Outcome of patients with chronic myeloid leukemia with multiple ABL1 kinase domain mutations receiving tyrosine kinase inhibitor therapy

Anti-Cancer Effects of Oxygen-Atom-Modified Derivatives of Wasabi Components on Human Leukemia Cells

1-Isothiocyanato-6-(methylsulfinyl)-hexanate (6-MITC) is a natural compound found in Wasabia japonica. The synthetic derivatives 1-Isothiocyanato-6-(methylsulfenyl)-hexane (I7447) and 1-Isothiocyanato-6-(methylsulfonyl)-hexane (I7557) were obtained from 6-MITC by deleting and adding an oxygen atom to the sulfone group, respectively. We previously demonstrated that extensive mitotic arrest, spindle multipolarity, and cytoplasmic vacuole accumulation were induced by 6-MITC and inhibited the viability of human chronic myelogenous leukemia K562 cells. In this study, we examined the anti-cancer effects of 6-MITC derivatives on human chronic myelogenous leukemia (CML) cells. Autophagy was identified as the formation of autophagosomes with double-layered membranes using transmission electron microscopy. Cell cycle and differentiation were analyzed using flow cytometry. Apoptosis was detected by annexin V staining. After treatment with I7447 and I7557, the G2/M phase of cell cycle arrest was revealed. Cell death can be induced by a distinct mechanism (the simultaneous occurrence of autophagy and aberrant mitosis). The expression levels of acridine orange were significantly affected by lysosomal inhibitors. The natural wasabi component, 6-MITC, and its synthetic derivatives have similar effects on human chronic myelogenous leukemia cells and may be developed as novel therapeutic agents against leukemia.

Genomic Mechanisms Influencing Outcome in Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) represents the disease prototype of genetically based diagnosis and management. Tyrosine kinase inhibitors (TKIs), that target the causal BCR::ABL1 fusion protein, exemplify the success of molecularly based therapy. Most patients now have long-term survival; however, TKI resistance is a persistent clinical problem. TKIs are effective in the BCR::ABL1-driven chronic phase of CML but are relatively ineffective for clinically defined advanced phases. Genomic investigation of drug resistance using next-generation sequencing for CML has lagged behind other hematological malignancies. However, emerging data show that genomic abnormalities are likely associated with suboptimal response and drug resistance. This has already been supported by the presence of BCR::ABL1 kinase domain mutations in drug resistance, which led to the development of more potent TKIs. Next-generation sequencing studies are revealing additional mutations associated with resistance. In this review, we discuss the initiating chromosomal translocation that may not always be a straightforward reciprocal event between chromosomes 9 and 22 but can sometimes be accompanied by sequence deletion, inversion, and rearrangement. These events may biologically reflect a more genomically unstable disease prone to acquire mutations. We also discuss the future role of cancer-related gene mutation analysis for risk stratification in CML.

Prevalence of BCR-ABL T315I Mutation in Different Chronic Myeloid Leukemia patients Categories

<b>Background and Objective:</b> Chronic Myelogenous Leukaemia (CML) is a clonal myeloproliferative tumor distinguished by the existence of the Philadelphia chromosome (Ph) resulting from the t (9, 22) (q34, q11) translocation. The BCR-ABL gene and the fusion protein, which has constitutive tyrosine kinase activity, are the outcome of this translocation. The purpose of this study is to determine the prevalence of the BCR-ABL T315I mutation in CML patients. <b>Materials and Methods:</b> Descriptive cross-sectional studies were conducted on 100 CML patients who visited RICK hospital between May, 2018-2019. T315I mutation analysis was done on all patients utilizing (RT/PCR) followed by RLFP to quantify the prevalence of Kinase Domain Mutation analysis (KDM) in CML. <b>Results:</b> The link between haematological parameters and ABL mutations in CML patients was shown to be a substantial positive correlation between T315I and haematological parameters (HB and WBC) but no correlation with PLT. The data revealed that 43 out of 99 CML had T315I, with highly prevalent gene express (43.4%) detected in all CML 56.6%. The correlation of T315I mutations with clinical status was positive significant (p-000). <b>Conclusion:</b> It can be concluded that T315I mutation became significantly higher in CML patients than in other groups of mutations. The detection of ABL kinase domain mutations may be a proper and valuable strategy for optimizing therapeutic methods and preventing treatment delays.

Computational and Biological Investigations on Abl1 Tyrosine Kinase: A Review

Abl1 tyrosine kinase is a validated target for the treatment of chronic myeloid leukemia. It is a form of cancer that is difficult to treat and much research is being done to identify new molecular entities and to tackle drug resistance issues. In recent years, drug resistance of Abl1 tyrosine kinase has become a major healthcare concern. Second and third-generation TKI reported better responses against the resistant forms; still they had no impact on long-term survival prolongation. New compounds derived from natural products and organic small molecule inhibitors can lay the foundation for better clinical therapies in the future. Computational methods, experimental and biological studies can help us understand the mechanism of drug resistance and identify novel molecule inhibitors. ADMET parameters analysis of reported drugs and novel small molecule inhibitors can also provide valuable insights. In this review, available therapies, point mutations, structure-activity relationship and ADMET parameters of reported series of Abl1 tyrosine kinase inhibitors and drugs are summarised. We summarise in detail recent computational and molecular biology studies that focus on designing drug molecules, investigation of natural product compounds and organic new chemical entities. Current ongoing research suggests that selective targeting of Abl1 tyrosine kinase at the molecular level to combat drug resistance in chronic myeloid leukemia is promising.

The landscape of BCR-ABL mutations in patients with Philadelphia chromosome-positive leukaemias in the era of second-generation tyrosine kinase inhibitors

BCR-ABL mutations are associated with resistance to tyrosine kinase inhibitors (TKIs) in Philadelphia chromosome-positive leukaemia. The emergence of these mutations in the era of second-generation TKIs, such as dasatinib and nilotinib, remains an evolving field. We conducted a retrospective study to quantitatively characterize the BCR-ABL transcript and mutation status during treatment with first-generation and second-generation TKI therapies. BCR-ABL mutations were detected by direct sequencing for patients with Philadelphia chromosome-positive leukaemia receiving TKI therapies. The efficacy of TKI therapy was quantitatively assessed by calculating the log reduction of BCR-ABL transcripts, which was measured using real-time quantitative polymerase chain reaction. Fisher's exact test was performed to analyse the associations of log reduction <3 and mutation status. We found 35 patients harbouring 55 mutations of 43 different types, of which 30% occurred in patients receiving imatinib, 27% in nilotinib, and 43% in dasatinib. We found a novel germline mutation, N336 N (AAC➔AAT), and two novel frameshift mutations, Asn358Thr fs*14 and Gly251Ala fs*16. T315I was the most common missense mutation, followed by V299L and F317L. Intron 8 35-bp insertion was the most frequent frameshift mutation. Both missense and multiple BCR-ABL mutations were significantly associated with worse molecular response compared with the molecular response of patients without mutation. Missense mutations, rather than frameshift, were associated with less log reduction, while the T315I, F317L, and T315A mutations were significantly correlated with poor log reduction. Collectively, amino acid substitutions at T315I, F317L, and T315A accounted for the majority of missense mutations and the loss of major molecular response. Mutation analysis is essential for patients receiving TKI therapy who exhibit an unfavourable response. The present study provided a landscape of BCR-ABL mutations in the era of second-generation TKIs.

Wasabi Compound 6-(Methylsulfinyl) Hexyl Isothiocyanate Induces Cell Death with Coexisting Mitotic Arrest and Autophagy in Human Chronic Myelogenous Leukemia K562 Cells

A natural compound from Wasabia japonica, 6-(methylsulfinyl) hexyl isothiocyanate (6-MITC) was investigated for its anti-leukemia activity and mechanism of action. It was found that 6-MITC inhibited the viability of human chronic myelogenous leukemia K562 cells along with extensive mitotic arrest, spindle multipolarity, and cytoplasmic vacuole accumulation. The evidence of autophagy included the validation of autophagosomes with double-layered membranes under transmission electron microscopy, LC3I/II conversion, and the induction of G2/M phase arrest observed with acridine orange staining of treated cells, as well as the elevation of phosphorylated-histone H3 expression at the M phase. With regard to the expression of proteins related to mitosis, the down regulation of p-CHK1, p-CHK2, p-cdc25c, and p-cdc2, as well as the upregulation of cyclin B1, p-cdc20, cdc23, BubR1, Mad2, and p-plk-1 was observed. The knockdown of cdc20 was unable to block the effect of 6-MITC. The differentiation of k562 cells into monocytes, granulocytes, and megakaryocytes was not affected by 6-MITC. The 6-MITC-induced unique mode of cell death through the concurrent induction of mitosis and autophagy may have therapeutic potential. Further studies are required to elucidate the pathways associated with the counteracting occurrence of mitosis and autophagy.

Compound mutations involving T315I and P-loop mutations are the major components of multiple mutations detected in tyrosine kinase inhibitor resistant chronic myeloid leukemia

To analyze the pattern of multiple mutations detected by Sanger sequencing (SS), we performed subcloning sequencing using 218 samples from 45 patients with tyrosine kinase inhibitor resistant chronic myeloid leukemia. At the first time of multiple mutation detection by SS (baseline), a total of 19 major mutations from 45 samples were detected; these mutations were found in the following order: T315I (68.9%), E255 K (33.3%), Y253H (13.3%), G250E (13.3%), and F317 L (11.1%). Subcloning sequencing of 900 baseline colonies identified 556 different mutant types, and 791 among the 900 were colonies with major mutations (87.9%). The mutations were found in the following order: T315I (36.4%), E255 K (16.2%), Y253H (7.0%), G250E (6.7%), M351 T (6.6%), and E255 V (5.3%). In subcloning sequencing with 4357 colonies of 218 serial samples, 2506 colonies (57.5%) had compound mutations, among which 2238 colonies (89.3%) had at least one major mutation. The median number of mutations in compound mutant colonies was 2 (range, 2-7), and most were double (52.9%) or triple (28.7%) mutations. Additionally, some mutations in allosteric binding sites were detected as low level mutation in 13 patients. With the available retrospective samples before baseline, subcloning sequencing identified low-level mutations of various frequencies (median, 10%) to be major mutations in 20 patients. Thus, compound mutations involving T315I and P-loop mutations were the major components of multiple mutations, and some low-level mutations with potential clinical significance were detected by subcloning sequencing. Hence, more sensitive sequencing assays are needed in patients with multiple mutations.

Presence of novel compound BCR-ABL mutations in late chronic and advanced phase imatinib sensitive CML patients indicates their possible role in CML progression

BCR-ABL kinase domain (K_D) mutations are well known for causing resistance against tyrosine kinase inhibitors (TKIs) and disease progression in chronic myeloid leukemia (CML). In recent years, compound BCR-ABL mutations have emerged as a new threat to CML patients by causing higher degrees of resistance involving multiple TKIs, including ponatinib. However, there are limited reports about association of compound BCR-ABL mutations with disease progression in imatinib (IM) sensitive CML patients. Therefore, we investigated presence of ABL-K_D mutations in chronic phase (n = 41), late chronic phase (n = 33) and accelerated phase (n = 16) imatinib responders. Direct sequencing analysis was used for this purpose. Eleven patients (12.22%) in late-CP CML were detected having total 24 types of point mutations, out of which 8 (72.72%) harbored compound mutated sites. SH2 contact site mutations were dominant in our study cohort, with E355G (3.33%) being the most prevalent. Five patients (45%) all having compound mutated sites, progressed to advanced phases of disease during follow up studies. Two novel silent mutations G208G and E292E/E were detected in combination with other mutants, indicating limited tolerance for BCR-ABL1 kinase domain for missense mutations. However, no patient in early CP of disease manifested mutated ABL-K_D. Occurrence of mutations was found associated with elevated platelet count (p = 0.037) and patients of male sex (p = 0.049). The median overall survival and event free survival of CML patients (n = 90) was 6.98 and 5.8 y respectively. The compound missense mutations in BCR-ABL kinase domain responsible to elicit disease progression, drug resistance or disease relapse in CML, can be present in yet Imatinib sensitive patients. Disease progression observed here, emphasizes the need of ABL-K_D mutation screening in late chronic phase CML patients for improved clinical management of disease.

The Role of Mutation Testing in Patients with Chronic Myeloid Leukemia in Chronic Phase after Imatinib Failure and Their Outcomes after Treatment Modification: Single-institutional Experience Over 13 Years

Introduction:

BCR-ABL1 kinase domain mutations represent the most frequent mechanism of resistance to tyrosine kinase inhibitor (TKI) therapy, being detected in 40%–50% of imatinib-resistant patients with chronic myeloid leukemia in chronic phase (CML-CP). Over 100 BCR-ABL1 single-point mutations have been reported in patients with imatinib-resistant CML. There were few studies reported from India on BCR-ABL kinase mutations in imatinib failure patients. We present our data on imatinib resistance mutation analysis (IRMA) and use of imatinib dose hike and 2^nd-generation TKI at our institute.

Materials and Methods:

All patients with a diagnosis of CML in a university hospital from June 2003 to July 2016 and who were tested for IRMA in view of imatinib failure, those in CP, and age <18 years were included in the study.

Results:

A total of 2110 cases of CML reviewed and 269 cases of CML with imatinib failure were analyzed. The male to female ratio was 1.7:1. The median age at presentation was 36 years (range: 18–66 years). Among these, 26% were primary failures and 74% were secondary failures. The treatment was modified either as imatinib dose hike or nilotinib/dasatinib. Molecular response at 12 months was achieved in 25.7% in imatinib dose hike, 46.6% in nilotinib, and 53.8% in dasatinib arms. The 4-year overall survival in mutation detected group was 37.5% and in nonmutated group was 87.7%.

Conclusion:

Imatinib-resistant mutations were more common in the cases with secondary failure though not statistically significant. T315I mutation was the common mutation found in the study. Imatinib dose hike to the failure cases resulted in optimal hematological response rates.

Potential mechanisms of disease progression and management of advanced-phase chronic myeloid leukemia

Despite vast improvements in the treatment of Philadelphia chromosome-positive chronic myeloid leukemia (CML) in chronic phase (CP), advanced stages of CML, accelerated phase or blast crisis, remain notoriously difficult to treat. Treatments that are highly effective against CML-CP produce disappointing results against advanced disease. Therefore, a primary goal of therapy should be to maintain patients in CP for as long as possible, by (1) striving for deep, early molecular response to treatment; (2) using tyrosine kinase inhibitors that lower risk of disease progression; and (3) more closely observing patients who demonstrate cytogenetic risk factors at diagnosis or during treatment.

Drug resistance and BCR-ABL kinase domain mutations in Philadelphia chromosome-positive acute lymphoblastic leukemia from the imatinib to the second-generation tyrosine kinase inhibitor era: The main changes are in the type of mutations, but not in the frequency of mutation involvement

BACKGROUND

Patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) frequently relapse on imatinib with acquisition of BCR-ABL kinase domain (KD) mutations. To analyze the changes that second-generation tyrosine kinase inhibitors (TKIs) have brought in mutation frequency and type, a database review was undertaken of the results of all the BCR-ABL KD mutation analyses performed in the authors' laboratory from January 2004 to January 2013.

METHODS

Interrogation of the database retrieved 450 mutation analyses in 272 patients with Ph+ ALL. Prescreening of samples was performed with denaturing high-performance liquid chromatography (D-HPLC), followed by direct sequencing of D-HPLC-positive cases.

RESULTS

BCR-ABL KD mutations were detected in 70% of imatinib-resistant patients, with T315I, E255K, and Y253H mutations accounting for 75% of cases. Seventy-eight percent of the patients reported to be resistant to second-generation TKIs after imatinib failure were positive for mutations, and 58% of them had multiple mutations. Analysis of patients relapsing on dasatinib revealed a newly acquired T315I mutation in almost two-thirds of the cases. Direct sequencing detected no mutations at diagnosis, even in patients who relapsed after a few months.

CONCLUSIONS

Second-generation TKIs ensure a more rapid debulking of the leukemic clone and have much fewer insensitive mutations, but long-term disease control remains a problem, and the T315I mutation is revealed to be an even more frequent enemy. BCR-ABL KD mutation screening of patients with Ph+ ALL who are receiving imatinib or second-generation TKIs would be a precious ally for timely treatment optimization. In contrast, the clinical usefulness of conventional direct sequencing at diagnosis seems to be very low. American Cancer Society.

Implications of BCR-ABL1 kinase domain-mediated resistance in chronic myeloid leukemia

Patients with chronic myeloid leukemia develop resistance to both first-generation and second-generation tyrosine kinase inhibitors (TKIs) as a result of mutations in the kinase domain (KD) of BCR-ABL1. A wide range of BCR-ABL1 KD mutations that confer resistance to TKIs have been identified, and the T315I mutant has proven particularly difficult to target. This review summarizes the prevalence, impact, and prognostic implications of BCR-ABL1 KD mutations in patients with chronic myeloid leukemia who are treated with current TKIs and provides an overview of recent treatment guidelines and future trends for the detection of mutations.

Poor response to second-line kinase inhibitors in chronic myeloid leukemia patients with multiple low-level mutations, irrespective of their resistance profile

Specific imatinib-resistant BCR-ABL1 mutations (Y253H, E255K/V, T315I, F317L, and F359V/C) predict failure of second-line nilotinib or dasatinib therapy in patients with chronic myeloid leukemia; however, such therapy also fails in approximately 40% of patients in the chronic phase of this disease who do not have these resistant mutations. We investigated whether sensitive mutation analysis could identify other poor-risk subgroups. Analysis was performed by direct sequencing and sensitive mass spectrometry on 220 imatinib-resistant patients before they began nilotinib or dasatinib therapy. Patients with resistant mutations by either method (n = 45) were excluded because inferior response was known. Of the remaining 175 patients, 19% had multiple mutations by mass spectrometry versus 9% by sequencing. Compared with 0 or 1 mutation, the presence of multiple mutations was associated with lower rates of complete cytogenetic response (50% vs 21%, P = .003) and major molecular response (31% vs 6%, P = .005) and a higher rate of new resistant mutations (25% vs 56%, P = .0009). Sensitive mutation analysis identified a poor-risk subgroup (15.5% of all patients) with multiple mutations not identified by standard screening.