Ideaya Biosciences is betting $400 million in biobucks that a bispecific antibody-drug conjugate (ADC) can turbocharge the effect of its DNA damage repair molecules. The West Coast biotech dangled the cash to secure an option on a preclinical program in development at Biocytogen.
Biocytogen, the Chinese biotech that recently landed a deal with Sotio, is using a B7H3xPTK7 bispecific to deliver a topoisomerase I inhibitor payload to tumor cells. With candidate nomination scheduled for this year, Ideaya has paid an upfront fee for an option on a global license to the ADC. Exercising the $6.5 million option will put Ideaya on the hook for up to $400 million in milestones, including $100 million tied to development and regulatory events.
Ideaya singled out PARG inhibitor IDE161 as a candidate that could play nicely with the ADC. Talking at a Goldman Sachs event in June, Ideaya CEO Yujiro Hata said there are some monotherapy opportunities for IDE161, such as endometrial and colorectal cancers, but combinations will unlock more indications. Ideaya entered into a collaboration with Merck & Co. to test IDE161 in combination with Keytruda in March, and Hata said he had “another half a dozen conversations going” at the Goldman Sachs event.
An ADC with a topoisomerase I inhibitor payload looked likely to sit toward the top of Ideaya’s priorities as it worked to find molecules to pair with IDE161. The biotech has presented data showing topotecan, a topo I inhibitor, and IDE161 in combination induce stronger responses in preclinical lung cancer models than either molecule alone. Dual inhibition of the targets induces unresolvable DNA-protein crosslinks.
Bagging an option on Biocytogen’s ADC positions Ideaya to further explore potential synergies between the two mechanisms. Ideaya said the ADC could also be developed as a single agent and in combination with other candidates in its pipeline.
Other companies are advancing ADCs against the targets of Biocytogen’s ADC, but the bispecific design sets it apart. Merck’s big bet on Daiichi Sankyo’s pipeline included a B7H3-directed ADC. MacroGenics has an ADC aimed at the same target, although a recent report of five deaths dampened enthusiasm for the program. Genmab picked up a PTK7-directed ADC in its $1.8 billion takeover of ProfoundBio.