158 Real world outcomes in patients with recurrent, advanced or metastatic endometrial cancer treated with lenvatinib plus pembrolizumab in England

Introduction/Background The KEYNOTE-775 trial demonstrated that lenvatinib plus pembrolizumab (lenvatinib/pembrolizumab) significantly improved progression-free survival (PFS) and overall survival (OS) compared to chemotherapy in patients with advanced endometrial cancer. Patients also experienced high rates of toxicity resulting in dose reductions and treatment interruptions. Methodology We conducted a retrospective analysis of 70 patients from 7 cancer centres treated with lenvatinib/pembrolizumab for advanced endometrial cancer between May 2022 and June 2023. Data on patient demographics, treatment, toxicity and outcomes was extracted from medical records. Results The median age of patients treated with lenvatinib/pembrolizumab was 68.5years (range 45–85) with performance status (PS) 0–1 in 77.1% and 2 in 22.9%. Histological subtypes included serous (34.3%), endometrioid (32.9%), carcinosarcoma (14.3%), clear cell (7.1%), mixed (2.9%) and other (8.6%). Grade ≥3 toxicity was reported in 55.7% with any-grade toxicity observed in 85.7%. Fatigue and proteinuria were the only toxicities reported with increased frequency compared with previous data (grade≥3 rates 8.6% and 10.0% respectively). In those aged ≥70years the rate of grade ≥3 toxicity was 56.3%. Rates of dose reduction were 67.1% (71.9% in those ≥70) and toxicity-related treatment interruption 45.7% (40.6% in those ≥70). The proportion of patients alive and progression-free at 6months was 54.0% (95%CI: 39.0–66.8%). Median PFS (figure 1) was 9.0months (95%CI: 4.9–12.1months), with a median treatment duration of 4.9months (95%CI: 3.6–7.4months). Median follow-up was 8.0months. Conclusion Within the limitations of this retrospective analysis lenvatinib/pembrolizumab is tolerable with a comparable PFS to phase-III data in the real-world setting. Our data suggests comparable toxicity rates and PFS to that seen in KEYNOTE-775. Our real-world data included patients who were older and with a poorer PS than KEYNOTE-775, as well as those with carcinosarcoma (not included in this trial or recent UK Cancer Drug Fund applications). Initial analysis indicates that it is safe to use in an older population. Disclosures A. Pawsey, N. Senthivel, A. Ramessur, E. Waterhouse, S. Usman, R. Browne and N. Counsell have no disclosures. P. Mahalingam - research support (Cancer Research UK). L. Tookman - research support (Imperial Health Charity), honoraria or consultation fees (Clovis Oncology, Tesaro, AstraZeneca, GSK, MSD) and participation in a company sponsored speaker's bureau (Clovis Oncology, GSK, AstraZeneca and MSD). R. Miller - research support (MSD and GSK), honoraria or consultation fees (consultancy from MSD, GSK, AstraZeneca, Ellipses, Shionogi, Clovis Oncology and GI Innovation), participation in a company sponsored speaker's bureau (GSK, AstraZeneca and Clovis Oncology) and travel grants (AstraZeneca, MSD and GSK). S. Nicum - research support (AstraZeneca), honoraria or consultation fees (AstraZeneca, GSK, Roche and Clovis), participation in a company sponsored speaker's bureau (AstraZeneca, GSK and Clovis) and stock/shareholder including spouse/partner (AstraZeneca and GSK). G. Eminowicz - honoraria or consultation fees (MSD)