Morphological effects of imatinib mesylate (STI571) on the bone marrow and blood of patients with Philadelphia chromosome (Ph) positive chronic myeloid leukaemia

Leukemia Cells and the Cytokine Network: Therapeutic Prospects

The network and balance of cytokines is of major importance in maintaining proper homeostasis of hematopoiesis. Abnormalities in this network may result in a variety of blood disorders; however, the role of this network is not clear in leukemia. The use of antineoplastic agents has improved the survival rate of some types of leukemia, and adjunctive therapy with cytokines may be helpful. Chemotherapeutic approaches are no longer the best choice because cytotoxicity may affect normal and leukemic cells, and leukemic cells may develop resistance to the chemotherapeutic agent. Induction of differentiation to a mature phenotype and the control of apoptotic-gene expression have provided other possible alternative therapies. Combined effects of cytokines and vitamin derivatives such as retinoic acid (RA) and 1, 25 dihydroxyvitamin D3 (VD3) were found more beneficial than any of these agents individually. These agents exhibit cooperative effects, potentiate each other's effects, or both. Therefore, understanding the hematopoietic actions of these agents, their interactions with their receptors, and their differentiation signaling pathways may result In the design of new therapies. However, the role of cytokines in apoptosis is controversial because in some cases they were found to increase tumor cell resistance to apoptosis-inducing agents. Recent studies in the molecular biology of gene regulation, transcription factors, and repressors have led to new possible approaches such as differentiation therapy for the treatment of leukemia. In addition, the development of drugs that act on the molecular level such as imatinib is just the beginning of a new era in molecular targeted therapy in which the drug acts specifically on the leukemic cell. There are many possible combinations of cytokines, retinoids, and VD3, and perhaps the best therapeutic combination is yet to be described. This minireview is an update on the role of cytokines and the therapeutic potential of combinations with agents such as RA, VD3, and other chemotherapeutic agents.

Morphologic Changes in the Bone Marrow in Patients of Chronic Myeloid Leukemia (CML) Treated with ImatinibMesylate

Imatinib mesylate (Gleevec) is an effective treatment for chronic myeloid leukemia (CML). Though cytogenetic and molecular analyses are essential disease monitoring parameters in CML bone marrow morphological response is not well defined. We examined marrow samples from 40 patients with CML which have at least 2 or more follow-up marrow. A significant positive correlation with complete cytogenetic response shown for normalization of cellularity (P = 0.0097), absence of dry tap (P = 0.0368) and abnormal megakaryocytes (P = 0.005), reduction of blasts (P = 0.019), basophils (P = 0.031), M:E index (P = 0.018) and fibrosis (P = 0.018). Morphological criteria for complete cytogenetic response in CML patients treated with Imatinib can be defined.Morphologic response is also of potential clinical value in addition to cytogenetic and molecular response in patients of CML treated with Imatinib.

Transient trisomy 8 abnormality in Philadelphia-negative cells during imatinib mesylate treatment of chronic myelogenous leukemia

We investigated chronic myelogenous leukemia (CML) patients who developed trisomy 8 abnormalities in Philadelphia-negative (Ph-) cells during imatinib mesylate treatment to evaluate the clinical outcome and laboratory features. Of the 470 CML patients, 1.5% (n = 7) developed trisomy 8 chromosomal abnormalities in Ph- cells. The median interval of the first trisomy 8 observation was 12 months. Our follow-up cytogenetic evaluations revealed that six of the patients demonstrated a complete or partial cytogenetic response and that all of the six patients revealed no dysplastic changes following a bone marrow examination. Moreover, the percentage of trisomy 8 in metaphase karyotyping has decreased in five of the seven subjects. In conclusion, these results suggest that the emergence of trisomy 8 in Ph- cells is transient and not related to therapy-related myelodysplasia or acute leukemia.

Limited clinical value of regular bone marrow cytogenetic analysis in imatinib-treated chronic phase CML patients monitored by RQ-PCR for BCR-ABL

Real-time quantitative polymerase chain reaction (PCR) for BCR-ABL mRNA in the peripheral blood (RQ-PCR) provides an accurate and reliable measure of response to therapy in chronic myeloid leukaemia (CML). We wanted to determine in what circumstances additional clinically relevant information was provided by simultaneous cytogenetic analysis in RQ-PCR monitored patients receiving imatinib treatment. We analysed 828 simultaneous RQ-PCR and bone marrow cytogenetic analyses from 183 patients with chronic phase CML with a median follow-up of 20 months. Cytogenetic progression was defined as Philadelphia (Ph)-positive clonal evolution, loss of complete cytogenetic response or an increase of > or = 20% Ph-positive cells. Cytogenetic progression occurred in 24/183 (13%) patients. At the time of cytogenetic progression, none of the 24 patients had a major molecular response (MMR; > or = 3-log reduction in BCR-ABL from standardised baseline). There were 320 RQ-PCR results from 95 patients indicating MMR. No abnormality was detected in any of the corresponding cytogenetic analyses. A policy of regular RQ-PCR monitoring with cytogenetic analysis targetted only to patients who have not achieved, or have lost MMR would represent a rational approach to monitoring and spare most patients the discomfort of multiple marrow aspirates. This approach depends upon availability of an accurate, reproducible RQ-PCR assay with ongoing quality assurance.

Proposal of a morphologic bone marrow response score for imatinib mesylate treatment in chronic myelogenous leukemia

Cytogenetic and molecular analyses are essential disease-monitoring parameters in chronic myelogenous leukemia (CML) treated with imatinib. However, a bone marrow morphologic response has not been defined. We reviewed bone marrow histology and cytology of 39 imatinib-treated patients with CML over 49 weeks and introduced a morphologic response score. A significant positive correlation with a complete cytogenetic response was shown for absence of dry tap (P = .04) and abnormal megakaryocytes (P < 0.001), normalization of cellularity (P = .001) and reduction of fibrosis (P = .01), myelopoiesis:erythropoiesis index (P = .001), blast (P = .001) and basophil count (P < 0.001). The morphologic score integrating these parameters showed an early and late correlation with cytogenetic response. In conclusion, morphologic criteria for complete cytogenetic response in patients with CML treated with imatinib can be defined. Persistent high-level morphologic abnormalities herald early on a high likelihood to fail treatment and call for more intense or alternative therapy.