BCR::ABL1 levels at first month after TKI discontinuation predict subsequent maintenance of treatment-free remission: A study from the "GRUPPO TRIVENETO LMC"

Treatment free remission (TFR) after second-generation tyrosine kinase inhibitors (2G-TKIs) treatment in chronic myeloid leukemia (CML): from feasibility to safety

INTRODUCTION

Chronic myeloid leukemia (CML) prevalence is currently increasing due to the great efficacy of tyrosine kinase inhibitor (TKI) therapy. Discontinuation of treatment in the long-term, owing to avoid off-target side effects or treatment-free remission (TFR), has become an additional treatment goal in CML patients who achieved a deep molecular response (DMR). Second-generation TKIs (2 G-TKIs) have a significantly higher rate of DMR than imatinib. Hence, especially in young patients with a strategy of TFR, 2 G-TKIs are becoming the most frequently used TKIs and may increase TFR attempts in the future.

AREAS COVERED

In this review, the main findings extrapolated from clinical trials and real-life evidence regarding 2 G-TKIs discontinuation were discussed, through broad research on Medline, Embase, and archives from EHA and ASH congresses.

EXPERT OPINION

Overall, TFR rate after 2 G-TKIs is ranging from 40% to 60% for selected patients with sustained DMR and it can be considered a safe procedure, that have become, nowadays, a daily practice. However, many crucial aspects regarding treatment choices, timings, as well as predictive factors, patient communication, and optimal strategies need to be better clarified to improve successful TFR rate.

Molecular BCR::ABL1 Quantification and ABL1 Mutation Detection as Essential Tools for the Clinical Management of Chronic Myeloid Leukemia Patients: Results from a Brazilian Single-Center Study

Chronic myeloid leukemia (CML) is a well-characterized oncological disease in which virtually all patients possess a translocation (9;22) that generates the tyrosine kinase BCR::ABL1 protein. This translocation represents one of the milestones in molecular oncology in terms of both diagnostic and prognostic evaluations. The molecular detection of the BCR::ABL1 transcription is a required factor for CML diagnosis, and its molecular quantification is essential for assessing treatment options and clinical approaches. In the CML molecular context, point mutations on the ABL1 gene are also a challenge for clinical guidelines because several mutations are responsible for tyrosine kinase inhibitor resistance, indicating that a change may be necessary in the treatment protocol. So far, the European LeukemiaNet and the National Comprehensive Cancer Network (NCCN) have presented international guidelines on CML molecular approaches, especially those related to BCR::ABL1 expression. In this study, we show almost three years' worth of data regarding the clinical treatment of CML patients at the Erasto Gaertner Hospital, Curitiba, Brazil. These data primarily comprise 155 patients and 532 clinical samples. BCR::ABL1 quantification by a duplex-one-step RT-qPCR and ABL1 mutations detection were conducted. Furthermore, digital PCR for both BCR::ABL1 expression and ABL1 mutations were conducted in a sub-cohort. This manuscript describes and discusses the clinical importance and relevance of molecular biology testing in Brazilian CML patients, demonstrating its cost-effectiveness.