SapC-DOPS Nanovesicles for Treating Glioblastoma Multiforme

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DESCRIPTION (provided by applicant): Our goal is to develop a new molecular entity with a novel mechanism of action for targeting and eliminating glioblastoma multiforme (GBM, high grade glioma), a deadly and invasive brain tumor with no effective treatment. Of the 12,000 patients expected to be diagnosed with GBM this year, most will succumb within a year. There is an urgent demand for an efficacious anti-glioma drug. We are developing a new class of therapeutic proteolipid nanovesicle that can target and destroy glioma tumors. Composed of the small lysosomal sphingolipid activator protein saposin C (SapC, 80 aa) and the phospholipid dioleoylphosphatidylserine (DOPS); the stable 200 nm SapC-DOPS nanovesicles (clinical formulation is called BXQ-350) have unusually high affinity for phosphatidylserine-enriched membrane surfaces that occur widely in many types of tumor cells and tumor neovasculature. Consistent with sphingolipid activator function, BXQ-350 appear to selectively induce tumor cells to undergo ceramide-mediated cell death, apparently sparing non-tumor cells. In Phase I of this proposal, we demonstrated the feasibility of using SapC-DOPS to target and kill intracranial gliomas. Intravenous administration of SapC-DOPS in mice with orthotopically implanted gliomas resulted in dose-dependent improvement in survival. In Phase II, a GMP compliant formulation of SapC-DOPS (i.e., BXQ-350) was developed, and potency was confirmed in additional orthotopic preclinical GBM models. IND-enabling studies are in progress. Pharmacokinetics and toxicity studies thus far indicate favorable distribution and safety profiles in rodent and non-rodent studies. In this three-year Phase IIB proposal, the key objectives are to file the IND for BXQ-350, complete a Phase 1 clinical trial, and prepare for Phase 2. Recognizing that gliomas are highly heterogeneous, another objective is to identify and link biochemical factors (e.g., cell surface PS levels; genetic markers) to the degree of BXQ-350 tumoricidal activity. Understanding of these factors will improve dosing strategies and reduce the risk of variable therapeutic response. Specific Aims are: (1) Scale- up GMP production of BXQ-350; (2) File the IND and complete the Phase 1 clinical trial; and (3) Correlate susceptibility to killing by BXQ-350 with molecular and cellular characteristics of glioma cell lins (from a tumor bank). BXQ-350 offers an innovative and potentially powerful approach for slowing tumor growth and eliminating deep-seated brain tumors. Ultimately, we will progress this technology for treating other tumors and for developing tumor-targeted imaging diagnostics.