Astellas has struck a deal with Audax Biosciences that could be worth up to about $1.34 billion, giving the Japanese drugmaker an exclusive option to license DAX-044, a preclinical immuno-oncology candidate for solid tumors. Audax could receive an undisclosed upfront payment plus a potential option exercise fee totaling $285 million, alongside up to $1.05 billion in development and commercial milestones and tiered double-digit royalties on worldwide net sales.
The structure matters as much as the headline number. Audax will fund DAX-044 into Phase 1 development, which is expected to start in 2027, while Astellas is paying now to preserve a right to take over later. If Astellas exercises the option, it would become responsible for global development, manufacturing and commercialization, while Audax would retain an option to co-fund and co-promote in Australia and New Zealand.
Why DAX-044 Looks Different
DAX-044 is Audax’s attempt to solve the dosing and toxicity problems that have dogged IL-12 development for decades. According to the sources, Audax believes a key issue is the tendency of IL-12 drugs to bind receptors on peripheral immune cells, contributing to both systemic toxicity and drug consumption outside the tumor.
Its design response is multi-part. Audax engineered DAX-044 to have lower affinity for IL-12R, aiming to reduce activation of peripheral immune cells and potentially extend half-life because the drug is not being used up by circulating immune cells. The company also fused the candidate to the Fc region of an antibody to further extend half-life, and added an antibody fragment binding domain intended to direct the molecule to an antigen expressed on certain immune cells in the tumor microenvironment.
The investment thesis is straightforward: if limiting peripheral binding while increasing tumor microenvironment engagement works, DAX-044 could have a wider therapeutic window than earlier IL-12 programs. The risk is just as clear: Audax has not yet shown how the asset performs in humans.
The Road Back To IL-12
This is a notable return of large-company capital to a target that has repeatedly disappointed. One source points to a 17-patient phase 2 study from the 1990s that resulted in 12 hospitalizations and two deaths, an episode that still shapes how IL-12 is viewed. More recently, a renewed wave of interest faded in 2022 and 2023 when AstraZeneca, Bristol Myers Squibb and Merck KGaA cut IL-12 programs.
That history explains why the Astellas-Audax deal stands out. The company is not buying de-risked clinical data; it is buying an option on a new molecular architecture that aims to correct for the same biology that derailed prior efforts. In business terms, that is a higher-risk, potentially higher-leverage use of capital than licensing a later-stage checkpoint or ADC asset.
The move also fits a broader pattern in Astellas’ immuno-oncology strategy. BioSpace notes that the company’s lead asset in the area is ASP2138, a bispecific immune cell engager in Phase 3 testing for stomach and gastroesophageal junction cancers, with an additional Phase 1 study in pancreatic cancer. Astellas has also added other external programs, including a February pact with Vir Biotechnology that could be worth up to $1.7 billion and a May 2025 deal with Evopoint Biosciences that could top $1.5 billion.
For Audax, the agreement validates a preclinical platform at a time when much IL-12 development is being carried by smaller companies rather than large pharma groups. For Astellas, the signal is that selectively engineered cytokines remain investable if the delivery and toxicity argument is differentiated enough. The next real inflection point is whether DAX-044 can enter the clinic next year and show that its design translates beyond the preclinical rationale.
