BACKGROUND: Since the beginning of the tyrosine-kinase inhibitor (TKI) era in the treatment of chronic myeloid leukemia (CML), there have been attempts to stratify patients for optimal management. An essential requirement for perfect stratification was the identification of factors capable of predicting long-term response [1]. The Sokal and Hasford scores were developed in the chemotherapy and interferon alfa eras, respectively [2]. The EUTOS score was found to predict probability of complete cytogenetic response (CCyR) within 18 months of Imatinib initiation and progression-free survival (PFS) for patients receiving Imatinib [3]. However, the usefulness of the EUTOS score in predicting survival and outcome in patients with early chronic phase CML treated with TKI was questioned [4]. The Hasford score failed to differentiate patients who achieved low and intermediate risk scores according to CCyR, MMR, and 5 years EFS [5] and in our study we found Hasford score correlated with the long-term molecular response.

PATIENTS AND RESULTS: We analyzed a cohort of 88 patients (F/M:42/46, median age 51 (21-83)) receiving standard dose Imatinib treatment for first chronic phase of CML. As assessed by Hasford risk analysis, the group comprised 57 low risk and 31 intermediate risk patients. In the initial group of patients, there were 5 high risk patients who were excluded from the study. No additional chromosomal abnormalities were identified at diagnosis. All patients achieved complete cytogenetic response (CCyR) and major molecular response (MMR) at time points defined by the European Leukemia Net (ELN). Of these, 42 patients lost MMR in a median time of 47 months. Within this group we identified 20 low risk (LR) and 22 intermediate risk (IR) patients. There was a significant difference in maintenance of the MMR between IR and LR patients (p=0.03, Figure 1). This analysis revealed that all intermediate risk patients lost MMR after approximately 85 months of Imatinib treatment, while 62% of the low risk patients maintained MMR throughout this time frame. During analysis, all 42 patients were switched to second generation TKI. After 3 months of second generation TKI treatment, median bcr-abl transcript levels in the LR group were 0.01 (0.000-0.295) but in the IR group bcr-abl levels were 0.301 (0.000-44.5) (p=0.0006, Figure 2).

CONCLUSIONS: As the Hasford metric was designed for assessing patients treated with interferon alpha, we found our results to be interesting, and to be relevant to the discussion on optimizing scoring systems in chronic myeloid leukemia patients. If the observed difference between low and intermediate risk patients in maintaining MMR on Imatinib is confirmed, IR patients will become candidates for different first line treatment. Despite clinical studies, the choice between Imatinib and second generation TKI as the first line treatment remains an issue. Our results (if confirmed) promise to directly impact treatment decisions affecting IR patients.

References:

1. Breccia M, Alimena G. Bringing prognostic scores for chronic myeloid leukemia patients up to date. Expert Rev Hematol. 2011 Aug;4(4):373-5.

2. Hu B1, Savani BN. Impact of risk score calculations in choosing front-line tyrosine kinase inhibitors for patients with newly diagnosed chronic myeloid leukemia in the chronic phase. Eur J Haematol. 2014 Apr 26.

3. Hasford J1, Baccarani M, Hoffmann V, Guilhot J, Saussele S, Rosti G, Guilhot F, Porkka K, Ossenkoppele G, Lindoerfer D, Simonsson B, Pfirrmann M, Hehlmann R. Predicting complete cytogenetic response and subsequent progression-free survival in 2060 patients with CML on imatinib treatment: the EUTOS score. Blood. 2011 Jul 21;118(3):686-92

4. Jabbour E, Cortes J, Nazha A, O'Brien S, Quintas-Cardama A, Pierce S, Garcia-Manero G, Kantarjian H. EUTOS score is not predictive for survival and outcome in patients with early chronic phase chronic myeloid leukemia treated with tyrosine kinase inhibitors: a single institution experience. Blood. 2012 May 10;119(19):4524-6.

5. Yahng SA, Jang EJ, Choi SY, Oh YJ, Bang JH, Park JE, Jeon HL, Lee SE, Kim SH, Byun JY, Kim DW. Comparison of Sokal, Hasford and EUTOS Scores in Terms of Long-Term Treatment Outcome According to the Risks in Each Prognostic Model: A Single Center Data Analyzed in 255 Early Chronic Phase Chronic Myeloid Leukemia Patients Treated with Frontline Imatinib Mesylate. Blood 2012;120:Abstract 2794

Figure 1
Figure 1.
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Figure 2
Figure 2.
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Disclosures

No relevant conflicts of interest to declare.

Topics:
imatinib mesylate, leukemia, myelocytic, chronic, protein-tyrosine kinase inhibitor, measles-mumps-rubella vaccine, leukemia, myeloid, chronic-phase, bcr-abl tyrosine kinase, interferon-alpha, chemotherapy regimen, leukemia, chromosome abnormality

Author notes

*

Asterisk with author names denotes non-ASH members.

© 2014 by The American Society of Hematology
2014
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