Effects of ubenimex, a biological response modifier, on myelodysplastic syndrome and chronic leukemia

Twenty cases of myelodysplastic syndrome (MDS) were treated with ubenimex. Seventeen cases were treated with the drug over 90 d. Among these, 10 showed improvement of anemia, 12 an increase in platelet count which had decreased before treatment and 10 an increase in neutrophil count; however, 14 showed an increase in blast percentage in bone marrow aspirate. CD4/CD8 ratio was increased in 4 cases and shifted to a normal from an abnormal range in 6 cases. When the MDS cases were observed in refractory anemia (RA) and refractory anemia with excess blasts (RAEB), great improvement was seen, but in RAEB increase in blast percentage was also observed. CD4 increased mostly in RA and CD8 increased in RAEB. Ten cases of chronic myelocytic leukemia (CML) were first treated with ubenimex and cytostatics, then with ubenimex only. Six cases attained partial remission within 3 months, but one case showed a marked increase in white cell count and blast count and in another case a progression of splenomegaly associated with increase in white cell count. From these findings we conclude that ubenimex could be utilized in MDS or CML if the patient was at risk for strong chemotherapy.