In-Vitro Cytotoxicity of Tipifarnib (Zarnestra TM) in Pediatric AML and ALL Samples Is Independent of RAS Mutations.

Abstract The farnesyltransferase inhibitor tipifarnib (Zarnestra™) was originally developed to target malignancies harbouring RAS mutations. In the first clinical studies with tipifarnib, in adults with leukemia, it was found that patients who responded did not harbour any RAS mutations, suggesting a different mechanism of response. In a previous study we showed that 18% of 150 untreated pediatric AML patients harbour mutations in RAS, of which 30% were CBF-AML. We now studied 44 untreated and 13 relapsed pediatric AML, as well as 22 untreated ALL samples for mutations in RAS, using D-HPLC and direct sequencing. In vitro tipifarnib resistance was determined by a 4-day MTT assay (concentration 0.016-51μM, kindly provided by Janssen Research). The LC50 value, the concentration at which 50% of cells are killed by tipifarnib, was used as a measure of resistance. Patient characteristics were; for untreated AML: 64% boys; median age 9.3 years; median WBC 74.8x109/L; FAB 2xM0, 2xM1, 8xM2, 3xM3, 16xM4, 8xM5, 5x unclassified; for relapsed AML: 77% boys; median age 4.0 years; median WBC 41.6x109/L; FAB 2xM0, 2xM2, 3xM4, 2xM5, 2xM7, 2x unclassified; for untreated ALL: 73%boys; median age 6.0 years; median WBC 10.2x109/L; 15 B-cell precursor (BCP) ALL and 7 T-ALL. We found RAS mutations in 14 (32%) untreated AML samples (N-RAS : 8 samples exon 1, 1 sample exon 2; K-RAS: 5 samples exon 1 mutations). In relapsed AML 2 samples showed an N-RAS exon 1 mutation (15.4%). In ALL 18.2% had a RAS mutation: an N-RAS exon 1 mutation was found in 2 patients (9.1%) and a K-RAS exon 1 mutation in another 2 patients (9.1%). The distribution of tipifarnib sensitivity was similar in RAS mutated- and non-mutated untreated AML patients [median LC50 RAS mutated 7.1μM (P25-P75: 6.0-9.6μM) vs. non-mutated 4.9μM (P25-P75 2.3-8.2μM); p=0.199]. When we compared N-RAS mutated samples with K-RAS mutated samples there was no statistically significant difference in sensitivity to tipifarnib (median LC50 [p25-p75] 3.2μM [2.9-3.9μM] and 4.9μM [3.7-23.1μM], p=0.20), and comparing them separately with non-mutated AML did not show differences in sensitivity to tipifarnib (p=0.172 and p=0.463 respectively). One out of 9 (11%) N-RAS mutated and 3 out of 5 (60%) K-RAS mutated samples had an LC50 value above the 75th percentile for non-mutated AML and were considered resistant. Within relapsed AML the 2 RAS mutated samples had LC50 values of 0.83 and 6.3μM, versus a median value of 6.9μM for non-mutated relapsed AML. In ALL, we found similar results [median LC50 RAS mutated 7.8μM (P25-75: 4.1-12.8μM) vs. non-mutated 17.4μM (P25-75: 4.5-22.9μM), p=0.3], but the groups were very small. In conclusion, primary pediatric AML and ALL samples withRAS mutations show similar distributions of tipifarnib sensitivity as samples withoutRAS mutations. Hence, some RAS mutated samples may be relatively in-vitro resistant to tipifarnib, and some non-mutated samples may be relatively sensitive. Therefore, clinical studies with these compounds should not be restricted to RAS-mutated leukemia. Further studies are necessary to determine the molecular targets of farnesyltransferase inhibitors.

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Preclinical and clinical validation of a novel injected molded swab for molecular assay detection of SARS-CoV-2 virus

10.1101/2021.10.19.21265200 ◽

2021 ◽

Author(s):

Chiara Elia Ghezzi ◽

Devon R Hartigan ◽

Justin Hardick ◽

Rebecca Gore ◽

Miryam Adelfio ◽

...

Keyword(s):

Health Care Providers ◽

Medical Devices ◽

Clinical Studies ◽

Nasal Swab ◽

Cost Effective ◽

Slight Reduction ◽

Care Providers ◽

Significant Difference ◽

Injection Molded

During the COVID-19 public health emergency, many actions have been undertaken to help ensure that patients and health care providers had timely and continued access to high-quality medical devices to respond effectively. The development and validation of new testing supplies and equipment, including collection swab, help expand the availability and capability for various diagnostic, therapeutic, and protective medical devices in high demand during the COVID-19 emergency. Here, we report the validation of a new injection-molded anterior nasal swab, ClearTip™, that was experimentally validated in a laboratory setting as well as in independent clinical studies in comparison to gold standard flocked swabs. We have also developed an in vitro anterior nasal tissue model, that offers an efficient and clinically relevant validation tool to replicate with high fidelity the clinical swabbing workflow, while being accessible, safe, reproducible, time and cost effective. ClearTi™ displayed a greater efficiency of release of inactivated virus in the benchtop model, confirmed by greater ability to report positive samples in a clinical study in comparison to flocked swabs. We also quantified in multi-center pre-clinical and clinical studies the detection of biological materials, as proxy for viral material, that showed a statistically significant difference in one study and a slight reduction in performance in comparison to flocked swabs. Taken together these results underscore the compelling benefits of non-absorbent injected molded anterior nasal swab for COVID-19 detection, comparable to standard flocked swabs. Injection-molded swabs, as ClearTip™, could have the potential to support future swab shortage, due to its manufacturing advantages, while offering benefits in comparison to highly absorbent swabs in terms comfort, limited volume collection, and potential multiple usage.

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Preclinical Validation of a Novel Injection-Molded Swab for the Molecular Assay Detection of SARS-CoV-2

Diagnostics ◽

10.3390/diagnostics12010206 ◽

2022 ◽

Vol 12 (1) ◽

pp. 206

Author(s):

Chiara E. Ghezzi ◽

Devon R. Hartigan ◽

Justin P. Hardick ◽

Rebecca Gore ◽

Miryam Adelfio ◽

...

Keyword(s):

Health Care Providers ◽

Medical Devices ◽

Clinical Studies ◽

Cost Effective ◽

Care Providers ◽

Nasal Tissue ◽

Significant Difference ◽

Injection Molded ◽

Development And Validation

During the COVID-19 public health emergency, many actions have been undertaken to help ensure that patients and health care providers have timely and continued access to high-quality medical devices to respond effectively. The development and validation of new testing supplies and equipment, including collection swabs, has helped to expand the availability and capability for various diagnostic, therapeutic, and protective medical devices in high demand during the COVID-19 emergency. Here, we report the initial validation of a new injection-molded anterior nasal swab, ClearTip™, that was experimentally validated in a laboratory setting as well as in independent clinical studies in comparison to gold standard flocked swabs. We have also developed an in vitro anterior nasal tissue model which offers a novel, efficient, and clinically relevant validation tool to replicate the clinical swabbing workflow with high fidelity, while being accessible, safe, reproducible, and time- and cost-effective. ClearTip™ displayed greater inactivated virus release in the benchtop model, confirmed by its greater ability to report positive samples in a small clinical study in comparison to flocked swabs. We also quantified the detection of biological materials, as a proxy for viral material, in multi-center pre-clinical and clinical studies which showed a statistically significant difference in one study and a reduction in performance in comparison to flocked swabs. Taken together, these results emphasize the compelling benefits of non-absorbent injection-molded anterior nasal swabs for COVID-19 detection, comparable to standard flocked swabs. Injection-molded swabs, as ClearTip™, could have the potential to support future swab shortages, due to its manufacturing advantages, while offering benefits in comparison to highly absorbent swabs in terms of comfort, limited volume collection, and potential multiple usage.

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Effect of 5' splice site mutations on splicing of the preceding intron

Molecular and Cellular Biology ◽

10.1128/mcb.10.12.6299-6305.1990 ◽

1990 ◽

Vol 10 (12) ◽

pp. 6299-6305

Author(s):

M Talerico ◽

S M Berget

Keyword(s):

Splice Site ◽

Exon Skipping ◽

Splicing Factors ◽

Exon 2 ◽

Intron 1 ◽

Direct Assembly ◽

Internal Exon ◽

Exon 1 ◽

Lariat Rna

Three exon constructs containing identical intron and exon sequences were mutated at the 5' splice site beginning intron 2 and assayed for the effect of the mutation on splicing of the upstream intron in vitro. Alteration of two or six bases within the 5' splice site reduced removal of intron 1 at least 20-fold, as determined by quantitation of either spliced product or released lariat RNA. The prominent product was skip splicing of exon 1 to exon 3. Examination of complex formation indicated that mutation of the 5' splice site terminating exon 2 depressed the ability of precursor RNAs containing just the affected exon to direct assembly in vitro. These results suggest that mutation at the end of an internal exon inhibits the ability of the exon to be recognized by splicing factors. A comparison of the known vertebrate 5' splice site mutations in which the mutation resides at the end of an internal exon indicated that exon skipping is the preferred phenotype for this type of mutation, in agreement with the in vitro observation reported here. Inhibition of splicing by mutation at the distal and of the exon supports the suggestion that exons, rather than splice sites, are the recognition units for assembly of the spliceosome.

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Whether mCRC patients with other RAS mutations benefit from the addition of bevacizumab as first-line therapy.

Journal of Clinical Oncology ◽

10.1200/jco.2016.34.4_suppl.579 ◽

2016 ◽

Vol 34 (4_suppl) ◽

pp. 579-579

Author(s):

Mingyi Zhou ◽

Ping Yu ◽

Kezuo Hou ◽

Xiujuan Qu ◽

Yunpeng Liu ◽

...

Keyword(s):

Meta Analysis ◽

Large Sample Size ◽

First Line ◽

Exon 2 ◽

Ras Mutations ◽

First Line Therapy ◽

Line Therapy ◽

Significant Difference ◽

Ras Status ◽

Kras Exon

579 Background: It is not clear whether Bevacizumab plus chemotherapy could improve the prognosis of mCRC patients with other RAS mutations beyond KRAS exon 2. Methods: The MEDLINE, EMBASE, Cochrane databases, and Clinical Trials databases were reviewed to September 2015. The data of patients with KRAS exon 2 mutations was only available in FIRE3 study. So we could not perform the meta-analysis by KRAS exon 2 mutations. The data of patients with other RAS mutations beyond KRAS exon 2 were available in PEAK and FIRE3 studies. Hazard ratio (HR) was used to analyze the progressive-free survival (PFS) and overall survival (OS). Relative risk (RR) was used to analyze overall response rate (ORR). Results: Patients with other RAS mutations beyond KRAS exon 2 benefited from the addition of Bevacizumab. Bevacizumab + chemotherapy significantly improved the PFS compared with anti-EGFR moAb + chemotherapy (HR: 1.82, CI: 1.20–2.77, P =.005). The addition of Bevacizumab tended to improve ORR, though there is no significant difference (RR: 0.83, CI: 0.58–1.18, P =.288). But the OS tended to be shorter in Bevacizumab + chemotherapy arm than anti-EGFR moAb + chemotherapy arm without significant difference (HR: 0.72, CI: 0.25–2.05, P =.534). Conclusions: Patients with other RAS mutations beyond KRAS exon 2 could choose Bevacizumab plus chemotherapy as first-line therapy. But there is still no adequate evidence to reject or support the predictive value of RAS status in the effect of the addition of Bevacizumab. Moreover, which is the better primary endpoint, PFS or OS? Which is the better consequence of strategy, anti-EGFR moAb followed by Bevacizumab or Bevacizumab followed by anti-EGFR moAb? RCTs with large sample size comparing the efficacy of anti-VEGF moAb + chemotherapy and chemotherapy alone by RAS status as the first-line therapy in mCRC patients are required in the future.

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Gel electrophoretic isolation of splicing complexes containing U1 small nuclear ribonucleoprotein particles.

Molecular and Cellular Biology ◽

10.1128/mcb.8.2.814 ◽

1988 ◽

Vol 8 (2) ◽

pp. 814-821 ◽

Cited By ~ 78

Author(s):

M Zillmann ◽

M L Zapp ◽

S M Berget

Keyword(s):

Gel Electrophoresis ◽

Splice Junction ◽

Rnase H ◽

Exon 2 ◽

Small Nuclear Ribonucleoprotein ◽

Complementary Oligonucleotide ◽

Exon 1 ◽

Precursor Rna ◽

Splice Junctions

Assembly of splicing precursor RNAs into ribonucleoprotein particle (RNP) complexes during incubation in in vitro splicing extracts was monitored by a new system of RNP gel electrophoresis. The temporal pattern of assembly observed by our system was identical to that obtained by other gel and gradient methodologies. In contrast to the results obtained by other systems, however, we observed requirements of U1 small nuclear RNPs (snRNPs) and 5' splice junction sequences for formation of specific complexes and retention of U1 snRNPs within gel-fractionated complexes. Single-intron substrate RNAs rapidly assembled into slow-migrating complexes. The first specific complex (A) appeared within a minute of incubation and required ATP, 5' and 3' precursor RNA consensus sequences, and intact U1 and U2 RNAs for formation. A second complex (B) containing precursor RNA appeared after 15 min of incubation. Lariat-exon 2 and exon 1 intermediates first appeared in this complex, operationally defining it as the active spliceosome. U4 RNA was required for appearance of complex B. Released lariat first appeared in a complex of intermediate mobility (A') and subsequently in rapidly migrating diffuse complexes. Ligated product RNA was observed only in fast-migrating complexes. U1 snRNPs were detected as components of gel-isolated complexes. Radiolabeled RNA within the A and B complexes was immunoprecipitated by U1-specific antibodies under gel-loading conditions and from gel-isolated complexes. Therefore, the RNP antigen remained associated with assembled complexes during gel electrophoresis. In addition, 5' splice junction sequences within gel-isolated A and B complexes were inaccessible to RNase H cleavage in the presence of a complementary oligonucleotide. Therefore, nuclear factors that bind 5' splice junctions also remained associated with 5' splice junctions under our gel conditions.

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Association of RAS mutations with race in metastatic colorectal cancer: CALGB/SWOG 80405 (ALLIANCE).

Journal of Clinical Oncology ◽

10.1200/jco.2018.36.4_suppl.638 ◽

2018 ◽

Vol 36 (4_suppl) ◽

pp. 638-638 ◽

Cited By ~ 2

Author(s):

Amikar Sehdev ◽

Donna Niedzwiecki ◽

Alan P. Venook ◽

Heinz-Josef Lenz ◽

Federico Innocenti ◽

...

Keyword(s):

Colorectal Cancer ◽

Multivariate Analysis ◽

Adjuvant Chemotherapy ◽

Multivariate Analyses ◽

Exon 2 ◽

Ras Mutation ◽

Pelvic Radiation ◽

Ras Mutations ◽

Mutational Status ◽

Significant Difference

638 Background: Colorectal cancer (CRC) is a heterogeneous disease with distinct molecular subtypes in part based on RAS mutational status. It is plausible that RAS mutations are differentially distributed between CC and AA and may contribute to poor outcomes in AAs with CRC. Methods: We did a retrospective analysis of CALGB/SWOG 80405 trial patients. We divided the entire cohort into 2 groups: a) Common RAS: mutation in KRAS exon 2, codon 12 or 13; b) Extended RAS: any NRAS mutations or mutation in KRAS except those listed above. We then analyzed these two subgroups for association between RAS mutations and race (3 categories: Caucasian, AA, Others) using chi-square test for univariate analyses and logistic regression for multivariate analysis. We also analyzed the effect of extended RAS testing on prognosis of metastatic CRC by estimating the overall survival (OS) using Kaplan-Meier method and 95% confidence interval (CI). Cox proportional-hazard model was used for multivariate analyses. Results: There were 1729 CRC patients in common RAS group of which 357 (20.6%) had mutations present. Extended RAS group had 621 patients of which 95 (15.5%) had mutations present. There was no significant difference in the rate of common RAS mutations between CC and AA (20.5% vs. 24%, p=0.22). However, extended RAS mutations were significantly more in AA as compared to CC (25% vs. 14%, p=0.02). Multivariate analysis adjusted for age, gender, prior adjuvant chemotherapy and pelvic radiation confirmed higher odds of extended RAS mutation in AA compared to CC (adjusted OR 1.12; 95% CI 1.01-1.23; p=0.02). The median OS in patients with an extended RAS mutation was shorter as compared to those without extended RAS mutation (25.3 vs. 31.9 months; HR 1.26; 95% CI 0.99-1.62; p=0.05). Multivariate analyses adjusted for age, gender, race, prior adjuvant chemotherapy and pelvic radiation showed a trend towards longer OS in patients without extended RAS mutation as compared those with extended RAS mutation (adjusted HR= 1.24, 95% CI, 0.97-0.1.58, p=0.08). Conclusions: Extended RAS mutations are significantly more common in AA as compared to CC. Additionally, presence of extended RAS mutation may confer a poor prognosis in CRC patients.

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Prevalence and Clinical Implications of N-RAS Mutations in Childhood AML – A Report From the Children's Oncology Group.

Blood ◽

10.1182/blood.v114.22.3115.3115 ◽

2009 ◽

Vol 114 (22) ◽

pp. 3115-3115

Author(s):

Jason N. Berman ◽

Robert B. Gerbing ◽

Lillian Sung ◽

Kristen Miller ◽

Jessica A. Pollard ◽

...

Keyword(s):

Signal Transduction ◽

High Risk ◽

Prognostic Significance ◽

Low Risk ◽

Signal Transduction Pathways ◽

Free Survival ◽

Ras Mutations ◽

Significant Difference ◽

Pediatric Aml ◽

The Impact

Abstract Abstract 3115 Poster Board III-52 Mutations in the RAS proto-oncogenes are frequent in acute myeloid leukemia (AML) and serve as prototypic Class I lesions, initiating key downstream hyper-proliferative signal transduction pathways. N-RAS mutations (N-RASmut) are common in AML, occurring in 10-20% of adult and pediatric AML patients; however their prognostic significance in both adults and children remains disputed. Due to a frequent association with a normal karyotype, delineating the impact of these mutations on outcome may enable appropriate risk-adapted therapeutic approaches. Here, we report on the incidence and prognostic significance of N-RASmut in a cohort of 825 pediatric AML patients treated on 2 recent co-operative group studies, CCG-2961 and COG AAML03P1. In total, of the 825 children with de novo AML who underwent N-RAS mutational analysis, 86 (10%) were positive. Gender, age, race, presence of hepatosplenomegaly and FAB subtype were comparable between patients with and without N-RASmut. There was no statistically significant difference between those with and without N-RASmut with respect to specific chromosome class. FLT3/Internal tandem duplications (FLT3/ITD) were less common in those with N-RASmut (2% vs. 9%, p=0.03). In contrast, nucleophosmin (NPM) mutations were more common in those with N-RASmut (13% vs. 5%, p=0.02). Overall, N-RASmut showed a significant correlation with low risk AML (CBF, CEBPαa, or NPM, p=0.04) and an inverse relationship with high risk disease (-5/5q- or -7, FLT3/ITD/high allelic ratio, p=0.007). Patients with N-RASmut had similar complete remission (CR) rates following two courses of induction chemotherapy compared with non-mutated patients (79% vs. 79%, p=0.92). Those in CR had a similar relapse rate regardless of the presence of N-RASmut (RR 39% vs. 36%, p=0.97). Five year event free survival (EFS) and overall survival (OS) from study entry were also comparable, however N-RASmut patients demonstrated a marked increase in overall treatment related mortality (TRM) (21% vs. 14%, p=0.03), which was maintained when high and low risk patients were excluded (22% vs. 11%, p=0.05). Evaluation of TRM in CCG-2961 compared with COG AAML03P1 demonstrated that increased TRM in N-RASmut was only seen in patients treated on CCG-2961 and TRM was primarily due to invasive fungal and gram negative infections. Interestingly, for patients treated on CCG-2961, who received interval compressed intensive induction therapy, this increase in TRM correlated with a decrease in both OS and disease free survival from CR. Remission specimens from patients with N-RASmut were negative for the mutation, demonstrating that an increased infectious risk could not be attributed to a host polymorphism. We found N-RASmut did not contribute to increased disease recurrence in pediatric AML. Our findings indicate that N-RAS mutations do not identify a high risk population, however, as such mutations lead to downstream activation of signal transduction pathways, they may identify a target for directed therapy. Disclosures No relevant conflicts of interest to declare.

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Transcription initiation of the rat insulin-like growth factor-I gene in hepatocyte primary culture

Journal of Endocrinology ◽

10.1677/joe.0.1510215 ◽

1996 ◽

Vol 151 (2) ◽

pp. 215-223 ◽

Cited By ~ 9

Author(s):

A Y Krishna ◽

C-I Pao ◽

P M Thulé ◽

B C Villafuerte ◽

L S Phillips

Keyword(s):

Transcription Initiation ◽

Rat Hepatocytes ◽

Regulatory Mechanisms ◽

Exon 2 ◽

Factor I ◽

Igf I ◽

Exon 1 ◽

Normal Rat

Abstract Transcription initiation in the insulin-like growth factor-I (IGF-I) gene is complex, involving multiple sites in two exons. While most transcripts are initiated in exon 1 in vivo, critical regulatory mechanisms are difficult to assess in intact animals. To examine the impact of insulin and growth hormone (GH) under more controlled conditions, we have studied the utilization of different exon 1 and exon 2 transcription-initiation sites in normal rat hepatocytes in primary culture. Normal rat hepatocytes were cultured for 48 h in serum-free medium, with insulin at 10−6 or 10−11 m, and with or without human GH 200 ng/ml. Relative abundance of IGF-I transcripts was evaluated by the RNase-protection assay, using a probe which permitted identification of initiation in exon 1 (site 1 (−380 bp from the 3′ end of exon 1), site 2 (−343 bp), site 3 (−242 bp), sites 1 and 2 spliced, and site 4 (−32 bp)), as well as in exon 2. After normalization of signal intensity to adjust for differences in length of protected probe, the utilization of initiation sites in vitro was remarkably similar to that in vivo: 1, 14, 6, 23, 19 and 37% for sites 1, 2, 3, 1 and 2 spliced, 4 and exon 2 respectively in the cultured hepatocytes, compared with 1, 12, 8, 21, 18 and 40% for these sites in normal liver. Insulin alone increased transcripts initiated from exon 1, site 2 by over 3 times, and both sites 1 and 2 spliced and exon 2 transcripts by about 5 times. GH alone had similar effects, producing a 4–5 times increase in transcripts from these initiation sites. Addition of both insulin and GH had additive effects, increasing transcripts from exon 1, sites 2, 3 and 4 by 4–6 times, and from exon 1, sites 1 and 2 spliced, and exon 2 by over 8 times. Of the total IGF-I mRNA transcripts, 37% were initiated from sites 2 and/or sites 1 and 2 spliced, and 37% from exon 2. Analysis of the relative contribution of individual initiation sites revealed hormone-induced increases which were statistically significant only for exon 2, in the presence of insulin alone and in combination with GH. In conclusion, in cultured hepatocytes, insulin or GH alone produced a coordinated increase in all exon 1 transcripts, and the effect of the combination of insulin and GH was additive for these transcripts. Exon 2 appeared to be more sensitive to insulin alone, and to GH in the presence of insulin, than exon 1. Since utilization of initiation sites in hepatocytes mimics that found in liver, this in vitro system should be useful for examining underlying transcriptional regulatory mechanisms. Journal of Endocrinology (1996) 151, 215–223

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Effect of 5' splice site mutations on splicing of the preceding intron.

Molecular and Cellular Biology ◽

10.1128/mcb.10.12.6299 ◽

1990 ◽

Vol 10 (12) ◽

pp. 6299-6305 ◽

Cited By ~ 91

Author(s):

M Talerico ◽

S M Berget

Keyword(s):

Splice Site ◽

Exon Skipping ◽

Splicing Factors ◽

Exon 2 ◽

Intron 1 ◽

Direct Assembly ◽

Internal Exon ◽

Exon 1 ◽

Lariat Rna

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Frequency of KRAS mutations in female colorectal cancer (CRC) patients: Findings of a Brazilian cohort of 8,234 cases.

Journal of Clinical Oncology ◽

10.1200/jco.2012.30.15_suppl.e14101 ◽

2012 ◽

Vol 30 (15_suppl) ◽

pp. e14101-e14101

Author(s):

Carlos G. M. Ferreira ◽

Mariano Zalis ◽

Ilana Zalcberg-Renault ◽

Martin H Bonamino ◽

Marcos Barcelos de Pinho ◽

...

Keyword(s):

Clin Oncol ◽

Kras Mutation ◽

Direct Sequencing ◽

Reference Laboratory ◽

Wild Type ◽

Kras Mutations ◽

Significant Difference ◽

Exon 1 ◽

The Impact ◽

Brazilian Cohort

e14101 Background: Although major advances in the last decades, there are still important gaps in our understanding of CRC carcinogenesis, particularly whether sex-linked factors play any role. Some groups, including ours, observed that KRAS mutation may be more frequent in female than male (Ferreira C.G. et al. J Clin Oncol 28: 2010 suppl abstr 3614; Uetake H. et al. J Clin Oncol 29: 2011 suppl abstr 3605). Methods: Between July 2008 and July 2011, we analyzed 8,234 consecutive patient samples sent to a reference laboratory for KRAS genotyping as a screening for cetuximab use. DNA was extracted from paraffin-embedded tissue, exon 1 was amplified by PCR and submitted to direct sequencing. Codons 12 and 13 were analyzed. Results: The median age was 59 years and well balanced according to gender with 51.9% of male and 48.1% female patients. The percentage of wild-type and mutated KRAS was 66.4 and 33.6%, respectively. Corroborating previous findings a significant difference in the percentage of mutated KRAS patients was observed between female and male (34.8% versus 32.5%, p = 0.03). However there were no differences in the distribution of any specific KRAS mutation according to gender. Among the 2,626 mutated cases, 83% were in codon 12 versus 17% in codon 13. Mutation Gly12Asp was the most common being detected in 36% of the mutated cases. Conclusions: This is one of the largest cohorts of KRAS genotyping in CRC patients. In line with previous data our present findings indicate that KRAS-mutations are more frequent in female than male. Further research is required to better address the impact of gender differences and/or hormones as potential drivers of CRC carcinogenesis.

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