
Merck Inc., announced positive overall survival results from the pivotal phase III KEYNOTE-355 trial evaluating Keytruda, + chemotherapy for the treatment of patients with metastatic triple-negative breast cancer .
Findings from the final analysis show first-line treatment with Keytruda in combination with chemotherapy (nab-paclitaxel, paclitaxel or gemcitabine/carboplatin) demonstrated a statistically significant and clinically meaningful improvement in OS compared with chemotherapy alone in patients with mTNBC whose tumors expressed PD-L1 (Combined Positive Score [CPS] ?10). No new safety signals were identified. These OS results will be presented at an upcoming medical meeting and submitted to regulatory authorities.
These OS results follow a previous interim analysis that showed Keytruda in combination with chemotherapy significantly improved progression-free survival (PFS) compared with chemotherapy alone in these patients. In the U.S., Keytruda is currently approved in combination with chemotherapy for the treatment of patients with locally recurrent unresectable or metastatic TNBC whose tumors express PD-L1 (CPS ?10) as determined by an FDA-approved test.
About KEYNOTE-355 : KEYNOTE-355 is a randomized, two-part, placebo-controlled Phase III trial (ClinicalTrials.gov, NCT02819518) evaluating Keytruda in combination with one of three different chemotherapies compared with placebo plus one of the three chemotherapy regimens for the treatment of locally recurrent inoperable or metastatic TNBC that has not been previously treated with chemotherapy in the advanced setting. The study endpoints included PFS and OS in patients whose tumors expressed PD-L1 (CPS ?1 and CPS ?10) and in all participants (intention-to-treat [ITT] population). The other endpoints include objective response rate (ORR), duration of response (DOR), disease control rate (DCR), patient reported outcomes (PROs), and safety.
KEYNOTE-355 Part 2 enrolled 847 patients who were randomized 2:1 to receive Keytruda (200 mg every 3 weeks) plus chemotherapy (investigator’s choice of nab-paclitaxel, paclitaxel or gemcitabine/carboplatin); or placebo plus nab-paclitaxel, paclitaxel or gemcitabine/carboplatin. Among enrolled patients in each treatment group, approximately 75% had tumors expressing PD-L1 with CPS ?1 (n = 425/566 for Keytruda plus chemotherapy; n = 211/281 for chemotherapy alone) and approximately 38% had had tumors expressing PD-L1 with CPS ?10 (n = 220/566 for KEYTRUDA plus chemotherapy; n = 103/281 for chemotherapy alone).