Project Summary
Pancreatic ductal adenocarcinoma (PDAC) is a notorious malignancy with no change to the dismal survival rate.
Surgery is still the first option where most tumors are still unresctable and also highly resistant to chemo and
radiotherapies. There is dire need for spatially and temporally localized therapies with low or non-overlapping
toxicity such as photodynamic therapy (PDT) which has demonstrated 1) its effectiveness on chemo- and drug-
resistant cells, 2) Enhanced drug penetration despite the stroma present in PDAC tumors and 3) decreased
metastasis. PDT is a photochemistry-based modality that imparts preferential light-mediated cytotoxicity locally
to target tissues via activation of a photosensitizer (PS) molecule by laser light of specific wavelength.7 Recent
clinical studies also show PDT efficacy in reducing PDAC tumor volume, making previously unresectable tumors
resectable.11–15 However,a major roadblock for PDT use in PDAC treatment is specific delivery of the PS to the
tumor and accurate dosimetry that is based on PS accumulation in the tumor. In this proposal we overcome
these two roadblocks for PDT via the use of biocompatible liquid metal nanoparticles (NPs), namely the eutectic
alloy of gallium and indium (EGaIn, 75% Ga, 25% In) NPs as chaperones, breakdown in acidic tumor
environment and deliver high payloads of PS to tumor sites. EGaIn NPs can be fabricated with ease and are
extremely chemically and mechanically stable due to the presence of a gallium oxide skin on its surface4,5 which
can be functionalized with targeting ligands and PS creating EGaPs (EGaIn + PS). These NPs not only provide
high surface area for ligands and PS loading but also have higher optical absorption than blood in the near-
infrared (NIR) region, making them conducive for photoacoustic imaging (PAI), a deep tissue imaging modality
based on optical absorption coefficient. PAI can be transparently integrated with ubiquitously available
ultrasound imaging (USPAI) as shown by us1-4 previously to obtain multi-parametric 3D information on tumor
volume, nanoparticle uptake, vascular density, vascular perfusion and tumor oxygenation status simultaneously
for designing an effective PDT dose. The overall hypothesis of this project is that photoacoustic image-guided
PDT with EGaPs will yield superior results compared to passive PDT in PDAC models and will be achieved with
the following 3 specific aims: Aim-1: We will synthesize, characterize and evaluate in vitro treatment efficacy of
EGaPs; Aim-2: We will establish the pharmacokinetics, biodistribution and safety profile of EGaPs; and Aim-3:
we will evaluate in vivo efficacy of EGaPs in orthotopic PDAC models with different pathophysiology. EGaPs
integrated with clinically translatable USPAI will provide a novel treatment platform for PDAC. The insights on
biodistribution of EGaPs, evaluation of drug uptake using photoacoustic imaging techniques, and design of
dosimetry in a patient specific manner can be applied to broad range of solid tumor treatments.