A Ras antagonist represented by the formula (I): R1-R2-R3-R4 (I) in which: R1 represents CN, 5 C (>； = O) R5, S (>； = O) (>； = O) R5, CO2M, SO3M, or an N-substituted tetrazole (R8)； R2 represents a 5-membered heterocyclic ring with one or two heteroatoms, R3 represents S, O, NH, SO, SO2, or Se； R4 represents farnesyl or geranyl-geranyl； R5 represents hydrogen, hydroxy, C1-C4 alkyloxy, C2-C4 alkenyloxy, C1-C4 hydroxyalkyloxy, C1-C4 aminoalkyloxy or NR6R7； R6 represents hydrogen, hydroxy, C1-C4 alkyl, C2-C4 alkenyl, C1-C4 aminoalkyl, C1-C4 hydroxyalkyl, C1-C4 alkyloxy or C1-C4 alkylamino and R7 represents hydrogen, C1-C4 alkyl, C2-C4 alkenyl, C1-C4 aminoalkyl, C1-C4 hydroxyalkyl, C1-C4 alkyloxy or C1-C4 alkylamino, or wherein R6 and R7 together form a ring that includes morpholine, piperazine or piperidine； M is an organic or inorganic counterion that forms salt； R8 represents hydrogen or C1-C4 alkyl； and pharmaceutically acceptable salts and solvates thereof.Un antagonista de Ras representado por la fómula (I): R1-R2-R3-R4 (I) en el que: R1 representa CN, 5 C(>；=O)R5, S(>；=O)(>；=O)R5, CO2M, SO3M, o un tetrazol sustituido en N(R8)； R2 representa un anillo heterocíclico de 5 miembros con uno o dos heteroátomos, R3 representa S, O, NH, SO, SO2, o Se； R4 representa farnesilo o geranilo-geranilo； R5 representa hidrógeno, hidroxilo, alquiloxi C1-C4, alqueniloxi C2-C4, hidroxialquiloxi C1-C4, aminoalquiloxi C1-C4 o NR6R7 ； R6 representa hidrógeno, hidroxilo, alquilo C1-C4, alquenilo C2-C4, aminoalquilo C1-C4, hidroxialquilo C1-C4, alquiloxi C1-C4 o alquilamino C1-C4 y R7 representa hidrógeno, alquilo C1-C4, alquenilo C2-C4, aminoalquilo C1-C4, hidroxialquilo C1-C4, alquiloxi C1-C4 o alquilamino C1-C4, o en el que R6 y R7 juntos forman un anillo que incluye morfolina, piperazina o piperidina； M es un contraión orgánico o inorgánico que forma sal； R8 representa hidrógeno o alquilo C1-C4； y sales y solvatos farmaceuticamente aceptables del mismo.
