Asciminib resistance of a new BCR::ABL1 p.I293_K294insSSLRD mutant detected in a Ph + ALL patient.

Chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia patients largely benefit from an expanding tyrosine kinase inhibitors (TKIs) toolbox that has improved the outcome of both diseases. However, TKI success is continuously challenged by mutation-driven acquired resistance and therefore, close monitoring of clonal genetic diversity is necessary to ensure proper clinical management and adequate response to treatment. Here, we report the case of a ponatinib-resistant Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL) patient harboring a BCR::ABL1 p.

Integrating allele-specific PCR with CRISPR-Cas13a for sensitive KRAS mutation detection in pancreatic cancer.

Background: The clustered regulatory interspaced short palindromic repeats (CRISPR)-Cas13a system has strong potential for highly sensitive detection of exogenous sequences. The detection of KRAS point mutations with low allele frequencies may prove powerful for the formal diagnosis of pancreatic ductal adenocarcinoma (PDAC).

Results: We implemented preamplification of KRAS alleles (wild-type and mutant) to reveal the presence of mutant KRAS with CRISPR-Cas13a.

In vivo vulnerabilities to GPX4 and HDAC inhibitors in drug-persistent versus drug-resistant BRAF lung adenocarcinoma.

The current targeted therapy for BRAF-mutant lung cancer consists of a dual blockade of RAF/MEK kinases often combining dabrafenib/trametinib (D/T). This regimen extends survival when compared to single-agent treatments, but disease progression is unavoidable. By using whole-genome CRISPR screening and RNA sequencing, we characterize the vulnerabilities of both persister and D/T-resistant cellular models.

CRISPR Base Editing to Create Potential Charcot-Marie-Tooth Disease Models with High Editing Efficiency: Human Induced Pluripotent Stem Cell Harboring Variants.

Human induced pluripotent stem cells (hiPSCs) represent a powerful tool to investigate neuropathological disorders in which the cells of interest are inaccessible, such as in the Charcot-Marie-Tooth disease (CMT), the most common inherited peripheral neuropathy. Developing appropriate cellular models becomes crucial in order to both study the disease's pathophysiology and test new therapeutic approaches. The generation of hiPS cellular models for disorders caused by a single nucleotide variation has been significantly improved following the development of CRISPR-based editing tools.

Specific High-Sensitivity Enzymatic Reporter UnLOCKing-Mediated Detection of Oncogenic and Rearrangements.

Advances in molecular medicine have placed nucleic acid detection methods at the center of an increasing number of clinical applications. Polymerase chain reaction (PCR)-based diagnostics have been widely adopted for their versatility, specificity, and sensitivity. However, recently reported clustered regularly interspaced short palindromic repeats-based methods have demonstrated equivalent to superior performance, with increased portability and reduced processing time and cost.

Antimetabolic cooperativity with the clinically approved l-asparaginase and tyrosine kinase inhibitors to eradicate CML stem cells.

Objective: Long-term treatment with tyrosine kinase inhibitors (TKI) represents an effective cure for chronic myeloid leukemia (CML) patients and discontinuation of TKI therapy is now proposed to patient with deep molecular responses. However, evidence demonstrating that TKI are unable to fully eradicate dormant leukemic stem cells (LSC) indicate that new therapeutic strategies are needed to control LSC and to prevent relapse. In this study we investigated the metabolic pathways responsible for CML surviving to imatinib exposure and its potential therapeutic utility to improve the efficacy of TKI against stem-like CML cells.

Relevance of treatment-free remission recommendations in chronic phase chronic leukemia patients treated with frontline tyrosine kinase inhibitors.

Background: Tyrosine kinase inhibitors (TKI) can be safely discontinued in chronic phase chronic myeloid leukemia (CP-CML) patients who had achieved a sustained deep molecular response. Based on the results of discontinuation trials, recommendations regarding patient selection for a treatment-free remission (TFR) attempt had been proposed. The aims of this study were to evaluate the rate of patients eligible for TKI discontinuation and molecular recurrence-free survival (MRFS) after stop according to recommendations.

Incidences of Deep Molecular Responses and Treatment-Free Remission in de Novo CP-CML Patients.

Tyrosine Kinase Inhibitors (TKIs) discontinuation in patients who had achieved a deep molecular response (DMR) offer now the opportunity of prolonged treatment-free remission (TFR). Aims of this study were to evaluate the proportion of de novo chronic-phase chronic myeloid leukemia (CP-CML) patients who achieved a sustained DMR and to identify predictive factors of DMR and molecular recurrence-free survival (MRFS) after TKI discontinuation. Over a period of 10 years, 398 CP-CML patients treated with first-line TKIs were included.

A genome-scale CRISPR knock-out screen in chronic myeloid leukemia identifies novel drug resistance mechanisms along with intrinsic apoptosis and MAPK signaling.

Understanding resistance mechanisms in cancer is of utmost importance for the discovery of novel "druggable" targets. Efficient genetic screening, now even more possible with CRISPR-Cas9 gene-editing technology, next-generation sequencing and bioinformatics, is an important tool for deciphering novel cellular processes, such as resistance to treatment in cancer. Imatinib specifically eliminates chronic myeloid leukemia (CML) cells by targeting and blocking the kinase activity of BCR-ABL1; however, resistance to treatment exists.

Inhibition of DDR1 enhances in vivo chemosensitivity in KRAS-mutant lung adenocarcinoma.

Platinum-based chemotherapy in combination with immune-checkpoint inhibitors is the current standard of care for patients with advanced lung adenocarcinoma (LUAD). However, tumor progression evolves in most cases. Therefore, predictive biomarkers are needed for better patient stratification and for the identification of new therapeutic strategies, including enhancing the efficacy of chemotoxic agents.

The Expression of Myeloproliferative Neoplasm-Associated Calreticulin Variants Depends on the Functionality of ER-Associated Degradation.

Background: Mutations in observed in myeloproliferative neoplasms (MPN) were recently shown to be pathogenic via their interaction with MPL and the subsequent activation of the Janus Kinase - Signal Transducer and Activator of Transcription (JAK-STAT) pathway. However, little is known on the impact of those variant CALR proteins on endoplasmic reticulum (ER) homeostasis.

Methods: The impact of the expression of Wild Type (WT) or mutant CALR on ER homeostasis was assessed by quantifying the expression level of Unfolded Protein Response (UPR) target genes, splicing of X-box Binding Protein 1 (XBP1), and the expression level of endogenous lectins.

Novel analytical methods to interpret large sequencing data from small sample sizes.

Background: Targeted therapies have greatly improved cancer patient prognosis. For instance, chronic myeloid leukemia is now well treated with imatinib, a tyrosine kinase inhibitor. Around 80% of the patients reach complete remission.

Incidence and outcome of BCR-ABL mutated chronic myeloid leukemia patients who failed to tyrosine kinase inhibitors.

Purpose: To assess the incidence of BCR-ABL kinase domain (KD) mutation detection and its prognostic significance in chronic phase chronic myeloid leukemia (CP-CML) patients treated with tyrosine kinase inhibitors (TKIs).

Patients And Methods: We analyzed characteristics and outcome of 253 CP-CML patients who had at least one mutation analysis performed using direct sequencing. Of them, 187 patients were early CP (ECP) and 66 were late CP late chronic phase (LCP) and 88% were treated with Imatinib as first-line TKI.

Killer immunoglobulin-like receptor genotypes and chronic myeloid leukemia outcomes after imatinib cessation for treatment-free remission.

Background: Natural Killer (NK) cells are innate lymphoid cells that can be cytotoxic toward a large panel of solid tumors and hematological malignancies including chronic myeloid leukemia (CML). Such a cytotoxicity depends on various receptors. Killer immunoglobulin-like receptors (KIR) belong to these receptors and are involved in maturation process, then in the activation abilities of NK cells.

Impact of second decline rate of BCR-ABL1 transcript on clinical outcome of chronic phase chronic myeloid leukemia patients on imatinib first-line.

Early molecular response has been associated with clinical outcome in chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitors. The BCR-ABL1 transcript rate decline from baseline to 3 months has been demonstrated to be more predictive than a single BCR-ABL1 level at 3 months (M3). However, it cannot be used routinely because ABL1, as an internal gene control, is not reliable for BCR-ABL1 quantification above 10%.

Dasatinib-Loaded Erythrocytes Trigger Apoptosis in Untreated Chronic Myelogenous Leukemic Cells: A Cellular Reservoir Participating in Dasatinib Efficiency.

Dasatinib is an ABL1 tyrosine kinase inhibitor (TKI) with a short in vivo plasmatic half-life but with good efficiency, which is not fully understood. We investigated the possibility that circulating erythrocytes store and then provide dasatinib to target cells. In vitro coincubation of dasatinib-treated cells with naïve leukemic cells followed by analysis of kinase inhibition, apoptosis induction, fluorescent molecule exchanges, and dasatinib dosage were performed.

A new mechanism of resistance to ABL1 tyrosine kinase inhibitors in a BCR-ABL1-positive cell line.

Tyrosine kinase inhibitors (TKI) constitute the frontline treatment for chronic myeloid leukemia patients. Dasatinib, a second-generation TKI, was developed to overcome TKI resistances. However, dasatinib resistances are also described but remain less characterized.

Loss of mutL homolog-1 (MLH1) expression promotes acquisition of oncogenic and inhibitor-resistant point mutations in tyrosine kinases.

Genomic instability drives cancer progression by promoting genetic abnormalities that allow for the multi-step clonal selection of cells with growth advantages. We previously reported that the IL-9-dependent TS1 cell line sequentially acquired activating substitutions in JAK1 and JAK3 upon successive selections for growth factor independent and JAK inhibitor-resistant cells, suggestive of a defect in mutation avoidance mechanisms. In the first part of this paper, we discovered that the gene encoding mutL homolog-1 (MLH1), a key component of the DNA mismatch repair system, is silenced by promoter methylation in TS1 cells.

A single nucleotide polymorphism in cBIM is associated with a slower achievement of major molecular response in chronic myeloid leukaemia treated with imatinib.

Purpose: BIM is essential for the response to tyrosine-kinase inhibitors (TKI) in chronic myeloid leukaemia (CML) patients. Recently, a deletion polymorphism in intron 2 of the BIM gene was demonstrated to confer an intrinsic TKI resistance in Asian patients. The present study aimed at identifying mutations in the BIM sequence that could lead to imatinib resistance independently of BCR-ABL mutations.

ABT-737 increases tyrosine kinase inhibitor-induced apoptosis in chronic myeloid leukemia cells through XIAP downregulation and sensitizes CD34(+) CD38(-) population to imatinib.

Chronic myeloid leukemia (CML) tumorigenicity is driven by the oncogenic BCR-ABL tyrosine kinase. Specific tyrosine kinase inhibitors (TKI) have been designed and are now used for the treatment of CML. These TKI induce apoptosis in leukemic cells in a BIM-dependent mechanism.

α-defensin 1-3 and α-defensin 4 as predictive markers of imatinib resistance and relapse in CML patients.

Objective: Imatinib mesylate is a tyrosine kinase inhibitor used as first line treatment in chronic myeloid leukaemia. Despite a remarkable effectiveness, treatment failure cases have been reported in 20 percent of CML patients. The identification of biomarkers which can predict the response to imatinib is our point of interest.

Evidence that resistance to nilotinib may be due to BCR-ABL, Pgp, or Src kinase overexpression.

Targeting the tyrosine kinase activity of Bcr-Abl is an attractive therapeutic strategy in chronic myeloid leukemia (CML) and in Bcr-Abl-positive acute lymphoblastic leukemia. Whereas imatinib, a selective inhibitor of Bcr-Abl tyrosine kinase, is now used in frontline therapy for CML, second-generation inhibitors of Bcr-Abl tyrosine kinase such as nilotinib or dasatinib have been developed for the treatment of imatinib-resistant or imatinib-intolerant disease. In the current study, we generated nilotinib-resistant cell lines and investigated their mechanism of resistance.

Proteomic analysis of an imatinib-resistant K562 cell line highlights opposing roles of heat shock cognate 70 and heat shock 70 proteins in resistance.

Understanding the molecular basis of resistance to imatinib, a tyrosine kinase inhibitor used as front-line therapy in chronic myeloid leukemia, remains a challenge for successful treatment. In an attempt to identify new mechanisms of resistance, we performed a comparative proteomic analysis of an imatinib-resistant cell line generated from the erythroblastic cell line K562 (K562-r) for which no known mechanism of resistance has been detected. Bidimensional gel electrophoresis was carried out to compare the protein expression pattern of imatinib-sensitive and of imatinib-resistant K562 cells.