A Water-Soluble Pro-Drug of Acetaminophen Has Increased Intracellular Delivery of Active Drug and Anti-Cancer Activity in Triple-Negative Breast Cancer and Pancreatic Ductal Adenocarcinoma

Background/Objectives. Triple-negative breast cancer (TNBC) and pancreatic ductal adenocarcinoma (PDAC) are two of the deadliest adult cancers. High-dose acetaminophen (AAP) has anti-cancer activity when given in conjunction with CYP2E1 inhibitors to block liver toxicity. However, the administration of high doses of AAP presents practical challenges stemming from limited water solubility, making it difficult to create a concentrated treatment solution in limited volume. Propacetamol (PROP) is a water-soluble AAP pro-drug that has been used clinically as an IV AAP formulation for analgesia. Methods. We sought to investigate the pharmacokinetics, safety and anti-cancer activity of PROP in comparison to AAP using transplantable syngeneic models of TNBC and PDAC. Results. In vivo, PROP was rapidly converted to AAP within minutes of administration. PROP demonstrated enhanced effectiveness in suppressing tumor growth in the TNBC and PDAC syngeneic murine tumor models compared to AAP. The enhanced efficacy of PROP appears to stem from increased cellular uptake, leading to intracellular AAP concentrations that are 2.7-fold higher within 5 min compared to cells treated with unmodified AAP. PROP demonstrated enhanced modulation of intracellular JAK/STAT signaling, a key mediator of AAP anti-cancer activity, using both murine and humanized models. STAT3 and STAT6 inhibition by PROP led to modulation of macrophage polarization, likely contributing to its anti-TNBC and anti-PDAC activity. While parenteral administration is the preferred route of administration for PROP in anti-cancer indications, we also evaluated the safety and efficacy of oral PROP in comparison to AAP. High-dose PROP demonstrated improved safety following oral administration compared to AAP in the BALB/c murine model while maintaining anti-cancer activity in vivo. Conclusions. PROP, an AAP pro-drug, demonstrates enhanced intracellular delivery of AAP and in vivo anti-cancer activity compared to unmodified AAP, setting the stage for investigation as an anti-cancer drug across different indications.