USFDA grants priority review to Merck application for Keytruda plus chemotherapy for Metastatic Malignant Pleural Mesothelioma

The sBLA is based on data from the pivotal Phase 2/3 IND.227/KEYNOTE-483 trial. Results from the final analysis of the study, presented at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting, showed KEYTRUDA in combination with chemotherapy demonstrated a statistically significant improvement in overall survival (OS), reducing the risk of death by 21% (HR=0.79 [95% CI, 0.64-0.98]; two-sided p value=0.0324), with a median OS of 17.3 months (95% CI, 14.4-21.3) versus 16.1 months (95% CI, 13.1-18.2) for chemotherapy alone. KEYTRUDA plus chemotherapy also demonstrated a significant improvement in progression-free survival (PFS) (HR=0.80 [95%CI, 0.65-0.99], two-sided p value = 0.0372; median PFS 7.13 months versus 7.16 months respectively) and objective response rate (ORR) compared to chemotherapy alone. At 12 months, the estimated PFS rate was 26% for KEYTRUDA plus chemotherapy versus 17% for chemotherapy alone. The ORR was significantly higher for KEYTRUDA plus chemotherapy versus chemotherapy alone (62% versus 38%, p<0.0001). The safety profile of KEYTRUDA plus chemotherapy in this study was consistent with previously reported studies.

IND.227/KEYNOTE-483 is a randomized, open-label Phase 2/3 trial (ClinicalTrials.gov, NCT02784171) sponsored and conducted by Canadian Cancer Trials Group (CCTG) in collaboration with National Cancer Institute of Naples (NCIN) and Intergroupe Francophone de Cancérologie Thoracique (IFCT).

Merck provided KEYTRUDA and support for the trial. The trial evaluated KEYTRUDA plus chemotherapy versus chemotherapy alone for the treatment of patients with unresected advanced pleural mesothelioma. The study’s primary endpoint is OS and secondary endpoints include PFS and ORR as assessed by blinded independent central review (BICR) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) modified for mesothelioma, safety and quality of life. The Phase 3 part of the trial enrolled 440 patients who were randomized to receive:

♦ KEYTRUDA (200 mg intravenously [IV] every three weeks [Q3W] for up to 35 cycles) plus pemetrexed (500 mg/m2 Q3W for six cycles) and cisplatin (75 mg/m2 Q3W for six cycles; carboplatin substitution [AUC 5-6 Q3W for six cycles] was permitted), or

♦ Pemetrexed and cisplatin (carboplatin substitution was permitted) alone.

“Malignant pleural mesothelioma is typically diagnosed in advanced stages when curative surgery is not an option, and progresses quickly,” said Dr. Gregory Lubiniecki, vice president, oncology clinical research, Merck Research Laboratories. “We continue to evaluate KEYTRUDA in new and difficult-to-treat tumors and look forward to working with the FDA to help bring KEYTRUDA as a potential treatment option to certain patients with advanced malignant pleural mesothelioma.”

KEYTRUDA is an anti-programmed death receptor-1 (PD-1) therapy that works by increasing the ability of the body’s immune system to help detect and fight tumor 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 tumor cells and healthy cells.