 The evaluation of patients at enrollment includes: medical history; physical examination; peripheral blood examinations to count blood cells, to examine blood cells by microscope, to measure some parameters related to liverkidney function and platelet production; standard urine analysis; ophthalmic assessment. Studies for dose adjustment includes the same examinations performed at enrollment with the exception of ophthalmic assessment. Evaluation of patients at the end of the Phases 1 or 2 and 30 days after the end of treatment includes the same examinations performed at enrollment: moreover, in patients who will obtain a platelet count higher than 100 x10e9L, the in vitro platelet function will be studied. 