A phase II trial of IDO-inhibitor, BMS-986205 (IDO), and PD-1 inhibitor, nivolumab (NIVO), in recurrent or persistent endometrial cancer (EC; CA017-056).

Abstract

5589 Background: Indoleamine 2,3-dioxygenase 1 (IDO1) allows tumor escape through kynurenine production, which induces regulatory T cells and suppresses effector T-cell proliferation. NIVO, an anti-PD-1 inhibitor can upregulate IDO1, supporting the rationale for combining NIVO with IDO. We report results of NIVO as monotherapy and in combination with IDO inhibitor BMS-986205 in the treatment of pts with recurrent EC. Methods: In this single-institution, randomized phase 2 study, eligible pts must have received 1-4 prior lines of chemotherapy and have measurable disease by RECIST v 1.1. All EC histologies, including carcinosarcoma, were allowed. Pts with microsatellite insufficient (MSI-H) or mismatch repair (MMR)-deficient tumors were excluded. Pts were randomized to NIVO 480mg IV every 4 weeks (wks) with or without IDO 100mg orally daily. Primary endpoints were Overall Response Rate [ORR = Complete Response (CR) + Partial Response (PR)] by RECIST v 1.1. Secondary objectives were duration of response (DOR), median progression free survival (mPFS), PFS rate at 24 wks (PFS24wks) and safety. Overall survival (OS) was also evaluated. Results: Between 10/2019 and 11/2021, pts were randomized to receive either NIVO (n = 12) or NIVO + IDO (n = 12). Median age was 67 years (range 48-82) and median number of prior lines of therapy was 2 (range 1-3). Histologies included serous (n = 5, 21%), endometrioid (n = 10, 42%), clear cell (n = 1, 4.2%), carcinosarcoma (n = 6, 25%), undifferentiated (n = 1, 4.2%), and mucinous (n = 1, 4.2%). In the NIVO + IDO arm, 1 pt achieved partial response (8.3%, CI: 0.9-100%) with DOR of 17.6 months. In the NIVO arm, no responses were observed. Efficacy outcomes are summarized in the table. Treatment-related adverse events (TRAEs) grade ≥ 3 in the NIVO arm included acute kidney injury (n = 1, 8.3%), hypokalemia (n = 1, 8.3%), and thromboembolic event (n = 1, 8.3%). In the NIVO + IDO arm, TRAEs grade ≥ 3 included fatigue (n = 1, 8.3%), and elevated liver function (n = 1, 8.3%). No TRAEs led to study-drug interruption or dose reductions. Conclusions: NIVO monotherapy and in combination with IDO showed acceptable safety in pts with recurrent EC. NIVO in combination with IDO showed ORR of 8.3%. No responses were observed with NIVO monotherapy. The trial closed to accrual due to lack of observed clinical efficacy. Clinical trial information: NCT04106414. [Table: see text]