Abstract CT257: First-in-human phase 1 studies of PTPN2/1 inhibitors ABBV-CLS-484 and ABBV-CLS-579 in locally advanced or metastatic tumors

Abstract Background: Protein tyrosine phosphatase non-receptor type 2 and type 1 (PTPN2/1) antagonists inhibit PTPN2/1-mediated negative regulation of immune response pathways. They may promote antitumor activity by increasing function of immune cells such as T cells and dendritic cells, inducing cytokine production, increasing antigen presentation, and amplifying interferon gamma-mediated tumor growth arrest. ABBV-CLS-484 and ABBV-CLS-579 are potent, orally bioavailable, first-in-class PTPN2/1 inhibitors that showed promising antitumor activity and were well tolerated in preclinical models. Preclinical data also indicated that PTPN2/1 inhibitors have improved efficacy when combined with PD-1-targeting agents (eg, pembrolizumab) or vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors (TKIs) in multiple tumor models. Here, we describe 2 first-in-human trials of ABBV-CLS-484 or ABBV-CLS-579 as monotherapy and in combination with pembrolizumab or VEGFR TKI in patients with locally advanced/metastatic tumors. Methods: These phase 1, open-label, multicenter, non-randomized trials (ABBV-CLS-484: NCT04777994; ABBV-CLS-579: NCT04417465) comprise dose-escalation (ESC) and dose-expansion (EXP) phases. ESC is guided by a Bayesian optimal interval design based on dose-limiting toxicities. ESC data are used to inform evaluation of EXP cohorts in select tumor types including relapsed/refractory (R/R) head and neck squamous cell carcinoma, R/R non-small cell lung cancer, advanced renal cell carcinoma, and microsatellite instability-high tumors. In both ESC and EXP phases, the study drug (ABBV-CLS-484 or ABBV-CLS-579) is administered orally either alone or in combination with pembrolizumab (200 mg intravenously once every 3 weeks) and is slated to also be administered in combination with a VEGFR TKI. Eligible patients have locally advanced/metastatic tumors for which no effective standard therapy exists (or has failed), and Eastern Cooperative Oncology Group performance status ≤2. Patients (≥18 years) must have received ≥1 prior systemic anticancer therapy for the indication being considered, have relapsed or be refractory to ≥1 prior anti-PD-1/PD-L1 therapy (EXP monotherapy and pembrolizumab combination), or have relapsed after ≤1 (ABBV-CLS-484) or ≥1 (ABBV-CLS-579) prior VEGFR TKI therapy (EXP VEGFR TKI combination). Primary objectives are to assess safety, tolerability, pharmacokinetics, and to determine the recommended expansion dose and/or maximum tolerated dose of ABBV-CLS-484 or ABBV-CLS-579, both as monotherapy and in combination. Evaluation of objective response rate (RECIST v1.1) is a primary objective in EXP phase and a secondary objective in ESC phase. Both studies are active, and as of 30 Nov 2022, 30 (ABBV-CLS-484) and 45 (ABBV-CLS-579) patients had been enrolled in ESC phase. Citation Format: Patricia M. LoRusso, Emiliano Calvo Aller, Noboru Yamamoto, Chia-Chi Lin, Thaddeus Beck, David Sommerhalder, Do-Youn Oh, John D. Powderly, Talia Golan, Linu Sara Abraham, Joel S. Hayflick, Tamar Uziel, Priya Brunsdon, Wijith Munasinghe, Marcia Paddock, Cathleen Brdlik Hartman, Jonathan Powell, Bruno Medeiros, Martha R. Neagu, Benedito A. Carneiro. First-in-human phase 1 studies of PTPN2/1 inhibitors ABBV-CLS-484 and ABBV-CLS-579 in locally advanced or metastatic tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT257.