Effects of Deeper Molecular Responses on Outcomes in Chronic Myeloid Leukemia Patients in Chronic Phase Treated With Imatinib Mesylate

Hsa-miR-181a-5p, hsa-miR-182-5p, and hsa-miR-26a-5p as potential biomarkers for BCR-ABL1 among adult chronic myeloid leukemia treated with tyrosine kinase inhibitors at the molecular response

BACKGROUND

Tyrosine kinase inhibitors (TKIs) as first-line therapy for Chronic Myeloid Leukemia (CML) show a high success rate. However, a low number of patients with long-term treatment-free remission (TFR) were observed. Molecular relapse after imatinib discontinuation occurred at 50% at 24 months, with 80% occurrence within the first 6 months. One of the reasons for relapse is untimely TKIs discontinuation caused by large errors from estimates at very low-level or undetectable disease, thus warranting new biomarkers for CML.

METHODS

Next Generation Sequencing (NGS) was used to identify microRNAs (miRNAs) at the molecular response in CML adult patients receiving TKIs treatment. A total of 86 samples were collected, 30 from CML patients responsive and 28 from non-responsive to imatinib therapy, and 28 from blood donors. NGS was conducted whereby 18 miRNAs were selected and validated by real-time RT-qPCR in triplicate.

RESULTS

Hsa-miR-181a-5p was expressed significantly (p-value< 0.05) with 2.14 and 2.33-fold down-regulation in both patient groups, respectively meanwhile hsa-miR-182-5p and hsa-miR-26a-5p were significant only in the non-responsive group with 2.08 and 2.39 fold up-regulation. The down-regulation was consistent with decreased amounts of BCR-ABL1 in patients taking TKIs regardless of molecular responses. The up-regulation was consistent with the substantial presence of BCR-ABL1 in CML patients treated with TKIs at the molecular response.

CONCLUSIONS

Therefore, these miRNAs have potential as new therapeutic biomarkers for BCR-ABL1 status in adult CML patients treated with TKIs at molecular responses. These could improve current approaches and require further analysis to look for targets of these miRNAs in CML.

The Efficacy of Generic Imatinib as First- and Second-line Therapy: 3-Year Follow-up of Patients With Chronic Myeloid Leukemia

INTRODUCTION

Generics of imatinib mesylate, the first tyrosine kinase inhibitor targeting the BCR-ABL1 fusion protein, have recently been approved in many countries as the alternative, low-cost forms for the treatment of patients with chronic myeloid leukemia (CML). The aim of this study was to evaluate the long-term clinical outcomes of patients with CML receiving first-line and second-line generic imatinib in Bosnia and Herzegovina.

PATIENTS AND METHODS

This was a multicenter retrospective cohort study of patients (n = 41) treated with generic imatinib in Bosnia between September 1, 2013 and August 5, 2016. Patients were categorized into 2 study groups: Group 1 (n = 27) included newly diagnosed patients with CML receiving front-line generic imatinib, and Group 2 (n = 14) consisted of patients who started with front-line Glivec and were mandated to switch to the second-line generic imatinib.

RESULTS

The median follow-up for Group 1 (first-line generic imatinib) and Group 2 (second-line generic imatinib) was 16 and 36 months, respectively. At 36 months, the overall survival for patients in Group 1 was 85%, and the achievement of complete cytogenetic response was 81%. At 24 months, the major molecular response rate was 48%. Overall, 52% of patients switched from first-line generic imatinib to nilotinib owing to treatment failure and side-effects. In Group 2, 93% of patients sustained cytogenetic and molecular response at 3 years after the switch from branded to generic imatinib.

CONCLUSION

Our results lead us to conclude that generic imatinib as second-line therapy does not have deleterious effects on patient outcomes. However, first-line generic imatinib showed suboptimal efficacy compared with branded imatinib.