Treatment of Canine Oral Melanoma with Nanotechnology-Based Immunotherapy and Radiation

Abstract

The presence and benefit of a radiation therapy-associated immune reaction is of great interest as the overall interest in cancer immunotherapy expands. The pathological assessment of irradiated tumors rarely demonstrates consistent immune or inflammatory response. More recent information, primarily associated with the "abscopal effect", suggests a subtle radiation-based systemic immune response may be more common and have more therapeutic potential than previously believed. However, to be of consistent value, the immune stimulatory potential of radiation therapy (RT) will clearly need to be supported by combination with other immunotherapy efforts. In this study, using a spontaneous canine oral melanoma model, we have assessed the efficacy and tumor immunopathology of two nanotechnology-based immune adjuvants combined with RT. The immune adjuvants were administered intratumorally, in an approach termed "in situ vaccination", that puts immunostimulatory reagents into a recognized tumor and utilizes the endogenous antigens in the tumor as the antigens in the antigen/adjuvant combination that constitutes a vaccine. The radiation treatment consisted of a local 6 × 6 Gy tumor regimen given over a 12 day period. The immune adjuvants were a plant-based virus-like nanoparticle (VLP) and a 110 nm diameter magnetic iron oxide nanoparticle (mNPH) that was activated with an alternating magnetic field (AMF) to produce moderate heat (43 °C/60 min). The RT was used alone or combined with one or both adjuvants. The VLP (4 × 200 μg) and mNPH (2 × 7.5 mg/gram tumor) were delivered intratumorally respectively during the RT regimen. All patients received a diagnostic biopsy and CT-based 3-D radiation treatment plan prior to initiating therapy. Patients were assessed clinically 14-21 days post-treatment, monthly for 3 months following treatment, and bimonthly, thereafter. Immunohistopathologic assessment of the tumors was performed before and 14-21 days following treatment. Results suggest that addition of VLPs and/or mNPH to a hypofractionated radiation regimen increases the immune cell infiltration in the tumor, extends the tumor control interval, and has important systemic therapeutic potential.

Viral nanoparticles for drug delivery, imaging, immunotherapy, and theranostic applications

“…We further verified the immunotherapeutic efficacy of CPMV in separate studies in the treatment of murine dermal melanoma [110], intracranial glioma [111] and ovarian cancer [109]. In addition to the mouse studies, we have begun testing the immunotherapy in canine patients, and our data indicate similar efficacy in these patients [112]. In the aforementioned CPMV studies, the immunotherapeutic vaccines are administered multiple times; however, multiple dosing regimens can lead to low patient compliance and increased hospital burden.…”

“…Indeed, combining radiation therapy with CPMV in situ vaccination significantly improved tumor growth delay in ID8-Def29/Vegf-A-Luc tumors compared to either therapy alone [121]. The potent efficacy of CPMV + radiation therapy has also been translated to canine patients with melanoma [112]; therefore, this approach demonstrates high translational potential.…”

Biomimetic Nanotechnology toward Personalized Vaccines

“…In all cases, the combination led to enhanced survival and prolonged tumor suppression compared to either treatment alone. VLP administration combined with radiation therapy has been validated in a canine preclinical trial with impressive results . All canine patients treated with this combination became tumor‐free, firmly supporting the clinical potential of VLPs as a therapeutic modality against cancer.…”

CD47 Blockade and Cowpea Mosaic Virus Nanoparticle In Situ Vaccination Triggers Phagocytosis and Tumor Killing

“…More recently we demonstrated that the immunostimulatory properties of VNPs can be harnessed also in the context of tumors: when applied as in situ vaccine, the VNPs formed by the cowpea mosaic virus (CPMV) reverse the immunosuppressive tumor microenvironment and promote the antigen‐presenting ability of innate immune cells, therefore restarting the cancer immunity cycle . Preclinical data in several mouse models indicate potent efficacy; we also demonstrated the translational potential by successfully treating canine patients with spontaneous melanoma using a combination of CPMV in situ vaccination and radiation therapy …”