Clinical experience with tyrosine kinase inhibitors (TKIs) over the past two decades has shown that, despite the apparent therapeutic benefit, nearly 30% of patients with chronic myelogenous leukemia (CML) display primary resistance or intolerance to TKIs, and approximately 25% of those treated are forced to switch TKIs at least once during therapy due to acquired resistance. Safe and effective treatment modalities targeting leukemic clones that escape TKI therapy could hence be game changers in the professional management of these patients. Here, we aimed to investigate the efficacy of a novel therapeutic oligonucleotide of unconventional design, called ASP210, to reduce BCR-ABL1 mRNA levels in TKI-resistant CML cells, with the assumption of inducing their apoptosis. Imatinib- and dasatinib-resistant sublines of BCR-ABL1-positive MOLM-7 and CML-T1 cells were established and exposed to 0.25 and 2.5 µM ASP210 for 10 days. RT-qPCR showed a remarkable reduction of the target mRNA level by >99% after a single application. Cell viability was monitored daily by trypan blue staining. In response to the lack of driver oncoprotein BCR-ABL1, TKI-resistant CML cells underwent apoptosis regardless of the presence of the clinically relevant T315I mutation by day 5 after redosing with ASP210. The effect was selective for cancer cells, indicating a favorable safety profile for this therapeutic modality. Furthermore, the spontaneous uptake and high intracellular concentrations of ASP210 suggest its potential to be effective at relatively low doses. The present findings suggest that ASP210 is a promising therapeutic avenue for patients with CML who fail to respond to TKI therapy.NEW & NOTEWORTHY Effective treatment modalities targeting leukemic clones that escape tyrosine kinase inhibitor (TKI) therapy could be game changers in the professional management of patients displaying primary resistance, intolerance, or acquired resistance to TKIs. Although delivering authentic innovations today is more complex than ever, we developed a highly potent and safe oligonucleotide-based modality against BCR-ABL1 mRNA named ASP210 that effectively induces cell death in BCR-ABL1-positive TKI-resistant cells while sparing BCR-ABL1-negative healthy cells.

• Klíčová slova
• BCR-ABL1, chronic myelogenous leukemia, oligonucleotide therapeutics, resistance to therapy, tyrosine kinase inhibitors,
• MeSH
• antitumorózní látky farmakologie   MeSH
• apoptóza * účinky léků   MeSH
• bcr-abl fúzové proteiny * genetika   antagonisté a inhibitory   metabolismus   MeSH
• chemorezistence * účinky léků   MeSH
• chronická myeloidní leukemie * farmakoterapie   genetika   patologie   MeSH
• dasatinib farmakologie   MeSH
• imatinib mesylát * farmakologie   terapeutické užití   MeSH
• inhibitory proteinkinas * farmakologie   MeSH
• lidé MeSH
• messenger RNA genetika   metabolismus   MeSH
• nádorové buněčné linie MeSH
• oligonukleotidy * farmakologie   MeSH
• viabilita buněk účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antitumorózní látky MeSH
• bcr-abl fúzové proteiny * MeSH
• BCR-ABL1 fusion protein, human MeSH Prohlížeč
• dasatinib MeSH
• imatinib mesylát * MeSH
• inhibitory proteinkinas * MeSH
• messenger RNA MeSH
• oligonukleotidy * MeSH

One of the indications for BCR::ABL1 mutation testing in chronic myeloid leukemia (CML) is when tyrosine kinase inhibitor therapy (TKI) needs to be changed for unsatisfactory response. In this study, we evaluated a droplet digital PCR (ddPCR)-based multiplex strategy for the detection and quantitation of transcripts harbouring mutations conferring resistance to second-generation TKIs (2GTKIs). Parallel quantitation of e13a2, e14a2 and e1a2 BCR::ABL1 fusion transcripts enables to express results as percentage of mutation positive- over total BCR::ABL1 transcripts. We determined the limit of blank in 60 mutation-negative samples. Accuracy was demonstrated by further analysis of 48 samples already studied by next generation sequencing (NGS). Mutations could be called down to 0.5% and across 3-logs of BCR::ABL1 levels. Retrospective review of BCR::ABL1 NGS results in 513 consecutive CML patients with non-optimal response to first- or second-line TKI therapy suggested that a ddPCR-based approach targeted against 2GTKI-resistant mutations would score samples as mutation-negative in 22% of patients with warning response to imatinib but only in 6% of patients with warning response to 2GTKIs. We conclude ddPCR represents an attractive method for easy, accurate and rapid screening for 2GTKI-resistant mutations impacting on TKI selection, although ddPCR cannot identify compound mutations.

• MeSH
• bcr-abl fúzové proteiny * MeSH
• chemorezistence MeSH
• chronická myeloidní leukemie * MeSH
• inhibitory proteinkinas MeSH
• lidé MeSH
• mutace MeSH
• polymerázová řetězová reakce MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bcr-abl fúzové proteiny * MeSH
• inhibitory proteinkinas MeSH

Most reports on chronic myeloid leukaemia (CML) treatment with tyrosine kinase inhibitors (TKIs) focus on efficacy, particularly on molecular response and outcome. In contrast, adverse events (AEs) are often reported as infrequent, minor, tolerable and manageable, but they are increasingly important as therapy is potentially lifelong and multiple TKIs are available. For this reason, the European LeukemiaNet panel for CML management recommendations presents an exhaustive and critical summary of AEs emerging during CML treatment, to assist their understanding, management and prevention. There are five major conclusions. First, the main purpose of CML treatment is the antileukemic effect. Suboptimal management of AEs must not compromise this first objective. Second, most patients will have AEs, usually early, mostly mild to moderate, and which will resolve spontaneously or are easily controlled by simple means. Third, reduction or interruption of treatment must only be done if optimal management of the AE cannot be accomplished in other ways, and frequent monitoring is needed to detect resolution of the AE as early as possible. Fourth, attention must be given to comorbidities and drug interactions, and to new events unrelated to TKIs that are inevitable during such a prolonged treatment. Fifth, some TKI-related AEs have emerged which were not predicted or detected in earlier studies, maybe because of suboptimal attention to or absence from the preclinical data. Overall, imatinib has demonstrated a good long-term safety profile, though recent findings suggest underestimation of symptom severity by physicians. Second and third generation TKIs have shown higher response rates, but have been associated with unexpected problems, some of which could be irreversible. We hope these recommendations will help to minimise adverse events, and we believe that an optimal management of them will be rewarded by better TKI compliance and thus better CML outcomes, together with better quality of life.

• MeSH
• chronická myeloidní leukemie komplikace   farmakoterapie   MeSH
• inhibitory proteinkinas škodlivé účinky   terapeutické užití   MeSH
• lidé MeSH
• nežádoucí účinky léčiv MeSH
• tyrosinkinasy antagonisté a inhibitory   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• inhibitory proteinkinas MeSH
• tyrosinkinasy MeSH

• MeSH
• akutní lymfatická leukemie diagnóza   farmakoterapie   genetika   MeSH
• antitumorózní látky terapeutické užití   MeSH
• bcr-abl fúzové proteiny antagonisté a inhibitory   genetika   MeSH
• chemorezistence genetika   MeSH
• dospělí MeSH
• inhibitory proteinkinas terapeutické užití   MeSH
• lidé středního věku MeSH
• lidé MeSH
• lokální recidiva nádoru diagnóza   genetika   MeSH
• mutace MeSH
• mutační analýza DNA metody   MeSH
• reziduální nádor diagnóza   genetika   MeSH
• senioři MeSH
• vysoce účinné nukleotidové sekvenování metody   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• dopisy MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antitumorózní látky MeSH
• bcr-abl fúzové proteiny MeSH
• BCR-ABL1 fusion protein, human MeSH Prohlížeč
• inhibitory proteinkinas MeSH

In chronic myeloid leukemia (CML) and Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL) patients who fail imatinib treatment, BCR-ABL1 mutation profiling by Sanger sequencing (SS) is recommended before changing therapy since detection of specific mutations influences second-generation tyrosine kinase inhibitor (2GTKI) choice. We aimed to assess i) in how many patients who relapse on second-line 2GTKI therapy next generation sequencing (NGS) may track resistant mutations back to the sample collected at the time of imatinib resistance, before 2GTKI start (switchover sample) and ii) whether low level mutations identified by NGS always undergo clonal expansion. To this purpose, we used NGS to retrospectively analyze 60 imatinib-resistant patients (CML, n = 45; Ph+ ALL,n = 15) who had failed second-line 2GTKI therapy and had acquired BCR-ABL1 mutations (Group 1) and 25 imatinib-resistant patients (CML, n = 21; Ph+ ALL, n = 4) who had responded to second-line 2GTKI therapy, for comparison (Group 2). NGS uncovered that in 26 (43%) patients in Group 1, the 2GTKI-resistant mutations that triggered relapse were already detectable at low levels in the switchover sample (median mutation burden, 5%; range 1.1%-18.4%). Importantly, none of the low level mutations detected by NGS in switchover samples failed to expand whenever the patient received the 2GTKI to whom they were insensitive. In contrast, no low level mutation that was resistant to the 2GTKI the patients subsequently received was detected in the switchover samples from Group 2. NGS at the time of imatinib failure reliably identifies clinically relevant mutations, thus enabling a more effective therapeutic tailoring.

• Klíčová slova
• BCR-ABL1, Next-generation sequencing, acute lymphoblastic leukemia, chronic myeloid leukemia, tyrosine kinase inhibitors,
• MeSH
• akutní lymfatická leukemie farmakoterapie   genetika   MeSH
• bcr-abl fúzové proteiny genetika   MeSH
• chemorezistence genetika   MeSH
• chronická myeloidní leukemie farmakoterapie   genetika   MeSH
• dasatinib terapeutické užití   MeSH
• dospělí MeSH
• imatinib mesylát terapeutické užití   MeSH
• inhibitory proteinkinas terapeutické užití   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mutační analýza DNA metody   MeSH
• retrospektivní studie MeSH
• senioři MeSH
• vysoce účinné nukleotidové sekvenování metody   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bcr-abl fúzové proteiny MeSH
• BCR-ABL1 fusion protein, human MeSH Prohlížeč
• dasatinib MeSH
• imatinib mesylát MeSH
• inhibitory proteinkinas MeSH