The FDA recently granted expanded approval for Gilead Sciences’ Trodelvy (sacituzumab govitecan-hziy) for patients with HR-positive/HER2-negative metastatic breast cancer who have received hormonal therapy and at least two additional therapies in the metastatic setting. Trodelvy gained approval by outperforming traditional chemotherapies in this patient group. The drug is expected to become a standard of care for these breast cancer patients, who have had limited treatment options, says GlobalData, a leading data and analytics company.

This is Trodelvy’s second approval for breast cancer patients after it started being marketed for triple-negative breast cancer in 2021. Sales of the drug rose 79% from $380 million in 2021 to $680 million in 2022. GlobalData’s analyst consensus forecasts project Trodelvy sales to reach 2.8 billion by 2028.

Israel Stern, Oncology & Hematology Analyst at GlobalData, comments: “Patients with HR+/HER2- metastatic breast cancer who are treated with hormone therapy and chemotherapy often develop resistance to these treatments. Trodelvy, an antibody-drug conjugate (ADC) that targets the Trop-2 protein found on the surface of most breast cancer cells, presents a statistically significant improvement in overall survival compared to retreating with chemotherapy.”

In the Phase lll TROPiCS-02 study, Trodelvy showed a superior overall survival (OS) of 3.2 months (hazard ratio [HR]: 0.79) as well as a higher median progression-free survival (PFS) compared to those who were treated with chemotherapy.

Stern continues: “A challenge for Trodelvy’s market penetration is the approval of AstraZeneca and Daiichi Sankyo’s ADC Enhertu for HER2-low metastatic breast cancer in 2022. The majority of HER2-negative patients display some HER2 expression making them good candidates for Enhertu. Aside from being first-to-market, Enhertu may be more active than Trodelvy and reported impressive results in both OS (median 23.4 months) and PFS in a comparable trial of patients who received prior lines of chemotherapy.”

Although the two drugs target different receptors on the cancer cells, they share a TOP1 inhibitor warhead aimed at interrupting DNA replication resulting in cell death. If a patient develops resistance to one of the drugs due to antigen loss, they may be eligible to receive the other treatment in succession.

Stern concludes: “Gilead hopes to withstand the challenge of Enhertu by utilizing Trodelvy in other indications such as first-line therapy in triple-negative breast cancer, and non-small cell lung cancer. Trodelvy represents a foundational piece for Gilead’s oncology pipeline and the company will seek every opportunity to utilize the drug in different cancer types. The company purchased Immunomedics, the innovator of Trodelvy, for $21 billion in 2020, and they’re relying on the success of this asset to justify the acquisition.”