Gilead’s Trodelvy Helps HR/HER2 Metastatic Breast Cancer Patients

Gilead recently announced that the Phase 3 clinical trial of Trodelvy in patients with HR/HER2-metastatic breast cancer met its primary endpoint.

The Phase 3 TROPiCS-02 study evaluated Trodelvy versus physician’s choice of chemotherapy in 543 patients previously treated with endocrine therapy, CDK4/6 inhibitors, and two to four lines of chemotherapy.

The primary endpoint of the trial was progression-free survival. Overall, researchers targeted a 30%-reduction in the risk of disease progression or death. Secondary endpoints included overall survival, duration of response, clinical benefit rate, and the overall response rate.

The study results were consistent with those observed in the Phase 1/2 IMMU-132-01 study in a subset of HR+/HER2-metastatic breast cancer patients. The safety profile of Trodelvy was consistent with prior studies and no new safety concerns emerged.

“Trodelvy demonstrated consistent activity in this difficult-to-treat patient population,” Merdad Parsey, MD, PhD, chief medical officer at Gilead, said in the announcement.

“As we work to expand the patient benefit of Trodelvy beyond its current indications for second-line metastatic triple-negative breast cancer and accelerated approval in second-line metastatic bladder cancer, we are pursuing studies across multiple tumor types and earlier lines of therapy,” Parsey continued.

The HER2 protein is present at high levels (HER2 positive) in about 30 percent of breast cancers. High levels of HER2 are linked to a greater likelihood of metastasis and relapse and an overall decrease in patient survival.

In previous studies, researchers found that the ER+, PR+, and HER2- subtype had a 5-year survival of 84%, whereas the triple-negative subtype had a survival of 55%.

In April 2021, FDA approved Trodelvy for adults with unresectable, locally advanced, or metastatic triple-negative breast cancer (TNBC).

The agency based its approval on results from the Phase 3 ASCENT study, in which Trodelvy demonstrated a statistically significant (57%) reduction in the risk of disease worsening or death.

The drug also extended median overall survival to 11.8 months versus 6.9 months, representing a 49 percent reduction. Notably, no regulatory agencies have approved Trodelvy to treat HR+/HER2- metastatic breast cancer. And its safety and efficacy have not been established for this indication.