The invasive forms of brain tumors, such as glioblastoma multiforme (GBM) are recognized as one of the deadliest forms of cancer with current therapies offering only palliation complicated by significant toxicities. Current approaches for the treatment of glioma are limited in their effectiveness, because brain tumors are characteristically diffuse, highly invasive, non-localized, and drug penetration across the blood-tumor barrier (BTB) is poor for most drugs. In addition to limited drug delivery, brain tumor cells tend to be particularly resistant to drugs, especially after tumor recurrence. To address both challenges of drug delivery and drug resistance, the objective of this proposal is to integrate the unique features of a chain-like nanoparticle with the appropriate combination of complementary drugs to enable effective treatment of invasive brain tumors. To tackle the drug delivery issue, we have developed a multicomponent, flexible chain-like nanoparticle, termed nanochain, which is comprised of three iron oxide nanospheres and one drug-loaded liposome chemically linked into a linear, chain-like assembly. The multicomponent nature of nanochains results in two features that synergistically facilitate effective treatment of difficult-to-treat GBMs. First, the oblong-shaped, flexible nanochain possesses a unique ability to seek and rapidly deposit on the blood vessel walls of glioma sites via vascular targeting. Second, after nanochains slip from the blood stream and dock on the vascular bed of GBMs, an external low-power radiofrequency (RF) field remotely triggers rapid drug release due to mechanical disruption of the liposomal membrane facilitating widespread and effective drug delivery into GBMs. To address the drug resistance issue, we have identified glioma stem cell (GSC)-specific regulators amenable to pharmacologic targeting. We recently showed that the inducible nitric oxide synthase (iNOS) is a unique signal regulator in GSCs. Due to the flexibility of loading various types of drugs within the nanochain, the nanochain will be loaded with standard chemotherapy and an iNOS inhibitor that eliminates the small fraction of GBM cells that are resistant, and can migrate to cause tumor recurrence. By using nanochains, we hypothesize that guaranteeing the effective and simultaneous delivery of these drugs with synergistic activity to glioma sites will facilitate effective treatment and ultimately eradication of the disease using a safe dose.
Specific Aim 1 : Optimize the targeting efficacy of a chain-like nanoparticle to invasive brain tumors and evaluate drug delivery across the BTB in the CNS-1 glioma model in mice.
Specific Aim 2. Determine (A) the effect of iNOS inhibition on GBM tumor growth and GBM stem cell subpopulations and (B) the effective delivery of iNOS inhibitors to GBM xenografts via nanochains and RF.
Specific Aim 3. Evaluate the therapeutic efficacy of nanochains loaded with a chemotherapeutic and an iNOS inhibitor in GBM xenografts of highly invasive brain tumors.
To overcome the limitations of current drugs to treat brain tumors, we seek to integrate the unique features of a chain-like nanoparticle with the appropriate combination of complementary drugs. In addition to the enhanced targeting capabilities of these nanoparticles, the nanoparticle's drug cargo includes standard chemotherapy and an inhibitor that eliminates the fraction of resistant brain tumor cells.
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