Gilead Sciences has shared positive top-line results from a late-stage study evaluating its antibody-drug conjugate (ADC) Trodelvy (sacituzumab govitecan-hziy) with Merck & Co’s anti-PD-1 therapy Keytruda (pembrolizumab) in triple-negative breast cancer (TNBC) patients.
The phase 3 ASCENT-04/KEYNOTE-D19 trial met its primary endpoint, with the combination significantly improving progression-free survival compared to Keytruda and chemotherapy in patients with unresectable locally advanced or metastatic TNBC whose tumours express PD-L1.
There was also an early trend in improvement for overall survival, the study’s secondary endpoint, with Trodelvy plus Keytruda, but this data was not mature at the time of analysis and will continue to be monitored.
Additionally, the safety profile of the combination was consistent with the known profiles of each agent, with no new safety signals identified.
TNBC is the most aggressive type of breast cancer and has historically been difficult to treat. The disease accounts for approximately 15% of all breast cancer cases and is more commonly diagnosed in younger and premenopausal women.
Patients with TNBC are at an increased risk of recurrence and metastases compared to those with other breast cancer types and, despite advances in treatment, first-line metastatic TNBC has seen limited approvals in recent years for tumours expressing PD-L1.
Gilead’s chief medical officer, Dietmar Berger, said the findings are “the first to show the transformative potential of an ADC combined with an immuno-oncology agent in early treatment lines of metastatic breast cancer”.
“For patients with this difficult to treat type of breast cancer, these results potentially offer a new pathway that may redefine their treatment options,” he added.
Gilead and Merck – known as MSD outside the US and Canada – entered into a collaboration in 2021 to investigate the Trodelvy/Keytruda combination in ASCENT-04/KEYNOTE-D19.
Detailed results from the study will be presented at a future medical meeting and discussed with regulatory authorities, Gilead outlined.
Primary investigator Sara Tolaney, Dana-Farber Cancer Institute, said: “This data suggests that the combination of [Trodelvy] and [Keytruda] may offer a new treatment approach – bringing together a potent ADC with immunotherapy to improve outcomes for patients.”