Merck Keytruda, Chemotherapy combo meets endpoint for first-line treatment of Breast Cancer

New Delhi: Merck known as MSD outside the United States and Canada, recently announced that the pivotal Phase 3 KEYNOTE-355 trial investigating KEYTRUDA, Merck's anti-PD-1 therapy, in combination with chemotherapy met one of its dual primary endpoints of progression-free survival (PFS) in patients with metastatic triple-negative breast cancer (mTNBC) whose tumours expressed PD-L1 (Combined Positive Score [CPS] ≥10).

Based on an interim analysis conducted by an independent Data Monitoring Committee (DMC), first-line treatment with KEYTRUDA in combination with chemotherapy (nab-paclitaxel, paclitaxel or gemcitabine/carboplatin) demonstrated a statistically significant and clinically meaningful improvement in PFS compared to chemotherapy alone in these patients. Based on the recommendation of the DMC, the trial will continue without changes to evaluate the other dual primary endpoint of overall survival (OS). The safety profile of KEYTRUDA in this trial was consistent with that observed in previously reported studies; no new safety signals were identified.

"Triple-negative breast cancer is an aggressive malignancy. It is very encouraging that KEYTRUDA in combination with chemotherapy has now demonstrated positive results as both a first-line treatment in the metastatic setting with this trial and as neoadjuvant therapy in the KEYNOTE-522 trial," said Dr Roger M. Perlmutter, president, Merck Research Laboratories. "We look forward to sharing these findings with the medical community at an upcoming congress and discussing them with the FDA and other regulatory authorities."

The KEYTRUDA breast cancer clinical development program encompasses several internal and external collaborative studies. In addition to KEYNOTE-355, in TNBC these include the ongoing registration-enabling studies KEYNOTE-242 and KEYNOTE-522.

KEYNOTE-355 is a randomized, two-part, Phase 3 trial (ClinicalTrials.gov, NCT02819518) evaluating KEYTRUDA in combination with one of three different chemotherapies (investigator's choice of either nab-paclitaxel, paclitaxel or gemcitabine/carboplatin) compared with placebo plus one of the three chemotherapy regimens for the treatment of locally recurrent inoperable or mTNBC that has not been previously treated with chemotherapy in the metastatic setting. Part 1 of the study was open-label and evaluated the safety and tolerability of KEYTRUDA in combination with either nab-paclitaxel, paclitaxel or gemcitabine/carboplatin in 30 patients. Part 2 of KEYNOTE-355 was double-blinded, with dual primary endpoints of OS and PFS in all participants and in participants whose tumours expressed PD-L1 (CPS ≥1 and CPS ≥10). The secondary endpoints include objective response rate (ORR), duration of response (DOR), disease control rate (DCR) and safety.

Part 2 of KEYNOTE-355 enrolled 847 patients who were randomized to receive KEYTRUDA (200 mg intravenously [IV] on day 1 of each 21-day cycle) plus nab-paclitaxel (100 mg/m2 IV on days 1, 8 and 15 of each 28-day cycle), paclitaxel (90 mg/m2 IV on days 1, 8 and 15 of each 28-day cycle) or gemcitabine/carboplatin (1,000 mg/m2 [gemcitabine] and Area Under the Curve [AUC] 2 [carboplatin] on days 1 and 8 of each 21-day cycle); or placebo (normal saline on day 1 of each 21-day cycle) plus nab-paclitaxel (100 mg/m2 IV on days 1, 8 and 15 of each 28-day cycle), paclitaxel (90 mg/m2 IV on days 1, 8 and 15 of each 28-day cycle) or gemcitabine/carboplatin (1,000 mg/m2 [gemcitabine] and AUC 2 [carboplatin] on days 1 and 8 of each 21-day cycle).

KEYTRUDA is an anti-PD-1 therapy that works by increasing the ability of the body's immune system to help detect and fight tumour cells. KEYTRUDA is a humanized monoclonal antibody that blocks the interaction between PD-1 and its ligands, PD-L1 and PD-L2, thereby activating T lymphocytes which may affect both tumour cells and healthy cells.

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