Mutation t315i expression system mammalian amino acid startstop s229k512. Overcoming t315i and other tkiresistant mutations in cml alfonso quintascardama, md hematologyoncology fellow division of cancer medicine the university of texas m. Register samples in text file and in the web system. In addition, it has resulted in resistance to other anticancer drugs, including dasatinib. Mutation could be in somatic cells or germline cells. Of special interest is the gatekeeper t315i mutation, which confers complete resistance to abl kinase inhibitors. This drug is the only one at this point that is showing good results against the dreaded t3151 mutation. The drug is a bit unique in that it is given intravenously at this time. T315i mutation of bcrabl1 into human philadelphia chromosome. Cml is a malignant chronic myeloproliferative disorder mpd of the hematopoietic stem cell. Cml and all patients with the t315i mutation often become resistant to standard treatment. A major molecular response was achieved or maintained by 12 months in 5 patients 28% with a t315i mutation at baseline. This study evaluated a ph chromosome positive cml case resistant to imatinib mesylate.
Hence, novel strategies or compounds that can inhibitkill cml cells carrying bcrablt315i are needed. Bcrabl1 compound mutations combining key kinase domain. Apr 20, 2020 25,26,4146 among the bcrabl mutations, there are 9 that account for more than 85% of all mutations. B activation is widely found in diverse types of hematopoietic malignancies.
In addition, in baf3 transfected with p185 bcrabl t315i mutation, which are refractory to imatinib, dasatinib, and gnf2, presence of imatinib and dasatinib at 1. Original article detecting t315i bcrabl mutants in. Chronic myeloid leukemia cml with t315i mutation has been reported to have poor prognosis. Compound mutations involving t315i and ploop mutations. Clinical features and outcomes in chronic myeloid leukemia with t315i mutation article pdf available in cellular therapy and transplantation 62. Of course, generally speaking, once a patient has been monitored for cml, for the most part, bone marrows are required less frequently perhaps than peripheral blood monitoring. Pdf overcoming bcrabl t315i mutation by combination of gnf2. The t315i mutation in bcrabl1 was reported to be responsible for the resistance of chronic myeloid leukemia to several anticancer drugs. Optimizing the selection of kinase inhibitors for chronic myeloid leukemia patients. Of the trials that contain abl1 t315i as an inclusion criterion, 1 is phase 1 1 open, 2 are phase 1phase 2 2 open, and 2 are phase 2 2 open. Resistance mechanisms, bcrabl mutations, and monitoring.
Pharmacokinetics of dasatinib for philadelphiapositive acute. Rebastinib also potently inhibits abl1h396p ic50 1. Mutation specific control of bcrabl t315i positive leukemia with. We show here the first crystal structure of the kinase domain of abl t315i in complex with pha739358, an aurora kinase inhibitor currently in clinical development for solid and hematologic malignancies. Cultures were sorted once and enrichment was measured by facs above and sanger sequencing of 8 clones, each of which contained the t315i mutation. Both inhibitors overcame tki resistance imposed by bcrabl t315i fig. A singletube allele specificpolymerase chain reaction aspcr method was developed to detect t315i mutation in a mixture of normal and mutant alleles of varying dilutions.
The abl t315i assay kit is designed to measure abl activity for screening and profiling applications using kinaseglo max as a detection reagent. View clinical trials for abl1 t315i abl1 t315i serves as an inclusion eligibility criterion in 5 clinical trials, of which 5 are open and 0 are closed. A costeffectiveness method for detection of abl mutations in. Recent developments in the third generation inhibitors of bcr. Asciminib in chronic myeloid leukemia after abl kinase. Ponatinib thwarts t315i gene mutation in chronic myeloid leukemia november 29, 2012, news medical analysis of mutations in the bcrabl1 kinase domain, using direct sequencing. Workflow for pacbio bcrabl1 mutation screening step 1. Resistant t315i clone may be present prior to initiating dasatinib, which could expand under selective pressures during treatment. Pdf background philadelphia positive leukemias are characterized by the presence of bcrabl fusion protein which exhibits an abnormal kinase activity. The most relevant bcrabl mutation results from the replacement of threonine by isoleucine at abl amino acid position 315, referred to as the t315i mutation. Despite three approved therapeutic options, the crossresistant bcrabl t315i mutation and compound mutants selected on sequential inhibitor therapy remain major clinical challenges. Thirdgeneration tyrosine kinase inhibitors show clinical ac. Mutation t315i chronic myeloid leukemia cml chronic. Jun 30, 2017 certain genetic changes in cml and all can make it more difficult to treat.
Characteristics and outcomes of patients with chronic myeloid. Home uppsalagenomecenterbcrabl1screening wiki github. Supplementary appendix this appendix has been provided by the authors to give readers additional information about their work. Hu and the cdk4cdk6blocker palbociclib inhibit growth of cml clones expressing bcrabl1t315i or complex t315iincluding compoundmutations. Supplemental experimental procedures, figures s1s4, and tables s1s5. In other words, growth competition between mutant clones can lead to a change in major mutations by varying kinase activity from an addon mutation within the clone 6,30, and the presence of the t315i mutation appears to play an important role in the selection and deselection processes of compound mutant clones 24,31,32. Nov 27, 2012 similarly to abl kinase inhibitors akis, gnf2 failed to inhibit activity of mutated bcrabl carrying the t315i mutation. Treating t315ipositive chronic myeloid leukemia cml.
In the forest of abl mutations identified in cml patients, the t315i mutation takes particular importance for four different reasons. We report design and preclinical evaluation of ap24534, a potent, orally available multitargeted kinase inhibitor active against t315i and other bcrabl mutants. New orleansseveral thirdgeneration tyrosine kinase inhibitors tkis have shown clinical activity in patients with chronic myeloid leukemia cml who harbor the bcrabl t315i mutation and are resistant to firstline therapy with imatinib and secondline therapy with secondgeneration tkis, according to data reported here at the ash annual meeting. Pdf chronic myelogenous leukemia cml is a hematological stem cell disorder caused by increased and unregulated growth of myeloid cells in the bone. Compound mutations involving t315i and ploop mutations are. The clonal evolution of two distinct t315ipositive bcrabl1. Baf3 cells harboring native or t315i mutated bcrabl constructs were treated with gnf2 and akis. However, t315i mutation also was observed in 10 cases post im failure 4 cp, 5 ap, and 1 blast phase and 2 cases post nilotinib treatment in the study by cortes et al. Bcrabl point mutations and tki treatment in cml patients. Mutations can occur either in noncoding or coding sequences mutation in the coding sequence is recognized as an. Despite three approved therapeutic options, the crossresistant bcrablt315i mutation and compound mutants selected on sequential inhibitor therapy remain major clinical challenges.
A combined computational and experimental strategy identifies. Similarly to abl kinase inhibitors akis, gnf2 failed to inhibit activity of mutated bcrabl carrying the t315i mutation. Chronic myeloid leukemia, bcrabl mutations, t315i, rtqpcr introduction chronic myelogenous leukemia cml is a type of leukemia that accounts for about 15% of adult leukemia cases, as characterized by the. A simple and sensitive method is thus required to detect t315i mutation at the earliest stage. It is caused by a single cytosine to thymine c t base pair substitution at position 944 of the abl gene codon 315 of the abl protein sequence resulting in amino acid threonine being substituted by isoleucine at.
T315i bcrabl mutation analysis quantitative indication. The chromosomal defect in the philadelphia chromosome is a reciprocal translocation, in which parts of two chromosomes, 9 and 22, swap places. A mutation arising in a somatic cell cannot be transmitted to offspring, whereas if it occurs in gonadal tissue or a gamete it can be transmitted to future generations. The aim of this study was to evaluate the prevalence of this mutation in bcrablpositive cml and all patients. The result is that a fusion gene is created by juxtaposing the abl1 gene on chromosome 9 region q34 to a part of the bcr breakpoint cluster region gene on chromosome 22 region q11. Association of t315i mutation with resistance to tyrosine kinase. Pdf clinical features and outcomes in chronic myeloid. Our patient achieved a major cytogenetic response and major. Mutations in the kinase domain of bcrabl are the most common cause of resistance to therapy with imatinib in patients with chronic. Hyperdiploidy associated with t315i mutation in bcrabl. As was mentioned in the section about targeted therapy, in some patients on tki treatment, the cancer cells develop a gene change called the t315i mutation that keeps most of the tkis from working.
F311l, m351t, and t315i and all patients with preexisting bcrabl mutations exhibited imatinib resistance 33. Our study utilized gnf2, and other akis that are not active in inhibiting the t315i mutation, resulting in the inhibition of proliferation and clonigenicity of the t315i cells via a mechanism that is not dependent on bcrabl, but rather on an alternative or downstream pathways. M244v, g250e, y253fh, e255kv, t315i, m351t, and f359v. However, previous reports demonstrated that bcrabl1 represses genes involved in the hr pathway such as brca1 and rad51. We analyzed 27 patients with t315i, including 20 who developed t315i after imatinib failure representing 11% of 186 patients with imatinib failure, and 7 of 23 who developed new mutations after second tyrosine kinase inhibitor tki.
Hence, more sensitive sequencing assays are needed in patients with multiple mutations. The specific bcrabl1 kinase domain mutations detected by cloning and sequencing for indicated patient samples are listed, related to figure 4. Strategies to circumvent the t315i gatekeeper mutation in the. Optimizing kinase inhibitor selection for cml patients. This compound inhibits in vitro the kinase activity of wildtype abl and of several mutants, including t315i. The t315i mutation within the ablgene is the most frequent one associated with resistance to tyrosine kinase inhibitors. Pre and posttransplant ponatinib for a patient with acute megakaryoblastic blast phase chronic myeloid leukemia with t315i mutation who underwent allogeneic hematopoietic stem cell transplantation march 16, 2019, pubmed ponatinib tops bosutinib for thirdline treatment of cml in a comparative analysis october 15, 2018, cancer therapy advisor. An activating mutation of gnb1 is associated with resistance.
Cdk4cdk6 inhibition as a novel strategy to suppress the. This is a pdf file of an unedited manuscript that has been. Given the mutation she has is a particularly bad one, the gatekeeper mutation of t315i, it will almost certainly impact her therapy. Overcoming t315i and other tkiresistant mutations in cml. The t315i mutation, one of the most common mutations of bcrabl, occurs when threonine at amino acid position 315 in the abl sequence is. The singlepoint mutation t315i has been linked to drug resistance and poor prognosis, making it an important drug target.
Human abelson murine leukemia viral oncogene homolog 1 abl1, genbank accession no. Inhibitors of abl and t he ablt315i mutation current topics in medici nal chemistry, 2008, vol. The efficacy of sf and ax was comparable to po, while the classical tkis im, dst and nl only affected kbm5 cells lacking the t315i mutation fig. Certain genetic changes in cml and all can make it more difficult to treat. We monitored the effect of gnf2 with akis on the proliferation and clonigenicity of the different baf3 cells. Overcoming bcrabl t315i mutation by combination of gnf2. Axitinib and sorafenib are potent in tyrosine kinase. Among these mutations, the most frequent mutation, t315i mutation, is resistant to all presently registered bcrabl tyrosine kinase inhibitors tkis with the. This mutation has emerged following treatment with imatinib, and therefore mutant cells are resistant to imatinib.
Thus, the usefulness of crisprcas9 system for functional analysis of somatic mutations in cancers was demonstrated. T315i is one of the most common acquired mutations in this domain, which occurs in atp binding site and inhibits the formation of hydrogen bond with im. Researchpristimerin induces apoptosis in imatinibresistant. About 20% of patients with relapsed or resistant cml show a specific mutation on the threoninetoisoleucine gene at position 315 t315i mutation. For monitoring of the levels of the thr to ile mutation at codon 315 t315i of the bcrabl kinase seen in cml patients who have developed resistance to imatinib or other kinase inhibitors. Overcoming bcrabl t315i mutation by combination of gnf2 and. The t315i is a unique mutation because of its resistance to all approved bcrabl inhibitors, prior to ponatinib. A singletube allele specificpolymerase chain reaction to. If your cml stops responding to treatment with a tki, another one may be tried. The bcrablt315i mutation confers drug resistance to. Thus, compound mutations involving t315i and ploop mutations were the major components of multiple mutations, and some lowlevel mutations with potential clinical significance were detected by subcloning sequencing. Recently, gnf2, abl allosteric kinase inhibitor, was demonstrated to possess cellular activity against bcrabl transformed cells. Nov 29, 2014 however, t315i mutation also was observed in 10 cases post im failure 4 cp, 5 ap, and 1 blast phase and 2 cases post nilotinib treatment in the study by cortes et al.
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