OrbiMed-backed Theseus debuts with $100M round in heroic quest for 'pan-variant' kinase inhibitors
Despite the promise of kinase inhibitors in treating rare tumors, narrow therapeutic targets for most candidates can halt efficacy the moment a patient’s tumor cells mutate. Now, an OrbiMed-backed startup will take a nine-figure fundraising round to advance its purposefully broad candidates against treatment-resistant tumors.
Boston-based Theseus Pharmaceuticals has bagged a $100 million Series B round it will use to advance a suite of “pan-variant” tyrosine kinase inhibitors (TKI), including a lead compound targeting KIT-mutant gastrointestinal stromal tumors, the company said Tuesday.
Theseus’ plan is to create a pipeline of next-gen TKIs that attack solid tumors across a broad range of variants, potentially putting an end to treatment resistance, the company said. The emerging biotech was kickstarted by OrbiMed with a Series A round back in 2018.
The biotech’s lead compound, dubbed THE-630, is a broad TKI targeting KIT-mutant GIST, and Theseus plans to file an IND for that molecule by the end of the year. Meanwhile, the company’s pipeline includes an EGFR inhibitor designed to beat C797S-mediated resistance to first- or later-line Tagrisso treatment for patients with non-small cell lung cancer. The company is also working on a third kinase-target candidate for which it has yet to disclose an indication.
The company’s science is led by co-founder and president of R&D William C. Shakespeare, formerly the head of drug discovery at Ariad Pharmaceuticals. In a statement, co-founder and interim CEO Iain Dukes said Shakespeare’s Ariad team was responsible developing two molecules that eventually made it to market — RTK inhibitor Iclusig and ALK targeting small molecule inhibitor Alunbrig — and a third, Takeda’s TKI candidate mobocertinib, that is currently in Phase III trials to tackle EGFR and HER2 exon 20 insertion mutations.
In addition to Foresite Capital, the Series B gathered a syndicate of other investors, including Adage Capital Management, Boxer Capital, Farallon Capital Management, Longitude Capital, Nextech Ventures, Omega Funds, Pontifax Venture Capital, Rock Springs Capital, and T. Rowe Price, as well as OrbiMed. As part of the round, Foresite managing director Michael Rome will join the Theseus board.