San Diego, Calif., November 4, 2021 – Plexium Inc., (Plexium), a leading next-generation targeted protein degradation (TPD) company, today announced the appointment of experienced biopharmaceutical leader Percival Barretto-Ko as President and Chief Executive Officer and a member of the Board of Directors.

Mr. Barretto-Ko joins Plexium following a sixteen-year tenure with Astellas Pharma Inc., a global pharmaceutical company, where he held several prominent roles and was most recently Chief Business Officer and a member of the Executive Committee where he led the execution of Astellas’ Corporate Strategic Plan. 

“Percival is a highly accomplished veteran with the leadership, track record and breadth of experience that make him uniquely suited to lead Plexium,” said Mike Grey, Executive Chairman of Plexium. “I look forward to working with Percival to advance the company’s promising drug discovery programs against challenging targets utilizing Plexium’s best-in-class technology.”

“I am delighted to join Plexium at this exciting stage, and help achieve its aspiration to be the premier, next generation TPD company. Plexium is well-positioned for success, with its comprehensive proprietary platform, novel approach, top-tier investors, and a world-class team, to create TPD therapies that address the limitations of PROTACs and cereblon,” said Mr. Barretto-Ko. “I look forward to advancing the important and innovative work we’re doing to advance protein degraders as a new class of medicines with the potential to treat a wide range of diseases.”

Prior to serving as CBO for Astellas Pharma, Mr. Barretto-Ko was President, Astellas Pharma US, where he was responsible for United States operations with annual revenues of over $4.5 billion and more than 3,000 employees. Mr. Barretto-Ko’s earlier roles at Astellas include Senior Vice President, Head of International, and Senior Vice President, Corporate Strategy, Business Development & Government Affairs. Mr. Barretto-Ko joined Astellas in 2005 in London where he served in several roles including EMEA Head of Corporate Strategy, Business Development, and Corporate Communications, and EMEA Head of Immunology and Transplant. Before joining Astellas, Mr. Barretto-Ko held increasingly senior commercial positions with the Roche Group in the United States and United Kingdom, across various therapeutic areas including Oncology, Hematology, Virology, Immunology, and Infectious Diseases.

Mr. Barretto-Ko earned a Bachelor of Science in Biological Sciences with Honors from Cornell University and a Master of Business Administration from Yale University. In addition, Mr. Barretto-Ko served as a Sloan Fellow for Innovation and Global Leadership at the MIT Sloan School of Management, where he was awarded a Master of Science degree in Management. He is a board member of Americares, a health-focused relief and development organization that serves people affected by poverty or disaster with life-changing medicine and health programs.

About Plexium

Plexium is the premier, next-generation targeted protein degradation company, seeking to discover a wide range of monovalent target protein degraders that address the limitations of PROTACs and cereblon. The company’s platform is a proprietary drug discovery platform designed to identify novel small molecules that induce selective degradation of drug target proteins through E3 ligase mediated proteasomal degradation. From molecular glues to monovalent degraders, Plexium is advancing a pipeline of novel targeted protein degraders for the treatment of cancer, neurodegeneration, and other diseases. For more information, visit and engage with us on LinkedIn.

Plexium Investor and Media Contact:

Amy Conrad
Juniper Point