Hope for hematopoietic hormones

Mitoxantrone and high-dose cytosine arabinoside for the treatment of refractory acute lymphocytic leukemia

Twenty-five adult patients with refractory acute lymphocytic leukemia received salvage therapy with mitoxantrone 5 mg/m2 intravenously over 1 hour daily for 5 days and cytosine arabinoside 3 g/m2 intravenously over 2 hours every 12 hours for six doses. Overall, nine patients (36%) achieved complete remission, eight (32%) died during induction, and eight (32%) had resistant disease. No significant associations were found between pretreatment patient characteristics and remission. Remission durations toxic effects were related to myelosuppression. Febrile episodes requiring hospitalization occurred in 23 patients (92%), including five episodes of fever of unknown origin (20%) and 18 episodes of documented infections (72%). The authors conclude that the combination of mitoxantrone and high-dose cytosine arabinoside has significant activity in adults with refractory acute lymphocytic leukemia. The addition of colony-stimulating growth factors to the intensive chemotherapy, and the use of the combination regimen as part of front-line maintenance intensification therapy may further improve the prognosis in these patients.

Lymphoid cell regulation of hematopoiesis

It is clear from extensive in vitro data that different subsets of lymphocytes stimulate and inhibit the growth of hematopoietic stem and progenitor cells. In order to clarify the complexity of the network between regulatory lymphocytes and hematopoietic target cells, we have examined the stimulatory and inhibitory effects derived from different lymphoid subsets. The regulatory influence of lymphocytes is transmitted mainly through the release of cytokines including the interleukins, granulocyte-macrophage colony-stimulating factor, tumor necrosis factor-beta and the interferons, all of which have non-specific effects on a variety of hematopoietic cells. Since these cytokines amplify the effects of other, more lineage-specific cytokines (e.g., erythropoietin, thrombopoietin and granulocyte or macrophage colony-stimulating factor) on the proliferation and differentiation of progenitor cells, the present review supports the conclusion that lymphoid subsets play a critical role in ensuring an optimal hematopoietic response to specific demands.

Treatment of the blastic phase of chronic myelogenous leukemia with mitoxantrone and high-dose cytosine arabinoside

Twenty-seven patients in the blastic phase of chronic myelogenous leukemia received combination chemotherapy with mitoxantrone 5 mg/m2 intravenously daily for 5 days, and cytosine arabinoside 3 g/m2 intravenously over 2 hours every 12 hours for six doses. The patients' median age was 42 years (range, 19-61 years), and 26 of them had Philadelphia chromosome-positive disease. Overall, seven patients (26%) achieved complete remission, and one (4%) had a partial remission for an overall response rate of 30%. Eight patients died during remission induction, and 11 had resistant disease. The median survival was 14 weeks for the total population, and 24 weeks for patients achieving a complete remission. The nonmyelosuppressive toxicity of the combination was acceptable; serious neurologic and pulmonary toxicities were uncommon. Significant marrow hypoplasia was observed resulting in a high incidence of febrile episodes (85% of patients). The combination of mitoxantrone and high-dose cytosine arabinoside did not significantly improve overall prognosis. Since chemotherapy continues to produce disappointing results, other innovative approaches need to be explored.