Preliminary results of a phase II trial with sacituzumab govitecan-hziy in patients with recurrent endometrial carcinoma overexpressing Trop-2.

Abstract

5599 Background: Despite recent advances, there remains a significant need for targeted, efficacious treatments for advanced and recurrent endometrial carcinoma (EC). Trop-2 has been demonstrated to be overexpressed in several EC including grade 3 endometrioid adenocarcinoma (96%), and uterine serous carcinoma (65%). Trop-2 overexpression has been found to confer a worse prognosis and predicts disease recurrence. Sacituzumab govitecan-hziy (SG) is an antibody-drug conjugate comprised of a humanized anti-Trop-2 antibody conjugated with the active metabolite of irinotecan, a topoisomerase-I inhibitor. SG is currently FDA-approved for use in metastatic urothelial cancer and metastatic triple-negative breast cancer. Methods: We report results from the stage 1 of an open-label non-randomized phase 2 trial (NCT04251416) established to evaluate the clinical activity of SG in patients with persistent or recurrent EC of epithelial origin with Trop-2 overexpression. Criteria for study participation included radiographically confirmed and measurable persistent or recurrent EC, progression after or during platinum-based chemotherapy, and at least 2+ staining of Trop-2. One target lesion by RECIST v1.1 and adequate bone marrow, renal, and hepatic function were required. Patients were at least two weeks beyond prior treatment, major surgery, or high dose systemic corticosteroid use. Patients were given 10mg/kg of SG administered as an intravenous infusion once weekly on days 1 and 8 of 21-day treatment cycles. This 3-week cycle was continued without rest until disease progression or unacceptable toxicity. Results: Twenty-one patients were enrolled into stage 1. Ten patients (48%) had uterine serous carcinoma, seven (33%) had endometrioid adenocarcinoma, three (14%) had carcinosarcoma, and one patient had mixed serous and clear cell histology. All patients received at least one prior line of chemotherapy, (median 3 lines, range 1-6). At the time of submission, 20 patients were response-evaluable (Table); seven (35%) achieved objective response (5 out of 7 confirmed). Eighteen patients were evaluable for durable disease control; 7 (39%) achieved it. Follow-up durations had a median (IQR) of 15.6 (5.7–22.5) months. Median OS was 22.5 months, and median PFS was 5.7 months. The treatment was well-tolerated with no new or unexpected safety signals reported. Conclusions: Sacituzumab govitecan shows remarkable clinical activity against some of the most historically challenging and chemotherapy-resistant endometrial pathologies and demonstrates a favorable safety profile. With these promising results, we will begin the stage 2 expansion of this phase 2 trial. Clinical trial information: NCT04251416 . [Table: see text]