Glioblastoma PDT Design: Nanoagent Uptake and Tumor Oxygenation based dosimetry

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DESCRIPTION (provided by applicant): Glioblastoma (GBM) is an aggressive cancer with dismal survival rates and few new treatment options. Fluorescence guided resection of GBM followed by photodynamic therapy (PDT) has shown promise in several chemo- or radiotherapy non-responsive GBM treatments clinically. PDT is an emerging light and photosensitizer (PS) mediated cytotoxic method. However, as with other therapeutic modalities, the outcomes are variable largely due to the non-personalization of dose parameters and the highly localized nature of conventional PDT that ignores distant disease. The variability can primarily be attributed to the inter-patient differences in two key parameters - PS concentration and tumor oxygenation. These need to be incorporated in the design of patient-specific PDT. Also, because PDT has built in dual selectivity (confinement of light and localization of PS), using targeted PS would impact distant disease,an approach not yet exploited in GBM PDT. Building upon our previous findings, we propose a strategy for addressing these issues by establishing 3D PS tumoral uptake and oxygenation using photoacoustic imaging (PAI). The variation in PS uptake is addressed by adjusting the light dose while the tumor oxygenation variation is compensated by adjusting the light irradiance and using a combination of oxygen-dependent and oxygen-independent PSs. These PSs are co-delivered to the tumor in a targeted liposome for enhanced selectivity and impact on distant disease. The research will be accomplished in three specific aims: (1) Synthesis and characterization of Targeted Dual photosensitizer Encapsulation Liposomes (TDELs) for enhanced PDT. (2) Establish in-vivo pharmacokinetics and tumoral uptake of TDELs in orthotopic GBM tumors and (3) Evaluation of the TDELs and customized image guided PDT dosimetry impact on treatment response in vivo. Major deliverables will be (a) reproducible, well-characterized TDELs for targeted co-delivery of two PSs with optimized therapeutic agent payload; (b) a platform for determining the optimal interval between TDEL and light administration (c) irradiance for PDT that causes least decrease in tumor oxygenation status and (d) establishment of the benefit of customized active on-line PDT dosimetry compared to conventional "one size fits all" passive dosimetry approach in tumor volume reduction and survival. The findings of this study will form the basis for customized GBM treatments and serve as a platform for treatment of other cancers. A mentoring committee has been assembled to offer scientific guidance and career advice to the applicant in her translation to being an independent investigator. She will obtain extensive training in the fields of nanotechnology, photochemistry, tumor biology and GBM PDT strategies. The committee comprises of Dr. T. Hasan (PDT, targeted delivery and cancer biology), Dr. B. Pogue (quantitative image-guided algorithms and PDT dosimetry), Dr. X. Breakefield (GBM tumor biology and animal models), Dr. R. Martuza (clinical translational aspects of GBM-PDT) and Dr. L. Wang at Univ. of Washington (PAI and imaging tumor hypoxia).