Astellas Takes Option on Audax IL-12 Antibody-Cytokine Fusion DAX-044

Astellas Pharma and Audax Biosciences announced on October 28, 2026, an exclusive option and license agreement for DAX-044, Audax's investigational immune-targeted interleukin-12 (IL-12) antibody-cytokine fusion for solid tumors.¹ If Astellas exercises its option, it will receive a worldwide license to develop, manufacture, and commercialize the preclinical candidate. The deal has a total potential value of up to $1.34 billion, excluding royalties.¹

"This partnership will expedite the planned phase 1 clinical evaluation of DAX-044 for the benefit of patients with various types of solid tumor," said Jai Rautela, PhD, CEO of Audax, in a company press release.¹

What are the terms of the agreement?

Audax will receive an up-front payment and a potential future option exercise payment totaling $285 million.¹ The Melbourne, Australia-based company will fund and continue development of DAX-044 into a phase 1 study expected to begin in 2027.¹

Once Astellas exercises its option, it will assume sole responsibility for global development, manufacturing, and commercialization. Audax will retain an option to co-fund and co-promote DAX-044 in Australia and New Zealand.¹ Audax is also eligible for development and commercial milestone payments of up to $1.05 billion, plus tiered double-digit royalties on worldwide net sales if the therapy is approved.¹ Option exercise is subject to customary conditions, including antitrust clearances.¹

Takahiko Iwaya, chief strategy officer at Astellas, said in the release that the company hopes "to advance a potential new treatment option for patients with solid tumors, including cancers where effective immune stimulation remains an important therapeutic challenge."¹ According to the companies, immuno-oncology is one of the primary focuses of Astellas' research and development strategy.¹

How is DAX-044 designed?

DAX-044 was developed with Audax's Avikine technology. It is designed to concentrate IL-12's immune-activating activity within the tumor microenvironment while limiting the systemic toxicity that has historically constrained IL-12-based therapy.¹ According to the companies, DAX-044 showed a potential best-in-class therapeutic index for an IL-12 agent in preclinical studies. The candidate is in investigational new drug (IND) and clinical trial notification (CTN)-enabling development.¹

Why has IL-12 been difficult to develop as a cancer therapy?

IL-12 is a potent immune-activating cytokine, but systemic toxicity has held back its clinical development.¹ In an early phase 2 study of recombinant human IL-12 (rhIL-12) given at 500 ng/kg, 12 of 17 patients were hospitalized and 2 patients died.² The preceding phase 1 study had used a single test dose of rhIL-12 followed 14 days later by repeated dosing, a step the phase 2 schedule omitted.² The investigators concluded that a single injection 2 weeks before consecutive dosing had "a profound abrogating effect on IL-12-induced interferon-gamma (IFN-gamma) production and toxicity."²

DAX-044 takes an engineering approach to the same problem rather than changing the dosing schedule. According to the companies, the Avikine design fuses IL-12 to an immune-targeting antibody to keep the cytokine's activity concentrated in the tumor microenvironment rather than throughout the body.¹

What are the limitations?

DAX-044 has not yet been tested in humans, and its preclinical therapeutic index may not translate to clinical safety or efficacy. The companies did not disclose the molecule's specific targeting mechanism, its preclinical data, or how the $285 million splits between the up-front and option exercise payments. Astellas has not yet exercised its option, which still requires antitrust clearances. Most of the deal's value depends on future development and commercial milestones that may not be reached.

References

1. Astellas Pharma. Astellas and Audax Biosciences enter exclusive option and license agreement for DAX-044, a novel immune-targeted IL-12 antibody-cytokine fusion for immuno-oncology. Press release. Published October 28, 2026. Accessed October 29, 2026. https://newsroom.astellas.com/2026-10-28-astellas-and-audax-biosciences-enter-exclusive-option-and-license-agreement-for-dax-044-a-novel-immune-targeted-il-12-antibody-cytokine-fusion-for-immuno-oncology
2. Leonard JP, Sherman ML, Fisher GL, et al. Effects of single-dose interleukin-12 exposure on interleukin-12-associated toxicity and interferon-gamma production. Blood. 1997;90(7):2541-2548. https://pubmed.ncbi.nlm.nih.gov/9326219/