ALBERT

Description: The majority of patients with adult acute myeloid leukaemia (AML) that present with an apparently normal karyotype (NK-AML) are grouped together in the “intermediate” risk category and constitute 40-45% of all adult AML patients. Mutations in the FMS-like tyrosine kinase 3 (FLT3) receptor whether it is internal tandem duplication (ITD) of its juxtamembrane domain or point mutations in its kinase domain are one of the most common mutations in NK-AML. The presence of FLT3-ITD mutation in NK-AML results in a more aggressive disease, resistance to therapy and poor survival. Acquired copy neutral loss of heterozygosity (CN-LOH) also referred to as uniparental disomy (UPD) is a common phenomenon of myeloid malignancies where an oncogenic allele is duplicated on the other chromosome. The use of single nucleotide phenotype analysis (SNP-A) karyotyping detects CN-LOH in 20% and 40% of newly diagnosed and relapsed AML respectively. CN-LOH at 6p or at the FLT3 locus 13q associated with a FLT3-ITD mutation in NK-AML results in an even more aggressive disease compared to NK-AML + FLT3-ITD without CN-LOH. It has been proposed that CN-LOH is the result of a homologous recombination (HR) DNA repair event. However, the underlying mechanisms that confer CN-LOH have yet to be determined. To elucidate the mechanisms that produce CN-LOH in NK-AML we determined whether oncogenes such as FLT3-ITD have the propensity to generate CN-LOH through up-regulation of inter chromosomal (between maternal and paternal chromosomes) HR DNA repair. We have showed previously that constitutional FLT3-ITD kinase activity increased reactive oxygen species resulting in elevated double strand breaks. Moreover, FLT3-ITD mutation increases homologous recombination activity through transcriptional augmentation of HR factor, RAD51 expression. Firstly, to evaluate FLT3-ITD induced genomic instability we measured sister chromatid exchanges (SCE) that result from HR mediated chromosome cross-over. It has been shown previously in the pre-leukaemic chromosomal instability disorder, Blooms syndrome is characterised by increased SCE and an increased propensity for CN-LOH. FLT3/ITD primary AML (n=17), MOLM-13 and FLT3-ITD transfected U937 cells show a significant increase in SCE compared to WT FLT3 primary AML cells, U937 cells transfected with empty vector, (10 vs. 6 SCE per metaphase, p

Description: Key Points There is 100% concordance in the cytogenetic and mutation profile between PB and BM in myelodysplastic syndrome.

Description: Abstract 2795 Interstitial deletions of chromosome 5q are common in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS), pointing towards the pathogenic role of this region in disease phenotype and clonal evolution. The higher level of resolution of single nucleotide polymorphism array (SNP-A) karyotyping may be used to find cryptic abnormalities, and to precisely define the topographic features of the genomic lesions allowing for more accurate clinical correlations. In order to better address the genetic and genomic complexity of 5q abnormalities in myeloid malignances, we analyzed a large series of 1,155 clinically well-annotated patients with malignant myeloid disorders with SNP-A-based karyotyping to define: i) the extent of the 5q deletion, investigating whether loss of genes is different among 5q disorders; ii) minimally deleted region(s); iii) associated non-5q genomic lesions with 5q abnormalities; and iv) the association of genomic abnormalities with clinical features. We identified chromosome 5q deletions in 142/1155 patients (12%) and uniparental disomy segments (UPD) in 4/1155 patients (0.35%). With increased resolution there was a shift towards more complex karyotypes and increased identification of additional lesions among the patients with 5q aberrations. By SNP-A, previously cryptic lesions were identified in 52% of the patients who otherwise showed a singular del(5q) lesion by metaphase cytogenetics (MC). The presence of chromosome 5q material in all our cases with apparent monosomy 5 (N=11) by conventional MC serves as an illustration for SNP array-based mapping allowing for a more precise definition of the breakpoints; in addition, 48% of MC results localized both the beginning and end of the deletion to a different band than SNP-A, and in only 9% of cases, MC and SNP-A boundaries coincided. The CDR defined in our 5q-syndrome, though with wider limits (145,279,940–153,809,148), encompasses the CDR described by Boultwood et al; the CDR in advanced del(5q) MDS and AML patients is centered on a sub-section of bands 5q31.2 and 5q31.3 (137,528,564–139,451,907) and includes the defect initially mapped by Le Beau et al. Patients with MDS and deletions involving the centromeric and telomeric extremes of 5q have a more aggressive disease phenotype (median overall survival: 32 months, p=0.04, HR 1.9; median number of chromosome lesions: 5.8 vs. 1.1, p

Description: Introduction 5-azacitdine (aza) treatment in myelodysplastic syndrome (MDS) induces a response rate of 40-45% and prognostic factors for response and survival remain still largely unknown. Presence of mutant TET2 has been shown to predict better response to aza and the recently described French Azacitidine prognostic score segregates patients into 3 groups with varying median overall survival. Although a plethora of somatic mutations have been described in MDS, none has been consistently shown to be prognostically important in the context of response to hypomethylating agent(s). Patients and methods To identify the mutation signature associated with aza response, we undertook screening of 24 myeloid genes (splicing, epigenetic, transcription factors, STAG2, TP53) in 66 MDS patients treated with aza at our institution over a period of 2004-2012. Mutation analysis was done by deep (454 FLX) and Sanger sequencing. SNP-6 karyotyping was also performed in a subset to correlate with mutation status. Responses were assessed as per the international working group for MDS criteria. The median age was 67 years (range 36–87 years), median number of courses 7(range 2–42), 79% of patients belonged to int-2/high risk IPSS category. WHO category subtypes were; RA/RARS-2; RCMD-9; RAEB-39; s-AML (evolved from pre-existing MDS) -5, therapy related myeloid neoplasm (t-MDS/t-AML) -8 and CMML-3.IPSS cytogenetic subgroups were, good risk: 22, intermediate: 7, and poor risk: 37. One fourth of patients had received prior therapy, with only two receiving low dose cytarabine. Median time from diagnosis to aza treatment was 8.6 months. The overall response rate (ORR) to Aza was 47% (31/66) with complete response (CR) 17%, partial response (PR) 11%, marrow CR (mCR) 12% and stable disease with hematological improvement (SD-HI) 7%. Results Candidate mutations were seen in 82% (54/66) of patients, with the more than half harboring ≥2 mutations each. The most frequently (≥5 %) mutated genes being ASXL1 (29%), TP53 (23%), TET2 (14%), DNMT3A (12%), SRSF2 (12%), EZH2 (11%), NRAS (8%), U2AF1 (8%), IDH2 (8%), RUNX1 (8%), CCBL (6%) and FLT3-ITD (5%). On univariate analysis presence of EZH2 mutations predicted for a better ORR compared to wild type EZH2 (21% vs. 3%, p

Description: Abstract 1707 With the advent of high throughput and high resolution techniques, 〉80% of myelodysplastic syndrome (MDS) patients harbour somatic mutations and/or genomic aberrations, which provide diagnostic and prognostic utility; however, frequent bone marrow (BM) aspirates are required. In a significant minority, the BM is hypocellular and fibrotic with suboptimal in vitro growth and, additionally, the procedure causes discomfort particularly in the elderly. This led us to investigate the use of peripheral blood (PB) and serum to identify and monitor BM derived genetic markers using high resolution single nucleotide polymorphism array (SNP-A) karyotyping and 454 parallel sequencing (454-PS) of a 22 gene myeloid panel comprising of all the exons of DNMT3a, RUNX1, CEBPα, TP53, EZH2, TET2 and ZRSR2 and mutations ‘hotposts’ for NPM1, FLT3, ASXL1, IDH1, IDH2, MPL, JAK2, BRAF, cCBL, NRAS, KRAS, C-KIT, SF3B1, SRSF2, and U2AF1. We selected 23 MDS patients with concurrent BM and PB samples and detected 45 mutations in TET2, SF3B1, ASXL1, TP53, DNMT3a, FLT3, U2AF1, NRAS, cCBL, JAK2 and IDH2 in BM and subsequently analysed their PB using 454-PS with independent validation performed by Sanger sequencing (SS). All the mutations identified in BM were detected in PB with the exception of a single NRAS (BM-11%). Nine patients had a single mutation in SF3B1, ASXL1, TP53, TET2, DNMT3a and U2AF1 with the remaining patients having multiple coexisting mutations. Overall there was no significant difference in the mutation burden between the PB (median 25%(1.5%-50%)) and the BM (median 33%(5%-68%)). Concurrent analysis of unamplified and whole genome amplified PB DNA from 3 patients with mutations in TET2, U2AF1, ASXL1 and NRAS showed no difference in their mutation profile. As expected, in three patients post therapy the mutation burden in the PB was lower than in the pre-treatment BM sample. The lower mutation burden and sequence context in the PB contributed significantly to the quality of SS analysis. Prior knowledge of the mutation site resulted in 98% concordance (smallest clone size - 1.5%) between BM and PB, however, a blind approach decreased this to 84% (smallest clone size - 15%). In addition, serum was available from 14 patients (22 known mutations in BM) and SS of serum DNA identified 12 mutations correctly (U2AF1, FLT3, SF3B1, TET2, TP53, ASXL1, DNMT3a and IDH2, 4 as wildtype (TET2, cCBL, ASXL1 and SF3B1) and 6 failed to amplify (ASXL1, TP53 and TET2) without any preference for specific genes and the failure attributed to the quantity of serum DNA. Karyotype aberrations in PB were assessed using Affymetrix SNP 6.0 arrays on 31 MDS patients; normal karyotype (n=11), del5q (n=9), del7q/-7 (n=5), trisomy 8 (n=2), complex (n=2), isodiXq13 (n=1) and t(2:4)(q33;q27). An overall karyotype concordance of 94% was observed in PB with the 2 discordant cases showing normal karyotype in PB and BM by SNP-A but having monosomy 7 (partial cytogenetic remission after 5-azacitidine) and t(2:4)(q33;q27) respectively in their BM by MC. The mean copy number (CN) in the PB was lower than BM (PB vs BM); deletions (CN of 1.8 vs 1.6) and gains(CN of 2.2 vs 2.4), implying a smaller abnormal clone in the PB. Concurrent SNP-A karyotype from BM from 9 patients was concordant with SNP-A karyotype from PB, although a patient with complex karyotype determined by SNP-A in the BM and having 30 aberrations had only 15 aberrations detected in the PB. To determine if the 5q deletion was lineage restricted, we enriched PB for CD3+, CD19+ and CD3-CD19- populations from 4 patients. FISH and SNP-A karyotyping showed the presence of the 5q deletion using both techniques in all three fractions, however at a lower level in PB lymphocytes indicating the presence of a smaller clone. In conclusion, our study showed an excellent concordance between BM and PB, both for karyotype and mutational analyses using high resolution SNP-A karyotyping and 454-PS suggesting its clinical utility as a surrogate for BM, thereby, avoiding the discomfort of repeated BM aspirates and help in monitoring response to therapy more frequently. Disclosures: No relevant conflicts of interest to declare.

Description: Introduction Discovery of cytogenetic abnormalities together with specific aberrations in RNA splicing, cell signalling, translational regulation and tumour suppressor genes are increasingly been applied for the prognostic stratification well as understanding the pathobiology of myelodysplastic syndromes (MDS) and acute myeloid leukaemia (AML).Epigenetic regulation of transcription has attracted particular attention, because of the efficacy of DNA methyltransferase and Histone deacetylase inhibitor therapies for the treatment of both MDS and AML. The Jumonji (JMJ) family of histone demethylases are epigenetic regulators that demethylate lysine residues of histones in a site and methylation state specific context. Given the importance of these in the transcriptional machinery of myeloid progenitors, we examined the role of seventeen Jumonji genes; JARID1A-1D, JARID2, JMJD3, UTX, JMJD4, JMJD2A-2D, JMJD1A-1C, JHJDM1A-1B in the bone marrow samples from patients with MDS/AML. Majority of the genes tested are involved in the demethylation of H3K4, H3K9, H3K27 or H3K36 histone tails while others associate with the polycomb repressive complex (PRC), abnormalities of which are well documented in both MDS/AML. Methods SNP6 array karyotyping was carried out in 124 MDS patients [M/F ratio = 1:1.7, median age= 69 yrs, WHO subtypes: RCMD 21%, RAEB I/II 50 %, AML 1%, sAML/tMDS 16 %, CMML 6.5 %, MDS/MPD 5.5 %], focusing exclusively on the Jumonji genes loci to identify copy number variations [CNVs] (deletion/ gain) & Uniparental disomy. The patients with SNP6 aberrations in the Jumonji genes were examined by 454 DNA parallel sequencing and Real-time PCR for mutational analysis and alterations in gene expression respectively. The sequencing depth was 350-450 reads / amplicon. Results Of the 124 cases, 28 patients (22.5%) were identified with a deletion, gain or UPD at 15/17 Jumonji gene loci while two genes showed no SNP6 abnormalities. Of the 22.5 % patients, the highest frequencies of deletions were found in JMJD1B (chr 5q31.2) [41 %], JARID2 [10.7 %] and JMJD3, JMJD2D, JMJD1A [7.14 %] each. On the other hand, the highest frequency of gain was observed in JMJD2C [10.7 %], followed by JMJD2A & UTX [7.14 %] each. Interestingly, only three genes showed both deletion and amplification in different patients in our cohort (JARID2, JMJD4, and JMJD2D) while the rest were either deleted or amplified. Compared to CNVs (69 %), only twelve patients (44 %) carried UPD [telomeric, size: majority were 〉20Mb]. JMJD2D and JMJD4 had the highest frequency (14.3 %) while JMJD3 had [10.7 %] of UPDs. 454 DNA parallel sequencing of the fifteen Jumonji genes in the 28 patients with SNP6 abnormalities revealed no mutations. To elucidate changes in gene expression as a result of CNVs; two patients with CN gain at the UTX locus showed 5 fold increase (p value 〈 0.0001) in the expression of this gene while two patients with deletion at the JARID1A locus showed knock down in the expression levels as compared to patients with normal SNP6 profile (n =20). Conclusion In summary, 22.5 % of high-risk MDS patients show SNP6 aberrations at the Jumonji gene loci. No mutations were associated with the SNP6 abnormalities even with a read depth of 350-450 reads/ amplicon. However, alteration in the expression of JARIDA and UTX was consistent with the CNVs detected on SNP6 which might have direct consequence on the methylation status of the genome or may assist as yet unidentified targets in the pathogenesis of MDS. Table 1: Table 1:. Gain, deletion and UPD in the Jumonji genes. Numbers in brackets indicate size of the aberration in Mb Figure 1 (a) Five-fold increase in UTX expression in two patients, one with trisomy chr: Xp and second with CN=4 (b) Knock down of JARID1A expression in two patients with CN=1 in compared to twenty control patients with normal SNP6 profile at the UTX and JARID1A loci. cDNA from K562 cell line was used as a positive technical control in all experiments. Figure 1. (a) Five-fold increase in UTX expression in two patients, one with trisomy chr: Xp and second with CN=4 (b) Knock down of JARID1A expression in two patients with CN=1 in compared to twenty control patients with normal SNP6 profile at the UTX and JARID1A loci. cDNA from K562 cell line was used as a positive technical control in all experiments. Disclosures Shinde: Celgene: Research Funding.

Description: Telomerase complex maintains telomeres and protects genomic DNA from degradation during cell divisions. Abnormal telomerase function can result in chromosomal instability predisposing to malignant transformation. Short telomere is a typical feature of inherited bone marrow failures syndromes (BMFs), especially dyskeratosis congenital (DC), caused by mutations in genes encoding components of the telomerase gene complex (TGC), shelterin proteins and DNA helicases. Telomere attrition have been associated with leukemic transformation in myelodysplastic syndromes (MDS), as well as complex cytogenetic aberrations, and also with the development of secondary MDS and acute leukemia (AML) after chemotherapy. However, the incidence of TGC mutations in de novo MDS remains largely unknown. Recurrent somatic mutations in genes involving epigenetic, spliceosome, cell signaling and proliferation pathways are common in MDS and have prognostic significance. Identifying specific associations between mutational patterns helps characterize disease biology and thereby improve the therapeutic strategies To determine the incidence of TGC mutations and study theassociation of TGC mutation patterns with recurrently mutated genes in MDS. To correlate TGC mutations with telomere length, clinical phenotypes and outcome of patients. We undertook a massively parallel targeted sequencing of all 10 TGC, (TERT, TERC, TINF2, NHP2, NOP10, RTEL1, CTC1, DKC1, USB1 and WRAP53) in a cohort of 174 MDS patients. Furthermore, we measured the telomere length (T/S ratio) by a multiple quantitative real-time PCR in bone marrow mononuclear cells. Additionally, in 151/174 MDS patients, we studied 22 recurrently mutated MDS-associated genes (MGP) by targeted sequencing. Among the whole cohort, 61% were male. The median age of patients was 63 years (range 17–87). WHO subtypes were 45 RA/RARS/isolated de5q (26%); 50 RCMD/RCMD-RS, (29%); 41 RAEB 1/2, (24%); 8 AML secondary to MDS, (5%); 8 (5%) MDS/MPD and 3 CMML (2%). IPSS cytogenetic risk groups were: 108 patients with good risk (62%), 21 intermediate (12%) and 32 poor risk, (18%) and cytogenetics failed in 10 patients (6%). IPSS categories were low risk 41(24%), intermediate-1: 54 (31%), intermediate-2: 30 (17%), high risk: 13 (7%) and 10 (6%) patients were not evaluated (proliferative CMML and MPD/MDS). Transfusion dependency was present in 80 patients (46%). Twenty nine TGC mutations were present in 26 patients (15%)(figure 1). Twenty-three patients (88%) had TERT mutations, 3 RTEL1 mutations (13%) and 1 TINF2 mutations (4%) with variant allelic frequency around 50%. Two patients presented more than one mutation in TGC genes. Most of mutations in TGC genes were previously described as germ line variants inpatients with DC and inherited aplastic anemia. All mutations found in TERT gene were missense. In patients with TGC mutations, the median T/S ratio was 1.1 (range 0.4–3.5), shorter than the T/S ratio of age-matched controls, although no statistically significant difference was seen in T/S ratio when compared to wild type. (P=0.527). TGC variations did not correlate with clinical features such as age, cytogenetic risk or IPSS, and had no impact on the overall survival (P=0.659). In 151 MDS patients, 73% (n=110) had at least one known somatic mutation in the MGP (21% TET2, 15% ASXL1, 14% TP53, 11% DNMT3A, 11% U2AF1, 9% IDH2, 9% SRSF2, 6% EZH2, 4% NRAS, 4% CEBPA, 3% SF3B1, 3% RUNX1, 2% JAK2, 2% FLT3, 1% cCBL). Among the MGP mutated patients, 13% carried also TGC mutations concurrently (Table 1). Chromatin remodeling gene mutationswere less frequent in patients with TGC mutations (P=0,001) as compared to patient with wild type TGC. We show TGC mutations are frequent in MDS patients (15%). The presence of known TERT variants seen in our cohort demonstrates a clear pathogenic association between MDS phenotype and telomerase mutations, rather than these being bystander variants. Although the heterozygous nature of these abnormalities indicates an inherited variant, the absence of telomere shortening argues against this concept and needs further evaluation. Chromatin remodeling gene mutations are less frequent in patients with TGC mutations. These findings suggest that defective telomere maintenance through TGC mutations might play an important etiological role in the multistep process in pathogenesis of a subset of MDS. Figure 1 Figure 1. Disclosures Mufti: Onconova Therapeutics, Inc: Research Funding.

Description: AMM and MA – Joint first authors Diagnosis of myelodysplastic syndromes (MDS) relies on demonstrating peripheral blood (PB) / bone marrow (BM) dysplasia and cytogenetic abnormalities, forming the backbone of the revised International Prognostic Scoring System (IPSS-R). However, assessment of dysplasia is operator dependent and metaphase cytogenetic analysis (MC) is often normal or uninformative creating diagnostic challenges, particularly in patients with early or low risk MDS. Impressive advances have taken place in the last decade in the identification and chronicling of the genetic lesions leading to phenotypic diversity of MDS. We sought to evaluate the value of single nucleotide polymorphism array (SNP-A) based cytogenetic assessment and high throughput sequencing of the 24 genes most frequently mutated in MDS to determine if genetic abnormalities in the BM are reflected in the PB thus enabling easy assessment of response to treatment and/or disease progression. A MiSeq based gene panel comprising of 24 frequently mutated MDS genes: ASXL1, CBL, CEBPA, DNMT3A, ETV6, EZH2, FLT3, GATA2, IDH1, IDH2, JAK2, KDM6, KIT, KRAS, NPM1, NRAS, RUNX1, SF3B1, SRSF2, STAG2, TET2, TP53, U2AF1, ZRSR2 and CytoHD/750K SNP-A karyotyping was applied to both PB and BM concurrent samples. Genomic aberrations and non-synonymous variant calls were filtered using public databases to exclude polymorphisms. PB and BM from 201 MDS patients [median 62 years (17-88)] followed up for median 21 months (0.3-171) was analysed. Sixty (30%) patients received supportive care only whilst others were treated with MDS/AML directed therapies. The WHO subtypes were: 5q- syndrome (n=26), refractory cytopenia/s (RA/RCMD, n=53), refractory anaemia with excess blasts/acute myeloid leukaemia (RAEB/AML, n=51), refractory anaemia with ringed sideroblasts (RARS/RCMD-RS, n=20) and other subtypes (including myeloproliferative and hypoplastic MDS, n=51). Based on the IPSS-R risk groups 62% had low risk disease: classified as very low (n=35), low (n=89), intermediate (n=42), high (n=16) and very high (n=19) risk groups. Metaphase cytogenetic analysis was normal (NK-MC) in 113(56%), abnormal (AK-MC) in 65(32%) patients and in 23(12%) MC failed. SNP-A was informative in all patients identifying a normal (NK-SNP) in 93(46%) and abnormal (AK-SNP) in 108(54%) patients, respectively. A comparison of BM and PB by SNP-A, showed 190 patients having an identical karyotype (95% concordance). BM SNP-A identified 36 (32%) patients with SNP-A abnormalities not detected by MC, changing the IPSS-R in 49 (24%) patients overall. Inclusion of SNP-A abnormalities changed the IPSS-R risk group in 28 (25%) of NK-MC patients; from good to intermediate (n=21), poor (n=5) and very poor (n=2) groups, respectively. In 9/11 patients with discordant SNP-A karyotypes between BM and PB, the IPSS-R remained unchanged. We found no difference in the clonal burden between PB and BM for gains and CN-LOH. However, for deletions, the clonal size was significantly lower in BM [median 1.4 (1 – 1.9)], than PB [median 1.5 (1 – 1.95), p

Description: Mutations in the TET2 gene are frequent in myeloid disease, although their biologic and prognostic significance remains unclear. We analyzed 355 patients with myelodysplastic syndromes using “next-generation” sequencing for TET2 aberrations, 91 of whom were also subjected to single-nucleotide polymorphism 6.0 array karyotyping. Seventy-one TET2 mutations, with a relative mutation abundance (RMA) ≥ 10%, were identified in 39 of 320 (12%) myelodysplastic syndrome and 16 of 35 (46%) chroni myelomonocytic leukemia patients (P 〈 .001). Interestingly, 4 patients had multiple mutations likely to exist as independent clones or on alternate alleles, suggestive of clonal evolution. “Deeper” sequencing of 96 patient samples identified 4 additional mutations (RMA, 3%-6.3%). Importantly, TET2 mutant clones were also found in T cells, in addition to CD34+ and total bone marrow cells (23.5%, 38.5%, and 43% RMA, respectively). Only 20% of the TET2-mutated patients showed loss of heterozygosity at the TET2 locus. There was no difference in the frequency of genome-wide aberrations, TET2 expression, or the JAK2V617F 46/1 haplotype between TET2-mutated and nonmutated patients. There was no significant prognostic association between TET2 mutations and World Health Organization subtypes, International Prognostic Scoring System score, cytogenetic status, or transformation to acute myeloid leukemia. On multivariate analysis, age (〉 50 years) was associated with a higher incidence of TET2 mutation (P = .02).

Description: Abstract 748 NCL, AA, AK & AS contributed equally to the study A large number of acquired mutations have been identified in haematological malignancies in recent years. An increasing number of targets present a new problem for diagnostic molecular pathology laboratories. It is not practical for a laboratory to design increasing numbers of gene specific assays for these targets. For these reasons a single assay capable of detecting a large number of gene mutations is desirable. Here we describe a next generation sequencing approach using the Roche 454 platform which is capable of the simultaneous mutation analysis of 17 genes at an appropriate sensitivity level in multiple patient samples. This methodology allows mutation scanning of all coding exons of 5 complete genes (TP53, EZH2, DNMT3a, RUNX1 and CEBPa) scanning of the mutational hotspots of 5 genes (ASXL1 exon 12, JAK2 exon 12, FLT3, MPL and CBL) and the analysis of specific mutation hotspots in a further 8 genes (NRAS, KRAS, NPM1, IDH1, IDH2, KIT, BRAF, JAK2 exon 14). In order to cover all these regions, a total of 99 PCR amplicons (average length 300bp range 250–400bp) were amplified for each patient sample. To avoid time consuming quantification and normalisation of individual amplicons downstream of PCR, we developed a simple method to first designate the amplicons into 4 groups based on the efficiency of PCR amplification. Following amplification the 1st round PCR products are diluted according to the grouping assigned to the particular amplicon prior to a second round of PCR in which MIDs or “barcodes” are added in a patient specific manner. The products of the 2nd round PCRs are then pooled for each patient and normalised before pooling the entire library for subsequent sequencing. The sequencing is carried out using the Roche GS FLX titanium reagents. To validate this approach we have prepared libraries from 80 AML patients with normal cytogenetics. Sequencing of these patients was split over 3 runs of the FLX instrument using standard conditions recommended by the manufacturer. The average number of reads per amplicon was 300 with 95% of amplicons having a minimum coverage of 200 reads. The approach allows the detection of mutations at a sensitivity of approximately 5%. Mutations were detected in 14 /17 genes in at least one patient sample. No mutations of BRAF, JAK2 or MPL were detected. In line with previously published data, mutations were found frequently in NPM1 (67%), DNMT3a (55%) FLT3 ITD (44%) and less frequently in the remaining genes. These data correlate well with published data for normal karyotype AML. In 6/17 genes the mutation status of the patient samples had been previously analysed using: Fragment analysis (NPM1 and FLT3 ITD), RFLP (FLT3 TKD), Sanger Sequencing (IDH1, IDH2, ASXL1, TP53). Significantly, 12 additional mutations were detected (NPM1 n=2, FLT3 ITD n=2, FLT3 TKD n=4, IDH1 n=2, IDH2 n=2, ASXL1 n=4) using the new methodology demonstrating an improvement in sensitivity over and above individual gene specific assays. A single run of the FLX instrument enables the analysis of 30 patients in a batch. In our hands library preparation, sequencing and analysis of 30 patients using the workflow described takes a skilled operator 10 full days. With an estimated test price of P650 ($1000), this compares extremely favourably with the price of providing these analyses separately estimated to be in excess of P4000 ($6500). To conclude we have developed a next generation amplicon sequencing approach to assay 17 individual target genes including whole gene coding sequences and more focused mutational hotspots. In addition we have validated a strategy which dramatically reduces the amount of operator time required compared with most amplicon sequencing approaches. This approach offers a highly flexible platform for analysing multiple gene targets in multiple samples. Changes to the targets analysed or the effective sensitivity can easily be incorporated without the need to make major modifications to the procedure. Disclosures: No relevant conflicts of interest to declare.