MabCare out-licenses ADC to Day One Bio in potential $1.2bn deal

MabCare is also eligible for low-to-mid single-digit royalties. The deal is Day One’s first foray into antibody drug conjugates (ADCs). The US Food and Drug Administration (FDA) approved an Investigational New Drug (IND) for MTX-13 (now known as DAY30) earlier this year. MabCare said the candidate showed efficacy against solid tumors in preclinical testing. Day One expects to start US trials at the end of 2024.

DAY301 targets PTK7, a highly-conserved, catalytically inactive transmembrane protein that is overexpressed in multiple adult cancers, including esophageal, ovarian, lung, and endometrial cancer, as well as pediatric cancers such as neuroblastoma, rhabdomyosarcoma and osteosarcoma. PTK7 has limited expression in normal tissues or organs, making it an attractive target for therapeutic development.

Day One believes the linker-payload technology of DAY301 will overcome the limitations of earlier PTK7-targeted ADCs, giving the company a potentially first-in-class drug against a clinically-validated target.

According to MabCare, MTX-13 is a PTK7-targeting ADC consisting of a novel antibody (Ab13) conjugated to eight molecules of Topoisomerase I inhibitor exatecan through T1000, a novel self-immolative moiety. In animal models, MTX-13 showed PTK7-specific cell binding, efficient internalization and exatecan release. It caused cytotoxic activity through DNA damage and apoptosis induction along with a strong bystander killing. The company said MTX-13 displayed potent antitumor activities on CDX and PDX models from a wide range of solid tumors, outperforming earlier PTK7 targeting drugs.

Earlier this year, Day One was granted its first FDA approval to start a clinical trial. The candidate, Ojemda (tovorafenib), is an oral, brain-penetrant, type II RAF kinase inhibitor aimed at treating pediatric brain tumors. Following the FDA approval, the company sold a priority review voucher for $108 million, without disclosing the name of the buyer.

Day One’s goal as a company is to prioritize therapies that treat pediatric cancers. Its name refers to the conversation – on Day One – between doctor and patient (or parent of the patient) following a cancer diagnosis. The company wants to improve the offerings that doctors offer their patients in this initial discussion.

“Our priorities for 2024 are to successfully launch Ojemda (tovorafenib), to advance our existing programs and to expand our pipeline by in-licensing clinical-stage assets that have the potential to transform outcomes for patients of all ages living with cancers,” said Jeremy Bender, CEO of Day One. “We are excited by the opportunity presented by DAY301, and we believe we have the right team in place to develop the program to its full potential.”

“The addition of DAY301 to our pipeline strategically fits our mission of advancing both pediatric and adult medicines in areas of unmet need with equal urgency,” said Samuel Blackman, co-founder and head of research and development at Day One.

Day One Biopharma is a commercial-stage company that partners with leading clinical oncologists, families, and scientists to identify, acquire and develop important targeted cancer treatments. The Company’s pipeline includes tovorafenib and pimasertib.

A version of this article was first published in ChinaBio Today on June 20, 2024.