Imatinib mesylate in idiopathic and postpolycythemic myelofibrosis.

Imatinib mesylate targets the adenosine triphosphate (ATP)-binding sites of the protein tyrosine kinase domains associated with Bcr-abl, the platelet-derived growth factor (PDGF) and c-kit. In idiopathic myelofibrosis (IMF) PDGF is considered to be one of the growth factors responsible for the development of bone marrow fibrosis. Recently, it has been shown that imatinib has antifibrogenic effect on bone marrow fibrosis in chronic myelogenous leukemia. Treatment with imatinib alone in IMF has been associated with significant side effects. In this study, the safety and efficacy of imatinib therapy in IMF, either administered as a single agent or in combination with hydroxyurea (HU) and/or alpha-interferon (IFN-alpha) are evaluated. Eleven patients (median age, 63 years; range, 33-82 years) with IMF (n = 8) or postpolycythemic myelofibrosis (PPMF) (n = 3) were studied All patients had been treated with HU (n = 9) and/or IFN (n = 7) before study entry. In all but one patient, treatment with these agents was discontinued when imatinib therapy was instituted. One patient continued IFN when treatment with imatinib was started. Imatinib was given at a dose of 400 mg/day. Nine patients were in an advanced disease phase. The patients have been followed for a median period of 2 months (range, 0.5-12 months). Treatment with imatinib has been stopped in six patients (55%), because of overt side effects (n = 4), recurrence of transitory dizziness and visual defects owing to a rising platelet count (n = 1), or the occurrence of an acute subdural hemorrhage that was evacuated without neurological deficits (n = 1). In nine patients imatinib treatment was followed by a rise in leukocyte and platelet counts that required combination with HU or IFN. The combined treatment modalities were followed by a rapid decrease in cell counts and were well tolerated apart from IFN side effects. A beneficial effect of imatinib was documented in three patients. It is concluded that leukocytosis and thrombocytosis are seen in most patients with myelofibrosis during treatment with imatinib. Combination therapy with HU or IFN seems safe and well tolerated and followed by a decrease in disease activity. A subgroup of patients in an early disease phase might benefit from imatinib therapy alone.

Successful treatment of anemia in idiopathic myelofibrosis with recombinant human erythropoietin.

Thirteen patients with idiopathic myelofibrosis (5 osteomyelosclerosis) were treated with recombinant human erythropoietin (rHuEpo) for transfusion-dependent anemia. All but 7 patients were concomitantly treated with alpha interferon, and 5 patients also received a interferon before the start of erythropoietin (EPO) treatment. All but two patients became transfusion independent. The highly positive results of the present study of transfusion-dependent patients with idiopathic myelofibrosis calls for further studies to delineate more precisely in larger series those patients who are likely to respond to rHuEpo.

Aggressive growth of epithelial carcinomas following treatment with nucleoside analogues.

Two patients, one with B-cell chronic lymphocytic leukemia (CLL) and one with hairy-cell leukemia (HCL), were treated with immunosuppressive chemotherapy. The patient with CLL was a 54-year-old female, who had had a squamous cell carcinoma (SCC) excised from her forehead 5 months before receiving the first course of fludarabine. During the fludarabine treatment, the patient developed a local SCC relapse and metastases in the neck. The carcinoma was treated by excision and radiotherapy, and further fludarabine treatment was withheld. Nevertheless, the SCC metastasized aggressively and the patient died 3 months after the start of fludarabine treatment, primarily due to respiratory failure. The autopsy revealed heavy SCC infiltrations involving the lungs, pleura, mediastinum, pericardium, and liver. The patient with HCL was a 69-year-old male. At the time of diagnosis of HCL, the patient had two solid tumors in the liver containing poorly differentiated epithelial carcinoma cells of unknown origin. During treatment with 2-chlorodeoxyadenosine (2CdA), the tumors in the liver rapidly spread in multiple intrahepatic metastases, followed by liver failure and death within 1 month. Fludarabine and 2CdA cause a substantial suppression of all lymphocyte subsets, in particular the T-cell line. T-lymphocytes are believed to be responsible for the usually slow growth and the low metastatic rate of the SCC skin lesions. It is therefore assumed that fludarabine and 2CdA in these two cases triggered an exacerbation of both tumors due to the T-cell depletion.