GSK Taps Alteogen for Simpler, Subcutaneous Jemperli Formulation

DAEJEON, South Korea – January 20, 2026 – In a strategic move to enhance its oncology portfolio, GSK's subsidiary Tesaro has entered into an exclusive licensing agreement with South Korean biotech firm Alteogen Inc. The deal, announced today, grants GSK worldwide rights to Alteogen's proprietary Hybrozyme™ technology to develop a subcutaneous, or under-the-skin, formulation of its PD-1 inhibitor dostarlimab (Jemperli).

Under the terms of the agreement, Alteogen will receive an upfront payment of $20 million and is eligible for up to an additional $265 million in payments tied to development, regulatory, and sales milestones. Alteogen will also earn tiered royalties on net sales of the commercialized product and will be responsible for the clinical and commercial supply of its key enzyme, ALT-B4, to GSK.

This partnership aims to transform the administration of Jemperli, currently an intravenous (IV) infusion, into a simple injection that could drastically reduce treatment time and improve convenience for cancer patients.

The High-Stakes Race for Subcutaneous Cancer Drugs

The GSK-Alteogen deal does not exist in a vacuum. It is the latest move in a fierce industry-wide race to convert blockbuster intravenous cancer therapies into more patient-friendly subcutaneous formulations. The PD-1/PD-L1 inhibitor market, valued at nearly $36 billion in 2023, is dominated by Merck’s Keytruda and Bristol Myers Squibb’s Opdivo. Both companies have already made significant strides in this area.

Roche was an early mover, gaining FDA approval in September 2024 for Tecentriq Hybreza, the first subcutaneous anti-PD-(L)1 inhibitor, which cuts administration time from an hour to just seven minutes. Not far behind, Merck secured approval in September 2025 for a subcutaneous version of its market-leading Keytruda, known as Keytruda Qlex, which was notably also developed in collaboration with Alteogen. Bristol Myers Squibb has also rolled out its own subcutaneous version of Opdivo, named Opdivo Qvantig, after a successful Phase 3 trial.

For GSK, developing a subcutaneous version of Jemperli is less of a luxury and more of a competitive necessity. As a relative latecomer to the PD-1 inhibitor space, Jemperli faces an uphill battle for market share. While it has shown impressive results in specific patient populations, such as those with dMMR/MSI-H endometrial cancer, competing on convenience is a critical strategy. This move also serves as a defensive measure, extending the product's life cycle as patents for the original IV formulations of its rivals begin to expire around 2028.

Alteogen's Technology Platform Gains Another Major Endorsement

For Alteogen, this agreement is another powerful validation of its Hybrozyme™ technology. The platform is centered on ALT-B4, a proprietary human recombinant hyaluronidase enzyme. This enzyme works by temporarily and locally breaking down hyaluronan, a gel-like substance in the body's tissues, allowing for the rapid dispersal and absorption of large-volume biologic drugs that would otherwise require a lengthy IV drip.

"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, Ph.D., CEO of Alteogen, in the company's official statement.

The GSK deal cements Alteogen's position as a go-to partner for subcutaneous drug delivery innovation. The company has recently inked a series of high-profile agreements with other pharmaceutical giants. In March 2025, it signed a major deal with AstraZeneca, potentially worth over $1.3 billion, to develop subcutaneous versions of several oncology assets. In late 2024, it partnered with Daiichi Sankyo to create a subcutaneous version of the highly successful antibody-drug conjugate (ADC) ENHERTU, a first-of-its-kind application for the technology. These partnerships, combined with its foundational work with Merck on subcutaneous Keytruda, demonstrate the broad applicability and high demand for Alteogen's platform.

From Infusion Chair to Quick Injection: A New Era for Patients

The most profound impact of this technology will be felt by patients. Standard intravenous infusions of checkpoint inhibitors like Jemperli can take anywhere from 30 to 60 minutes, not including travel, check-in, and preparation time at a hospital or infusion center. This places a significant time and logistical burden on individuals already managing a difficult disease.

Subcutaneous formulations can reduce this administration process to a matter of minutes. This shift promises to dramatically improve a patient's quality of life by giving them back valuable time and reducing the stress associated with prolonged clinic visits. Studies on other subcutaneous cancer therapies have shown an overwhelming patient preference for the less invasive and much faster injection method.

Beyond individual patients, the shift has major benefits for healthcare systems. Freeing up infusion chairs allows clinics to increase their capacity and treat more patients. It reduces the demand on pharmacy and nursing staff, leading to greater operational efficiency and potential cost savings across the healthcare system. While not all subcutaneous drugs are suitable for at-home administration, the possibility opens the door to even greater convenience and a reduced burden on facilities in the future.

A Strategic Lifeline for GSK's Jemperli

Jemperli is a cornerstone of GSK's growing oncology franchise, generating approximately $598 million in sales in 2024 and tracking toward blockbuster status. Its success has been built on strong clinical data, particularly in becoming a standard of care for certain types of endometrial cancer. However, to expand its reach and challenge the dominance of Keytruda and Opdivo, GSK must differentiate.

By pursuing a subcutaneous formulation, GSK is investing in Jemperli's long-term viability. It provides a tangible advantage in "dosing convenience" that can appeal to both physicians and patients, potentially helping it capture a larger share of the market. The partnership with a proven leader like Alteogen de-risks the technical development and accelerates the timeline to bring this more convenient option to market. This strategic pivot ensures that as the oncology landscape evolves toward less invasive treatments, Jemperli will be positioned not just to compete, but to lead in patient-centric care.