This invention relates to an oral formulation containing an effective amount of N-(3-methylisothiazol-5-yl)-2-[1-(3-methylisoxazol-5-ylmethyl)-1H-indol-3-yl]-2-oxoacetamide or its analogues described herein, d-alpha-tocopheryl polyethylene glycol 1000 succinate ("TPGS"); and 2-(2-ethoxyethoxy)ethanol ("Transcutol"). Also disclosed is a method of treating cancer by administering this formula to a subject orally.