Shuttle Pharmaceuticals Holdings, Inc., a clinical stage pharmaceutical company, develops novel therapies to cure cancers. It develops Ropidoxuridine, an oral halogenated pyrimidine to treat patients with brain tumors and sarcomas, SP-1-161, an HDAC inhibitor that initiates the mutated in ataxia-telangiectasia response pathway for radiation sensitizing cancer cells and protecting normal cells; SP-2-225, a pre-clinical class IIb that effects on the regulation of the immune system; and SP-1-303, a pre-clinical selective Class I HDAC for the treatment of ER positive cancers. The company was founded in 2012 and is based in Rockville, Maryland.