NEW YORK – Ideaya Biosciences on Monday said it will begin evaluating the pol theta helicase inhibitor GSK101 with GlaxoSmithKline's PARP inhibitor Zejula (niraparib) in a Phase I/II clinical trial involving patients with homologous recombination repair-deficient advanced solid tumors.
Ideaya and GSK jointly discovered and preclinically evaluated GSK101, also known as IDE705. The US Food and Drug Administration cleared an investigational new drug application for the Phase I/II trial, which GSK will sponsor. The study will include patients with tumors bearing BRCA1/2 mutations or other homologous recombination deficiencies that have not responded to standard-of-care treatments.
GSK101 is designed to block the pol theta enzyme, which facilitates DNA repair through a process called microhomology-mediated end joining. In preclinical studies, GSK101 and Zejula together shrunk tumors more effectively than single-agent GSK101 or single-agent Zejula.
For the upcoming trial, GSK will pay all R&D costs. As stipulated in a deal inked last year, Ideaya will receive a $7 million milestone payment for having achieved FDA clearance of its IND application and will be eligible for another $10 million once the Phase I trial begins its expansion portion. Should the agent progress to later-stage development, Ideaya will be eligible for up to $465 million.
Down the line, if GSK101 were to enter the market, Ideaya can receive up to $475 million in commercial milestones and royalties in the range of high single-digit to sub-teen double-digit percentages.