Press Releases
Synthekine Presents Data at AACR Annual Meeting 2021 Demonstrating Selective IL-2 Partial Agonist, STK-012, Promotes Anti-Tumor Response without Related Toxicities

Synthekine to advance STK-012 to IND Filing in 2021


April 10, 2021 / MENLO PARK, Calif. — Synthekine Inc., an engineered cytokine therapeutics company, today announced preclinical data presented at the American Association of Cancer Research Annual Meeting 2021 demonstrating its alpha/beta selective IL-2 partial agonist, STK-012, induced potent anti-tumor activity while avoiding the toxicities that have hindered the development of IL-2 therapeutics, including vascular leak syndrome (VLS). Synthekine also presented new data on its orthogonal IL-2 and CD-19 CAR-T system (STK-009 and SYNCAR-001).

“IL-2 offers a wealth of therapeutic promises and challenges. While wild-type IL-2 is a potent T-cell stimulator and has shown single agent activity in late-stage cancers, its broad and non-specific activation leads to critical, dose-limiting toxicities,” said Martin Oft, M.D., chief development officer at Synthekine. “We believe that the efficacy of IL-2 is driven by the proliferation and activation of antigen activated T cells, while the toxicity of IL-2 is driven by its broad and non-specific proliferation, extravasation, and activation of all lymphocytes, including NK cells and naïve T cells. We have designed our alpha/beta IL-2 to selectively bias towards antigen activated T-cells and avoid NK cells and naïve T cells, a new approach designed to improve on both the efficacy and the toxicity of wild-type IL-2. STK-012 demonstrates improved therapeutic index compared to wild-type IL-2 and a non-alpha comparator. We look forward to advancing this program to an IND filing in 2021.”

Efficacy of STK-012 was evaluated in multiple mouse models using a mouse surrogate of STK-012 (alpha/beta IL-2). In these studies, the alpha/beta IL-2 achieved superior efficacy in control of tumor growth and rate of complete responses compared to both wild-type IL-2 and a non-alpha IL-2. Synthekine’s alpha/beta IL-2 was significantly more effective than these comparators at increasing intratumoral CD8+ T-cells, including the ratio of CD8 T cells to Tregs. Importantly, studies showed the alpha/beta IL-2 did not induce lethality or VLS at therapeutic or supratherapeutic doses. Both wild-type and non-alpha IL-2 showed vascular toxicity, including VLS and lethality in mice. This finding was also supported by data from non-human primates, with the comparators resulting in significantly more infiltration of inflammatory cells in the lung relative to STK-012.

Synthekine also presented new data on its orthogonal IL-2 and CD-19 CAR-T system (STK-009 and SYNCAR-001). New analyses further demonstrate STK-009 upregulates markers for expansion and activation of SYNCAR-001 cells in a CAR refractory lymphoma model and confers a gene signature indicative of long-term memory T cell development.

Copies of both posters presented are available on Synthekine’s website.

About Synthekine

Synthekine is an engineered cytokine therapeutics company developing disease-optimized treatments. The company uses immunological insights to guide targeted protein engineering to generate transformative medicines for cancer and autoimmune disorders. Using the principles of cytokine partial agonism and immunological specificity, Synthekine designs differentiated therapeutics to be both safe and efficacious. Its lead programs have shown promising efficacy and tolerability in preclinical studies, and it is developing additional cytokine partial agonists that selectively modulate key pathways of the immune system. For more information, visit

Ian Stone
Canale Communications