On October 27, 2025 OncoNano Medicine, Inc. ("OncoNano") reported encouraging first-in-human results from Part 1 of its Phase 1 ON-5001 trial evaluating ONM-501, a dual-acting STING agonist, as monotherapy and in combination with Libtayo (cemiplimab), Regeneron’s PD-1 inhibitor, in patients with advanced solid tumors and lymphomas. The findings were shared during a poster presentation at the AACR (Free AACR Whitepaper)-NCI-EORTC AACR-NCI-EORTC (Free AACR-NCI-EORTC Whitepaper) International Conference on Molecular Targets and Cancer Therapeutics (EORTC-NCI-AACR) (Free ASGCT Whitepaper) (Free EORTC-NCI-AACR Whitepaper) in Boston, Massachusetts.

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ONM-501 is designed to activate the STING pathway and stimulate both innate and adaptive immune responses within the tumor microenvironment. By linking a cyclic dinucleotide (cGAMP) to a proprietary polymer, ONM-501 prolongs STING activation and overcomes key limitations of earlier STING agonists. In preclinical models, this approach produced durable anti-tumor responses without triggering systemic inflammation, an effect now supported by emerging clinical results.

In the dose-escalation and dose-finding study, ONM-501 was well tolerated and demonstrated early signs of clinical benefit. Among 39 patients treated (15 with ONM-501 monotherapy and 24 in combination with cemiplimab), no dose-limiting toxicities were observed, and the most common adverse events were mild fatigue and injection-site reactions. Systemic interferon-γ levels remained within normal limits across all cohorts.

In the monotherapy arm, one patient achieved an objective response and three patients had prolonged stable disease, including a case of recurrent, immunotherapy-refractory uveal melanoma with disease control lasting over one year (390 days). In the combination arm, five patients experienced objective responses, including two complete in patients with cutaneous squamous cell carcinoma (cSCC).

"These data provide the first clinical evidence that sustained STING activation through our proprietary polymer conjugate can drive meaningful immune responses in solid tumors," said Kartik Krishnan, MD, PhD, Chief Executive Officer of OncoNano Medicine. "The safety profile and emerging efficacy signals, particularly in patients with advanced cutaneous malignancies, highlight the potential of ONM-501 to expand the reach of STING-based immunotherapy."

Part 2 of the ON-5001 study (NCT06022029) is now open and enrolling patients with advanced basal cell carcinoma, cutaneous squamous cell carcinoma and melanoma.

About ONM-501
ONM-501 is a dual-activating agonist of the stimulator of interferon genes ("STING") pathway composed of cGAMP (the endogenous activator of STING) linked to a proprietary pH-activated polymer (the OMNI polymer). ONM-501 is presently being studied in a Phase 1 clinical trial (ON-5001). In preclinical models, the dual activation of STING by ONM-501 has been shown to lead to a direct anti-tumor effect, as well as leading to an anti-tumor immune response over an extended period of time. Development of ONM-501 was funded in part by the Cancer Prevention and Research Institute of Texas.

(Press release, OncoNano Medicine, OCT 27, 2025, View Source [SID1234657048])