Shuttle Pharmaceuticals Holdings, Inc. announced they have received the 'Safe to Proceed' letter from the U.S. Food and Drug Administration (FDA) for the Company's investigational new drug (IND) application for its Phase II study of Ropidoxuridine (IPdR) as a radiation sensitizing agent during radiotherapy in patients with newly diagnosed IDH-wildtype glioblastoma with unmethylated MGMT promoter. Receipt of the letter allows Shuttle to commence the Phase II study. Shuttle Pharma is currently finalizing site enrollment with 'first patient, first dose' expected in the coming months.

Ropidoxuridine is Shuttle Pharma's lead radiation sensitizer candidate for use in combination with radiation therapy (RT) to treat glioblastoma, a deadly malignancy of the brain with no known cure. An estimated 800,000 patients in the US are treated with radiation therapy for their cancers yearly. According to the American Cancer Society and the American Society of Radiation Oncologists, about 50% are treated for curative purposes and the balance for therapeutic care.

The market opportunity for radiation sensitizers lies with the 400,000 patients treated for curative purposes, with this number expected to grow by more than 22% over the next five years. Shuttle Pharma has received Orphan Drug Designation from the FDA, providing potential marketing exclusivity upon first FDA approval for the disease.