Pyxis Oncology to prioritize PYX-201, suspends investment in PYX-106

Pyxis Oncology (PYXS) announced a portfolio prioritization, focusing resources on advancing its lead clinical program, PYX-201, a first-in-concept antibody-drug conjugate with a microtubule inhibitor payload that uniquely targets Extradomain-B Fibronectin, or EDB+FN, a non-cellular structural component within the tumor extracellular matrix. In November, Pyxis Oncology reported preliminary data from the ongoing Phase 1 dose-escalation study of PYX-201, evaluating its safety and efficacy in multiple solid tumor types. Among patients with HNSCC, PYX-201 achieved a confirmed 50% objective response rate based on RECIST 1.1 criteria, including one complete response and a disease control rate of 100% in six heavily pretreated HPV-positive and HPV-negative evaluable patients with a median of four prior lines of therapy. Across six solid tumor types of interest at therapeutically active dose levels, including HNSCC, ovarian, non-small cell lung cancer, HR+/HER2- breast cancer, triple-negative breast cancer, and sarcoma, PYX-201 achieved a 26% ORR in the Phase 1 trial, with dose-dependent responses observed including patients who had previously progressed on taxanes. The data supports further development in both monotherapy and combination therapy expansion trials, including a frontline HNSCC study in combination with pembrolizumab, with patient dosing in both the monotherapy and combination therapy trials expected to begin in early 2025. The portfolio prioritization further supports a robust development plan for PYX-201 in several dose expansion studies, including monotherapy in 2/3L HNSCC, in combination with pembrolizumab in 1/2L+ HNSCC, as well as pembrolizumab combination studies in other solid tumors including HR+/HER2- and triple-negative breast cancer. Preliminary data from these cohorts is expected across both the second half of 2025 and the first half of 2026. Pyxis Oncology’s second clinical program, PYX-106 – a fully human IgG1 monoclonal antibody targeting Siglec-15 – is being deprioritized to allocate resources toward advancing the lead asset, PYX-201. As a result, Pyxis Oncology has decided to suspend further clinical investment in PYX-106, which was in-licensed from Biosion Inc., with Biosion retaining rights for Greater China. To date, the Phase 1 monotherapy trial of PYX-106 enrolled 45 patients with advanced solid tumors. PYX-106 was observed as generally safe and well-tolerated across all tested doses, ranging from 0.5 mg/kg to 22.5 mg/kg. At this time, a maximum tolerated dose has not been established. The pharmacokinetic and pharmacodynamic results demonstrated dose-proportional pharmacokinetics, a half-life of 9 to 11 days, no detection of antidrug antibodies in a variety of heavily pretreated solid tumors across tested dose levels. The Company’s current cash position is expected to fund its planned monotherapy and combination therapy trials of PYX-201 into the second half of 2026.