Abstract 4152: Irreversible electroporation induces immunogenic cell death and mediates durable response in orthotopic PDAC model in combination with anti-PD-1

Immunotherapy has only limited efficacy against pancreatic ductal adenocarcinoma (PDAC) because of the presence of an immunosuppressive tumor-associated stroma. Here, we showed that combined IRE and anti-PD-1 immune checkpoint blockade significantly suppressed tumor growth and prolonged the lives of immunocompetent mice bearing well-established orthotopic PDAC. Remarkably, more than 35% of mice had a durable response, and were found to be free of residual tumor upon necropsy. All mice that survived for 60 days after IRE and anti-PD1 treatments rejected tumor cell re-challenge. Analyses of splenocytes confirmed that these long-term survivors developed an anti-tumor memory T cell response. Further mechanistic studies unveiled that the efficacy of IRE + anti-PD-1 could be attributed to multiple factors, including rapid release of danger associated molecular patterns, activation of DCs, and alleviation of immunosuppressive tumor microenvironment. Neutralization of CD8+ T cells by anti-CD8 antibody nullified the antitumor effect of combined IRE and anti-PD-1, suggesting that tumor-infiltrating CD8+ T cells played a key role in mediating the anti-tumor efficacy of IRE + anti-PD-1.Given that both IRE and anti-PD-1 antibodies are already used in the clinic, our results support the translation of this combination as a promising approach for treating patients with PDAC.

Citation Format: Jun Zhao, Xiaofei Wen, Tingting Li, Marites Melancon, Sanjay Gupta, Weiyi Peng, Chun Li. Irreversible electroporation induces immunogenic cell death and mediates durable response in orthotopic PDAC model in combination with anti-PD-1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4152.

Precision Nanomedicine Using Dual PET and MR Temperature Imaging-Guided Photothermal Therapy

Imaging-based techniques have enabled the direct integration of noninvasive imaging with minimally invasive interventions such as photothermal therapy (PTT) to improve the precision of treatment.

METHODS

We investigated the feasibility of PTT for ovarian cancer under the guidance of PET and MR temperature imaging using copper sulfide nanoparticles (CuS NPs). The tumor distribution of the CuS NPs after systemic administration was assessed using highly sensitive, quantifiable PET imaging. Two wavelengths of near-infrared (NIR) lasers-808 and 980 nm-were tested for PTT using noninvasive MR temperature imaging real-time monitoring.

RESULTS

The in vivo studies revealed that the 980-nm NIR laser had better photothermal effects than the 808-nm NIR laser. These results were in accord with the histologic findings. In vivo PTT using CuS NPs combined with 980-nm laser irradiation achieved significant tumor ablation compared with no treatment control in both subcutaneous (P = 0.007) and orthotopic (P < 0.001) models of ovarian cancer with regard to the percentage of necrotic damage.

CONCLUSION

Our results indicate that real-time monitoring of the accuracy of PTT is a promising approach for future clinical translation of this emerging thermal ablation technique.

Photoacoustic imaging driven by an interstitial irradiation source

Photoacoustic (PA) imaging has shown tremendous promise in providing valuable diagnostic and therapy-monitoring information in select clinical procedures. Many of these pursued applications, however, have been relatively superficial due to difficulties with delivering light deep into tissue. To address this limitation, this work investigates generating a PA image using an interstitial irradiation source with a clinical ultrasound (US) system, which was shown to yield improved PA signal quality at distances beyond 13 mm and to provide improved spectral fidelity. Additionally, interstitially driven multi-wavelength PA imaging was able to provide accurate spectra of gold nanoshells and deoxyhemoglobin in excised prostate and liver tissue, respectively, and allowed for clear visualization of a wire at 7 cm in excised liver. This work demonstrates the potential of using a local irradiation source to extend the depth capabilities of future PA imaging techniques for minimally invasive interventional radiology procedures.

Gold-Based Magneto/Optical Nanostructures: Challenges for In Vivo Applications in Cancer Diagnostics and Therapy

Nanoparticles with gold shell and iron core have unique optical and magnetic properties which can be utilized for simultaneous detection and treatment strategies. Several nanoparticles have been synthesized and shown to mediate a variety of potential applications in biomedicine, including cancer molecular optical and magnetic resonance imaging, controlled drug delivery, and photothermal ablation therapy. However, to be effective, these nanoparticles must be delivered efficiently into their targets. In this review, we will provide an updated summary of the gold-shelled magnetic nanoparticles that have been synthesized, methods for characterization, and their potential for cancer diagnosis and treatment. We will also discuss the biological barriers that need to be overcome for the effective delivery of these nanoparticles. The desired nanoparticle characteristics needed to evade these biological barriers were also explained. Hopefully, this review will help researchers in designing nanoparticles by carefully choosing the optimum size, shape, surface charge, and surface coating.