Detection of BCR-ABL kinase domain mutations in CD34+ cells from newly diagnosed chronic phase CML patients and their association with imatinib resistance

BCR-ABL kinase domain (KD) mutations, the most common cause of imatinib resistance, are infrequently detected in newly diagnosed chronic-phase chronic myeloid leukemia (CP-CML) patients. Recent studies indicate pre-existing mutations (PEMs) can be detected in a higher percentage of CML patients using CD34+ stem/progenitor cells, and these mutations may correlate with imatinib resistance. We investigated KD mutations in CD34+ stem cells from 100 CP-CML patients by multiplex ASO-PCR and sequencing ASO-PCR products at the time of diagnosis. PEMs were detected in 32/100 patients and included F311L, M351T, and T315I. After a median follow-up of 30 months (range 8-48), all patients with PEMs exhibited imatinib resistance. Of 68 patients without PEMs, 24 developed imatinib resistance. Mutations were detected in 21 of these patients by ASO-PCR and KD sequencing. All 32 patients with PEMs had the same mutations. In imatinib-resistant patients without PEMs, we detected F311L, M351T, Y253F, and T315I mutations. All imatinib-resistant patients without T315I and Y253F mutations responded to imatinib dose escalation. In conclusion, BCR-ABL PEMs can be detected in a substantial number of CP-CML patients when investigated using CD34+ stem/progenitor cells. These mutations are associated with imatinib resistance, and mutation testing using CD34+ cells may facilitate improved, patient-tailored treatment

Imatinib-induced interstitial pneumonitis – a literature review and case report

Imatinib is generally well tolerated, with mild common side effects such as nausea and vomiting, diarrhea, muscle cramps, fatigue, skin rash and edema; however, pulmonary complications are uncommon. A 73-year-old woman undergoing one month treatment with Imatinib for chronic myeloid neoplasm associated with eosinophilia was admitted for sudden alteration of her performance status, dyspnea at rest and productive cough. On clinical examination, the patient was hypoxic (oxygen saturation on room air was 87%), and auscultation of her lungs revealed diffuse bilateral fine crackles. Computed tomography showed bilateral pulmonary interstitial syndrome. Imatinib was discontinued and the patient received systemic corticosteroid therapy and oxygen therapy. After one month, the symptoms and radiological findings were resolved. When Imatinib therapy was resumed, respiratory symptoms reappeared, which is why treatment with Imatinib was interrupted. Imatinib-induced pneumonitis should take into consideration when patients develop respiratory symptoms or abnormal pulmonary radiological features

A rare case of melanosis of the hard palate mucosa in a patient with chronic myeloid leukemia

Imatinib Mesylate, also known as Gleevec or ST1-571, is a tyrosine-kinase inhibitor used as the gold standard medication for the chronic myeloid leukemia (CML); Imatinib has indeed deeply revolutionized the CML therapy allowing most patients to have a good quality of life. Despite its beneficial effects, Imatinib has significant side effects such as mucosal pigmentation. A 72-year-old female having an Imatinib induced mucosal pigmentation is presented: she has been treated with Imatinib since 2003 and only in 2014 discovered, during a routine dental visit, having a pigmented lesion on her hard palate mucosa. Histopathologically, the lesion shows the deposition of fine dark brown spherical bodies within the lamina propria and cloaked in between the collagen fibers. There was no sign of inflammation, hyperplasia, or hemorrhage in the tissu

Eradication of chronic myeloid leukemia stem cells: a novel mathematical model predicts no therapeutic benefit of adding G-CSF to imatinib

Imatinib mesylate induces complete cytogenetic responses in patients with chronic myeloid leukemia (CML), yet many patients have detectable BCR-ABL transcripts in peripheral blood even after prolonged therapy. Bone marrow studies have shown that this residual disease resides within the stem cell compartment. Quiescence of leukemic stem cells has been suggested as a mechanism conferring insensitivity to imatinib, and exposure to the Granulocyte-Colony Stimulating Factor (G-CSF), together with imatinib, has led to a significant reduction in leukemic stem cells in vitro. In this paper, we design a novel mathematical model of stem cell quiescence to investigate the treatment response to imatinib and G-CSF. We find that the addition of G-CSF to an imatinib treatment protocol leads to observable effects only if the majority of leukemic stem cells are quiescent; otherwise it does not modulate the leukemic cell burden. The latter scenario is in agreement with clinical findings in a pilot study administering imatinib continuously or intermittently, with or without G-CSF (GIMI trial). Furthermore, our model predicts that the addition of G-CSF leads to a higher risk of resistance since it increases the production of cycling leukemic stem cells. Although the pilot study did not include enough patients to draw any conclusion with statistical significance, there were more cases of progression in the experimental arms as compared to continuous imatinib. Our results suggest that the additional use of G-CSF may be detrimental to patients in the clinic

Analysis of imatinib in bone marrow and plasma samples of chronic myeloid leukaemia patients using solid phase extraction LC-ESI-MS

The LC-ESI-MS was developed and validated for the analysis of imatinib in plasma and bone marrow samples using deuterated imatinib (D(8)-IM) as an internal standard. The biological samples were extracted using Strata-X-C SPE cartridges and separated on C<sub>8</sub> column (50 x 3 mm, 3 µm), and methanol: 0.1% formic acid (70:30) was delivered at the rate of 0.7 ml/min as a mobile phase. Imatinib was quantified in samples by monitoring the ions m/z 494.3 for imatinib and 502.3 for D<sub>8</sub>-imatinib on mass spectrometer. The method was linear in the concentration range of 1-1500 ng/250 µl in spiked human plasma samples and limit of quantification was 5 ng/mL. Inter-day and intra-day variations in spiked human plasma spiked with 50, 250 and 500 ng /mL were less than 3.16%. The repeatability and reproducibility and other parameters of the methods were also validated. The method was employed for the analysis of the imatinib in human plasma and bone marrow samples. The drug levels in bone marrow and plasma samples were correlated to the degree of cytogenetic response. No significant difference of imatinib level between blood and bone marrow in IM-treated patients dosed to steady state was observed

Management of imatinib-resistant CML patients

Imatinib has had marked impact on outcomes in chronic myelogenous leukemia (CML) patients for all stages of the disease and is endorsed by international treatment guidelines as the first line option. Although imatinib is highly effective and well tolerated, the development of resistance represents a clinical challenge. Since the most frequently identified mechanism of acquired imatinib resistance is bcr-abl kinase domain point mutations, periodic hematologic, cytogenetic, and molecular monitoring is critical throughout imatinib therapy. Once cytogenetic remission is achieved, residual disease can be monitored by bcr-abl transcript levels as assayed by reverse transcription polymerase chain reaction (RT-PCR). Detection of bcr-abl mutants prior to and during imatinib therapy can aid in risk stratification as well as in determining therapeutic strategies. Thus, mutation screening is indicated in patients lacking or losing hematologic response. Moreover, search for mutations should also be performed when a 3-log reduction of bcr-abl transcripts is not achieved or there is a reproducible increase of transcript levels. In patients harboring mutations which confer imatinib resistance, novel second line tyrosine kinase inhibitors have demonstrated encouraging efficacy with low toxicity. Only the T315I bcr-abl mutant has proved totally resistant to all clinically available bcr-abl inhibitors. Strategies to further increase the rates of complete molecular remissions represent the next frontier in the targeted therapy of CML patients

Delivery as nanoparticles reduces imatinib mesylate-induced cardiotoxicity and improves anticancer activity

Clinical effectiveness of imatinib mesylate in cancer treatment is compromised by its off-target cardiotoxicity. In the present study, we have developed physically stable imatinib mesylate-loaded poly(lactide-co-glycolide) nanoparticles (INPs) that could sustainably release the drug, and studied its efficacy by in vitro anticancer and in vivo cardiotoxicity assays. MTT (methylthiazolyldiphenyl-tetrazolium bromide) assay revealed that INPs are more cytotoxic to MCF-7 breast cancer cells compared to the equivalent concentration of free imatinib mesylate. Wistar rats orally administered with 50 mg/kg INPs for 28 days showed no significant cardiotoxicity or associated changes. Whereas, increased alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase levels, and reduced white blood cell, red blood cell, and hemoglobin content were observed in the animals administered with free drug. While the histological sections from hearts of animals that received INPs did not show any significant cardiotoxic symptoms, loss of normal architecture and increased cytoplasmic vacuolization were observed in the heart sections of animals administered with free imatinib mesylate. Based on these results, we conclude that nano-encapsulation of imatinib mesylate increases its efficacy against cancer cells, with almost no cardiotoxicity

Safe discontinuation of nilotinib in a patient with chronic myeloid leukemia: a case report

Case presentation. We report the case of a 64-year-old Caucasian man diagnosed with chronic-phase chronic myeloid leukemia in April 2005. After 4 years of treatment with imatinib, he became intolerant to the drug and was switched to nilotinib. Two years later, he decided to stop nilotinib. Undetectable molecular response persisted for 30 months after discontinuation of the drug. Introduction. Although there is a considerable amount of data in the literature on safe discontinuation of first-generation tyrosine kinase inhibitor therapy in patients with chronic myeloid leukemia, little is known about discontinuation of second-generation tyrosine kinase inhibitor therapy. Most previous studies have been focused on dasatinib, and the few cases of nilotinib withdrawal that have been reported had a median follow-up of 12 months. To the best of our knowledge, the present report is the first to describe nilotinib withdrawal with 30 months of follow-up. Conclusion: Our present case suggests that nilotinib withdrawal is safe for patients with chronic myeloid leukemia who achieve a stable undetectable molecular response. Our patient was homozygous for killer immunoglobulin-like receptor haplotype A, previously reported to be a promising immunogenetic marker for undetectable molecular response. We recommend additional studies to investigate patient immunogenetic profiles and their potential role in complete response to therap

Current Information and Recommendations on the Discontinuation of TKI Inhibitors in Chronic Myeloid Leukemia

PURPOSE OF REVIEW: Discontinuation of tyrosine kinase inhibitors (TKIs) in chronic phase chronic myeloid leukemia (CP-CML) patients has become a reality. Treatment-free remission (TFR) is the term that identifies success after discontinuation. RECENT FINDINGS: Several trials have demonstrated that with imatinib about 40% of patients discontinuing treatment in deep and stable molecular response remain disease-free. Second-generation TKIs have improved the rate of deep molecular responses and allowed to increase the percentage of patients attempting treatment discontinuation. We hereby review the current information based on the available published data and discuss the current suggestions on how to move TFR into the clinical practice