Abstract 3733: Development of photoimmunotherapy for colon cancer in nude mice models

Abstract

Abstract Introduction: Photoimmunotherapy (PIT) uses tumor specific monoclonal antibodies conjugated to photosensitizer phthalocyanine dye IR700 to produce cytotoxicity. To date, there is no published data on the use of PIT in colorectal cancers, which could be useful as an adjunct to surgery to prevent local recurrence, or as a primary therapy. Methods: Humanized anti-CEA antibody (m5A) was conjugated to IR700CW dye (LI-COR). In vitro PIT was performed using a human colon cancer cell line LS174T. Cancer cells (2x103) were seeded on a 96-well plate and incubated for 24 hours. m5A-IR700CW containing media was added to the cells. Cells received either 2 minutes of PIT or no treatment. PIT was administered at 4 J/cm2, 8 J/cm2 or 16 J/cm2. Cell viability was measured on a microplate reader with CellTiter 96 Aqueous One Solution (Promega, Madison, WI). Subcutaneous implantation of LS174T was performed on the bilateral flanks of four male nude mice. Tail vein injection of 25 micrograms of m5A-IR700CW reconstituted in 100 microliters PBS was performed for each mouse. Animal imaging was performed with a LI-COR Pearl Trilogy imaging system. Right flank tumors of three mice were treated with a 690 nm laser at 150 mW/cm2 for 30 minutes, delivering a total of 270 J/cm2. A non-treated mouse served as the control. Images were obtained prior to PIT, immediately after PIT and 10 minutes, 20 minutes, 30 minutes and 24 hours after treatment. Maximum fluorescence intensity was measured at each time point. Tumor size was measured prior to treatment, 24 hours, 48 hours, 5 days and 10 days after treatment. Results: In vitro PIT was effective to kill the cancer cells in a dose response manner. In vivo PIT decreased tumor fluorescence intensity in a time-dependent manner. PIT arrested tumor growth in all mice, compared to the control, which demonstrated continuous tumor growth. Conclusion: PIT affects cancer cell death in vitro and arrests tumor growth in colon cancer models. Citation Format: Hannah Hollandsworth, Siamak Amirfakhri, Filemoni Filemoni, Sahar Razemjooie, Paul Yazaki, Robert Hoffman, Michael Bouvet. Development of photoimmunotherapy for colon cancer in nude mice models [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 3733.