Synthekine Announces Clinical Trial Collaboration with Merck to Evaluate STK-012 In Combination with Keytruda® (Pembrolizumab) and Chemotherapy in Ongoing Randomized Phase 2 Trial in First-Line, PD-L1 Negative Nonsquamous Non-Small Cell Lung Cancer

MENLO PARK, Calif.--(BUSINESS WIRE)--Synthekine Inc., an engineered cytokine therapeutics company, today announced that it has entered into a clinical trial collaboration and supply agreement with Merck (known as MSD outside of the United States and Canada). STK-012, a first-in-class α/β-IL-2 receptor biased partial agonist, will be evaluated in combination with standard of care chemotherapy and Keytruda® (pembrolizumab), Merck’s anti-PD-1 (programmed cell death receptor-1) therapy, in the ongoing SYNERGY-101 randomized Phase 2 study in first-line, PD-L1 negative nonsquamous (NSQ) non-small cell lung cancer (NSCLC).

“In our Phase 1b study, STK-012 in combination with pembrolizumab and chemotherapy has shown promising efficacy in first-line PD-L1 negative NSQ NSCLC patients, with a 50% response rate in this population presented at the Society for Immunotherapy of Cancer Annual Meeting 2025,” said Debanjan Ray, Chief Executive Officer of Synthekine. “We are excited to collaborate with Merck on our randomized Phase 2 study to further demonstrate the potential of this combination to deliver improved clinical outcomes for these patients, who receive limited benefit from current standard of care therapies.”

STK-012 is a first-in-class α/β-IL-2 receptor biased partial agonist engineered to selectively stimulate antigen-activated T cells, which are associated with potent anti-tumor activity, and avoid broad stimulation of other lymphocytes, such as natural killer (NK) cells, which are associated with IL-2 toxicity.

Under the terms of the agreement, Merck will provide its anti-PD-1 therapy, Keytruda, to be used in combination with STK-012 and standard of care chemotherapy in the SYNERGY-101 trial. SYNERGY-101 is a global, randomized Phase 2 study that has already begun enrollment, with the first patient dosed in November 2025. This study will investigate the safety and efficacy of STK-012 in combination with standard dose pembrolizumab and chemotherapy vs. the safety and efficacy of standard dose pembrolizumab and chemotherapy in patients with first-line, PD-L1 negative NSQ NSCLC. Synthekine and Merck will each retain all commercial rights to their respective compounds for use as monotherapies or in combination regimens.

For additional information about the trial, please visit www.clinicaltrials.gov using the identifier NCT05098132.

About Synthekine

Synthekine is harnessing the potential of cytokine therapeutics to develop selective immunotherapies designed to improve the treatment paradigm of cancer and inflammatory disease. Using insights on cytokine structure and function, the company engineers therapeutics designed to unlock the full efficacy potential of cytokines while avoiding their associated toxicities. Synthekine is applying principles of cytokine partial agonism and immunological specificity across multiple therapeutic areas to create a broad and deep pipeline of product candidates. These novel immunotherapies include modified cytokines and surrogate cytokine agonists. For more information, visit www.synthekine.com, and follow us on X @synthekine and LinkedIn.

KEYTRUDA® is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.