Principal Scientist Merck & Co., Inc., United States
Background: Novel microsatellite instability (MSI) biomarker-based therapies have been approved in the United States (US) since 2017 for patients with recurrent or advanced endometrial cancer (aEC) following prior systemic therapy; new therapies are under investigation for first-line (1L) use. However, little is known about patient characteristics and real-world treatment patterns with traditional 1L therapies.
Objectives: To evaluate patient characteristics, MSI/mismatch repair (MMR) biomarker status/testing patterns, and treatment patterns of patients with aEC on 1L systemic therapy in clinical practice in the US.
Methods: Endometrial Cancer Health Outcomes-US-1L (ECHO-US-1L) is a multicenter, retrospective chart review study of patients diagnosed with recurrent or aEC in the US. Physicians who consented to participate in the study extracted data from medical records of patients (≥18 years) diagnosed with aEC (stages III-IV) with known MSI/MMR status, who initiated 1L systemic therapy between 07/01/2016-03/31/2020 after recurrent or aEC diagnosis. Data included patient and clinical characteristics, treatment patterns, and MSI/MMR tumor status. Descriptive analyses were conducted using de-identified data. This study was IRB approved.
Results: In this study, 71 physicians provided data on 234 eligible patients. Physicians were medical (81.7%) or gynecologic (18.3%) oncologists from academic (33.8%) or community/private (73.3%) practices, and 59.2% were practicing for over 15 years. At aEC diagnosis, median age of patients was 62 years, 62.8% were White, 47.9% had endometrioid carcinoma histology, and 72.6% had ECOG status of 0-1 at 1L therapy initiation. Overall, 161 (68.8%) patients had non-MSI-high/MMR proficient tumors, 53 (22.6%) had MSI-high/MMR deficient tumors, while 20 (8.5%) had discordant results. Over 78% of patients received tumor testing before initiation of 1L treatment. In 1L, 163 (69.7%) patients received platinum-based chemotherapy (most common was carboplatin plus paclitaxel (n=125, 76.7%)); 37 (15.8%) had non-platinum-based chemotherapy, 9 (3.8%) had endocrine therapy and 25 (10.7%) had other therapy. A total of 198 (84.6%) patients discontinued 1L therapy after a median duration of 5.9 (95% confidence interval: 5.6-6.4) months. Discontinuation was mostly due to completion of planned regimen (53.5%) or disease progression (28.3%). Among those who discontinued, 42 (21.2%) initiated a subsequent therapy.
Conclusions: In US real-world clinical practice, prior to March 2020, most aEC patients received platinum-based chemotherapy as 1L systemic therapy, with median time to discontinuation of 1L treatment being less than 6 months.
