A Comparative Study of Leukemic Stem Cells in Patients With BCR-ABL-positive Hematopoiesis and Chronic Myeloid Leukemia Patients With BCR-ABL Activity Inhibition Under Tyrosine Kinase Inhibitor Treatment

In the present study, its aimed to compare the amount of CD45+/CD34+/CD38-/CD26+ levels of CML stem cells in CML patients with and without BCR-ABL hematopoiesis. Therefore, the amount of CD45+/CD34+/CD38-/CD26+ levels of CML stem cells in CML patients will be analyzed using bone marrow and peripheral blood samples and whether leukemic stem cells are present in the bone marrow and at what amount, if present, although these cells are cleared from the peripheral blood, will be investigated. Additionally this study would pave the way for further cellular treatment strategies against CML stem cells, being the pioneer of development of curative treatments in CML. Until now, TKI discontinuation studies have failed in patients with long-term BCR-ABL negativity. There is a chance for cure in patients in whom the BCR-ABL status becomes negative with chimeric antigen receptor (CAR) T-cell treatment modalities which target leukemic stem cells. Also, monoclonal antibodies and/or cellular treatments targeting leukemic stem cells are the main treatment strategy is to reduce the CML treatment-related cost. In the international platform, the accurate definition of leukemic stem cell in CML and development of targeted cellular treatments have been also paid a great attention with a given priority for patent application. The primary objective of the present study is to accurately detect leukemic stem cells in CML and to estimate the threshold value for the prediction of recurrence or cure.

To the best of investigators knowledge, there is a very limited number of studies in the literature and there is no study available comparing leukemic stem cells (CD45+/CD34+/CD38-/CD26+) in patients with BCR-ABL-positive hematopoiesis and CML patients with BCR-ABL activity inhibition under TKI therapy in Turkey. Therefore,for the first time, it is planned to evaluate the prognostic value of the amount of leukemic stem cells in CML and to tailor individual treatment options.

Newly diagnosed CML patients or patients with a previous diagnosis under follow-up with or without TKIs will be included in this study. The patients will be divided into two groups as follows:

Group 1: Patients with BCR-ABL-positive hematopoiesis (newly diagnosed CML patients, CML patients with leukocytosis, CML patients without a hematological and/or cytogenetic and/or molecular response, CML patients whose BCR-ABL status becomes negative and then positive) will be included.

Group 2: Patients with CML with BCR-ABL activity inhibition under TKI therapy (patients with major molecular response (MMR) and/or deeper response) will be included.