IVMT-Rx-3 Microemulsion as Low-Dose Metronomic Chemotherapy for Melanoma Metastasis

The pro-metastatic gene MDA-9/Syntenin-1 and its tandem PDZ domains (PDZ1 and PDZ2) provide established targets for intervening in tumor progression and metastasis. Recently, we generated and validated MDA-9/Syntenin-1 antagonists targeting a single PDZ domain (PDZ1i) or both PDZ domains (IVMT-Rx-3) in carcinomas and melanoma. Data reveal that IVMT-Rx-3 possesses immunomodulatory and anti-angiogenic properties, in addition to its well-established anti-invasive capabilities. Despite its significant druggable properties, it cannot be delivered orally, limiting its clinical potential. Here, we characterized an oral microemulsion (ME) formulation of IVMT-Rx-3, IVMT-Rx-3-ME to enhance intestinal permeability, bioavailability, and therapeutic efficacy. Physicochemical analyses demonstrated that the optimized formulation produced a stable IVMT-Rx-3-ME with high drug content (>90%). In vitro permeability and dissolution assays confirmed improved membrane transport and solubility compared with the free drug dispersion control. Pharmacokinetic studies in rats revealed that the ME enabled rapid absorption and sustained systemic exposure, whereas the free drug showed negligible bioavailability. In murine metastatic melanoma models, oral IVMT-Rx-3-ME suppressed tumor growth and lung metastases, and when combined with anti-PD-L1 antibody, produced synergistic antitumor effects with minimal toxicity. Collectively, these findings highlight IVMT-Rx-3-ME as a potent and viable oral metronomic chemotherapy platform for metastatic melanoma, with enhanced combinatorial translational potential with immunotherapies.