Note: Some citations in the text of this section are followed by a level of evidence. The PDQ editorial boards use a formal ranking system to help the reader judge the strength of evidence linked to the reported results of a therapeutic strategy. (Refer to the PDQ summary on Levels of Evidence for more information.)

Treatment of patients with chronic myelogenous leukemia (CML) is usually initiated when the diagnosis is established, which is done by the presence of an elevated white blood cell (WBC) count, splenomegaly, thrombocytosis, and identification of the BCR/ABL (breakpoint cluster region/Abelson) translocation.[1] The optimal frontline treatment for patients with chronic-phase CML is the subject of active clinical evaluation but involves specific inhibitors of the BCR/ABL tyrosine kinase. In a randomized trial comparing imatinib mesylate with interferon plus cytarabine, with 5 years' median follow-up, imatinib mesylate induced complete cytogenetic responses in more than 80% of newly diagnosed patients; in addition, the annual rate of progression to accelerated phase or blast crisis dropped from 2% to less than 1% in the fourth year on the imatinib arm.[2][Level of evidence: 1iiDiii] However, most of these continually responding patients still showed detectable evidence of the BCR/ABL translocation by the most sensitive measurement of reverse transcriptase–polymerase chain reaction (RT–PCR).[3-5] The clinical implication of this finding after 10 years or more is unknown, but these results have changed clinical practice. Although evidence-based survival benefits are unavailable because of crossover in randomized trials, the preferred initial treatment for newly diagnosed patients in chronic phase involves imatinib mesylate.[6,7] In addition, the overall survival rate for all patients at 5 years is 89%, with fewer than 50% of all deaths (4.5%) caused by CML. Higher doses of imatinib, alternative tyrosine kinase inhibitors such as dasatinib or nilotinib, and allogeneic stem cell transplantation (SCT) are implemented for suboptimal response or progression and are under clinical evaluation as frontline approaches.[8-15]

The only consistently successful curative treatment of CML beyond 10 years' follow-up has been allogeneic bone marrow transplantation (BMT) or SCT.[16] Long-term data beyond 10 years of therapy are available, and most long-term survivors show no evidence of the BCR/ABL translocation by any available test (e.g., cytogenetics, RT–PCR, or fluorescent in situ hybridization [FISH]). Many patients, however, are not eligible for this approach because of age, comorbid conditions, or lack of a suitable donor. In addition, substantial morbidity and mortality result from allogeneic BMT or SCT; a 15% to 30% treatment-related mortality can be expected, depending on whether a donor is related and on the presence of mismatched antigens.[16]

Long-term data are also available for patients treated with interferon-alpha.[17-19] Approximately 10% to 20% of these patients have a complete cytogenetic response with no evidence of BCR/ABL translocation by any available test, and the majority of these patients are disease-free beyond 10 years.[16] Maintenance of therapy with interferon is required, however, and some patients experience side effects that preclude continued treatment.

Newly diagnosed patients with very high levels of circulating leukocytes (WBC >100,000/mm³) require immediate therapy with imatinib mesylate to avoid cerebrovascular events or death from leukostasis. Leukophoresis and plateletpheresis are sometimes required for an even more emergent reduction of counts.

References

1. Sawyers CL: Chronic myeloid leukemia. N Engl J Med 340 (17): 1330-40, 1999.  [PUBMED Abstract]
   
   
2. Druker BJ, Guilhot F, O'Brien SG, et al.: Five-year follow-up of patients receiving imatinib for chronic myeloid leukemia. N Engl J Med 355 (23): 2408-17, 2006.  [PUBMED Abstract]
   
   
3. Bhatia R, Holtz M, Niu N, et al.: Persistence of malignant hematopoietic progenitors in chronic myelogenous leukemia patients in complete cytogenetic remission following imatinib mesylate treatment. Blood 101 (12): 4701-7, 2003.  [PUBMED Abstract]
   
   
4. Hughes TP, Kaeda J, Branford S, et al.: Frequency of major molecular responses to imatinib or interferon alfa plus cytarabine in newly diagnosed chronic myeloid leukemia. N Engl J Med 349 (15): 1423-32, 2003.  [PUBMED Abstract]
   
   
5. Rosti G, Martinelli G, Bassi S, et al.: Molecular response to imatinib in late chronic-phase chronic myeloid leukemia. Blood 103 (6): 2284-90, 2004.  [PUBMED Abstract]
   
   
6. Kantarjian HM, Talpaz M, O'Brien S, et al.: Survival benefit with imatinib mesylate versus interferon-alpha-based regimens in newly diagnosed chronic-phase chronic myelogenous leukemia. Blood 108 (6): 1835-40, 2006.  [PUBMED Abstract]
   
   
7. Baccarani M, Saglio G, Goldman J, et al.: Evolving concepts in the management of chronic myeloid leukemia: recommendations from an expert panel on behalf of the European LeukemiaNet. Blood 108 (6): 1809-20, 2006.  [PUBMED Abstract]
   
   
8. Jabbour E, Cortes J, Kantarjian HM, et al.: Allogeneic stem cell transplantation for patients with chronic myeloid leukemia and acute lymphocytic leukemia after Bcr-Abl kinase mutation-related imatinib failure. Blood 108 (4): 1421-3, 2006.  [PUBMED Abstract]
   
   
9. Kantarjian H, Giles F, Wunderle L, et al.: Nilotinib in imatinib-resistant CML and Philadelphia chromosome-positive ALL. N Engl J Med 354 (24): 2542-51, 2006.  [PUBMED Abstract]
   
   
10. Talpaz M, Shah NP, Kantarjian H, et al.: Dasatinib in imatinib-resistant Philadelphia chromosome-positive leukemias. N Engl J Med 354 (24): 2531-41, 2006.  [PUBMED Abstract]
    
    
11. Hochhaus A, Kantarjian HM, Baccarani M, et al.: Dasatinib induces notable hematologic and cytogenetic responses in chronic-phase chronic myeloid leukemia after failure of imatinib therapy. Blood 109 (6): 2303-9, 2007.  [PUBMED Abstract]
    
    
12. Quintas-Cardama A, Kantarjian H, Jones D, et al.: Dasatinib (BMS-354825) is active in Philadelphia chromosome-positive chronic myelogenous leukemia after imatinib and nilotinib (AMN107) therapy failure. Blood 109 (2): 497-9, 2007.  [PUBMED Abstract]
    
    
13. Cortes J, Rousselot P, Kim DW, et al.: Dasatinib induces complete hematologic and cytogenetic responses in patients with imatinib-resistant or -intolerant chronic myeloid leukemia in blast crisis. Blood 109 (8): 3207-13, 2007.  [PUBMED Abstract]
    
    
14. Kantarjian H, Pasquini R, Hamerschlak N, et al.: Dasatinib or high-dose imatinib for chronic-phase chronic myeloid leukemia after failure of first-line imatinib: a randomized phase 2 trial. Blood 109 (12): 5143-50, 2007.  [PUBMED Abstract]
    
    
15. Guilhot F, Apperley J, Kim DW, et al.: Dasatinib induces significant hematologic and cytogenetic responses in patients with imatinib-resistant or -intolerant chronic myeloid leukemia in accelerated phase. Blood 109 (10): 4143-50, 2007.  [PUBMED Abstract]
    
    
16. Lee SJ, Anasetti C, Horowitz MM, et al.: Initial therapy for chronic myelogenous leukemia: playing the odds. J Clin Oncol 16 (9): 2897-903, 1998.  [PUBMED Abstract]
    
    
17. Ozer H, George SL, Schiffer CA, et al.: Prolonged subcutaneous administration of recombinant alpha 2b interferon in patients with previously untreated Philadelphia chromosome-positive chronic-phase chronic myelogenous leukemia: effect on remission duration and survival: Cancer and Leukemia Group B study 8583. Blood 82 (10): 2975-84, 1993.  [PUBMED Abstract]
    
    
18. Kantarjian HM, Smith TL, O'Brien S, et al.: Prolonged survival in chronic myelogenous leukemia after cytogenetic response to interferon-alpha therapy. The Leukemia Service. Ann Intern Med 122 (4): 254-61, 1995.  [PUBMED Abstract]
    
    
19. Long-term follow-up of the Italian trial of interferon-alpha versus conventional chemotherapy in chronic myeloid leukemia. The Italian Cooperative Study Group on Chronic Myeloid Leukemia. Blood 92 (5): 1541-8, 1998.  [PUBMED Abstract]
    
    

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