Treatment of myelodysplastic syndromes with daily oral idarubicin. A phase I-II study

Idarubicinol myelotoxicity: a comparison of in vitro data with clinical outcome in patients treated with high-dose idarubicin

We evaluated in vitro the toxicity of idarubicin and its active metabolite idarubicinol on haematopoietic progenitors, using human umbilical cord blood and peripheral blood progenitors to obtain dose-response curves. We treated 16 patients with poor prognosis lymphoma in a phase I-II trial of high-dose idarubicin and melphalan and investigated if idarubicinol persisting in patients' plasma at the time of transplantation (day 0), on day +1 and +2 could result in an inhibition of infused progenitors. Colony inhibition was correlated with pharmacokinetic data and with the time of patients' engraftment. Plasma samples obtained before idarubicin treatment demonstrated a colony-stimulating effect, increasing the cloning efficiency by 72%. The inhibitory activity on colony forming unit granulocyte-macrophage (CFU-GM) of patients' plasma collected on the day of transplantation was lower than expected from dose-response curves (21% measured vs 70% expected). The time to patients' WBC and PLT recovery correlated with the amount of CD34+ cells reinfused and, to a lesser extent, with the colony-inhibiting effect of patients' plasma. The correlation between idarubicinol concentration and CFU-GM inhibition was not significant. These data suggest that plasma drug concentration on the day of stem cell reinfusion may overestimate the toxicity of residual anthracyclines to the transplanted cells.

Advances in the therapy of the myelodysplastic syndromes

The study of the proliferation and differentiation of the MDS clone at the molecular level, including the details of apoptosis, may hopefully lead to more effective differentiation-induction/antiapoptotic agents. The study of the cytokines at the cellular/molecular level may lead to more effective trails of combination therapy with differentiation-induction agents, chemotherapy, and/or early-acting cytokines. Further phenotypic characterization of the MDS clone may lead to negative selection of these cells or positive selection of normal stem cells as part of an autotransplant strategy, as is presently being done in chronic-phase chronic myeologenous leukemia. The use of agents such as the topoisomerase I inhibitors (e.g., topotecan), which have mechanisms of action disparate from agents already used in MDS, may increase the efficacy of chemotherapy for MDS. The further clinical refinements in reducing treatment-related mortality and the study of T cells at the molecular level may hopefully lead to improvement in the prevention and therapy of graft-versus-host disease, in turn increasing the upper age limit of allogeneic BMT for MDS and increasing the feasibility of matched unrelated allogeneic BMT. At present, we can tailor the approach to a MDS patient based on his or her IPSS risk stratification, degree of cytopenia, and age, as outlined in Figure 2. At present, we can tailor the approach to a MDS patient based on his or her IPSS risk stratification, degree of cytopenia, and age, as outlined in Figure 2.

Results of topotecan single-agent therapy in patients with myelodysplastic syndromes and chronic myelomonocytic leukemia

The activity of topotecan was evaluated in patients with myelodysplastic syndrome (MDS) and chronic myelomonocytic leukemia (CMML). Sixty patients with a diagnosis of MDS (n = 30) or CMML (n = 30) were treated. Their median age was 66 years, with 50 patients (83%) being over 60 years of age at time of study entry. Chromosomal abnormalities were present in 50% of patients and thrombocytopenia of less than 50 x 10(9)/L in 50%. Topotecan was administered as 2 mg/m2 by continuous infusion over 24 hours daily for five days (10 mg/m2 per course) every 4 to 6 weeks for two courses, then at maximum tolerated dose level (1-2 mg/m2 by continuous infusion over 24 hours daily for five days) once every 4-8 weeks for a maximum of 12 courses. Evaluation of outcome and of differences among subgroups was performed according to standard methods; the criteria for response were those used for acute leukemia. Nineteen patients (31%) achieved a complete response (CR). A CR was achieved in 11 of 30 patients with MDS (37%) and in eight of 30 with CMML (27%). A CR was achieved in 10 of 23 patients with previously untreated MDS (43%). Eight of 11 patients who presented with cytogenetic abnormalities (five of which involved chromosome 5 and/or 7 abnormalities) and achieved CR, were evaluated cytogenetically in CR: all were cytogenetically normal in CR. Characteristics associated with a higher CR rate were lack of previous chemotherapy, absence of ras oncogene mutations, and presence of less than 10% monocytes in either peripheral blood or bone marrow. In contrast, CR rates were similar by different agent groups, by different karyotype abnormalities, and by other pre-therapy peripheral blood counts. Non-myelosuppressive side effects were mucositis in 67% of patients (severe [grade 3-4] 23%), diarrhea in 38% (severe 17%), and nausea and vomiting in 28% (severe 5%). Febrile episodes during neutropenia occurred in 85% of patients and documented infections in 47 %. Mortality in the first four weeks was 20%. With a median follow-up duration of 31 months, the 12 month survival rate was 38%, median survival time 10.5 months, and median remission duration 7.5 months. In summary, topotecan has significant single-agent activity in MDS and CMML. Complete responses associated with topotecan therapy often involve the disappearance of abnormal, poor-prognosis karyotypes, which is particularly encouraging. Future strategies to optimize topotecan's role include combination regimens with topoisomerase II reactive agents, cytarabine, or hypomethylating agents (azacytidine and decitabine).

Anthracyclines in haematology: pharmacokinetics and clinical studies

The activity of anthracyclines in the treatment of a wide spectrum of haematological malignancies has long been established. Differences in the pharmacokinetic and pharmacodynamic properties of these drugs have resulted in the selection of individual compounds for particular indications while the recent reformulation of anthracyclines in liposomal preparations seems likely to significantly alter their range of activity and toxicity. The problems related to cumulative cardiotoxicity secondary to anthracycline exposure can be ameliorated by the use of dexrazoxane and a number of agents may prove to have a role in altering their cellular resistance to their cytotoxic actions.