Alteogen and Tesaro, a subsidiary of GSK, reached an exclusive license agreement to develop a subcutaneous formulation of dostarlimab.

Dostarlimab’s Indications

Dostarlimab is a programmed death receptor-1 (PD-1) blocking antibody. In August 2024, GSK’s Jemperli (dostarlimab), combined with chemotherapy, was approved by the FDA. Its approved indication is for treatment of adult patients with advanced or recurrent endometrial cancer.

In the agreement, Tesaro gains worldwide rights to use ALT-B4, a novel hyaluronidase enzyme, to develop and commercialize the dostarlimab formulation. To develop the enzyme, Alteogen used a proprietary technology, Hybrozyme.

“We are excited to expand our Hybrozyme technology by collaborating with Tesaro in the oncology field, and look forward to developing and bringing this potential subcutaneous medicine to market,” said Tae-Yon Chun, PhD, CEO of Alteogen.

Other Alteogen Activity

Alteogen previously agreed, in March 2025, with AstraZeneca to license ALT-B4 with an eye toward several oncology assets.

More recently, the FDA (in September 2025) and European Commission (in November) approved a subcutaneous form of Merck & Co.’s Keytruda (pembrolizumab). Merck worked with Alteogen on development of the subcutaneous form.

As an anti-PD-1 therapy, Keytruda’s indications cover approximately three dozen solid tumors.

Terms of Alteogen–Tesaro Deal

For the collaboration with Tesaro, Alteogen receives an upfront payment of $20 million. Additionally, the company may be paid up to an additional $265 million in milestone payments.

On both the clinical and commercial ends, Alteogen will supply ALT-B4 to Tesaro. Additionally, Alteogen receives royalties on any sales of the commercialized product.