Nanoconjugate delivery of proliferation and checkpoint inhibitors to treat glial tumors

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 DESCRIPTION (provided by applicant): Brain cancer, and its most common form, glioblastoma multiforme (GBM), with a 15-month average survival, still has limited treatment options. The emergence of efficacious nanodrugs able to cross blood-brain barrier (BBB) gives hope for new treatments of brain cancer. We will introduce new generation of nanoconjugates that pass through BBB and activate general and local brain tumor immune systems; at the same time they specifically block GBM molecular markers, which significantly increases survival of tumor-bearing animals. Preliminary data show that GBM are efficiently inhibited by nanoconjugates blocking protein kinase CK2, and epidermal growth factor receptor (EGFR and EGFRvIII) most frequently overexpressed by GBM per our Cell (2013) study from the NIH/NCI Cancer Genome Atlas Network GBM consortium. Antibodies to cytotoxic T lymphocyte (CTL)-associated antigen 4 (CTLA-4) or to lymphocytic surface receptor PD-1 turn off the inhibitory mechanism to allow CTL to activate powerful anti-tumor immune response. However, antibodies cannot cross the BBB and modulate brain cancer immune system. Based on preliminary data, we postulate that targeted nanocarrier delivery of such antibodies to local tumor environment could boost anti-tumor immune response and reduce systemic toxicity of these therapies. We will specifically deliver to brain tumors such antibodies attached to our nanopolymeric platform polyβ-(L-malic acid). Combining tumor targeted therapy against EGFR/EGFRvIII and CK2 with stimulation of anti-tumor immunity by anti-CTLA-4 and/or anti-PD-1 could provide the most profound GBM growth arrest. Our hypothesis is that targeted tumor suppression based on inhibition of cancer markers combined with specific immune system stimulation will increase the treatment efficacy of BBB-crossing drug nanoconjugates against GBM. We propose 3 specific Aims: 1. Synthesis and in vitro characterization of novel nano immunoconjugates. Physico-chemical characterization of nanoconjugates, optimization of synthesis, and functional activity of all moieties will be achieved in cultured brain cancer cells. 2. Examination of inhibitory effects f nanoconjugates on brain tumor growth. We will use BBB-crossing nanoconjugate treatment of human GBM xenografts in nude mice (for CK2-EGFR combination), and syngeneic brain tumors GL26/GL261 in immunocompetent mice (for CTLA- 4 and PD-1 blockade). Systemic CTLA-4 and PD-1 antibodies will serve as controls. Lead nanoconjugates and their combinations will be selected. 3. Pharmacokinetic and toxicological studies of nanoconjugates. Half- life, biodistribution, and tumor targeting of lead nanoconjugates will be examined upon systemic treatments. Dose escalating studies with maximum tolerated dose determination will include gross and micropathological organ evaluation and blood biochemistry for toxicity. The proposal based on specific tumor molecular marker blocking using targeted nanodrugs fits well NCI Precision Medicine Initiative.