Zachary Hornby

Callio Therapeutics, a clinical-stage biotechnology company developing dual-payload antibody-drug conjugates (ADCs) for targeted cancer therapy, has appointed Zachary “Zach” Hornby as Chief Executive Officer (CEO). 

Hornby brings experience in biotechnology leadership, clinical development, financing and strategic partnerships.

Hornby has held executive and board positions across several public and private biotechnology companies. Most recently, he served as CEO, President and Director of Boundless Bio (Nasdaq: BOLD), a precision oncology company. During his tenure, the company raised $350 million through private and public financing and advanced three internally discovered molecules into clinical development.

Previously, Hornby served as Chief Financial Officer and Chief Operating Officer at Ignyta. In these roles, he contributed to the company’s initial public offering, oversaw its development portfolio and served as team leader for the cancer therapy Rozlytrek. He also led the business development process that resulted in Ignyta’s $2 billion acquisition by Roche.

Hornby currently serves as a Director at Radionetics Oncology and Telperian, Inc. He holds Bachelor of Science and Master of Science degrees in Biology from Stanford University and an MBA from Harvard Business School.

As part of the leadership transition, Piers Ingram, PhD, Callio’s founding CEO, will become a Senior Advisor while continuing to serve on the company’s Board of Directors. Jerome Boyd-Kirkup, PhD, the company’s founding Chief Scientific Officer, will transition to Senior Scientific Advisor.

The leadership changes come as Callio advances its pipeline, including lead clinical program CLIO-8221, and expands its dual-payload ADC platform. Ingram will continue as CEO of Hummingbird Bioscience, while Boyd-Kirkup will remain its CSO. Callio exclusively licensed Hummingbird’s multi-payload ADC platform, intellectual property and pipeline assets for oncology in 2025.