Theseus Pharmaceuticals Raises $100M in Series B Funding


Theseus Pharmaceuticals, a Boston, MA-based biotechnology company focused on oncology by developing pan-variant kinase inhibitors, emerged from stealth with the close of a $100m Series B financing.

The round was led by Foresite Capital with participation from Adage Capital Management, Boxer Capital, Farallon Capital Management, Longitude Capital, Nextech Ventures, Omega Healthcare Investors, Pontifax Venture Capital, Rock Springs Capital, and T. Rowe Price, as well as OrbiMed. In conjunction with the financing, Michael Rome, Ph.D., Managing Director of Foresite Capital, has joined the Theseus Board of Directors, which also includes Carl Gordon, General Partner at OrbiMed.

Theseus Pharmaceuticals is developing a pipeline of pan-variant tyrosine kinase inhibitors (TKIs) that can anticipate and inhibit new cancer mutations. The company’s lead candidate, THE-630, is a next-generation pan-variant KIT inhibitor in development for the treatment of refractory GIST. Theseus expects to file an IND before the end of the year.

The pipeline also includes a selective EGFR inhibitor to overcome C797S-mediated resistance to first- or later-line osimertinib treatment for patients with non-small cell lung cancer, and a third kinase target candidate for an undisclosed indication.

The company is led by:

  • William C. Shakespeare, Ph.D., Co-founder and President of Research and Development, and
  • Iain Dukes, D. Phil., Co-founder and Interim CEO.