ALX Oncology highlights preclinical data, development plans for ALX2004

ALX Oncology (ALXO) Holdings provides an overview of the clinical development program for its highly-differentiated antibody-drug conjugate, ALX2004, at the Company’s R&D webcast event today. ALX Oncology leadership will discuss the unique design profile, preclinical data and clinical development plans for ALX2004, a potential best- and first-in-class ADC for the treatment of epidermal growth factor receptor-expressing solid tumors, that is planned to enter Phase 1 studies in mid-year 2025. The Company’s ALX2004 R&D webcast event will include presentations on: ALX2004 Unique Design: Optimized for Anti-Tumor Activity and Improved Outcomes: Developed by ALX Oncology’s protein engineers utilizing the Company’s proprietary topoisomerase I inhibitor payload and linker-payload platform, ALX2004 has been rigorously designed to maximize the therapeutic window and overcome toxicity challenges observed in this class. This includes an affinity-tuned EGFR antibody with a binding epitope distinct from approved EGFR antibodies. ALX2004 also has a proprietary linker-Top1i payload engineered to offer enhanced bystander effect with improved linker stability for on-target delivery of payload. Robust Preclinical Data: Supporting Differentiation in EGFR-ADC Class: Preclinical data supports ALX2004’s differentiated linker-payload construct, which has demonstrated superior stability versus other ADCs in its class, with dose-dependent activity and a favorable safety profile. In addition, ALX2004 has shown dose-dependent activity across a range of tumors, EGFR expression levels and mutations. Potent activity in tumor models supports its potential for treating patients with EGFR-expressing tumors. Preclinical model findings did not demonstrate EGFR-related skin toxicity at clinically relevant doses or payload-related interstitial lung disease, supportive of a potentially differentiated safety profile. Initiation of Phase 1 Clinical Development Program: The U.S. Food and Drug Administration cleared ALX Oncology’s Investigational New Drug application for ALX2004 in April 2025. ALX Oncology will provide an overview of its Phase 1 clinical trial design for ALX2004 planned to initiate mid-2025. The Company anticipates initiating a Phase 1 dose escalation trial in EGFR-expressing solid tumors, including non-small cell lung cancer, colorectal cancer, head and neck squamous cell carcinoma and esophageal squamous cell carcinoma, targeting patients with relapsed/refractory cancers. The Company anticipates initial safety data in the first half of 2026.