The role of low-dose chemotherapy in myelodysplastic syndromes

Low dose Ara-C for myelodysplastic syndromes: is it still a current therapy?

The myelodysplastic syndromes (MDS) are characterized by hemopoietic insufficiency associated with severe cytopenias, leading to serious morbidity, and acute leukemia development. MDS typically occur in elderly people, with a median age at diagnosis ranging between 60 and 75 years. The patients' prognosis, estimated according to the International Prognostic Scoring System, age and performance status should be considered before choosing among the various treatment options. A therapeutic dilemma exists in MDS, due to the multifactorial pathogenetic features of the disease, the heterogeneous stage and the elderly age of patients at diagnosis. This is underlined by the absence of a Food and Drug Administration-approved agent with an indication for this disease. The therapeutic end-points vary from symptom management (using low-intensity treatment with biological targeted agents, or only supportive therapy), to attempts to change the natural history of the disease (generally using high intensity treatment, including intensive chemotherapy and hemopoietic stem cell transplantation). The main goal of low-intensity therapies is generally to induce hematological improvements and is mainly used for low-risk disease. On the other hand, high-intensity therapies generally aims to alter the disease's natural history (improving survival, and decrease progression to acute myeloid leukemia), and are mainly used for high-risk disease. This review will focus on the current role of low-dose Ara-C therapy in the management of MDS. In fact, there is evidence that low-dose chemotherapy with Ara-C can induce responses in patients with MDS. In particular, the use in combinations with growth factors, such as G-CSF or M-CSF, looks promising, suggesting further investigations about this old new therapeutic tool.

Myelodysplastic syndrome overview

Myelodysplastic syndrome (MDS) is a heterogeneous hematopoietic stem cell disorder characterized by bone marrow dysplasia and peripheral cytopenias. Eighty percent of patients found to have MDS are older than 60 years and therefore not eligible for the only potentially curative therapy, bone marrow transplantation. Currently, there is no standard for treating MDS; therapies range from supportive care with transfusions or hematopoietic growth factors and low-intensity cytarabine therapy, to intensive anti-acute myeloid leukemia-type chemotherapy. Some of these treatments induce a limited hematologic response, but none consistently extends survival. Many are highly toxic. More than half of patients with MDS die within 3 to 4 years of infections, bleeding complications, or progression to acute leukemia. Agents in development for MDS include all-trans retinoic acid (ATRA), decitabine, and thalidomide. Farnesyltransferase inhibitors modulate many of the cancer-signaling pathways implicated in MDS initiation or progression and may therefore be well suited for treatment of these biologically diverse hematologic malignancies. Phase I and II clinical studies in our center show that the oral FTI ZARNESTRA (formerly R115777, Ortho Biotech Oncology, Raritan, NJ) has promising anti-MDS activity, suggesting that further investigation of this agent and of this class in MDS is warranted.

Granulocyte dysplasia and dysfunction, and CD11/CD18 defects in myelodysplastic syndromes

In myelodysplastic syndromes (MDS), dysplastic changes in neutrophils are a common feature reflecting the total degree of bone marrow dysplasia. Furthermore, granulocyte function is abnormal, so that a high risk of life-threatening infections has been documented. In this review we shall focus on the defects of both granulocytes and their CD11b/CD18 glycoprotein complex, which regulate granulocyte adherence, locomotion, diapedesis and migration into inflammatory sites, in patients suffering from primary MDS. The defective surface membrane glycoprotein expression of myelodysplastic phagocytes is not only a useful diagnostic tool, but also a powerful prognostic one, since MDS patients with such defects present both an increased susceptibility to infections and a decreased survival. Moreover, the administration of colony-stimulating factors is known to be able to elicit long-lasting improvement in neutrophil count, CD11b/CD18 expression and function, marrow myeloid maturation, and possibly to decrease bacterial infections in MDS patients.

Low-dose ara-C in myelodysplastic syndromes (MDS) and acute leukemia following MDS: proposal for a predictive model

Patients with myelodysplastic syndromes (MDS) comprise an extremely heterogeneous group. There is a need for decision models both for predicting the natural course of the disease and the outcomes of different treatment alternatives. In 102 consecutive patients with MDS or acute myelogenous leukemia (AML) following MDS, pre-treatment variables were studied in relation to the response to treatment with low-dose ara-C. Thirty patients (29%) responded with either a complete remission or a significant rise in the hemoglobin level. For the remaining 71%, the treatment was ineffective and in some cases hazardous. The factors associated with a poor response to treatment could be divided into two groups: one included low platelet counts and the presence of chromosomal aberrations, both signs of progressive MDS with a short survival, and the other comprised morphological findings, indicating ineffective hemopoiesis. Patients with platelet counts > 150 x 10(9)/l had a response rate of 55%, compared to 24% in patients with subnormal platelet counts. Logistic regression identified low bone marrow cellularity, absence of ring sideroblasts and < 2 chromosomal aberrations as predictors of a favourable response in patients with platelet counts < 150 x 10(9)/l. These factors and the platelet count were combined in a predictive model which divided patients into three groups with different probabilities of response: one favourable (38% of the patients), with a response rate of > 50%; a second, intermediate group (33% of the patients), with a response rate of 24%; and a third, unfavourable group (29% of the patients) with only 3% responses.(ABSTRACT TRUNCATED AT 250 WORDS)

A randomized phase II trial of low-dose aclarubicin vs very low-dose cytosine arabinoside for treatment of myelodysplastic syndromes

We performed a randomized phase II trial comparing low-dose aclarubicin (LC-ACR) with very low-dose cytosine arabinoside (VLD-AC) in 39 consecutive untreated patients with myelodysplastic syndromes (MDS), including refractory anemia (RA), RA with excess of blasts (RAEB) and RAEB in transformation (RAEB-t). Nineteen patients received the VLD-AC therapy; 2 good responses (GR) and 2 partial responses (PR) were obtained in 11 patients with RAEB and RAEB-t, while 2 PR were obtained in 8 RA patients. Eighteen patients received the LD-ACR therapy; 2 GR and 4 PR were obtained in 11 RAEB/RAEB-t patients while 2 PR in 7 RA patients. There was no significant difference in the therapeutic effects and survival between these two groups of patients. These observations suggest that the LD-ACR therapy is effective in some patients with MDS and can be used as an alternative to the low-dose Ara-C therapy.

Age-related incidence and other epidemiological aspects of myelodysplastic syndromes

Although most haematologists perceive a rising prevalence and incidence of myelodysplastic syndromes (MDS), reliable epidemiological data on these disorders are largely lacking. The bone marrow register of the University of Düsseldorf allowed us to assess among other epidemiological features the incidence of MDS, which was compared to that of acute myeloid leukaemia (AML). Among a total of 18,416 different patients registered between 1975 and 1990, 584 cases of MDS (3.2%) and 506 cases of AML (2.8%) were identified. Over the study period, the percentage of newly diagnosed MDS rose from 1.3% to 4.5%, while there was no upward trend for AML. Among all patients undergoing bone marrow biopsy, the proportion of those over 60 years of age increased from 41.9% in 1975 to 54.1% in 1990. We found a strong correlation between the proportion of elderly patients and the relative frequency of MDS diagnoses. Thirty-one patients (5.3%) were classified as a secondary MDS because of previous treatment with cytotoxic chemotherapy and/or irradiation for a variety of malignancies. Twelve patients were identified in whom occupational exposure to organic solvents could not be ruled out. For calculating age-specific incidence rates, the analysis was confined to the town district of Düsseldorf (575,000 inhabitants), because exact demographical data were available for this population. In the last quinquennium of the study period (1986-90), myelodysplastic syndromes were more frequent than AML in the age group 50-70 years (4.9 v 1.8/100,000/year). In patients over 70, the incidence of MDS was more than 3 times that of AML (22.8 v 6.7/100,000). In this group, men had a higher incidence of MDS (33.9/100,000) than women (18/100,000). Crude annual incidence (all age groups) was also higher for MDS (4.1/100,000) than for AML (2.1/100,000) in recent years. We conclude that MDS are relatively common haematological neoplasias. The rising incidence in recent years is probably not due to changes in aetiological factors, but may reflect increased awareness on the part of physicians and extended use of diagnostic procedures in elderly patients.