Primmune Therapeutics Announces Enrollment Milestone in Phase 2 INFLECTION–003 Study of Polvitolimod HCl in Neoadjuvant Melanoma

SAN DIEGO, Sept. 24, 2026 (GLOBE NEWSWIRE) — Primmune Therapeutics, a biotech company harnessing the power of the innate and adaptive immune system, today announced the enrollment of the second patient in its Phase 2 INFLECTION-003 clinical study triggering the release of the second tranche of financing. The financing advances the development of Polvitolimod HCl (also known as PRTX007) as a curative therapy in the neoadjuvant and adjuvant settings for stage III melanoma.

“Polvitolimod HCl is a novel oral TLR7/IRF7 agonist that induces robust systemic interferon responses and has demonstrated a favorable safety and tolerability profile in two Phase 1 studies” said Andrew Sharabi, MD, PhD, Chief Medical Officer of Primmune Therapeutics. “We have designed the Phase 2 INFLECTION-003 study to evaluate whether the combination of polvitolimod HCl and pembrolizumab before surgery will increase major pathologic response rates in patients with resectable stage III melanoma. We believe that priming the immune system with polvitolimod will enhance the clinical activity of pembrolizumab without a significant increase in toxicity, which would be a meaningful step forward for patients with this diagnosis.”

INFLECTION-003 is a Phase 2, multi-center, single-arm study evaluating the safety, tolerability, and activity of neoadjuvant polvitolimod HCl in combination with pembrolizumab in participants with resectable stage III melanoma. Participants will receive oral polvitolimod HCl, a toll-like receptor 7 (TLR7) agonist prodrug, administered in combination with intravenous pembrolizumab for 9 weeks prior to surgical resection. The primary objective is to determine the major pathologic response (MPR) rate following neoadjuvant therapy. Secondary objectives include evaluation of safety, pathologic complete response (PCR) rate, event-free survival, overall survival, pharmacokinetics, and immune-related biomarkers. For more information, please visit ClinicalTrials.gov (NCT07565285).

“Polvitolimod HCl is the only oral TLR7/IRF7 specific agonist being developed for patients in the neoadjuvant solid tumor setting that we are aware of,” said Charlie McDermott, Chief Executive Officer and Director of Primmune Therapeutics. “We believe there is a significant opportunity for safer and better tolerated immunotherapy combinations in early-stage solid tumor disease given the drug-related morbidity observed in clinical studies evaluating other immunotherapy combinations, such as nivolumab plus ipilimumab or pembrolizumab plus high-dose interferon.”

About Polvitolimod HCl (PRTX007) 

Polvitolimod HCl is a novel orally administered, systemically acting, toll-like receptor 7 (TLR7) agonist designed to functionally tune immune signaling toward an IRF7-driven poly-interferon response and away from the NF-B-mediated pro-inflammatory cytokine signaling that has limited the utility of systemically acting TLR7, TLR7/8, and TLR8 agonists. Polvitolimod HCl has been administered to 118 healthy human volunteers in two Phase 1 clinical studies (Study PRTX007-001 and Study PRTX007-002). In these studies, PRTX007 drove the desired systemic IRF7 poly-IFN response without undesired NF-B driven pro-inflammatory response. PRTX007 was generally well-tolerated in both Phase 1 studies with no serious adverse events reported.

About Primmune Therapeutics 
Primmune Therapeutics is a clinical-stage therapeutics company dedicated to the design and development of systemically acting, orally administered, novel small molecule, toll-like receptor 7 (TLR7) agonists as immunotherapies for the treatment of cancer and other diseases responsive to immunotherapy. For more information, please visit: www.primmunerx.com

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