Abstract CT006: Phase 1 DKY709A12101C study in patients with advanced solid tumors treated with DKY709, an IKZF2 degrader, alone or in combination with PDR001, a PD-1 inhibitor

Abstract Background: DKY709 is an orally administered molecular glue degrader of IKZF2, a transcription factor expressed in regulatory T cells. PDR001 (spartalizumab) is a humanized monoclonal antibody directed against programmed cell death 1 protein (PD-1). This phase 1 study was designed to assess the safety, pharmacokinetics, and preliminary efficacy of DKY709 as monotherapy or in combination with PDR001 in patients with advanced solid cancers. Methods: DKY709A12101C (NCT03891953) was a global, phase 1, open-label study in patients with advanced cancers, including non-small cell lung cancer (NSCLC) and melanoma previously treated with anti-PD-1/PD-L1 therapy, or previously treated nasopharyngeal carcinoma (NPC). Patients received DKY709 alone (arm A) or in combination (arm B) with PDR001 (400 mg Q4W or 300 mg Q3W intravenously). During dose escalation, 20 mg was the starting dose and patients also received 4, 6, 10, or 40 mg (arm A only) of DKY709 by mouth QD continuously. An intermittent dosing schedule for DKY709 (20 or 10 mg) of either 3 or 2 weeks on followed by 1 week off was implemented in both arms. Primary endpoints were safety and tolerability. Secondary endpoints included pharmacokinetics, pharmacodynamics, and preliminary antitumor activity. Results: At data cutoff (Sep 5, 2024), 58 patients were treated with DKY709 (30 with melanoma, 4 with NPC, and 24 with NSCLC) and 40 with DKY709 + PDR001 (12 with melanoma, 13 with NPC, and 15 with NSCLC). Median age was 60 years; 46% of participants were female. DKY709 showed dose-proportional exposure with 2- to 3-fold accumulation and achieved IKZF2 degradation of ≥90% in peripheral regulatory T cells with all doses ≥6 mg. Dose-limiting toxicities occurred in 3 patients receiving monotherapy and 2 receiving the combination. The most common treatment-related adverse events were myalgia (17. 2%) with DKY709 monotherapy and AST/ALT increase (22. 5%) and diarrhea (22. 5%) with DKY709 + PDR001. Reversible peripheral neuropathy related to DKY709 was observed in 28% and 30% of patients receiving monotherapy and the combination, respectively; lower doses and intermittent schedules were associated with less neurotoxicity. The disease control rate in the monotherapy arm was 44. 8% and included 1 confirmed complete response (melanoma) and 3 confirmed partial responses (2 melanoma and 1 NSCLC). The disease control rate in the combination arm was 37. 5% and included confirmed partial responses in 5 patients (2 melanoma, 2 NPC, and 1 NSCLC). The recommended dose for expansion was 6 mg QD continuously in the monotherapy and combination arms. Conclusions: DKY709 achieved IKZF2 degradation of ≥90% in peripheral regulatory T cells at doses ≥6 mg. DKY709 as monotherapy and in combination with anti-PD-1 therapy reduced tumor volume in patients with NPC and those with NSCLC and melanoma previously treated with immunotherapy. Citation Format: Elena Garralda, Chia-Chi Lin, Takafumi Koyama, Brigette Ma, Melissa Johnson, Martin Schuler, Martin Wermke, Justin Gainor, Raj Gopal, Debby Long, Jaeyeon Kim, Divyasree Maddirala, Anhthu Dang, Xin Yang, Mark Awad. Phase 1 DKY709A12101C study in patients with advanced solid tumors treated with DKY709, an IKZF2 degrader, alone or in combination with PDR001, a PD-1 inhibitor abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts) ; 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86 (8Suppl): Abstract nr CT006.