on earlier studies demonstrating its ability to reduce tumor size. This approval was contingent on further confirmation of clinical benefits through trials like TROPiCS-04. The recent trial failure is a significant setback for Gilead's development of Trodelvy, a drug they acquired through a $21 billion acquisition of Immunomedics in 2020. Previously, Trodelvy also failed to significantly extend survival in a Phase 3 study involving patients with previously treated lung cancer compared to standard chemotherapy.

On Friday, Gilead released additional details from the lung cancer study, set to be presented at the American Society of Clinical Oncology's annual meeting. While Trodelvy reduced the relative risk of death by 16% compared to chemotherapy, this reduction did not meet the statistical threshold required for declaring the trial successful. The difference translated to a 1.3-month improvement in median overall survival. However, among patients whose tumors did not respond to prior immunotherapy, there was a more meaningful improvement in median overall survival of 3.5 months. This particular analysis, though prespecified, was not designed for formal statistical testing.

Trodelvy is approved for bladder cancer in the United States and is also available in multiple countries for two types of advanced breast cancer. Despite the challenges, Trodelvy remains a crucial part of Gilead's strategy to expand its oncology portfolio. According to Graybosch, bladder cancer accounts for less than 10% of Trodelvy's total sales, which reached approximately $310 million in the first quarter of 2024.

Gilead's stock experienced a 2.2% drop at market opening on Friday but managed to recover some of those losses by mid-morning. The company's next steps will be closely watched as it navigates the implications of the trial results on Trodelvy's future in cancer treatment.