A retrospective analysis of the prevalence of EGFR or KRAS mutations in patients (pts) with crizotinib-naïve and crizotinib-resistant, ALK-positive non-small cell lung cancer (NSCLC).

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 8083-8083
Author(s):  
Justin F. Gainor ◽  
Anna M. Varghese ◽  
Sai-Hong Ignatius Ou ◽  
Sheheryar Kabraji ◽  
Mark M Awad ◽  
...  
Keyword(s):  
Direct Sequencing ◽  
Acquired Resistance ◽  
Kinase Domain ◽  
Repeat Biopsy ◽  
Egfr Mutations ◽  
Tyrosine Kinase Domain ◽  
Kras Mutations ◽  
Anaplastic Lymphoma ◽  
Biopsy Specimens ◽  
Alk Positive

8083 Background: Anaplastic lymphoma kinase (ALK) gene rearrangements define a distinct molecular subset of NSCLC. Recently, several studies have reported that ALK+ pts occasionally harbor concomitant mutations in other oncogenic drivers. Methods: We retrospectively analyzed tumor genotyping data from 1,683 pts with NSCLC seen at 3 U.S. centers from 2009 – 2012 to determine rates of overlapping alterations in EGFR, KRAS and ALK. Mutations in EGFR and KRAS were mainly identified using the SNaPshot multiplexed assay (>95% of cases). ALK FISH was performed in all cases. To determine if this prevalence is impacted by crizotinib, we also updated our earlier analysis (Katayama et al., Sci Transl Med, 2012) of a series of repeat biopsy specimens from 34 crizotinib-resistant, ALK+ pts. Resistant specimens were examined using ALK FISH, SNaPshot, and direct sequencing of the ALK tyrosine kinase domain (TKD). Results: Screening identified 301 (17.8%) EGFR mutations, 465 (27.6%) KRAS mutations, and 75 (4.4%) ALK rearrangements. EGFR mutations and ALK rearrangements were mutually exclusive. 4 pts with KRAS mutations also had abnormal ALK FISH patterns, involving isolated 5’ green probes (3/4 cases) and an isolated 3’ red probe that was unusually small (1/4 cases). Sufficient tissue was available for confirmatory ALK immunohistochemistry (clone 5A4, Novacastra, UK) in 3 of these cases, all of which were negative for ALK expression. Among pts with ALK+ NSCLC and acquired crizotinib resistance, repeat biopsy specimens remained ALK fusion positive in 28/28 (100%) cases. Secondary mutations in the ALK TKD (1151Tins, L1196M, G1202R, S1206Y, and G1269A) were identified in 7/34 (20.6%) cases. L1196M was the most common secondary mutation (3/34, 8.8% cases). ALK gene amplification was present in 3/28 (10.71%) pts. No EGFR or KRAS mutations were identified in 23 crizotinib-resistant, ALK+ pts with sufficient tissue for testing. Conclusions: Functional ALK rearrangements were mutually exclusive with EGFR and KRAS mutations in a large Western patient population. This lack of overlap was also observed in ALK+ pts with acquired resistance to crizotinib.

Expanding the search for significant EGFR mutations in NSCLC outside of the tyrosine kinase domain with next-generation sequencing

2017 ◽  
Vol 34 (7) ◽  
Author(s):  
Matthew K. Stein ◽  
Lindsay Morris ◽  
Jennifer L. Sullivan ◽  
Moon Fenton ◽  
Ari VanderWalde ◽  
...  
Keyword(s):  
Next Generation Sequencing ◽  
Tyrosine Kinase ◽  
Kinase Domain ◽  
Egfr Mutations ◽  
Tyrosine Kinase Domain ◽  
Next Generation ◽  
Generation Sequencing

scholarly journals Roles of TrkC Signaling in the Regulation of Tumorigenicity and Metastasis of Cancer

Cancers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 147 ◽  
Author(s):  
Wook Jin
Keyword(s):  
Fusion Proteins ◽  
Epithelial Mesenchymal Transition ◽  
Tumor Regression ◽  
Acquired Resistance ◽  
Cell Lineage ◽  
Kinase Domain ◽  
Tyrosine Kinase Domain ◽  
Acquired Drug Resistance ◽  
Mesenchymal Transition ◽  
Trk Inhibitors

Tropomyosin receptor kinase (Trk) C contributes to the clinicopathology of a variety of human cancers, and new chimeric oncoproteins containing the tyrosine kinase domain of TrkC occur after fusion to the partner genes. Overexpression of TrkC and TrkC fusion proteins was observed in patients with a variety of cancers, including mesenchymal, hematopoietic, and those of epithelial cell lineage. Both microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) were involved in the regulation of TrkC expression through transcriptional and posttranscriptional alteration. Aberrant activation of TrkC and TrkC fusion proteins markedly induces the epithelial-mesenchymal transition (EMT) program, growth rate, tumorigenic capacity via constitutive activation of Ras-MAP kinase (MAPK), PI3K-AKT, and the JAK2-STAT3 pathway. The clinical trial of TrkC or TrkC fusion-positive cancers with newly developed Trk inhibitors demonstrated that Trk inhibitors were highly effective in inducing tumor regression in patients who do not harbor mutations in the kinase domain. Recently, there has been a progressive accumulation of mutations in TrkC or the TrkC fusion protein detected in the clinic and its related cancer cell lines caused by high-throughput DNA sequencing. Despite given the high overall response rate against Trk or Trk fusion proteins-positive solid tumors, acquired drug resistance was observed in patients with various cancers caused by mutations in the Trk kinase domain. To overcome acquired resistance caused by kinase domain mutation, next-generation Trk inhibitors have been developed, and these inhibitors are currently under investigation in clinical trials.

scholarly journals 4558 Investigating the functional consequences of anaplastic lymphoma kinase (ALK) mutations arising upon Lorlatinib treatment

2020 ◽  
Vol 4 (s1) ◽  
pp. 9-10
Author(s):  
Gabriela Maria Witek ◽  
Whelton Miller ◽  
David Slochower ◽  
Esther Berko ◽  
Yael Mossé ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Anaplastic Lymphoma Kinase ◽  
De Novo ◽  
Point Mutations ◽  
Md Simulations ◽  
Competitive Inhibitor ◽  
Kinase Domain ◽  
Tyrosine Kinase Domain ◽  
Anaplastic Lymphoma ◽  
Mechanism Of Resistance

OBJECTIVES/GOALS: Neuroblastoma (NB) is an embryonal cancer of the sympathetic nervous system that affects mostly infants and young children. The complex genetic background present across NB patients results in diverse clinical response and difficulty in individualizing therapy. Currently, NB patients undergo a regimen of genotoxic chemotherapeutics, radiation therapy, and new immunotherapy that, while effective, has significant side effects, including excruciating pain. One promising avenue for targeted therapy in neuroblastoma focuses on anaplastic lymphoma kinase (ALK), a cell surface neural receptor tyrosine kinase. We previously identified activating point mutations within the tyrosine kinase domain of ALK as the primary cause of hereditary NB, and we and others subsequently showed that these same alterations are the most common somatic single-nucleotide mutations in the sporadic forms of the disease. Crizotinib, a first-generation small molecule ATP-competitive inhibitor of the ALK tyrosine kinase, showed limited anti-tumor activity in patients with relapsed NB harboring ALK F1174 and F1245 mutations. We have demonstrated that lorlatinib, a novel ATP-competitive ALK inhibitor, overcomes this de novo resistance in preclinical models of ALK-driven NB. Recent clinical trials with lorlatinib in patients with non-small cell lung cancer harboring an ALK fusion, and in patients with NB harboring ALK mutations show the emergence of multiple or compound ALK mutations as a mechanism of resistance. We postulate that these compound mutations disrupt the interaction between and ALK and cause resistance. In this study, we employ a computational approach to model mutated ALK in complex with lorlatinib as well as ATP to understand whether the new mutations alter the affinity or mode of lorlatinib/ATP binding to ALK, and thus cause suboptimal ALK inhibition. METHODS/STUDY POPULATION: We employ methods in computational structural biology and drug design, primarily based on molecular modeling, molecular dynamics (MD), and molecular docking. Based on existing crystal structures of wildtype ALK, we model the mutations and perform MD simulations in order to characterize the activation state of the protein as well as perform ensemble docking calculations to assess the binding affinities and modes in ALK-lorlatinib and ALK-ATP complexes. RESULTS/ANTICIPATED RESULTS: We expect that the compound mutations cause resistance to lorlatinib either by lowering protein affinity for the drug or increasing the affinity for ATP. Alternatively, the compound mutations may disrupt the protein activation state, in which case ALK may no longer be active, and another protein/pathway could be driving the resistance. DISCUSSION/SIGNIFICANCE OF IMPACT: The results of this study will enable the understanding of the mechanism of resistance to lorlatinib and facilitate the design of new ALK inhibitors, or help develop more optimal and mechanism-guided therapies aimed to overcome the resistance.

Molecular analysis of NSCLC patients with acquired resistance to gefitinib or erlotinib

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 7078-7078 ◽  
Author(s):  
W. Pao ◽  
M. N. Balak ◽  
G. J. Riely ◽  
A. R. Li ◽  
M. F. Zakowski ◽  
...  
Keyword(s):  
Acquired Resistance ◽  
Kinase Domain ◽  
Site Mutation ◽  
Primary Resistance ◽  
Kras Mutations ◽  
T790m Mutation ◽  
Exon 2 ◽  
Nsclc Patients ◽  
Egfr Kinase ◽  
Exon 19

7078 Background: We previously reported that in 2 of 5 non-small cell lung cancer (NSCLC) patients with acquired resistance to the tyrosine kinase inhibitors (TKIs), gefitinib and erlotinib, tumors biopsied after disease progression contained a second site mutation (T790M) in the epidermal growth factor receptor (EGFR) kinase domain, in addition to a primary drug-sensitive mutation (exon 19 deletion (del) or exon 21 point mutation (L858R)) (Pao et al, PLoS Med ‘05). No patients had KRAS mutations, which are associated with primary resistance to these TKIs. We sought to determine the frequency of second site EGFR kinase domain and KRAS mutations in tumors from patients with acquired resistance to TKIs, administered either as monotherapy or with chemotherapy. Methods: 18 patients with NSCLC who responded to either TKI alone (n = 14) or TKI plus chemotherapy (n = 4) and then progressed were re-biopsied. Genomic DNA samples from tumors were examined for EGFR (exons 18–24) and KRAS (exon 2) mutations. Results: Sequence analysis was successfully performed on tumors from 17 patients. The T790M EGFR mutation was detected in 6 of 13 (46%, 95% CI 19–75%) on TKI monotherapy, and in 0 of 4 (0%, 95% CI 0–53%) on TKI plus chemotherapy. In one autopsy case, the T790M mutation was detected in 5 of 5 sites, which all harbored the same exon 19 del. No other EGFR or KRAS mutations were detected. Conclusions: Secondary EGFR T790M but not KRAS mutations are commonly associated with acquired resistance to TKI monotherapy. More patients are being studied, and we are trying to elucidate determinants of acquired resistance in the absence of T790M mutations. New therapies are needed to treat and/or suppress the development of acquired resistance to gefitinib or erlotinib. Support: Joan’s Legacy, DDCF, K08-CA097980, R21-CA115051. [Table: see text]

Expanding the search for significant EGFR mutations in NSCLC outside of the tyrosine kinase domain (TKD) with next-generation sequencing (NGS).

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e20506-e20506
Author(s):  
Matthew K Stein ◽  
Lindsay Kaye Morris ◽  
Jennifer Sullivan ◽  
Moon Jung Fenton ◽  
Ari M. Vanderwalde ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
In Silico ◽  
Kinase Inhibitors ◽  
Stage Iv ◽  
In Silico Analysis ◽  
Large Cell ◽  
Kinase Domain ◽  
Egfr Mutations ◽  
Tyrosine Kinase Domain ◽  
Carboxy Terminal

e20506 Background: While conventional organization of EGFR mutations in NSCLC includes classic lesions sensitive to tyrosine kinase inhibitors (TKI) and variants localized to TKD in exons 18-21, NGS raises the prospect of identifying clinically relevant variants in extra-TKD regulatory regions. Methods: Patients (pts) with lung cancer who received tumor profiling with NGS from 2013-2015 via Caris were identified. EGFR mutations were arranged based upon their known distribution relative to the TKD. In silico analysis was performed with PolyPhen-2 (Harvard) to predict nsSNPs’ pathogenicity. Results: 259 pts (248 NSCLC, 11 SC) had median age 65 years (26-85); 50% female; 64% white, 34% black; 73% with ≥20 pack-years (py), 12% non-smokers; 53% of samples were metastases. 65% NSCLC were adenocarcinoma (A), 21% squamous (S), 8% large-cell; 87% stage IV, 12% III. 44 EGFR variants were seen in 40 pts (15%; 39 NSCLC, 1 SC). While 32 pts had TKD lesions demonstrable through standard testing, 8 had extra-TKD mutations (8/44), of which 5 were extracellular domain (ECD), 1 juxtamembrane (JM) and 2 carboxy terminal (CT). Aside from pathogenic ECD mutation G598V, 5/7 extra-TKD nsSNPs were predicted-damaging (pnsSNP) with in silico (Table 1). 7/7 extra-TKD nsSNP+ pts smoked (6/7 ≥20 py) and all 6 NSCLC pts were stage IV; 50% A, 17% S; 83% male. The pt with JM R675Q had erlotinib, 150 mg daily, added following progression of stage IV NSCLC on carboplatin and paclitaxel and had a partial response for 4 months. No other pt received EGFR-directed therapy. Conclusions: 2% NSCLC cases in our cohort had EGFR pnsSNPs located outside of the TKD, representing >18% of all EGFR mutations. Extra-TKD variants should be characterized collaboratively to determine TKI sensitivity and additional therapeutic targets. [Table: see text]

Characteristics of EGFR uncommon mutations in Chinese cancer patients.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. e13527-e13527
Author(s):  
Minghui Wang ◽  
Shuben Li ◽  
Hongbiao Wang ◽  
Jianjiang Xie ◽  
Junhang Zhang ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Transmembrane Domain ◽  
Kinase Domain ◽  
Copy Number Variations ◽  
Chinese Patients ◽  
Next Generation Sequencing Data ◽  
Egfr Mutations ◽  
Tyrosine Kinase Domain ◽  
Lung Cancers ◽  
Exon 19

e13527 Background: Exon 19 deletions and exon 21 L858R substitutions are the most common mutations of epidermal growth factor receptor (EGFR) in cancers, and the remaining other mutations are called uncommon mutations. Recent studies have shown the clinical relevance of EGFR uncommon mutations with tyrosine kinase inhibitors (TKI) therapies and immunotherapies. Therefore, understanding the distribution and characteristics of EGFR uncommon mutations in cancers would provide evidence for future design of trials and drug development. Methods: Next-generation sequencing data were obtained from 3,026 Chinese tumor samples which have been identified with EGFR mutations. Single nucleotide variations (SNV), short and long insertions/deletions (indel), copy number variations and gene rearrangements were assessed. All tests were carried out in a College of American Pathologists (CAP) accredited and Clinical Laboratory Improvement Amendments (CLIA) certified laboratory in Shanghai, China. Results: EGFR mutations including 32% L858R substitutions, 28% exon 19 deletions, and 40% uncommon mutations were detected in this cohort. EGFR uncommon mutations were most frequently detected in lung cancers, followed by esophageal and gastric cancers. The uncommon mutations of EGFR including 54% SNVs, 30% amplifications, and 9% rare types of mutations such as rearrangement, long indels and complex mutations were detected. The SNVs in exon 18 to 21 which encode the tyrosine kinase domain of EGFR consisted of 16% EGFR mutations. Among them, the mostly frequently SNV was G719X in exon 18 and had 3% EGFR mutations. Mutations in other function domain of EGFR, including extracellular EGF binding domain (0.8%), transmembrane domain (0.03%) and intracellular autophosphorylation domain (0.7%) were also detected. Conclusions: Our data indicated that EGFR uncommon mutations were widely distributed in a variety of cancer types in Chinese patients, mostly in lung cancers. SNVs in the tyrosine kinase domain were the most frequent uncommon mutations. These data will provide clues for future clinical studies.

High incidence of DNA mutations and gene amplifications of the ALK gene in advanced sporadic neuroblastoma tumours

2008 ◽  
Vol 416 (2) ◽  
pp. 153-159 ◽  
Author(s):  
Helena Carén ◽  
Frida Abel ◽  
Per Kogner ◽  
Tommy Martinsson
Keyword(s):  
Kinase Domain ◽  
Comparative Genomic ◽  
Tyrosine Kinase Domain ◽  
Large Set ◽  
Anaplastic Lymphoma ◽  
Dna Mutations ◽  
High Incidence ◽  
Study Support ◽  
Alk Protein ◽  
Large Primary

ALK (anaplastic lymphoma kinase) is oncogenic in several tumours and has recently been identified as a predisposition gene for familial NB (neuroblastoma) harbouring mutations in the TKD (tyrosine kinase domain). We have analysed a large set of sporadic human NB primary tumours of all clinical stages for chromosomal re-arrangements using a CGH (comparative genomic hybridization) array (n=108) and mutations of the ALK gene (n=90), and expression of ALK and related genes (n=19). ALK amplification or in-gene re-arrangements were found in 5% of NB tumours and mutations were found in 11%, including two novel not previously published mutations in the TKD, c.3733T>A and c.3735C>A. DNA mutations in the TKD and gene amplifications were only found in advanced large primary tumours or metastatic tumours, and correlated with the expression levels of ALK and downstream genes as well as other unfavourable features, and poor outcome. The results of the present study support that the ALK protein contributes to NB oncogenesis providing a highly interesting putative therapeutic target in a subset of unfavourable NB tumours.

Association of EGFR mutation or ALK rearrangement with expression of DNA repair and synthesis genes in never-smoker females with pulmonary adenocarcinoma.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 10527-10527
Author(s):  
Xiaoxia Chen ◽  
Shengxiang Ren ◽  
Peng Kuang ◽  
ChunXia Su ◽  
Jiayu Li ◽  
...  
Keyword(s):  
Dna Repair ◽  
Mrna Expression ◽  
Egfr Mutation ◽  
Excision Repair ◽  
Egfr Mutations ◽  
Mrna Levels ◽  
Alk Rearrangement ◽  
Anaplastic Lymphoma ◽  
Alk Positive ◽  
Nsclc Patients

10527 Background: Epidermal growth factor receptor (EGFR) mutation or anaplastic lymphoma kinase (ALK) rearrangement was found not only predict the efficacy of targeted drugs, but also associate with the efficacy of chemotherapy drugs in non-small cell lung cancer (NSCLC) patients. We investigated the relationship of EGFR mutation status or ALK rearrangement and DNA repair or synthesis genes, such as excision repair cross-complementing 1 (ERCC1), ribonucleotide reductase subunit M1 (RRM1), thymidylate synthetase (TS) and breast cancer gene one (BRCA1) gene expression, as a potential explanation for these observations. Methods: In this surgical series, 104 resected lung adenocarcinomas from nonsmoker females were analyzed concurrently for the EGFR mutation, ALK rearrangement status and mRNA expression of ERCC1, RRM1, TS and BRCA1 genes. EGFR mutation detection was performed by the method of ADx-ARMS, ALK rearrangement was detected by PCR and the mRNA expression of different genes were tested using the method of real-time PCR. Results: 73 (70.2%) patients harbored EGFR mutations and 10 (9.6%) had ALK rearrangement. The ERCC1 mRNA level in patients with EGFR mutation was 3.44±1.94×10-3 , which is significantly lower than in the patients with ALK positive and both negative(4.60±1.95×10-3 and 4.95±2.33×10-3 respectively, P=0.010). While the TS mRNA levels were significantly lower in the patients with EGFR mutation(1.15±1.38×10-3 VS 2.69±3.97×10-3, P=0.006) or ALK positive (1.21±0.78×10-3VS 2.69±3.97×10-3, P=0.020) than in patients with both negative. Conclusions: NSCLC specimens harboring activating EGFR mutations are more likely to express low ERCC1 and TS mRNA levels, while NSCLC patients with ALK rearrangement are more likely to express low TS mRNA levels, which could be helpful to select a proper chemotherapy regimen for NSCLC patients with known EGFR mutation or ALK fusion status.

Outcomes of KRAS mutated, EGFR mutated, ALK mutated and wildtype patients in non-small cell lung cancer brain metastases.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e21028-e21028
Author(s):  
Yasmeen Rauf ◽  
Vineeth Tatineni ◽  
Patrick joseph Oshea ◽  
Xuefei Jia ◽  
David M. Peereboom ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Retrospective Study ◽  
Brain Metastases ◽  
Targeted Therapies ◽  
Small Cell ◽  
Egfr Mutations ◽  
Small Cell Lung ◽  
Kras Mutations ◽  
Alk Positive ◽  
Egfr Mutated

e21028 Background: Non-small cell lung cancer (NSCLC) is the most common primary tumor leading to brain metastases. Multiple genetic markers have been profiled in NSCLC patients for potential targeted therapies. EGFR is mutated in up 50% of NSCLCs, while ALK is mutated in around 4-7%. KRAS is the most commonly overexpressed marker, seen in up to 85% of all lung cancers. In this retrospective study, we evaluated the overall survival (OS) and progression-free survival (PFS) between NSCLCBM patients with KRAS mutations, ALK mutations, EGFR mutations, and wildtype. Methods: NSCLCBM patients diagnosed between 2010 and 2019 were analyzed. We collected information regarding molecular marker status, systemic therapies, and date of progression. We defined OS as the date of diagnosis of brain metastases to the date of last follow-up or death. OS and PFS were estimated by the Cox proportional model. Results: We found a total of 2989 NCSLCBM patients, 184 were KRAS mutated, 68 had an ALK gene rearrangement, 184 were EGFR mutated, and 1469 were wildtype. The respective median age was 64.3 years, 64.5 years, 58.2 years, and 64.2 years. Females made up 61.8% of KRAS-positive, 51.8% of ALK-positive, 63% of EGFR-positive, and 46.4% of wildtype patients. The median OS (mOS) in patients who were KRAS-positive, ALK-positive, EGFR-positive, and wildtype were 43.3 months, 119.2 months, 57.9 months, and 33.1 months, respectively. The median PFS (mPFS) for the same cohort was 38.0 months, 112.4 months, 55.3 months, and 30.5 months, respectively. ALK-positive patients showed statistically significant mOS (p-value (p) < 0.001) and mPFS (p = 0.002) when compared to EGFR-positive, KRAS-positive, and wildtype patients. Conclusions: Molecular mutations serve as both prognostic predictors and alternative targeted therapies for NSCLCBM treatment. Our retrospective study showed improved mOS and mPFS in NSCLCBM patients with ALK rearrangements when compared to patients with EGFR mutations, KRAS mutations, and the wildtype. While these results looked at patient outcomes with specific tumor markers, further investigation needs to be done regarding outcomes of specific therapies in each cohort, as well as, intracranial lesion response.

The K247R Substitution in ABL Tyrosine Kinase Domain Is Not a Mutation Leading to Imatinib Resistance but a Polymorphism Rarely Present in CML Patients and in Normal Subjects.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4831-4831
Author(s):  
Kaddour Chabane ◽  
Franck Nicolini ◽  
Jean-Michel Cayuela ◽  
Philippe Rousselot ◽  
Xavier Thomas ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Tyrosine Kinase ◽  
Disease Progression ◽  
Direct Sequencing ◽  
Point Mutations ◽  
Kinase Domain ◽  
Tyrosine Kinase Domain ◽  
Molecular Response ◽  
Imatinib Resistance ◽  
Abl Tyrosine Kinase

Abstract The major mechanism for resistance to imatinib mesylate (IM) is the onset of ABL point mutations altering functional inhibition of the tyrosine kinase activity by IM. Biochemical, cellular assays and clinical studies have demonstrated that different BCR-ABL mutations exhibit various degrees of resistance, and mutations occurring in the ATP-binding loop may be correlated with subsequent disease progression. In this study, we investigated the status of the K247R ABL polymorphism and correlated it to disease outcome. Patients and methods: Two patients (P1 and P2) were diagnosed with CML based on peripheral blood findings, karyotyping analysis (showing t(9;22)(q34;q11)) and molecular analysis for BCR-ABL (indicating M-BCR fusion transcripts) in 2,000 and 1,994, respectively. P1, a 54 years old male, enrolled in the Novartis IRIS study, was randomly assigned to the interferon + AraC arm after informed consent. The patient achieved a complete hematologic remission (CHR) at 3 months and a complete cytogenetic response (CCR) at 24 months. At time of cytogenetic relapse (2 years later), P1 had never received IM which was introduced in April 2,005. P2 received IM (400mg to 600mg/day) during 82 months and had shown only CHR during 14 months with no MCR. Epithelial cells were collected in the mouth through sterile foam tipped applicators for both patients. DNA was obtained from blood samples of 232 individuals, including 124 patients with CML, 72 patients with acute myeloid leukemias (AML) and 36 normal healthy donors. The K247R change was studied by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique (AluI restriction enzymatic site abolished) and was confirmed by direct sequencing. Results: Both patients, showing the K247R substitution located close to the P-loop, were retrospectively investigated during disease progression. We found that this change accounted for 100% of the BCR-ABL transcripts at CML diagnosis (and in all the further samples) for P1 (no material was yet available from P2 at this time) and for 50% of the ABL gene in extracted DNA from epithelial cells in the 2 patients. P1, despite of the K247R substitution received IM (400 mg/day) and achieved a CHR, a CCR and a good molecular response (one log reduction after two months of IM). IM resistance observed in P2 was probably due to the presence of an additional F317L mutation, known to induce a very strong resistance to IM. The F317L mutation accounted for 100% of the BCR-ABL transcripts at the resistance, was absent in DNA from epithelial cells. The screening showed the K247R exchange in 1 normal subject (heterozygote), in 2 CML patients (P1 and P2: at heterozygous state in normal cells and at homozygous state in BCR-ABL transcripts) and in none AML samples. According to that, the incidence of this polymorphism seems to reach nearly 1 to 1.5%. Conclusion: This study demonstrates that the K247R substitution in ABL tyrosine kinase domain is not a mutation leading to IM resistance but only a rare polymorphism. Detailed analysis of this polymorphism status will be reported.

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