Shortly after securing its first FDA approval and bagging $108 million from a priority review voucher sale, Day One Biopharmaceuticals is entering the hottest pocket of oncology drug development — antibody-drug conjugates — by way of a licensing deal.
The Brisbane, CA-based Day One will dish out $55 million upfront to Shanghai-based MabCare Therapeutics for an ADC named MTX-13, which is slated to enter Phase 1 “in the coming months,” the companies said Tuesday morning. Day One could dole out another $1.15 billion in biobucks, a figure that’s about $100 million more than the newly-minted commercial biotech’s market capitalization.
Day One joins a growing trend of smaller and mid-size biotechs hopping aboard the ADC train after most large pharmaceutical companies have either bought their way into the space or created homegrown programs. The move follows similar deals from Genmab, Ipsen, Endeavor BioMedicines, ArriVent, BioNTech and other biotechs.
And like many of its peers, Day One is linking up with a China-based drug developer.
Day One is buying into a PTK7-targeted ADC, now named DAY301. Genmab’s $1.8 billion ProfoundBio acquisition also involves a PTK7-targeted ADC, dubbed PRO1107. AbbVie and partner Pfizer were also in the space, but AbbVie dropped their ADC from the pipeline last fall.
In a Tuesday SEC filing, Day One highlighted the groundwork laid by AbbVie’s ADC asset, known as cofetuzumab pelidotin, adding that early clinical results of that experimental treatment “demonstrated proof of concept for PTK7-targeted ADCs.”
By going after PTK7, Day One thinks it can address both pediatric and adult cancers. The transmembrane protein is overexpressed in adult cancers like esophageal, ovarian, lung and endometrial, the company said. On the pediatric front, it’s found in neuroblastoma, rhabdomyosarcoma and osteosarcoma cases.
Samuel Blackman“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,” co-founder and R&D lead Samuel Blackman said in a press release.
Another advantage of the PTK7 target, the biotech said, is that the protein has “limited expression in normal tissues or organs,” which could mean fewer side effects or toxicity concerns. While ADCs have grown up over the past two decades, thanks to better chemistry, linker technology and other tinkering, they still come with some safety baggage, experts have said.
Day One said it plans to dose the first patient in a Phase 1 in the last quarter of this year or the first few months of 2025. The biotech snags rights to the ADC outside of Greater China. It could pay MabCare “low-to-mid single-digit” royalties if the treatment makes it to market.
Day One said it had $317.9 million in cash, equivalents and short-term investments as of March 31, enough to last “into 2026.” It will “explore selective partnerships” and continue investing on the business development side to boost its “multiple asset portfolio,” according to Tuesday’s corporate presentation.