PROJECT SUMMARY An area of significant unmet need is the treatment of glioblastoma (GBM), an aggressive, fast-growing and lethal brain cancer that represents 48% of all malignant brain tumors. Untreated, GBM is fatal within three months, and due to its high rate of recurrence and invasive nature, the current standard of care, consisting of safe maximal tumor resection, radiation therapy and chemotherapy, only extends survival following initial diagnosis to one year. Invasion and proliferation, also known as Go and Grow, are defining phenotypes of GBM, and GBM cells do only one or the other. However, blocking invasion stimulates proliferation and vice versa, implying that an ideal therapeutic needs to block both Go and Grow simultaneously. Extensive genetic interventions have shown that simultaneous disruption of two non-muscle myosin II (NMII) molecular motors (NMIIA and IIB) meet these criteria. However, the translational potential of this research has been limited by the lack of a clinically safe, CNS-penetrant NMII small molecule inhibitor. Following extensive medicinal chemistry efforts to optimize selectivity for safety and tolerability, MT-125 was identified. MT-125 is a well-tolerated, dual small molecule inhibitor of NMIIA and IIB with a high degree of brain penetrance, a requirement for an effective GBM therapeutic. Preclinical in vitro and in vivo studies show that MT-125 blocks the Go and Grow phenotypes and extends survival. Due to its unique mode of action, MT-125 also synergizes with existing FDA-approved treatments, presenting a path to a potentially curative treatment. The overarching goal of the current proposal is to ready MT-125 for rapid entry into IND-enabling studies. This will be achieved through several activities. Phase I will focus on confirmation of preclinical efficacy with a clinically viable route of administration, in vitro studies of synergy between MT-125 and additional existing FDA-approved treatments, and in vitro safety profiling, pre-formulation studies and demo batch scale-up of MT-125. Quantitative milestones for transition to Phase II are detailed in the application. In Phase II, in vivo efficacy testing will be performed on the most promising synergy combinations identified in Phase I, as well as a non-GLP dosing safety study, GLP synthesis, and formulations development with polymorph screening. The Commercialization Plan details the GBM market, as well as Myosin Therapeutics’ clinical and regulatory strategy for rapid advancement of MT-125 to the clinic.