First Patient Dosed in Phase 1b Clinical Trial of Synthekine’s α/β Biased IL-2, STK-012, for Treatment of Solid Tumors

Results from Phase 1a portion of trial show first-in-class α/β biased IL-2 has potential to decouple efficacy and toxicity of IL-2

First dose expansion cohorts in Phase 1b portion of trial will further evaluate STK-012 as monotherapy in renal cell carcinoma (RCC) and non-small cell lung cancer (NSCLC)

MENLO PARK, CA – September 28, 2023 – Synthekine Inc., a leader in engineered cytokine therapeutics, today announced that the company has completed phase 1a dose escalation and dosed the first patient in the Phase 1b portion of a clinical trial evaluating its α/β biased IL-2, STK-012, for the treatment of solid tumors.

STK-012 is 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 NK cells, which are associated with IL-2 toxicity. Synthekine recently completed the Phase 1a dose-escalation portion of the study in patients with various advanced solid tumors, with results suggesting a differentiated safety profile and monotherapy efficacy. The Phase 1b portion of the study will include dose expansion cohorts to evaluate STK-012 as monotherapy at the candidate recommended phase 2 dose (RP2D) in selected solid tumor types, including renal cell carcinoma (RCC) and non-small cell lung cancer (NSCLC).

“IL-2 is critical for T cell activation and promoting antitumor immunity,” said Naiyer Rizvi, M.D., chief medical officer of Synthekine. “However, to date, no one has been able to unravel the pleiotropic nature of IL-2 and develop a drug that truly expands therapeutic index. STK-012 is built from unique insights into IL-2 biology and is the first α/β biased IL-2 with clinical results. We have observed encouraging single-agent activity with STK-012 in dose escalation and are excited to begin our cohort expansion studies.”

“High-dose (HD) IL-2 has brought durable benefits to patients, even remissions for patients with metastatic melanoma and kidney cancer. But its significant toxicity and limited efficacy have prevented HD IL-2 from fulfilling its transformative potential in devastating cancers like non-small cell lung cancer,” said David McDermott, M.D., a study investigator and Chief of Medical Oncology at Beth Israel Deaconess Medical Center, and Professor of Medicine at Harvard Medical School. “STK-012 represents a promising new approach in the field of cancer immunotherapy, offering a highly selective strategy for targeting IL-2 pathways that could potentially transform the treatment paradigm for these and other solid tumor indications.”

The Phase 1b dose expansion portion of the clinical trial is an open-label, nonrandomized multi-center study currently enrolling patients. In addition to assessing the anti-tumor activity of STK-012 monotherapy, this study will continue to evaluate safety, tolerability and pharmacokinetics. For additional information about the trial, please visit using the identifier NCT05098132.

Results from the Phase 1a portion of the study will be presented at a future medical meeting.

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 protein engineering platforms to create a broad and deep pipeline of product candidates. These novel immunotherapies include modified cytokines, cytokine-enhanced cell therapies and surrogate cytokine agonists. For more information, visit, and follow us on Twitter @synthekine and LinkedIn.


Will Zasadny
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