On February 3, Gilead Sciences’ Trodelvy (sacituzumab govitecan-hziy) received FDA approval for the treatment of adult HR-positive/HER2-negative metastatic breast cancer in patients who have received hormonal therapy and at least two additional therapies in the metastatic setting. This is the third indication for which Trodelvy has received regulatory approval, with the antibody-drug conjugate (ADC) already marketed for advanced bladder cancer and metastatic triple-negative breast cancer.
The most common type of breast cancer is HR-positive, HER2-negative breast cancer, responsible for around 70% of new cases globally each year. Many patients develop resistance to hormone therapies or worsen with chemotherapy. Trodelvy is a targeted therapy that is made up of sacituzumab, a monoclonal antibody that targets the Trop-2 protein, conjugated to SN-38, a topoisomerase l inhibitor chemotherapy. The Trop-2 protein is found on the surface of about 80% of breast cancers. When the antibody binds to Trop-2, the SN-38 chemotherapy is taken up by the breast cancer cells, resulting in cytotoxicity.
The approval was based on data from the Phase III TROPiCS-02 study, which evaluated Trodelvy against physician’s choice of chemotherapy. Trodelvy demonstrated a significant benefit in overall survival (OS) of 3.2 months (median OS of 14.4 months vs. 12.2 months, hazard ratio [HR]: 0.79) as well as a higher median progression-free survival (5.5 months vs. 4.0 months, HR: 0.66) compared to the chemotherapy arm. Additionally, Trodelvy improved secondary endpoint measures such as objective response rate and time to deterioration. The most frequent adverse reactions observed were severe neutropenia (7%) (51% Grade ≥3) and diarrhea (5%) (10% Grade ≥3).
Trodelvy sales climbed to $680 million in 2022, up from $380 million in 2021. GlobalData’s analyst consensus forecast projects annual sales for Trodelvy to reach $2.8 billion by 2028. A challenge for Gilead’s market penetration was the approval of AstraZeneca and Daiichi Sankyo’s HER2-directed ADC Enhertu (fam-trastuzumab deruxtecan-nxki) in 2022. Enhertu was the first approved targeted therapy for HER2-low metastatic breast cancer. The majority of patients who are HER2-negative have some HER2 expression, making them candidates for Enhertu therapy. Gilead plans to incorporate Trodelvy in earlier lines of therapy and additional indications such as non-small cell lung cancer. The company is depending on the drug’s success to justify the purchase of Immunomedics, the innovator of Trodelvy, for $21 billion in 2020.