60P Bets on Preclinical Iminosugar for Tick-Borne Diseases: Option Deal Masks Deep Evidence Void

60 Degrees Pharma Secures Option for Castanospermine in Tick-Borne Diseases

60 Degrees Pharmaceuticals has entered an exclusive option agreement with the Florida State University Research Foundation (FSURF) for intellectual property related to castanospermine, a naturally occurring iminosugar. This agreement grants 60 Degrees Pharma an exclusive option to negotiate a U.S. license for castanospermine's therapeutic development in multiple tick-borne diseases, including Powassan virus disease, tick-borne encephalitis, alpha-gal syndrome, and post-treatment Lyme disease. The company will also have an evaluation period to develop a commercialization strategy. Castanospermine has shown broad antiviral and immunomodulatory activity in preclinical studies, and its pro-drug, celgosivir, has established human safety data. 60 Degrees Pharma is now prioritizing prescription drug development for castanospermine, re-evaluating its dietary supplement strategy.

• 60 Degrees Pharmaceuticals secured an exclusive option agreement with the Florida State University Research Foundation (FSURF) for intellectual property concerning castanospermine. This grants the company the right to negotiate an exclusive U.S. license for its therapeutic use across several tick-borne diseases, including Powassan virus disease, tick-borne encephalitis, alpha-gal syndrome, and post-treatment Lyme disease, alongside an evaluation period for commercialization.
• Castanospermine, derived from Australian Chestnut, is an iminosugar exhibiting broad antiviral and immunomodulatory activity in preclinical models. Its therapeutic promise is further supported by substantial human safety experience from clinical trials involving celgosivir, a pro-drug that converts almost completely to castanospermine, positioning it as a strong candidate for innovative prescription medicines.
• Following discussions with the U.S. Food and Drug Administration regarding a New Dietary Ingredient Notification, 60 Degrees Pharma is re-evaluating its regulatory strategy for Australian Chestnut Extract as a dietary supplement. The company is now prioritizing the development of castanospermine as a prescription drug, aiming to maximize its clinical and commercial value in addressing unmet needs in vector-borne infectious diseases.

Understanding Castanospermine's Safety and Tolerability Profile

Published safety and tolerability data for castanospermine and its oral prodrug celgosivir (6-O-butanoyl castanospermine) are most substantive in the antiviral setting. In preclinical work using bovine viral diarrhea virus (BVDV) as a surrogate model for HCV, castanospermine demonstrated no evidence of cytotoxicity — in contrast to N-nonyl DNJ, which exhibited toxicity at CC50 ≥ 120 µM. Castanospermine's antiviral activity in this model was characterized by IC50 values of 110 µM (plaque assay) and 367 µM (cytopathic effect assay), and preclinical combination studies showed that two-way combinations of castanospermine or celgosivir with interferon-alpha and ribavirin enhanced antiviral efficacy either additively or synergistically — a profile that informed subsequent clinical development. Celgosivir itself is well absorbed both in vitro and in vivo, with rapid conversion to the active moiety castanospermine following oral administration.

At the clinical level, the most granular safety dataset comes from a phase 1b randomized, double-blind, placebo-controlled trial conducted in Singapore (2012–2013) evaluating celgosivir in dengue fever. Across 50 randomized patients (24 celgosivir, 26 placebo), the incidence of adverse events was comparable between arms, and celgosivir was characterized as generally safe and well tolerated at the studied regimen — an initial 400 mg loading dose within six hours of randomization, followed by 200 mg every 12 hours for nine additional doses. In the HCV setting, celgosivir was found to be insufficient as monotherapy, but a phase II trial was initiated to evaluate its safety, tolerability, and antiviral effect in combination with PEGylated IFN-alpha2b plus ribavirin for up to one year in patients with chronic HCV infection.

Despite these encouraging early signals, the published evidence base carries notable limitations. As of 2010, long-term toxicity studies were explicitly identified as necessary to confirm the safety of celgosivir in humans, and no granular adverse event profiles or dose-limiting toxicity data have been reported in the available literature. Safety data for castanospermine across oncology and metabolic disorder indications remain absent from the published record, representing a significant gap in the overall tolerability characterization of this compound class.

Castanospermine's MoA in the Tick-Borne Disease Pipeline

Castanospermine exerts its effect as an alpha-glucosidase inhibitor, a mechanism shared with other compounds that have been investigated in clinical trials for different indications. The oral prodrug celgosivir and the established drug acarbose have both been studied for their effects via this pathway, providing potential models for future trial designs. Clinical data for these agents have been generated in the context of viral infections and type 2 diabetes.