In the first report from the pivotal phase III KEYNOTE-775/Study 309 trial, the combination of lenvatinib, a multikinase inhibitor of VEGFR1, VEGFR2, and VEGFR3 kinases, and the PD-1 inhibitor pembrolizumab significantly improved multiple outcomes compared with standard single-agent chemotherapy in patients with advanced, metastatic or recurrent endometrial cancer progressing after a prior platinum-based regimen.
Vicky Makker, MD
The randomized study of 827 patients met the dual primary endpoints assessed by blinded independent central review—progression-free survival and overall survival—as compared with physician’s choice of treatment (doxorubicin or paclitaxel). It also met the secondary endpoint of objective response rate in the all-comer population (which included patients with mismatch repair–proficient [pMMR] and mismatch repair–deficient [dMMR] tumors) and in the pMMR subgroup, reported Vicky Makker, MD, a medical oncologist at Memorial Sloan Kettering Cancer Center, New York, at the Society of Gynecologic Oncology (SGO) 2021 Annual Meeting on Women’s Cancer, held virtually.1
“Lenvatinib/pembrolizumab showed a statistically significant and clinically meaningful improvement in overall survival, progression-free survival, and objective response rate vs treatment by physician’s choice, regardless of MMR status, in endometrial cancer patients progressing after prior platinum-based therapy,” commented Dr. Makker.
KEYNOTE-775/Study 309 is the confirmatory trial for KEYNOTE-146/Study 111, which supported the U.S. Food and Drug Administration’s 2019 accelerated approval of the combination in patients with advanced endometrial carcinoma that is not dMMR or microsatellite instability–high (MSI-H), who have disease progression following systemic therapy, and are not candidates for curative surgery or radiation therapy.
The study enrolled 827 patients with advanced, metastatic or recurrent endometrial cancer that had experienced disease progression after one prior platinum-based regimen. Patients could have received two regimens if one was given in the neoadjuvant or adjuvant setting. Of the 827 patients, 697 patients had tumors that were pMMR, and 130 patients had tumors that were dMMR.
Patients were randomly assigned 1:1 to receive either:
Progression-free survival and overall survival were the primary endpoints. The statistical design called for progression-free survival to be tested first in the pMMR population, then in all comers, followed by overall survival and objective response rate for pMMR patients and then all comers.
Dual Primary Endpoints Met
At a median follow-up of 11.4 months, in the all-comer population, lenvatinib plus pembrolizumab reduced the risk of disease progression or death by 44% (P < .0001) and the risk of death by 38%, based on the following outcomes in the experimental vs standard arms:
Dr. Makker noted that the progression-free survival Kaplan-Meier curves separated early, around the time of the first radiologic assessment. Similarly, the overall survival curves diverged by around 3 months, “despite informal crossover.”
She further commented that the 38% reduction in the risk of death regardless of MMR status in this population “is very encouraging, as this arm included an investigational patient population for whom more data have been sought by the gynecologic oncology community.”
Lenvatinib/pembrolizumab led to a doubling in response rate: 31.9% vs 14.7% with physician’s choice of treatment (complete responses, 6.6% vs 2.6%; P < .0001). The median duration of response was 14.4 months vs 5.7 months, respectively.
Within the all-comer subgroups, comparable benefits in progression-free and overall survival were observed by age, race, region, MMR status, history of pelvic radiation, histology, and prior lines of therapy. The pMMR subgroup experienced a similar benefit as all comers with the combination vs standard therapy:
The safety profile of the doublet was generally consistent with the established safety profiles of the individual monotherapies. The median treatment duration was doubled in the experimental arm: 231 vs 104 days with single-agent chemotherapy.
In all comers, treatment-related adverse events leading to discontinuation of therapy were observed in 18.7% of those given pembrolizumab, 30.8% of patients given lenvatinib, 14.0% of those treated with both agents, vs 8.0% of those given chemotherapy. Treatment-related grade ≥ 3 events were seen in 88.9% and 72.7%, respectively. Hypertension was, by far, the most common toxicity in patients receiving lenvatinib/pembrolizumab and was grade ≥ 3 in 37.9%.
DISCLOSURE: Dr. Makker has received honoraria from Eisai, IBM Watson, Karyopharm Therapeutics, and Merck; has served as a consultant or advisor to ArQule, Eisai, GlaxoSmithKline, IBM Watson, Karyopharm, Merck, and Takeda; has received institutional research funding from AstraZeneca, Bristol Myers Squibb, Eisai, Karyopharm Therapeutics, Lilly, Merck, and Takeda; has been reimbursed for travel, accommodations, or other expenses by Eisai, Karyopharm Therapeutics, and Merck; and has held other relationships with IBM.
1. Makker V , Colombo N, Casado Herráez A, et al: A multicenter, open-label, randomized phase 3 study to compare the efficacy and safety of lenvatinib in combination with pembrolizumab vs treatment of physician’s choice in patients with advanced endometrial cancer: Study 309/KEYNOTE-775. Society of Gynecologic Oncology 2021 Virtual Annual Meeting on Women’s Cancer. Abstract 37/ID 11512. Presented March 19, 2021.
Invited discussant Ursula A. Matulonis, MD, Chief of the Division of Gynecologic Oncology at Dana-Farber Cancer Institute, Boston, applauded the improved outcomes favoring lenvatinib/pembrolizumab in the confirmatory KEYNOTE-775 trial. “This represents the start of a new era in endometrial cancer...