Gilead Sciences (GILD) said Monday that a phase 3 breast cancer study met its primary endpoint, showing that Trodelvy plus Keytruda "significantly" improved progression-free survival compared with Keytruda and chemotherapy.

The safety profile of the Trodelvy-Keytruda combination also showed consistency with the know safety profile of each agent, Gilead said.

The company said overall survival is a key secondary endpoint and was not mature during the progression-free survival analysis, but there was an early trend in improved overall survival with the combination.

Merck (MRK) and Gilead entered into a collaboration in 2021 to evaluate the Trodelvy-Keytruda combination compared to Keytruda plus chemotherapy in patients with previously untreated, inoperable locally advanced or metastatic triple-negative breast cancer whose tumors express PD-L1, Gilead said.