FDA Approves First Antibody-Drug Conjugate for Metastatic Triple-Negative Breast Cancer

The Food and Drug Administration (FDA) has granted accelerated approval to Trodelvy (sacituzumab govitecan-hziy; Immunomedics) for the treatment of adult patients with metastatic triple-negative breast cancer (mTNBC) who have received at least 2 prior therapies for metastatic disease.

Sacituzumab govitecan is a Trop-2-directed antibody and topoisomerase inhibitor drug conjugate that binds to Trop-2-expressing cancer cells and is internalized with the subsequent release of SN-38, the active metabolite of irinotecan. The resulting DNA damage leads to apoptosis and cell death.

The approval was based on data from a single-arm trial that included 108 patients with mTNBC who had received at least 2 prior treatments for metastatic disease. Patients received sacituzumab govitecan on Days 1 and 8 of a 21-day treatment cycle and were treated until disease progression or intolerance to the therapy. Co-primary end points of the study included investigator assessed overall response rate (ORR) and duration of response (DoR).

Results showed an ORR of 33.3% (95% CI, 24.6-43.1) with 2.8% of patients achieving a complete response and 30.6% having a partial response. Among the 36 responders, the median DoR was 7.7 months (95% CI, 4.9-10.8); 55.6% of these patients maintained response for ≥6 months, while 16.7% maintained response for ≥12 months. 

“In our trial, Trodelvy demonstrated clinically meaningful responses in patients with difficult-to-treat metastatic TNBC and moves the needle towards better outcomes for patients with metastatic breast cancer,” said Aditya Bardia, MD, MPH, Director of Precision Medicine at the Center for Breast Cancer, Massachusetts General Hospital Cancer Center and Assistant Professor of Medicine at Harvard Medical School and lead investigator of the phase 2 study. 

As for safety, the most common adverse reactions reported included nausea, neutropenia, diarrhea, fatigue, anemia, vomiting, alopecia, constipation, rash, decreased appetite, and abdominal pain. Trodelvy carries a Boxed Warning about the risk of severe neutropenia and diarrhea.

According to the Company, a phase 3 confirmatory trial (ASCENT) evaluating Trodelvy in mTNBC was recently stopped early due to “compelling efficacy.” Topline results from the trial are expected to be announced in mid-2020.

“This application was approved more than a month ahead of the FDA goal date,” said Richard Pazdur, MD, director of the FDA’s Oncology Center of Excellence and acting director of the Office of Oncologic Diseases in the FDA’s Center for Drug Evaluation and Research. “Our staff is continuing to meet with drug developers, academic investigators, and patient advocates to push forward the coordinated review of treatments for cancer.”

Trodelvy is supplied as 180mg lyophilized powder in single-dose vials. The product is not a substitute and should not be used with other drugs containing irinotecan or its active metabolite SN-38.

For more information visit immunomedics.com.