Treatment Patterns, Real-World Outcomes, and Resource Use in Patients with Non–MSI-High or Mismatch Repair Proficient Advanced Endometrial Cancer

Presenter: Vimalanand S. Prabhu, BE, MMgmt, PhD, Director, Outcomes Research, Merck & Co, Inc

Co-Authors: Sneha Kelkar, MSc, MPH, Open Health, Bethesda, MD; Shelby Corman, PharmD, MS, BCPS, Open Health, Bethesda, MD; Cynthia Macahilig, MR, RTI-Health Solutions, Research Triangle Park, NC; Jingchuan Zhang, PhD, Eisai Inc; Nifasha Rusibamayila, MPH, Open Health, Bethesda, MD; Shardul Odak, PharmD, MD, RTI-Health Solutions, Research Triangle Park, NC; Linda Duska, MD, MPH, Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, University of Virginia School of Medicine, Charlottesville, VA

BACKGROUND: Chemotherapy, the standard of care for patients with advanced endometrial cancer,¹ has suboptimal outcomes. In 2019, novel therapies specific to microsatellite instability (MSI) or mismatch repair (MMR) status changed the treatment landscape in the United States,² but real-world outcomes data by MSI or MMR status are sparse.

OBJECTIVE: To assess treatment patterns, real-world outcomes, and hospitalization stratified by treatment category, in patients with advanced endometrial cancer and non–MSI-high (MSI-H) or MMR proficient tumors in the United States.

METHOD: Endometrial Cancer Health Outcomes (ECHO) is a multicenter, retrospective, chart review US study in which physicians consented to participate and provided de-identified data for adult women with inoperable non–MSI-H or MMR proficient advanced endometrial cancer. Patients had received ≥1 previous systemic therapies and had disease progression between July 1, 2016, and June 30, 2019. Data collected included patient demographics, clinical characteristics, treatment category, clinical outcomes, and hospitalization. Kaplan-Meier analyses were performed to estimate time to treatment discontinuation, real-world progression-free survival (PFS) and overall survival (OS), stratified by chemotherapy or hormonal therapy. The study protocol was approved by the Institutional Review Board.

RESULTS: The study included 139 patients (average age, 64 years). Approximately 64% of the patients were white, and 53% had ECOG performance score of ≥2. For second-line therapy, 114 patients received chemotherapy, and 25 patients received hormonal therapy, with a median follow-up of 9 and 8 months, respectively. The median time to treatment discontinuation was 6 months in the hormonal therapy group and 4 months in the chemotherapy group. The median OS since the initiation of second-line therapy in the hormonal therapy and chemotherapy groups was 9 and 10 months, respectively; the median real-world PFS was 6 and 5 months, respectively; and the best overall response to second-line therapy was 24% and 42%, respectively. A total of 16% of the patients had ≥1 hospitalizations (mean length of stay, 6 days for the hormonal therapy group and 7 days for the chemotherapy group); of the hospitalized patients, 41% had an intensive care unit stay (mean, 2 days and 5 days for the hormonal therapy and chemotherapy groups, respectively).

CONCLUSION: These results show that there continues to be significant clinical unmet need in patients with non–MSI-H or MMR proficient advanced endometrial cancer in the United States, indicating the need for novel therapies that delay disease progression, improve OS, and/or reduce hospitalization rates for this patient population.

1. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines): Uterine Neoplasms. Version 3.2021. June 3, 2021. Accessed July 7, 2021.
2. Makker V, Green AK, Wenham RM, et al. New therapies for advanced, recurrent, and metastatic endometrial cancers. Gynecol Oncol Res Pract. 2017;4:19. doi: 10.1186/s40661-017-0056-7.