Hexagon Bio announces formation of Clinical Advisory Board of renowned Breast Cancer experts to support development of HEX-360, a next-generation her2-targeting ADC. Mon, Jun 22, 2026 * HEX-360's novel translation inhibitor payload is designed to overcome resistance and poor tolerability associated with existing payload classes * Recently presented preclinical data at the AACR Annual Meeting 2026 demonstrates HEX-360's potential to address critical gaps in the current ADC landscape * Hexagon Bio anticipates initiating clinical study of HEX-360 in the first half of 2027 MENLO PARK, Calif., June 22, 2026 - Hexagon Bio, a biopharmaceutical company pioneering the discovery of novel small molecule payloads for antibody-drug conjugates (ADCs), today announced the formation of a clinical advisory board (CAB) consisting of leading experts in the treatment and investigation of new therapies for breast cancer. CAB Members: * Hope Rugo, M.D., Division Chief of Breast Medical Oncology and a Professor of Medical Oncology and Therapeutics Research at City of Hope(R), Los Angeles, California, USA * Erika Hamilton, M.D., Chief Development Officer, Late Phase and Director of Breast Cancer Research at Sarah Cannon Research Institute, Nashville, Tennessee, USA * Javier Cortes, M.D., Ph.D., Co-founder and Scientific Director of IOB Institute of Oncology, Madrid, Spain Hexagon Bio's CAB members will provide strategic guidance as the company advances its lead development candidate, HEX-360, toward first-in-human study. HEX-360 is a HER2-targeting ADC that features a novel translation inhibitor payload discovered by Hexagon Bio. Current ADCs primarily deliver chemotherapeutic payloads for cancer cell killing, which often are associated with poor tolerability and patients' development of resistance mechanisms. Conversely, HEX-360's payload is designed to suppress oncogenic protein production, offering the potential for enhanced tolerability and the ability to overcome resistance mechanisms. In preclinical studies, HEX-360 has demonstrated a differentiated profile compared to topoisomerase inhibitor- and tubulin inhibitor-based ADCs. "We are excited to welcome our distinguished Clinical Advisory Board members, and look forward to their expert input and guidance as we rapidly advance HEX-360 toward planned clinic entry next year," said Maureen Hillenmeyer, Ph.D., Chief Executive Officer at Hexagon Bio. "By targeting translation, a key vulnerability in oncogene-driven tumors, HEX-360 has a mechanistically distinct ADC payload and the potential to be a much-needed therapeutic option for patients who have progressed on or cannot tolerate current treatments for HER2-positive cancers." "ADCs represent a significant advance in cancer care. But, unfortunately, most patients with advanced breast cancer treated with today's approved ADCs will eventually relapse primarily due to the development of payload resistance. The development of novel payload mechanisms to overcome these resistance mechanisms is critical to improving patient outcomes," said Hope Rugo, M.D., Chief of Breast Medical Oncology at City of Hope. "I look forward to working with the Hexagon Bio team and my fellow Clinical Advisory Board members as HEX-360 transitions to a clinical-stage candidate for the treatment of breast cancer." HEX-360 is currently in IND-enabling studies with anticipated initiation of clinical investigation in 1H of 2027. HEX-360 Preclinical Data Presented at AACR Annual Meeting 2026 Hexagon Bio recently reported preclinical efficacy and safety data for HEX-360 at the American Association for Cancer Research (AACR) Annual Meeting 2026, highlighting the potential of its novel payload to address critical gaps in the current ADC landscape. Transition inhibitor payload results: * Demonstrates potency at low (<= 10 nM) concentrations in the majority (>90%) of nearly 200 cell lines tested, including cell lines resistant to topoisomerase and tubulin inhibitors * Has low vulnerability to key mechanisms of payload resistance (e.g., drug efflux) * Has good properties (e.g., permeability, lipophilicity), enabling bystander tumor-cell killing similar to topoisomerase inhibitors HEX-360 results: * Shows equivalent or superior efficacy to a comparator analogous to ENHERTU(R) administered at matched payload exposure in cell line- and patient-derived xenograft models * Achieves deep and durable response in models resistant to topoisomerase inhibitors * Has favorable PK properties in preclinical species, supporting Q3W dosing in humans * Demonstrates good tolerability in both rat and non-human primates, without the hallmark toxicities observed with topoisomerase inhibitor-based ADCs The AACR poster is available on Hexagon Bio's website. About Hexagon Bio Hexagon Bio is a biopharmaceutical company pioneering the discovery of novel payloads for antibody-drug conjugates (ADCs) to address critical unmet needs in oncology. Leveraging a proprietary natural products platform, the company mines cytotoxic small molecules from microbial genomes for use as ADC payloads. Advances in DNA sequencing have enabled the identification of both existing ADC payloads - such as topoisomerase and tubulin inhibitors - and novel payload mechanisms targeting other essential cancer pathways such as protein translation. Hexagon Bio is advancing a pipeline of next-generation ADC candidates with novel payloads designed to treat a wide range of solid tumors and hematological malignancies, with the goal of overcoming resistance to existing ADCs and improving efficacy across tumor types. Learn more at https://www.hexagonbio.com/.

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