Introduction/Background*Chemotherapy, the standard of care for patients with advanced endometrial cancer (aEC), has sub-optimal outcomes. In 2019, novel therapies specific to microsatellite instability (MSI)/mismatch repair (MMR) status changed the treatment landscape in the US. With sparse real-world outcomes data by MSI/MMR status, our study aimed to assess treatment patterns, real-world outcomes, and hospitalization stratified by treatment category, in aEC patients with non-MSI-high/MMR proficient (pMMR) tumors in the US.

Methodology Endometrial Cancer Health Outcomes (ECHO) is a multi-center, retrospective, chart review US study in which physicians consented to participate and provided de-identified data for adult women with inoperable non-MSI-high/pMMR aEC. Patients had ≥1 prior systemic therapy and progressed 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 (rwPFS) and overall survival (OS), stratified by chemotherapy (CT) or hormonal therapy (HT). The study protocol was IRB approved.

Result(s)*The 139 patients included in this study were 64 years on average. About 64% were Caucasian, and 53% had ECOG ≥2. For 2^nd-line therapy, 114 patients received CT, and 25 received HT, with a median follow-up of 9 and 8 months, respectively. Median time to discontinuation was 6 and 4 months in the HT and CT groups, respectively (table 1). Median OS since 2^nd-line therapy initiation in the HT and CT groups was 9 and 10 months, respectively, median rwPFS was 6 and 5 months, respectively, and best overall response to 2^nd-line therapy was 24% and 42%, respectively. There were 16% patients with ≥1 hospitalization (mean length of stay, 6 and 7 days for HT and CT groups, respectively), and 41% of those had intensive care unit stay (mean, 2 and 5 days for HT and CT groups, respectively).

Conclusion*This study evaluated real-world treatment patterns, clinical outcomes, and hospitalization, stratified by treatment category in non-MSI-high/pMMR aEC patients in the US prior to July 2019. There continued to be significant clinical unmet need, indicating the need for novel therapies that delay progression, improve overall survival, and/or reduce hospitalization.