Day One Biopharmaceuticals is entering the field of ADCs through an exclusive licensing agreement with MabCare Therapeutics for its ADC MTX-13. 

The Brisbane, California-based biotech company is paying out $55m upfront for the novel ADC targeting protein-tyrosine kinase 7 (PTK7). Under the terms of the agreement, Day One has exclusive rights to develop, manufacture and commercialise MTX-13 worldwide, excluding Greater China. MabCare is eligible to receive an additional $1.15bn in development, regulatory and commercial success-based milestones, plus low-to-mid single-digit royalties on net sales outside of Greater China. 

The US Food and Drug Administration (FDA) cleared the investigational new drug application for MTX-13 – now dubbed DAY301 – in April 2024. According to the companies, DAY301 has shown anti-tumour activity in a wide range of solid tumours in preclinical studies. The first patient is expected to be dosed in an upcoming Phase I study at the end of this year or the start of 2025.  

Day One secured its first FDA approval in April 2024 for Ojemda (tovorafenib), an oral, brain-penetrant, type II RAF kinase inhibitor paediatric brain tumour treatment. Following the FDA approval, the company sold a priority review voucher for $108m, without disclosing the name of the buyer.  

Day One is among the latest biotechs targeting the ADC market, joining a growing list of companies that have entered into deals recently. In April 2024, Genmab announced that it had agreed to acquire ProfoundBio for $1.8m, inheriting its own PTK7-targeted ADC.  

In the same month, Ispen inked a global licensing agreement with Sutro Biopharma to develop ADCs in a deal worth up to $900m. Pharma giants Bristol Myers Squibb, Johnson and Johnson, and Pfizer have all made moves, with Pfizer’s buyout of ADC-specialist Seagen the biggest acquisition to date in the space, a deal that totalled $43bn, in December 2023. 

In the announcement accompanying the acquisition, Day One’s co-founder Samuel Blackman said: “We believe the linker-payload technology embodied in DAY301 will overcome the limitations of earlier PTK7-targeted ADCs, giving us a potential first-in-class drug against a clinically validated target. We are excited to add this program to Day One and will look to enter the clinic in the coming months.”