Near-infrared photoimmunotherapy with galactosyl serum albumin in a model of diffuse peritoneal disseminated ovarian cancer
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Toshiko Harada1, Yuko Nakamura1, Kazuhide Sato1, Tadanobu Nagaya1, Shuhei Okuyama1, Fusa Ogata1, Peter L. Choyke1, Hisataka Kobayashi1
1Molecular Imaging Program, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland, 20892, USA
Hisataka Kobayashi, email: firstname.lastname@example.org
Keywords: near-infrared photoimmunotherapy, ovarian cancer, peritoneal cancer metastases, galactosyl serum albumin, beta-D-galactose receptor
Received: August 15, 2016 Accepted: September 30, 2016 Published: October 17, 2016
Near-infrared photoimmunotherapy (NIR-PIT) is a highly cell-selective cancer therapy based on an armed antibody conjugated with a phthalocyanine-based photo-absorber, IRDye700DX (IR700). NIR-PIT can quickly kill target cells that express specific proteins on the cellular membrane but only when the antibody-IR700 conjugate binds to the cell membrane and is then exposed to NIR light. NIR-PIT is highly selective based on the specificity of the antibody. Galactosyl serum albumin (GSA) is composed of albumin decorated with galactose molecules conjugated to the carboxyl groups of albumin. GSA binds to beta-D-galactose receptors, a surface lectin, which are overexpressed on the cell surface of many cancers, including ovarian cancers and is quickly internalized after binding. Here, we demonstrate the feasibility of NIR-PIT in a model of disseminated peritoneal ovarian cancer (SHIN3 cells) using GSA-IR700 that binds to beta-D-galactose receptors. GSA-IR700 bound quickly to SHIN3 cells, then accumulated in the endo-lysosomes. Cell-specific killing was observed in vitro, yet a relatively large dose of NIR light exposure was required for cell killing compared to antibody-IR700 conjugates. To evaluate in vivo therapeutic effects of GSA-IR700 NIR-PIT, peritoneal disseminated SHIN3 tumor-bearing mice were separated into four groups: no treatment; NIR light only; GSA-IR700 only; and GSA-IR700 NIR-PIT. Repeated NIR-PIT showed significant suppression of tumor based on bioluminescence compared to the other groups (p < 0.05). Thus, repeated NIR-PIT using GSA-IR700 can achieve efficient antitumor effects, although GSA-IR700 NIR-PIT was less effective than antibody-IR700 NIR-PIT conjugates likely due to the rapid internalization of GSA-IR700.
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