Nitric Oxide (NO) acts as a signaling molecule in the body in different pathologic conditions, including cancer. Beyond Air is developing an innovative gaseous Nitric Oxide (gNO) based tumor ablation method. The highly diffusible nature of NO may ease its spreading inside the tumor, while its short half-life may limit its effect to the tumor site and not affect the surrounding area.

According to our preliminary data, exposure of gNO at 10,000-50,000ppm for a very short time (in some cases one minute or less) efficiently eradicates breast, colon, lung and prostate cancers and shows a potent mouse tumor's destruction in-vivo.

Methods: Mouse colon and breast cancer cell lines were exposed to gNO at 150-50,000 ppm for 10 seconds - 180 seconds. Cell viability was examined 24hrs later by XTT assay.

Mouse colon tumors were treated by gNO at 10,000ppm - 50,000ppm intratumorally by hypodermic needles or local exposure of the tumor using a plastic box or tube.

Results: To test if gNO at 150-50,000ppm can decrease cancer cell viability, cells were exposed (I) directly to NO in a 96 well plate or (II) in an acrylic glass box. Cell viability was tested 24hrs later by XTT. According to our findings, less than 3% of 4T1 cells remain viable when exposed to 10,000ppm NO for 3 minutes or 50,000ppm NO for 1 minute in a 96-well plate. ~1% of CT26 cells remain viable after exposure to 50,000ppm NO for 10 seconds in a 96 well plate; while less than 10% remain viable after 1 minute of exposure of 50,000ppm NO in a box.

To test if gNO at 10,000-50,000ppm can destroy mouse colon cancer tumors in-vivo, tumors were exposed to gNO locally by hypodermic needles or a plastic cover. Air treated tumor bearing mice served as the control group.

A complete tumor destruction was observed when the skin was removed from the tumor and the entire tumor was exposed to 10,000ppm gNO for 10 minutes.

Conclusion: In the current work, gNO at high concentration showed a substantial cytotoxic effect on cancer cells in-vitro and in-vivo. The proposed project represents development of a novel treatment for cancer. Our innovative gNO based treatment may serve to treat solid tumors locally or be used as an adjunctive therapy for surgery and can be synergized with common anticancer therapies, such as chemotherapy and radiotherapy, to further enhance the effect.

Citation Format: Hila Confino, Steve Lisi, Rinat Kalaora, Matan Goldshtein, Amir Avniel. Gaseous nitric oxide at high concentration is a powerful anti-tumor agent both in-vitro and in-vivo [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6371.