scholarly journals Leukemia Stem Cells as a Potential Target to Achieve Therapy-Free Remission in Chronic Myeloid Leukemia

Cancers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 5822
Author(s):  
Kyoko Ito ◽  
Keisuke Ito

Leukemia stem cells (LSCs, also known as leukemia-initiating cells) not only drive leukemia initiation and progression, but also contribute to drug resistance and/or disease relapse. Therefore, eradication of every last LSC is critical for a patient’s long-term cure. Chronic myeloid leukemia (CML) is a myeloproliferative disorder that arises from multipotent hematopoietic stem and progenitor cells. Tyrosine kinase inhibitors (TKIs) have dramatically improved long-term outcomes and quality of life for patients with CML in the chronic phase. Point mutations of the kinase domain of BCR-ABL1 lead to TKI resistance through a reduction in drug binding, and as a result, several new generations of TKIs have been introduced to the clinic. Some patients develop TKI resistance without known mutations, however, and the presence of LSCs is believed to be at least partially associated with resistance development and CML relapse. We previously proposed targeting quiescent LSCs as a therapeutic approach to CML, and a number of potential strategies for targeting insensitive LSCs have been presented over the last decade. The identification of specific markers distinguishing CML-LSCs from healthy HSCs, and the potential contributions of the bone marrow microenvironment to CML pathogenesis, have also been explored. Nonetheless, 25% of CML patients are still expected to switch TKIs at least once, and various TKI discontinuation studies have shown a wide range in the incidence of molecular relapse (from 30% to 60%). In this review, we revisit the current knowledge regarding the role(s) of LSCs in CML leukemogenesis and response to pharmacological treatment and explore how durable treatment-free remission may be achieved and maintained after discontinuing TKI treatment.

2021 ◽  
Vol 10 (24) ◽  
pp. 5805
Author(s):  
Mohammad Houshmand ◽  
Alireza Kazemi ◽  
Ali Anjam Najmedini ◽  
Muhammad Shahzad Ali ◽  
Valentina Gaidano ◽  
...  

Chronic myeloid leukemia stem cells (CML LSCs) are a rare and quiescent population that are resistant to tyrosine kinase inhibitors (TKI). When TKI therapy is discontinued in CML patients in deep, sustained and apparently stable molecular remission, these cells in approximately half of the cases restart to grow, resuming the leukemic process. The elimination of these TKI resistant leukemic stem cells is therefore an essential step in increasing the percentage of those patients who can reach a successful long-term treatment free remission (TFR). The understanding of the biology of the LSCs and the identification of the differences, phenotypic and/or metabolic, that could eventually allow them to be distinguished from the normal hematopoietic stem cells (HSCs) are therefore important steps in designing strategies to target LSCs in a rather selective way, sparing the normal counterparts.


Blood ◽  
2010 ◽  
Vol 115 (16) ◽  
pp. 3185-3195 ◽  
Author(s):  
Mirle Schemionek ◽  
Christian Elling ◽  
Ulrich Steidl ◽  
Nicole Bäumer ◽  
Ashley Hamilton ◽  
...  

Abstract In a previously developed inducible transgenic mouse model of chronic myeloid leukemia, we now demonstrate that the disease is transplantable using BCR-ABL+ Lin−Sca-1+c-kit+ (LSK) cells. Interestingly, the phenotype is more severe when unfractionated bone marrow cells are transplanted, yet neither progenitor cells (Lin−Sca-1−c-kit+), nor mature granulocytes (CD11b+Gr-1+), nor potential stem cell niche cells (CD45−Ter119−) are able to transmit the disease or alter the phenotype. The phenotype is largely independent of BCR-ABL priming before transplantation. However, prolonged BCR-ABL expression abrogates the potential of LSK cells to induce full-blown disease in secondary recipients and increases the fraction of multipotent progenitor cells at the expense of long-term hematopoietic stem cells (LT-HSCs) in the bone marrow. BCR-ABL alters the expression of genes involved in proliferation, survival, and hematopoietic development, probably contributing to the reduced LT-HSC frequency within BCR-ABL+ LSK cells. Reversion of BCR-ABL, or treatment with imatinib, eradicates mature cells, whereas leukemic stem cells persist, giving rise to relapsed chronic myeloid leukemia on reinduction of BCR-ABL, or imatinib withdrawal. Our results suggest that BCR-ABL induces differentiation of LT-HSCs and decreases their self-renewal capacity.


Blood ◽  
2011 ◽  
Vol 118 (10) ◽  
pp. 2849-2856 ◽  
Author(s):  
Steven W. Lane ◽  
Yingzi J. Wang ◽  
Cristina Lo Celso ◽  
Christine Ragu ◽  
Lars Bullinger ◽  
...  

Abstract Hematopoietic stem cells (HSCs) engage in complex bidirectional signals with the hematopoietic microenvironment (HM), and there is emerging evidence that leukemia stem cells (LSCs) may use similar interactions. Using a syngeneic retroviral model of MLL-AF9 induced acute myeloid leukemia (AML), we have identified 2 different stages of leukemia progression, propagated by “pre-LSCs” and established leukemia (LSCs) and compared the homing properties of these distinctive entities to that of normal HSCs. The homing and microlocalization of pre-LSCs was most similar to long-term HSCs and was dependent on cell-intrinsic Wnt signaling. In contrast, the homing of established LSCs was most similar to that of committed myeloid progenitors and distinct from HSCs. Although osteoblast-derived Dickkopf-1, a potent Wnt inhibitor known to impair HSC function, dramatically impaired normal HSC localization within the bone marrow, it did not affect pre-LSCs, LSC homing, or AML development. Mechanistically, cell-intrinsic Wnt activation was observed in human and murine AML samples, explaining the independence of MLL-AF9 LSCs from niche-derived Wnt signals. These data identify differential engagement of HM associated with leukemic progression and identify an LSC niche that is physically distinct and independent of the constraints of Wnt signaling that apply to normal HSCs.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 883-883 ◽  
Author(s):  
Jean-Claude Chomel ◽  
Marie Laure Bonnet ◽  
Nathalie Sorel ◽  
Angelina Bertrand ◽  
Marie Claude Meunier ◽  
...  

Abstract Abstract 883 Currently Imatinib Mesylate (IM) represent the first line therapy for chronic myeloid leukemia (CML). Recent data suggest that despite unprecedented rates of complete cytogenetic responses (CCR) and major molecular responses (MMR) obtained, leukemic stem cells (LSC) persist in the majority of patients (pts). LSC have been shown to be resistant to in vitro treatments with tyrosine kinase inhibitors (TKI). Consequently, discontinuation of IM in pts with undetectable molecular residual leukemia (UMRL) attested by RQ-PCR, leads to molecular relapses in the majority of the cases. Although the persistence of CD34+ CD38- leukemic stem cells has been demonstrated in pts with complete cytogenetic remission (CCR), the persistence of BCR-ABL+ leukemic stem cells in UMRL pts with has not been studied so far. For this purpose, we have performed an extensive analysis of bone-marrow-derived clonogenic and primitive hematopoietic stem cells in 6 pts with RQ-PCR constantly negative in their blood samples. Concerning the treatments; 5 out of 6 pts were off therapy, 3 pts (UPN1, 2, 3) had been treated with interferon-a only (IFN) for 6–13 years and their therapy was discontinued for 11, 16 and 8 years, respectively and 2 pts (UPN4 and 5) had been treated successively with IFN and IM and their IM therapy was discontinued for 2 years. One patient (UPN6) had been treated with IM followed by dasatinib and was on dasatinib at the time of the study. UPN7 was previously treated with first IFN then IM (which induced a stable UMRL) and then she switched to dasatinib because of side effect with IM. Bone marrow cells were collected and CD34+ cells purified using immunomagnetic columns. After performing a clonogenic assay, CD34+ cells were used in long-term culture initiating cell (LTC-IC) assays with weekly half medium changes. At week+5, clonogenic assays were performed and LTC-IC-derived clonogenic cells activity was calculated. For each patient 20 individual and 20 pools of 10 clonogenic cells and 20 individual and 20 pools of 10 LTC-IC derived CFU-C were plucked in order to obtain information in at least 220 CFU-C. After RNA extraction, BCR-ABL was quantified by RQ-PCR and in each positive CFU-C a nested PCR was performed to confirm the results. In one patient (UPN7) a NOD/SCID mouse assay was performed. All 3 pts treated with IFN alone, had BCR-ABL+ clonogenic cells varying from 0.5% (UPN1, 2) to 45 % (UPN3). All 3 had LTC-IC derived CFU-C positive for BCR-ABL (UPN1: 20%; UPN2 5%; UPN3 3%). In two pts previously treated with IFN and IM, clonogenic CFU-C BCR-ABL positivity was 10% and 5% whereas LTC-IC-derived CFU-C was 5% in UPN4) and undetected on UPN5. In UPN6 treated with IM then dasatinib, 5% of CFU-C was BCR-ABL+ whereas 100% of LTC-IC derived CFU-C was positive. The analysis of SCID-NOD assays performed in CD34+ cells from patient UPN7 is ongoing. Overall, these data show, for the first time to our knowledge, that in pts in IFN and IFN/IM-induced long-term remissions, there is persistent clonogenic BCR-ABL+ output maintained by BCR-ABL-expressing stem cells in the absence of relapse. In the only patient with successively treated with IM and dasatinib, 100 % of primitive hematopoietic stem cells are BCR-ABL+, despite PCR-negativity in peripheral blood, suggesting their possible quiescence in vivo and highlighting a theoretical risk of relapse. It remains to be determined if in pts with TKI-induced remissions, the analysis of stem cell compartments could be of use for clinical decisions to discontinue therapy. Disclosures: No relevant conflicts of interest to declare.


2014 ◽  
Vol 6 (252) ◽  
pp. 252ra121-252ra121 ◽  
Author(s):  
Leyuan Ma ◽  
Yi Shan ◽  
Robert Bai ◽  
Liting Xue ◽  
Christopher A. Eide ◽  
...  

Resistance to the BCR-ABL inhibitor imatinib mesylate (IM) poses a major problem for the treatment of chronic myeloid leukemia (CML). IM resistance often results from a secondary mutation in BCR-ABL that interferes with drug binding. However, in many instances, there is no mutation in BCR-ABL, and the basis of such BCR-ABL–independent IM resistance remains to be elucidated. To gain insight into BCR-ABL–independent IM resistance mechanisms, we performed a large-scale RNA interference screen and identified IM-sensitizing genes (IMSGs) whose knockdown renders BCR-ABL+cells IM-resistant. In these IMSG knockdown cells, RAF/mitogen-activated protein kinase kinase (MEK)/extracellular signal–regulated kinase (ERK) signaling is sustained after IM treatment because of up-regulation ofPRKCH, which encodes the protein kinase C (PKC) family member PKCη, an activator of CRAF.PRKCHis also up-regulated in samples from CML patients with BCR-ABL–independent IM resistance. Combined treatment with IM and trametinib, a U.S. Food and Drug Administration–approved MEK inhibitor, synergistically kills BCR-ABL+IMSG knockdown cells and prolongs survival in mouse models of BCR-ABL–independent IM-resistant CML. Finally, we showed that CML stem cells contain high levels ofPRKCH, and this contributes to their intrinsic IM resistance. Combined treatment with IM and trametinib synergistically kills CML stem cells with negligible effect on normal hematopoietic stem cells. Collectively, our results identify a therapeutically targetable mechanism of BCR-ABL–independent IM resistance in CML and CML stem cells.


2021 ◽  
Author(s):  
Huixin Li ◽  
Shunichiro Yasuda ◽  
Satoru Aoyama ◽  
Chenyang Zhang ◽  
Yohei Kawano ◽  
...  

2011 ◽  
Vol 121 (3) ◽  
pp. 1222-1222 ◽  
Author(s):  
Amie S. Corbin ◽  
Anupriya Agarwal ◽  
Marc Loriaux ◽  
Jorge Cortes ◽  
Michael W. Deininger ◽  
...  

Blood ◽  
1993 ◽  
Vol 81 (3) ◽  
pp. 801-807 ◽  
Author(s):  
T Leemhuis ◽  
D Leibowitz ◽  
G Cox ◽  
R Silver ◽  
EF Srour ◽  
...  

Chronic myeloid leukemia (CML) is a malignant disorder of the hematopoietic stem cell. It has been shown that normal stem cells coexist with malignant stem cells in the bone marrow of patients with chronic-phase CML. To characterize the primitive hematopoietic progenitor cells within CML marrow, CD34+DR- and CD34+DR+ cells were isolated using centrifugal elutriation, monoclonal antibody labeling, and flow cytometric cell sorting. Polymerase chain reaction analysis of RNA samples from these CD34+ subpopulations was used to detect the presence of the BCR/ABL translocation characteristic of CML. The CD34+DR+ subpopulation contained BCR/ABL(+) cells in 11 of 12 marrow samples studied, whereas the CD34+DR- subpopulation contained BCR/ABL(+) cells in 6 of 9 CML marrow specimens. These cell populations were assayed for hematopoietic progenitor cells, and individual hematopoietic colonies were analyzed by PCR for their BCR/ABL status. Results from six patients showed that nearly half of the myeloid colonies cloned from CD34+DR- cells were BCR/ABL(+), although the CD34+DR- subpopulation contained significantly fewer BCR/ABL(+) progenitor cells than either low-density bone marrow (LDBM) or the CD34+DR+ fraction. These CD34+ cells were also used to establish stromal cell-free long-term bone marrow cultures to assess the BCR/ABL status of hematopoietic stem cells within these CML marrow populations. After 28 days in culture, three of five cultures initiated with CD34+DR- cells produced BCR/ABL(-) cells. By contrast, only one of eight cultures initiated with CD34+DR+ cells were BCR/ABL(-) after 28 days. These results indicate that the CD34+DR- subpopulation of CML marrow still contains leukemic progenitor cells, although to a lesser extent than either LDBM or CD34+DR+ cells.


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