Company: SHPH
Filing Date: 2025-02-27
Form Type: 424B3
Source: 0001493152-25-008474
Chunk: 12

Company: Shuttle Pharmaceuticals Holdings, Inc.
Filing Date: 2025-02-27
Form: 424B3
Chunk 12
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 phosphorylation to triphosphates, they are then used in DNA replication, in competition with deoxythymidine triphosphate (dTTP), by DNA polymerase. DNA incorporation is a prerequisite for radiosensitization of human tumors by the halogenated TdR analogs, and the extent of radiosensitization correlates directly with the percentage TdR replacement in DNA. ( SeeLawrence TS, Davis MA, Maybaum J, Stetson PL, Ensminger WD. The Dependence of Halogenated Pyrimidine Incorporation and Radiosensitization on the Duration of Drug Exposure. International Journal of radiation oncology, biology, physics.Jun 1990; 18(6);1393-1398). The molecular mechanisms of radiosensitization are most likely the result of increased susceptibility of TdR analog-substituted DNA to the generation of highly reactive uracil free radicals by ionizing radiation (IR), which may also damage unsubstituted complementary-strand DNA. Repair of IR damage may also be reduced by pre-IR exposure to these analogs.

The rationale for using Ropidoxuridine as a radiation sensitizer is based on prior clinical studies with the active metabolite IUdR; identified in NIH laboratories as a potent radiation sensitizer. Ropidoxuridine is an orally available prodrug of IUdR. In the body, Ropidoxuridine is metabolized in the liver into IUdR. IUdR is incorporated into the DNA of actively growing cells and when cells are exposed to ionizing radiation, DNA strand breaks are generated, resulting in more cell death and radiation sensitization. ( SeeGurkan E, Schupp JE, Aziz MA, Kinsella TJ, Loparo KA. Probabilistic modeling of DNA mismatch repair effects on cell cycle dynamics and iododeoxyuridine-DNA incorporation. Cancer Res. Nov 15 2007; 67(22):10993-11000).

Most of the clinical efficacy data were obtained from NIH supported studies performed with IUdR, the active metabolite of Ropidoxuridine. However, IUdR requires constant infusion over six weeks of therapy which creates a significant compliance issue for patients. Ropidoxuridine can be given as a capsule for oral administration, resulting in greater ease of medication delivery and potentially improved compliance and fewer complications.

Over the last 20 years, there has been renewed interest in these hal