Refers to a Pharmaceutical composition comprising a compound derived from - 2.5 - pyrrolidine Dione, i\u00b4 i\u00b4\u00b4 formula, formula or a mixture thereof wherein: X is - or - NH - CQ2 = CQ3 - Q2 and Q3 are independently H or c1-c6 alkyl R1 and R2 are independently h, Halo, cyano, alkyd ILO C1 - C6 or c1-c6 alkoxy and at least a pharmaceutically acceptable Carrier.It also refers to a racemic mixture of both compounds being selected (3 - 5 - fluoro - 1H indole - 3 - yl) - pyrrolidin-3-yl 2.5 - dione, among others. These compounds are inhibitors of the Enzyme indolamina 2,3-dioxygenase (- 1 ido1) being useful in the Treatment or prevention of Cancer and endometriosisSe refiere a una composicion farmaceutica que comprende un compuesto, derivado de pirrolidina-2,5-diona, de formula I´, de formula I´´ o una mezcla de ellos en donde: X es -NH- o -CQ2=CQ3- Q2 y Q3 son, independientemente, H o alquilo C1-C6 R1 y R2 son, independientemente, H, halo, ciano, alquilo C1-C6 o alcoxi C1-C6 y al menos un portador farmaceuticamente aceptable. Tambien se refiere a una mezcla racemica de ambos compuestos, siendo seleccionado 3-(5-fluoro-1H-indol-3-il)pirrolidin-2,5-diona, entre otros. Dichos compuestos son inhibidores de la enzima indolamina 2,3-dioxigenasa-1 (IDO1) siendo utiles en el tratamiento o prevencion de cancer y endometriosis
