Detectable BCR-ABL Research Articles

Real-World Data from Long Term Follow-up in Chronic Myeloid Leukemia (CML) Patients (PTS) Treated with Imatinib. Predictive Factors for Achievement of Deep Molecular Responses and for Failure

BackgroundResponse to TKI is the most important predictor of survival in CML and its early acquisition predicts the achievement of deep molecular responses (MR) (Baccarani et al. Blood 2013). In current ELN recommendations, the optimal time point to achieve Major Molecular Response (MMR) is defined at 12 months (mo) after diagnosis of CML however, not achieving MMR is not a failure criterion at any time point (Saussele et al, Blood 2014). There are controversies about when CML therapy must be changed in pts who do not achieve MMR after 12 mo of treatment. We wonder if pts achieving late MMR are less likely to achieve deep MR or are at risk of progression to accelerated phase (AP) or blast crisis (BC).ObjectivesWe aim to identify predictive factors for achievement of deep MR and improvement of failure-free survival (FFS). Other objective was to determine if delay in MMR acquisition predicts outcomes in order to justify an optimal landmark for changing TKI reducing the risk of failure.MethodsBetween 2000 and 2015, 122 consecutive adult pts with CP CML were treated with various TKI modalities. Adherence (ADH) monitoring occurred in every visit and was reported in medical records, optimal ADH defined as >90% of dose completed. Cytogenetic and MR were defined according to ELN definitions and followed the procedures as described elsewhere (Cross et al. Leukemia 2012). In particular, BCR-ABL<1% corresponds to complete cytogenetic remission (CCyR) (Lauseker et al. 2014). MMR: BCR-ABL transcript <0.1% IS. Confirmed MR4.0: BCR-ABL detection ≤0.01% IS in two consecutive analyses. Failure was defined as loss of CCyR, AP or BC. Different models were performed for CCyR at 6mo, MMR at 12mo and MMR at 24mo as predictors of MR 4.0; in all cases age and Sokal were used as covariates. Failure-risk was evaluated with Cox regression including in the model: Time to MMR, ADH and Sokal as covariates.ResultsFrom 122 pts diagnosed with CP CML, 110 pts received 1st line imatinib (IM) 400mg daily and constitute the basis of the analysis. Median age was 48 years (14-82), 65% were males, 82% low Sokal score. With a median follow-up of 107 mo (IQR 69.5-141) 82% pts are still on initial IM, 4.5% died and 1.8% were lost to follow-up. A total of 20 pts (18%) discontinued Imatinib, 9% due to intolerance and 9% due to failure. At 15 years, FFS was 88% and OS 95%.The proportion of pts treated with IM who achieved CCyR at 6mo and MMR at 12mo was 84% and 38% respectively. Median-time to achieve MMR and MR4.0 was 2.6 and 3.6 years respectively. By logistic regression analysis CCyR at 6mo OR 5,6 (95% CI 1,6-19,00), MMR at 12mo OR 5,3 (95% CI 1,4-21,0), ADH OR 7,0 (95% CI 1,3-37,0) and not MMR at 24mo OR 2,5 (95% CI 0,9-7,2) resulted independent predictors for achieving MR4.0 and confirm earlier observations. In Cox model of proportional hazards for risk of failure, time to achieve MMR HR 1,02 (95% CI 1,01-1,04), ADH HR 6.1 (95% CI 1,38-26,8), and Sokal HR 4,7 (95% CI 1,12-19,3) were independent predictors of failure. Time to achieve MMR is a continuous variable, so the HR associated with it, is equivalent to a 2% monthly increase in the risk of failure. To calculate HR in other time intervals, the product of the coefficient model (B) and time of interest (in mo) were used as an exponent of the base of the natural logarithm (e). Not reaching MMR at 12 mo correlates with higher risk of failure: hazard-risk (HR) 1.30, (95% CI 1.28-1.30) and the risk increases with every passing year not achieving MMR (Table 1). Table 1Time to MMR as predictor of progressionNo MMR achievement in different time intervalsHRCI 95%After 12 mo of TKI1,30(1,3-1,3)After 24 mo of TKI1,70(1,7-1,7)After 30 mo of TKI2,21(2,2-2,2)After 60 mo of TKI3,74(3,7-3,8)ConclusionsThe prognostic value of CCyR at 6mo and MMR at 12mo was confirmed. The association between early MMR and deep MR was confirmed. In this long-term follow-up Latin American real-world cohort of patients ADH was also an early predictor for achievement of deep MR. Although good responses are obtained with IM, some patients still progress, this is the reason why it is necessary to identify those who will relapse so as to consider a change in treatment to another TKI at a convenient time point. Time to achieve MMR, ADH, and Sokal Risk score were independent predictors of failure. Not achievement of MMR at 12mo correlates with increased risk of failure. The risk increases annually in proportion to the time delay. Patients who are delayed in reaching MMR should be controlled closely. DisclosuresPavlovsky:Novartis: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau. Pavlovsky:Novartis - Bristol: Speakers Bureau.

Single Cell Whole Transcriptome Analysis Reveals Distinct Molecular Signatures of Therapy-Resistant Chronic Myeloid Leukemia Stem Cells

Molecularly targeted therapy frequently induces remissions in cancer, but rarely achieves complete disease eradication, with resulting risk of disease relapse/progression. Chronic myeloid leukemia (CML) is a good example, with rare, propagating stem cells (SCs) that are incompletely eradicated by BCR-ABL directed tyrosine kinase inhibitor (TKI) therapy in most cases. Consequently, CML relapse usually occurs following treatment discontinuation. Further, some patients fail to achieve a satisfactory response to TKI therapy and are at risk of disease progression. Ultimately, the depth of response to TKIs is dictated by CML-SCs, however, it has proven challenging to characterise this crucial population of cells as they reside in the same compartment as their normal hematopoietic stem cell (HSC) counterparts from which they cannot be reliably distinguished throughout the disease course.Advances in single cell transcriptomics are opening up unprecedented opportunities to unravel heterogeneity in cell populations. However, to date, this technology has primarily been used to analyse normal tissues, partly reflecting the lack of sensitivity for detection of somatic mutations using current techniques. Herein, we developed a novel protocol allowing targeted amplification of BCR-ABL during single cell cDNA library generation using a modification of a published protocol (PMID:24385147). We then applied this method to analyse 1082 bone marrow SCs (defined as Lin-CD34+CD38-) from a cohort of 10 patients with CML and 3 normal controls.We first validated our method using the BCR-ABL +ve K562 cell line. Surprisingly, using standard methods, BCR-ABL was only detected in a small minority of cells. With our modified technique, we demonstrate robust detection of BCR-ABL in 100% of single K562 cells with parallel whole transcriptome amplification from the same cell. Further, using a plasmid Òspike-inÓ, we demonstrate sensitivity to detect a single molecule of BCR-ABL per cell, without false +ve BCR-ABL amplification in 142 cells tested. We then analysed 40 SCs from a patient with CML who was in a cytogenetic remission (CyR) following 3 months of TKI therapy. BCR-ABL was detected in 16 cells and was absent in 24 cells. With an average of 3.3 million mapped reads per single cell, we detected over 4600 genes per cell with good correlation of single cell ensemble data with bulk analysis. Using this approach we were uniquely able to compare BCR-ABL +ve and -ve cells and identify a large number of differentially expressed genes, which would not have been detected through bulk analysis. We selected a number of genes of biologic interest for validation by Q-PCR and 80% of them were confirmed as differentially expressed, a number of these are highlighted in the heatmap (see Figure).We then analysed 717 single SCs from 8 CML diagnostic samples. This analysis identified marked heterogeneity of BCR-ABL expression with frequencies comparable to the published literature (9% to 92%). Unsupervised clustering analysis revealed many genes that were differentially expressed between BCR-ABL +ve and -ve SCs e.g. CML-SCs showed upregulation of cell cycle signatures and decreased expression of HSC-affiliated genes. We next analysed 223 single SCs from a series of 5 patients in CyR following TKI initiation. BCR-ABL positive SCs could still be detected, albeit at a reduced frequency (0.5% to 45%). In contrast to the diagnostic samples, CML-SCs showed quiescence and HSC signatures that were comparable to normal HSCs. Furthermore, through analysis of serial samples from diagnosis to remission from the same patient, this single-cell approach uniquely allowed analysis of gene expression specifically of the CML-SCs which evade TKI therapy, facilitating the identification of a number of candidate gene-sets including cell surface markers and potentially ÒdruggableÓ targets. Finally, through analysis of a patient with early blast crisis transformation of CML during TKI therapy, we illustrate how single cell RNA sequencing might be applied to predict such early disease progression events.We herein describe a new approach for single cell RNA sequencing of CML-SCs that might be applied to fate-map persistent CML-SCs during and following treatment for discovery research and also to refine precision medicine in CML. This approach could be applied across a range of clonal disorders with potential broader relevance for cancer research. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

ENESTnext Final Results: Deep Molecular Response (MR) with Nilotinib (NIL) in Patients (pts) with Newly Diagnosed Chronic Myeloid Leukemia in Chronic Phase (CML-CP)

ENESTnext Final Results: Deep Molecular Response (MR) with Nilotinib (NIL) in Patients (pts) with Newly Diagnosed Chronic Myeloid Leukemia in Chronic Phase (CML-CP)

Tyrosine Kinase Inhibitor Discontinuation in Chronic Myeloid Leukemia: Single US Center Experience

Imatinib (IM) can be safely discontinued in patients with chronic myeloid leukemia (CML) with sustained complete molecular remission. Previous publications from France and Australia have shown that overall 40% maintain MMR or MR5 for up to 5 years after IM is stopped. We report single US center experience with tyrosine kinase inhibitor (TKI) discontinuation. Between 06/2010 and 7/2015, 22 patients with CML in chronic (CP, n=19), accelerated (AP, n=2) and lymphoid blast phase (LBP, n=1) discontinued IM (n=17), dasatinib (DAS, n=3) or bosutinib (BOS, n=2), and were monitored by qPCR for BCR-ABL1 monthly for the first 3 months, quarterly for the following 2 years and then bi-annually. TKI was restarted in case of confirmed loss of MMR on a repeat qPCR. Reason for TKI discontinuation was predominantly driven by patients' request and TKI intolerance. Median age was 66 (range, 21-84). The 3 who discontinued DAS had IM-resistant (loss of CCyR; n=1), IM-intolerant CP (n=1), or received DAS as first-line agent (n=1). BOS was discontinued for IM-intolerant CP (n=1), or while in CR2 in a patient with LBP that transformed from IM resistant CP and relapsed following chemotherapy (HCVAD). Median duration of TKI therapy pre-discontinuation for the entire cohort was 89 months (range, 26-106). Three patients are not evaluable due to short follow-up (TKI stopped between 5/2015 and 7/2015). With a median follow-up of 40 months (range, 8-60), 7 (41%, 6 CP and 1 AP), all previously on IM lost MMR a median of 3 months (range, 3-24) after TKI was stopped and restarted IM. Loss of CHR occurred 13 months after loss of MMR in 1 patient who elected not to restart IM at the time MMR was lost, due to complications from cardiac transplant rejection. All 7 achieved MMR following restart of IM. Median duration of TKI therapy pre-discontinuation for these 7 patients was 60 months (range, 48-98). 12 patients (59%, 10 CP, 1 AP, 1 LBP) remain off TKI and have not lost MMR, 8 with continuously undetectable BCR-ABL1; and 4 had 1-2 transient detectable BCR-ABL1 at MR4 levels. Median duration of TKI therapy pre-discontinuation for these 12 patients was 87 months (range, 26-106). Loss of MMR-free survival is depicted in the Figure. We conclude that, similar to previous reports, TKI can be safely discontinued in patients with CML without reappearance of BCR-ABL1 in 50-60%. Figure 1. Figure 1. Disclosures Jillella: Seattle Genetics, Inc.: Research Funding. Kota:Leukemia Lymphoma Society: Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees.

Clinical Relevance of Low Burden BCR-ABL1 Mutations Detectable By Amplicon Deep Sequencing (DS) in Philadelphia-Positive (Ph+) Acute Lymphoblastic Leukemia (ALL) Patients (pts): The Type of Mutation Matters

Background and Aims- In Ph+ ALL pts treated with tyrosine kinase inhibitors (TKIs), the likelihood of acquiring TKI-insensitive mutations and the striking incidence of highly resistant T315I and compound mutants underscore the importance of BCR-ABL1 kinase domain (KD) sequence surveillance for timely and rational therapeutic reassessment.We used an amplicon DS strategy of the BCR-ABL1 KD to assess the following issues:i) whether DS allows earlier detection of emerging TKI-insensitive mutations in pts undergoing BCR-ABL1 KD mutation screening for minimal residual disease (MRD) persistence;ii) whether TKI-insensitive low burden mutations can be identified in relapsed pts with negative conventional sequencing results;iii) whether TKI-insensitive low burden mutations are necessary and sufficient to predict for treatment failure in all cases.Methods- This study was conducted in a total of 56 Ph+ ALL pts who received TKI-based therapies at our or collaborating institutions and were referred to our laboratory for MRD follow-up monitoring by RQ-PCR and for BCR-ABL1 KD mutation analysis in case of MRD positivity. These pts were divided into three different cohorts:i) 10 de novo and 24 advanced Ph+ ALL pts who relapsed and developed BCR-ABL1 KD mutations on TKI-based therapy administered 1st-line or for recurrent disease, respectively. To reconstruct the dynamics of mutation emergence, longitudinal re-analysis of monthly-collected samples from the time of hematologic relapse backwards was performed by DS. Whenever samples were available, the analysis was done back to the time of diagnosis (n=10/10) or back to the time of first or former relapse (n=15/24), respectively. Two to 6 samples were analyzed for each pt, for a total of 109 samples.ii) 14 Ph+ ALL pts who were known to be negative for mutations at the time of hematologic relapse as assessed by conventional sequencing. Relapse samples were reanalyzed by DS.iii) 8 Ph+ ALL pts with long-term relapse-free survival despite persistent or intermittent MRD positivity at multiple timepoints. Up to 5 samples were analyzed for each pt, for a total of 28 samples.DS was performed on a Roche GS Junior. Lower mutation detection limit of DS was 1%.Results- In the 34 de novo or advanced Ph+ ALL pts who were known to have acquired TKI-insensitive mutations at the time of relapse on tyrosine kinase inhibitor (TKI) therapy, longitudinal retrospective reanalysis by DS allowed mutation backtracking in 13 (41%) cases. One patient was found to harbour a low burden Y253H at diagnosis. In 3 imatinib (IM)-resistant pts who switched to dasatinib (DAS), a low burden T315I mutation was already detectable at baseline.In the 14 pts with no mutations detectable by conventional sequencing at the time of relapse on IM or DAS, low burden TKI-insensitive mutations were detected by DS in 6 (43%) cases. In 2 cases who had relapsed on DAS, a T315I and an F317L mutation, respectively, were present just below the lower detection limit of conventional sequencing (15.9% and 12.4%, respectively); in the remaining 4 pts, DS identified multiple (2 to 3) low burden mutations, all of which known to confer a moderate to high degree of insensitivity to the ongoing TKI.In the 8 pts with persistently or transiently detectable BCR-ABL1 transcripts at multiple timepoints despite stable hematologic remission, DS detected low burden mutations in 9 samples from 4 pts. However, no mutation known to be truly insensitive to the ongoing TKI could be recognized.Conclusions•MRD persistence in Ph+ ALL pts may hide emerging TKI-insensitive BCR-ABL1 KD mutations that DS may identify earlier than conventional sequencing - allowing a greater leeway before overt hematologic relapse occurs;•polyclonal resistance sustained by multiple TKI-insensitive low burden mutations may explain relapse in a proportion of cases with unmutated BCR-ABL1 KD sequences as assessed by conventional sequencing;•the type of mutation matters: detection of low burden mutations insensitive to the ongoing TKI was always found to predict/correlate with treatment failure. Detection of low burden mutations with low/unknown IC50 might explain low level MRD but does not predict for an impending relapse;•MRD-triggered, BCR-ABL1 KD mutation screening by DS may be precious for earlier and more effective use of preemptive rescue therapies.Supported by ELN, AIL, AIRC, FP7 NGS-PTL project, Progetto Regione-Università 2010-12 (L. Bolondi) DisclosuresSoverini:Ariad: Consultancy; Bristol-Myers Squibb: Consultancy; Novartis: Consultancy. Abruzzese:BMS, Novartis, Pfizer, Ariad: Consultancy. Baccarani:ARIAD Pharmaceuticals, Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; PFIZER: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; NOVARTIS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Cavo:Onyx: Honoraria; BMS: Honoraria; Novartis: Consultancy, Honoraria; Millenium Pharmaceuticals: Honoraria; Celgene: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Jansenn: Consultancy, Honoraria. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Martinelli:Pfizer: Consultancy; BMS: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; ROCHE: Consultancy; AMGEN: Consultancy; Ariad: Consultancy; MSD: Consultancy.

Molecular Response in Patients With Newly Diagnosed Chronic Myeloid Leukemia in Chronic Phase (CML-CP) Treated With Nilotinib: ENESTnext Update

study population the achievement of MMR and CCyR as well as the OS, PFS and EFS were similar to previous published data. Reaching high survival rates with first generation TKIs in a country with limited resources can be a reasonable option to approach CML patients.

Nilotinib rapidly reverses breakpoint cluster region-Abelson oncogene fusion gene and M244V mutations in a patient with chronic myelogenous leukemia: A case report

Chronic myelogenous leukemia (CML) is a condition characterized by a balanced genetic translocation, t (9;22) (q34;q11.2), which leads to a fusion of the Abelson oncogene (ABL) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2. This rearrangement is referred to as the Philadelphia chromosome. At a molecular level, this translocation results in the formation of the BCR-ABL fusion oncogene, which translates into a BCR-ABL oncoprotein. Imatinib, nilotinib and dasatinib are three tyrosine kinase inhibitors that have been approved by the US Food and Drug Administration for the treatment of patients diagnosed with CML in the chronic phase (CML-CP). The present study describes the case of a patient with imatinib-resistant CML who, following two months of treatment with nilotinib, no longer exhibited detectable BCR-ABL fusion genes or M244V mutations. This suggests that nilotinib may be effective for treating CML cases in which the BCR-ABL fusion protein has an M244V mutation.

Favorable outcome of haploidentical hematopoietic stem cell transplantation in Philadelphia chromosome-positive acute lymphoblastic leukemia: a multicenter study in Southwest China.

BackgroundSince the introduction of tyrosine kinase inhibitors (TKIs) into combination chemotherapy regimens, the majority of newly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) patients have achieved complete remission (CR). However, without allogeneic hematopoietic stem cell transplantation (HSCT), long-term outcomes in adults remain unsatisfactory. Indeed, haploidentical HSCT has become a common treatment for adult patients who lack an HLA-matched donor, though limited data are available on the efficacy of haploidentical HSCT in Ph+ ALL patients.MethodsWe analyzed the clinical outcomes of 82 Ph+ ALL patients who underwent haploidentical HSCT (n = 47) or HLA-matched HSCT (n = 35). Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to assess BCR-ABL expression. All of the patients were treated with an imatinib-based regimen before undergoing HSCT. Imatinib treatment was resumed in the patients’ posttransplantation following detection of BCR-ABL transcripts.ResultsAll of the patients achieved neutrophil and platelet engraftment, with the exception of five patients who died prior to engraftment. Haploidentical HSCT was associated with higher incidences of acute graft-versus-host disease (GVHD) (51.1 vs. 25.7 %, p < 0.05) and chronic GVHD (48.9 vs. 25.7 %, p < 0.05) compared with HLA-matched HSCT, but there was no difference in the incidence of either grades III–IV acute GVHD or extensive chronic GVHD. The incidence of cytomegalovirus (CMV) infection was significantly higher in the patients treated with haploidentical HSCT than in those treated with HLA-matched HSCT (38.3 vs. 14.3 %, p < 0.05). Haploidentical HSCT was associated with a significantly lower relapse rate compared with HLA-matched HSCT (44.8 vs. 19.1 %, p < 0.05). There were no differences in non-relapse mortality (NRM), leukemia-free survival (LFS), or overall survival (OS) between the patients who received HLA-matched HSCT and those who underwent haploidentical HSCT.ConclusionsOur data indicate that the incidence of NRM after HSCT is similar between the patients who receive HLA-matched donor cells and those who receive haploidentical donor cells and that haploidentical HSCT reduces the relapse rate. Haploidentical HSCT represents an encouraging treatment option for Ph+ ALL patients who lack a suitable HLA-matched donor.

Comparison of molecular responses based on BCR-ABL1%IS results from an in-house TaqMan-based qPCR versus Xpert® assay in CML patients on tyrosine kinase inhibitor therapy

Objectives:Tyrosine kinase inhibitors (TKIs) have drastically changed the prospects for chronic myeloid leukemia (CML) patients. The European LeukemiaNet (ELN) recommends molecular monitoring of BCR-ABL1 mRNA levels at distinct time points to define an optimal response, warning, or failure of treatment.Methods:Sixty-four follow-up peripheral blood samples from CML patients on TKI were tested by two methods. Molecular responses based on BCR-ABL1%IS from an Xpert® BCR-ABL1 Monitor assay were compared with TaqMan-based qPCR.Results:Seven samples showed ‘molecularly undetectable leukaemia’ by both methods (11%). In-house qPCR showed 57 BCR-ABL1+ samples; 45/57 samples (79%) were concordant for ‘major molecular response’ (MMR, n = 32) and ‘no MMR’ (n = 13) by both assays, whereas nine were BCR-ABL1 negative by Xpert®. Identical molecular responses (i.e. ‘optimal’) were defined in 41 samples. Discordances seen in patients < 10 months on TKI (n = 2) had no impact on clinical management, whereas for patients >12 months on TKI, a different molecular response was defined (‘warning’ versus ‘optimal’). Thirteen samples had ‘no MMR’ by both methods. 10/13 showed identical intervals (>10%IS, 1–10%IS or 0·1–1%IS), corresponding to seven ‘failures’ and three ‘warnings’. Discordant intervals were seen in 3/13 samples (all defined as ‘failures’). Deep molecular responses (MR4·0 or MR5·0) with detectable BCR-ABL1 showed some fluctuations between both methods, nevertheless, all had ‘optimal’ responses. ‘Molecularly undetectable leukaemia’ was observed more frequently by Xpert® (n = 16) as by our in-house assay (n = 7).Discussion:Based on current ELN recommendations, Xpert® BCR-ABL1 assay defines identical molecular responses as TaqMan-based qPCR BCR-ABL1%IS data in 98% (63/64) of samples.

Syndrome de Gorlin et mutations germinales du gène SUFU

Chronic myeloid leukemia (CML) patients who do not achieve landmark responses following treatment with imatinib mesylate (IM) are considered IM-resistant. Although IM-resistance can be due to BCR-ABL kinase domain (KD) mutations, many IM-resistant patients do not have detectable BCR-ABL KD mutations. MicroRNAs (miRNAs) are short non-coding RNAs that control gene expression. To investigate the role of miRNAs in IM-resistance, we recruited 8 chronic phase CML patients with IM-resistance who tested negative for BCR-ABL KD mutations and 2 healthy normal controls. Using miRNA sequencing, we identified 54 differentially expressed miRNAs; 43 of them downregulated. The 3 most differentially downregulated miRNAs were miR-146a-5p, miR-99b-5p and miR-151a-5p. Using real-time quantitative reverse transcriptase-polymerase chain reaction, the expression patterns of the 3 miRNAs were validated on the same cohort of 8 patients in addition to 3 other IM-resistant CML patients. In-silico analysis showed that the predicted gene targets are ATRIP, ATR, WDR48, RAD51C and FANCA genes which are involved in the Fanconi Anemia/BRCA pathway. This pathway regulates DNA damage response (DDR) and influences disease response to chemotherapy. Thus it is conceivable that DDR constitutes a key component in IM-resistance. Further research is needed to elucidate miRNA modulation of the predicted gene targets.

Paper or Plastic: RT-PCR of BCR-ABL from Blood Spots Stored and Shipped on Paper

▪In many parts of the world, diagnosis and monitoring of CML patients is limited by the availability and cost of molecular testing. In countries without molecular diagnostic capabilities, blood samples can be shipped to central labs, but this is both hampered by sample degradation, and the high costs of shipping. This study explores the method of directly spotting peripheral blood onto a paper template (dried blood spots), with subsequent shipping, RNA extraction, and BCR-ABL testing.Methods:Blood Spots and Shipment. We received dried blood spots from Australia and African countries by mail or courier, and blood from CML patients from our institution were also used for these experiments. 200μL of blood (PB) was pipetted onto Whatman 503 Protein Saver Cards (PSC; Sigma-Aldrich), where each card contains four 50μL spots. Cards were allowed to dry for at least 24 hours at room temperature. For mailing, PSCs were sealed into glassine envelopes with a packet of desiccant, and then placed inside a mailing envelope following DOT and IATA regulation for shipping non-regulated, exempt human specimens.RNA Extraction from Cards and %BCR-ABL determination. Blood spots were incubated with proteinase K followed by RNA isolation using RNeasy Mini Kits (Qiagen). Extracted RNA was quantified using a NanoDrop spectrometer (Thermo Scientific). %BCR-ABL was determined using the automated Cepheid GeneXpert platform or manual two-step quantitative RT-PCR on the 7900HT Fast Real-Time PCR System (Applied Biosystems).Results:Bench top time course: To test for effects of long transit times on RNA quality, we performed a time course study of cards at room temperature (RT) with 5 samples. For each sample, multiple cards were spotted with PB. The cards were then allowed to sit at RT for predetermined amounts of time, up to 42 days, before extracting RNA. We measured RNA integrity for one of the specimens (CML # 5) and found rapid degradation with the RIN number going from 8.7 for the fresh blood to 2.8 after 28 days on the card. However the amplification for both BCR-ABL and ABL differed less than one cycle between the fresh blood and the last time point by manual qRT-PCR (BCR-ABL Ct = 23.63 for fresh blood and 24.06 for day 28 PSC; ABL Ct = 26.69 for fresh blood and 27.64 for day 28 PSC). Figure 1 shows the results of the time course experiment for the 5 samples as a plot of ΔCt versus time in days.BCR-ABL qRT-PCR concordance studies: We compared the %BCR-ABL results obtained in fresh specimen at the institution sending the sample with the %BCR-ABL results we obtained from RNA extracted from PSC using the Cepheid GeneXpert. Paired evaluable results were available for 9 samples with a median WBC = 9.8 x 109/L (range: 3.37x109/L – 85.5x109/L). Samples were 8 to 49 days old at the time of extraction. The amount of RNA input into the GeneXpert reaction ranged from 38.75ng to 1μg. The %BCR-ABL detected ranged from 0.37% to 27% (see Table). The mean absolute difference between fresh blood and PSC BCR-ABL% is 2%; the relative mean percent change for BCR-ABL, using fresh blood as the reference is 13.1% (S.D., 31.2), P = 0.24.Conclusions and future directions:Dried blood spots are relatively inexpensive method to transport blood that preserves enough RNA stability to allow highly accurate BCR-ABL detection, when compared to results performed on an identical platform using fresh peripheral blood samples.Further studies are undergoing to accurately determine the sensitivity of this method and the feasibility of using regular mail for inexpensive transport of specimens. Table 1IDWBC (1000/μL)Sample Age at Spotting (Days)Sample Age at RNA extraction (Days)RNA ng/μlVolume GeneXPert (μL)Paper %BCR-ABL (IS)GeneXpertFresh Blood % BCR-ABL (IS) GeneXpertI1na010426349naI224.101311092745I38009181544naI47.4285102.4*3.1I55.50495241.92I63.61307.4225912I785.5130102102439I812.212912.415128.8I9na1281.5250.37*0.71I103.370273257.85.7I1115.912731102325I126.612714.415na2.3*%BCR-ABL was manually calculated due to late ABL Cts because of low starting material. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Early Disease Relapse after Tyrosine Kinase Inhibitor Treatment Discontinuation in CML Is Related Both to Low Number and Impaired Function of NK-Cells

▪Background: Recent reports suggest that approximately 40% of CML patients who have achieved sustained complete molecular remission are able to stop TKI treatment without disease relapse. However, there are no predictive markers for successful therapy discontinuation. Therefore, we set up an immunological sub-study in the ongoing pan-European EURO-SKI stopping study. Our aim was to identify predictive biomarkers for relapse/non-relapse and to understand more on the mechanisms of immune surveillance in CML.Methods: The EURO-SKI study started in 2012, and patients included were at least three years on TKI and at least one year in MR4 or deeper before the study entry. Basic lymphocyte immunophenotyping (the number of NK-, T- and B-cells) was performed at the time of therapy discontinuation and 1, 6, and 12 months after the TKI stop and in case of relapse (defined as loss of MMR, BCR-ABL1>0.1% IS). In addition, from a proportion of patients more detailed immunophenotypic and functional analyses (cytotoxicity of NK-cells and secretion of Th1 type of cytokines IFN-γ/TNF-α) were done at the same times.Results: Thus far 119 Nordic patients (imatinib n=105, dasatinib n=12, nilotinib n=2) who have discontinued TKI treatment within the EURO-SKI study have been included in the lymphocyte subclass analysis (results are presented from patients who have reached 6 months follow-up). Immunophenotyping analysis demonstrates that imatinib treated patients who were able to maintain remission for 6 months (n=36) had increased NK-cell counts (0.26 vs. 0.15x109cells/L, p=0.01, NK-cell proportion 18.9% vs. 11%, p=0.005) at the time of drug discontinuation compared to patients who relapsed early (before 5 months n=22).Furthermore, the phenotype of NK-cells was more cytotoxic (more CD57+ and CD16+cells and less CD62L+cells), and also their IFN-γ/TNF-α secretion was enhanced (19.2% vs. 13%, p=0.02). Surprisingly, patients who relapsed more slowly (after 5 months, n=16) had similar baseline NK-cell counts (0.37x109cells/L), NK-cell proportion (21.2%), and phenotype and function as patients, who were able to stay in remission. No differences in the NK-cell counts were observed between patients who had detectable or undetectable BCR-ABL1 transcripts at the baseline (0.22 x109cells/L vs. 0.31 x109cells/L, p=0.61). Interestingly, NK-cell count was higher in patients with low Sokal risk score than in patients with intermediate risk (0.33 x109cells/L vs. 0.20 x109cells/L, p=0.04). Furthermore, there was a trend that male patients had a higher proportion of NK-cells than females (21.6% vs. 15.7%, p=0.06). Pretreatment with IFN-α or the duration of imatinib treatment did not have an effect on NK-cell count or proportion. In comparison to the imatinib group, dasatinib treated patients had higher NK-cell counts at the baseline (median 0.52x109cells/L vs. 0.26x109cells/L, p=0.02), and also the proportion of CD27 (median 50% vs. 16%, p=0.01) and CD57 expressing (median 79% vs. 74%, p=0.05) NK-cells was higher. The follow-up time of dasatinib treated patients is not yet long enough to correlate the NK-cell counts with the success of the treatment discontinuation.The absolute number of T-cells or their function did not differ significantly between relapsing and non-relapsing patients at the time of treatment discontinuation. However, both CD4+ and CD8+ T-cells tended to be more mature in patients who stayed in remission compared to patients who relapsed early (CD4+CD57+CD62L- median 5.7% vs. 2.4%, p=0.06, CD8+CD62L+CD45RA+ 13% vs. 26.7%, p=0.05). The analysis of follow-up samples showed that in patients who stayed in remission the Th1 type cytokine (IFN-γ/TNF-α) secretion of CD8+T-cells increased at 6 months compared to baseline (23.6 vs. 18.5%, p=0.07). Same phenomenon was observed in the late relapsing group at relapse compared to baseline (37.9 vs. 13.5%, p=0.03). No similar increase was observed in the early relapsing group.Conclusions: Low NK-cell numbers and poor cytokine secretion may predict early disease relapse after TKI discontinuation. However, patients who relapse later have high numbers of normally functioning NK-cells. Further research (detailed phenotypic analysis of NK- and T-cells including activating and inhibitory receptors and immune checkpoint molecules) and correlation of biomarker data with clinical parameters are ongoing to understand the ultimate determining factors of relapse. DisclosuresSjälander:Novartis: Honoraria. Hjorth-Hansen:Novartis: Honoraria; Bristol-myers Squibb: Honoraria; Ariad: Honoraria; Pfizer: Honoraria. Porkka:BMS: Honoraria; BMS: Research Funding; Novartis: Honoraria; Novartis: Research Funding; Pfizer: Research Funding. Mustjoki:Bristol-Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria, Research Funding.

Backtracking BCR-ABL1 Mutants in Philadelphia-Positive Acute Lymphoblastic Leukemia Patients Relapsing on Tyrosine Kinase Inhibitors with Deep Sequencing: Implications for Routine Mutation Testing

Background: With the release of benchtop next-generation sequencers allowing to conjugate assay sensitivity and throughput with affordability, it was envisioned that NGS could soon replace conventional methods in the routine diagnostic identification of mutations relevant for diagnostication, prognostication and therapeutic tailoring. Having recently implemented and optimized a strategy for BCR-ABL1 kinase domain (KD) mutation screening based on the Roche-454 NGS technology, we decided to take advantage of its unique capability to capture the complexity and the clonal relationships of major and minor mutated populations present in a sample to focus on Philadelphia-positive (Ph+) acute lymphoblastic leukemias (ALL), where BCR-ABL1 KD mutations frequently arise and undermine the long-term efficacy of tyrosine kinase inhibitor (TKI)-based therapies.Aims: Next generation amplicon-based deep sequencing (DS) was used i) to study the dynamics of expansion of BCR-ABL1 KD mutations in relation to BCR-ABL1 transcript levels in Ph+ ALL patients who relapse on TKIs and ii) to assess whether emerging mutations can be detected earlier than with conventional Sanger sequencing (SS).Methods: This retrospective analysis was conducted on 35 Ph+ ALL patients who relapsed and acquired BCR-ABL1 KD mutations while receiving TKI-based therapy (imatinib, dasatinib, nilotinib) either first-line (Group A; n=10) or for recurrent disease (Group B; n=25). All the patients had been referred to our laboratory for minimal residual disease (MRD) follow-up monitoring by real-time reverse transcription-polymerase chain reaction and for BCR-ABL KD mutation analysis by SS in case of MRD positivity. To reconstruct the dynamics of mutation emergence, longitudinal re-analysis of bone marrow samples (n=113) from the time of hematologic relapse back to diagnosis (Group A) or back to TKI start (Group B) was performed on a Roche GS Junior instrument. Median time lapse between samples was 6 weeks (range, 4-15 weeks). Runs were designed to achieve high sequencing depth, allowing reliable detection of sequence variants at least down to 1% abundance.Results: DS was found to provide a more accurate picture of BCR-ABL1 KD mutation status, both in terms of presence/absence of mutations and in terms of clonal complexity. DS indeed detected low level mutations, alone or in addition to SS-detectable mutations, in 14/35 samples from patients in Group A and 24/72 samples from patients in Group B. In all the cases with two or more mutations, DS uncovered polyclonal mixtures of single and compound mutants, with up to five distinct mutant subclones detectable. With very few exceptions, compound mutants were found to represent the dominant clone. Patients in Group B, who had received two or even three lines of TKI therapy, generally displayed greater complexity than patients in Group A.TKI-resistant mutants were found to undergo rapid selection in Ph+ ALL patients. In 13/35 (37%) patients, however, DS would have allowed to detect emerging mutations earlier than SS actually did and before hematologic relapse – including a Y253H mutation in a sample collected at diagnosis from a patient who relapsed eight weeks later.Detection of emerging TKI-resistant mutations by DS was accompanied by total BCR-ABL1/ABL1 transcript increase from half a logarithm to two logarithms, or preceded by a shift from undetectable to detectable BCR-ABL1 transcripts. Even low MRD levels were found to hide low level TKI-resistant mutants.Conclusions: The enhanced sensitivity as well as the possibility to identify compound mutations point to next generation amplicon-based deep sequencing as an ideal alternative to conventional sequencing for BCR-ABL1 KD mutation screening of Ph+ ALL patients receiving TKI based therapies. Cost is not a concern even for small/medium scale laboratories, considering that many samples and many genes can be pooled and analyzed simultaneously. A turnaround time of 3-4 days is generally feasible, irrespective of chemistries and instruments, allowing DS results to be practically integrated in the clinical decision algorithm. Further, prospective evaluation of DS for BCR-ABL1 KD sequence surveillance in the framework of a clinical trial of TKI therapy and MRD monitoring of Ph+ ALL patients is warranted.Supported by: European LeukemiaNet, AIL, AIRC, FP7 NGS-PTL project, Progetto Regione-Università 2010-12 (L. Bolondi). DisclosuresSoverini:Ariad: Consultancy; Bristol-Meyers Squibb: Consultancy; Novartis: Consultancy. Baccarani:Bristol-Myers Squibb: Consultancy, Honoraria, Speakers Bureau.

Results from the Korean Imatinib Discontinuation Study (KIDS): Updated Data with 15-Month Median Follow up

▪Background Approximately 50% of CP CML patients achieve undetectable molecular residual disease (UMRD) at 6-7 years of first-line imatinib (IM) therapy. Although imatinib therapy is effective in chronic myeloid leukemia (CML) patients and a substantial portion of patients achieve UMRD with prolonged IM therapy, up to 10^7 leukemic cells can still be present in the absence of detectable BCR-ABL1 in RQ-PCR assay due to the sensitivity limit of current RQ-PCR technology. The recent several reports to assess whether IM can be discontinued in CML patients have shown that IM discontinuation can be employed based on clinical study in patients who had enough IM therapy and UMRD durations prior to IM discontinuation. In our previous report, the 12-month probability of sustained UMRD of 48 patients was 80.8% (78.4% in 37 patients with at least 12 months follow-up), a higher rate than that reported by the ‘STIM’ (Stop Imatinib) trial. To identify predictors for safer, successful IM discontinuation and to explore additional contributing factors for sustained molecular responses (MRs), this multicenter prospective Korean Imatinib Discontinuation Study (KIDS) is on-going.Methods Patients who were treated with IM for more than 3 years and whose BCR-ABL1 was undetectable in RQ-PCR for at least 2 years were enrolled in this study. After discontinuation, molecular response was monitored using RQ-PCR assay every month up to 6 month follow-up, every 2 months up to 12 month follow-up, and every 3 months thereafter. In case of relapse, defined as loss of MMR on 2 consecutive assessments, IM therapy was re-introduced and molecular response after resumption was observed every month using RQ-PCR. Our primary objectives were to evaluate the probability of persistent UMRD at 12 month follow-up after discontinuation, and to measure the duration of persistent UMRD after discontinuation. The secondary objective was to evaluate the probability of major molecular response (MMR) loss and the time taken to lose MMR after discontinuation.Results Of the 148 patients who were screened for KIDS, 30 patients have failed because of positive result of RQ-PCR tested in the central laboratory (N= 21, 70%), failure to meet inclusion criteria (N=7, 23%) and informed consents withdrawal (N=2, 7%).As of data cut-off date of 2 July 2014, a total of 115 patients (66 females, 49 males) who were diagnosed between 20 Mar 1996 and 12 Jul 2012 were enrolled on KIDS, with a median age of 44 years (range, 19 – 77), the percentages of patients with low, intermediate and high Sokal risk scores were 35%, 25% and 17%, respectively with unknown Sokal risk scores in 23%. And the median time on IM therapy and the median duration of sustained UMRD prior to discontinuation were 84 months (range, 32 – 149) and 44 months (range, 22 – 131), respectively.With a median follow-up of 15 months (range, 0.2 – 45.4), 28 patients loss MMR and the probability of sustained MMR was 73.5 ± 4.3%. The 12-month probability of sustained MMR was 67.0 ± 5.2%.Among 21 patients who lost UMRD without confirmed MMR loss, 10 spontaneously re-achieved UMRD, 2 fluctuated BCR-ABL1 transcript under MMR and 9 continuously increase BCR-ABL1 transcript. All of 28 patients who confirmed MMR loss were re-treated with IM for a median of 9.9 months (range, 0.7 – 34.2 months), 22 patients re-achieved MMR at a median of 4.1 months (range, 0.5 - 6.5 months) after resuming IM therapy and 14 of these patients re-achieved UMRD at a median of 6.7 months (range, 3.3 - 13.3 months). One patient, who lost MMR at 7.6 months after KIDS enrollment, resuming IM for 26.7 months and sustained UMRD for 23.9 months, currently discontinues IM therapy (KIDS2) with the follow up of 6.5 months. Univariate analysis showed that IM duration and UMRD duration before treatment discontinuation had a higher 12-month probability of sustained MMR.Conclusions Based on results, IM discontinuation with resuming after MMR loss can be applied safely. In particular, the rate of screening failure due to positive result of RQ-PCR tested in the central laboratory implied that a strict PCR sensitivity criterion is important for safer, successful IM discontinuation. Overall, both UMRD and IM duration on treatment were the most important predictors for successful IM-off. Further studies on underlying mechanisms about immunological control, minimal residual leukemia and stem cell biology during TKI-off study should be conducted. DisclosuresNo relevant conflicts of interest to declare.

Therapy-Free Remission after Interferon Alfa Maintenance with Imatinib Discontinuation in Patients with Chronic Myeloid Leukemia

Introduction: Imatinib mesylate (IM) induces sustained molecular remissions in patients with chronic myeloid leukemia (CML) but a life-long therapy is required for most of these patients. We previously reported that CD8+ memory T cells showed significant predominance over naive T cells in the patients with sustained therapy-free major molecular response (MMR), all of that had previously received IFN [1]. We have been performing a phase 2 study of treatment discontinuation after the drug change from IM to IFN (Japanese Imatinib Stop And Interferon Study; JISAS). This trial is comprised of 2 parts; the first part is to change therapy drug from imatinib to IFN and the second part is to stop IFN for therapy-free. We present here a final result of this trial.Patients: Patients with a confirmed diagnosis of CML in 1st chronic phase (CP1) as well as in CMR (undetectable BCR-ABL transcript) following over 2 years of MMR on IM were enrolled in this pilot study after obtaining the written informed consent. All the eligible patients were recruited from September 2009 to December 2011 whether or not any therapeutic drug had been given before IM.Evaluation and response criteria:Since a conversion factor for International scale was not available in Japan until recently, for entry to the study, BCR-ABL transcripts at a level equal to or below 100 copy/mg RNA in a real-time quantitative-polymerase chain reaction (RQ-PCR) assay or equal to or below 50 copy/assay in a highly sensitive transcription-mediated amplification (TMA) method were defined as MMR. CMR was defined as detection of no BCR-ABL transcript in RQ-PCR assay, nested reverse transcriptase-polymerase chain reaction (RT-PCR) assay, or TMA.During the study, molecular response was assessed at the baseline and every month thereafter, by determining the BCR-ABL to ABL mRNA transcript ratio isolated from the peripheral blood using RQ-PCR and RT-PCR. The BCR-ABL to ABL transcript ratio at a level below 0.001 was defined as MMR and no detectable BCR-ABL transcript in RT-PCR was defined as CMR. Molecular relapse defined as a loss of MMR was taken into account if confirmed in 2 successive assessments.Study design and treatment: Administration of IFN is started at a dose of 3 million units 2-5 times per week within 4 weeks after IM discontinuation. IFN administration was stopped after 2 years of IFN maintenance. In case of molecular relapse, IM was resumed at 400 mg daily.Statistical analysis: Non-parametric values or numbers were compared between the two groups using the Mann-Whitney test. Relapse-free survival was estimated using the Kaplan-Meier method.Results: Fifteen patients were enrolled from September 2009 to December 2011. Median age was 50 years (range, 28-67 years) and male to female ratio was 1.5. Sokal score at the diagnosis was low in 13 patients and high in 2 patients. Four patients had been treated before IM. Previous therapies comprised IFN in all these patients, including 1 patient who relapsed after allogeneic stem cell transplantation (SCT). The clinical stage of this patient was amended to be accelerated phase at the time of diagnosis. Two other patients withdrew the consent. Excluding these 3 patients, the remaining 12 patients with low Sokal score were analyzed.The average follow-up period is 1220 days (range: 797-1519 days). Four patients lost MMR (1, 3, and 6 months in IFN maintenance phase and 10 months after IFN discontinuation, respectively) and other 8 maintained CMR. Estimated molecular relapse-free survival at 1 year after discontinuation of IFN is 60%. The patients in therapy-free remission revealed significantly longer CMR period on IM (median 31 months, range 26-79 months) compared with relapsed patients (0, 9, and 14 months, respectively; p=0.0142). Molecular relapse free survival was significantly better in patients with over 2 years of CMR on IM than otherwise (80% vs 25%; log-rank test, p=0.0013). All the relapsed patients achieved MMR after 2, 2, 4, and 5 months of IM resumption, respectively.Conclusion: IFN maintenance can provide high probability of therapy-free remission in patients with sustained molecular response of IM treatment for CML, especially with over 2 years of sustained CMR of IM treatment.

Deep Molecular Response in Patients With Newly Diagnosed Chronic Myeloid Leukemia in Chronic Phase (CML-CP) Treated With Nilotinib: ENESTnext Update

Abstract Background: The BCR-ABL tyrosine kinase inhibitor nilotinib elicits faster and deeper molecular responses (MRs) vs imatinib in patients with CML-CP. Achievement of sustained deep MR is associated with improved long-term outcomes and is a key criterion for entry into treatment-free remission (TFR) studies. Given the importance of accurately measuring deep MR in patients with CML, increasingly sensitive techniques are needed for monitoring minimal residual disease. In ENESTnext, MR to nilotinib was assessed using conventional methodology (real-time quantitative reverse transcriptase polymerase chain reaction [RQ-PCR]) and a novel microfluidic digital PCR assay that is &gt; 1 log more sensitive than standard RQ-PCR. Methods: In this single-arm, open-label, multicenter study (NCT01227577), adults with CML-CP diagnosed within 6 months of enrollment were treated with nilotinib 300 mg twice daily (BID) for up to 2 years. Dose escalation to nilotinib 400 mg BID for patients with suboptimal response or treatment failure (per modified European LeukemiaNet 2009 recommendations) was permitted per physician discretion. RQ-PCR evaluation of peripheral blood samples was performed by a central laboratory (monthly for the first 3 months and every 3 months thereafter) according to the International Scale (IS). The primary endpoint is the rate of confirmed (≥ 2 samples taken 3 months apart) MR4.5 (≥ 4.5-log reduction of BCR-ABL transcript levels; BCR-ABLIS ≤ 0.0032%) with 2 years of nilotinib therapy; complete cytogenetic response (CCyR) and major MR (MMR; 3-log reduction of BCR-ABL transcript levels; BCR-ABLIS ≤ 0.1%) were evaluated as secondary endpoints. Per protocol, assessment of cytogenetic response was not required at specified time points for all patients on study. In an exploratory analysis, samples from patients with confirmed MR4.5by conventional RQ-PCR were also evaluated using the more sensitive Fluidigm digital PCR platform. The data cutoff date for this analysis was April 30, 2014. Results: A total of 128 patients were enrolled (median age, 56.5 years [range, 21.0-89.0 years]); 64 patients (50.0%) were male and 103 (80.5%) were Caucasian. As of the data cutoff, 45 patients (35.2%) had completed the study, 49 (38.3%) remained on treatment, and 34 (26.6%) had discontinued early. With a median treatment duration of 12.7 months, 88 (68.8%), 94 (73.4%), and 32 (25.0%) patients achieved CCyR, MMR, and MR4.5, respectively, at any time (Table). Of 32 patients who achieved MR4.5, 14 achieved MR4.5 by 6 months. A total of 169 samples from 32 patients with confirmed MR4.5 by conventional RQ-PCR were analyzed by digital PCR. Using the digital PCR platform, 6 of these patients initially had detectable BCR-ABL transcripts that subsequently became undetectable with continued nilotinib therapy. Of the remaining 26 patients, 12 had BCR-ABL transcripts that were initially undetectable and remained undetectable by digital PCR, 12 had detectable BCR-ABL transcripts that remained detectable, and 2 had undetectable BCR-ABL transcripts that became detectable. The most common (≥ 4 patients) grade 3/4 adverse events (AEs) regardless of relationship to study drug were increased lipase (n = 14), thrombocytopenia (n = 11), neutropenia (n = 8), hypophosphatemia (n = 5), anemia (n = 4), and nausea (n = 4). Reasons for study discontinuation were AEs (n = 15), unsatisfactory therapeutic effect (n = 5), withdrawn consent (n = 4), death (n = 3; causes of death were other malignancy, pneumonia, and not specified/no AE [n = 1 each]), protocol deviation (n = 3), abnormal laboratory values (n = 2), loss to follow-up (n = 1), and administrative problems (n = 1). Conclusions: Frontline treatment with nilotinib 300 mg BID in patients with newly diagnosed CML-CP led to rapid achievement of MR4.5 as assessed with conventional RQ-PCR. As &gt; 40% of samples with at least MR4.5according to standard RQ-PCR were positive using the digital PCR assay, this tool may have potential in evaluating MR to determine eligibility for TFR studies. Table Response CCyRa MMR MR4.5 Patients with response, n (%) 88 (68.8) 94 (73.4) 32 (25.0) Time to response, n (%) &lt; 3 mo 26 (20.3) 21 (16.4) 2 (1.6) 3 to &lt; 6 mo 42 (32.8) 41 (32.0) 12 (9.4) 6 to &lt; 12 mo 16 (12.5) 22 (17.2) 11 (8.6) 12 to &lt; 18 mo 4 (3.1) 9 (7.0) 7 (5.5) ≥ 18 mo 0 1 (0.8) 0 a Cytogenetic response was not assessed in all patients at all time points. Disclosures Mauro: Novartis Oncology: Consultancy; Bristol Myers Squibb: Consultancy; Ariad: Consultancy; Pfizer: Consultancy. Cortes:Ariad: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Teva: Consultancy, Research Funding. Rizzieri:Sanofi: Consultancy; Celgene: Consultancy, Speakers Bureau. Keir:Novartis: Employment, Equity Ownership. Yi:Novartis Pharmaceuticals: Employment. Heinrich:Novartis: Consultancy, Patents &amp; Royalties, Research Funding; MolecularMD: Consultancy, Equity Ownership. Goldberg:Novartis: Honoraria, Research Funding, Speakers Bureau; Bristol Myers Squibb: Honoraria, Research Funding, Speakers Bureau; Ariad: Research Funding, Speakers Bureau; Pfizer: Research Funding. Kuriakose:Teva: Speakers Bureau; Alexion: Speakers Bureau. Radich:Novartis: Consultancy, Research Funding; Ariad: Consultancy.

Patients with Philadelphia-Positive Leukemia with BCR-ABL Kinase Mutations before Allogeneic Transplantation Predominantly Relapse with the Same Mutation

Despite the successes of tyrosine kinase inhibitors (TKIs) in improving outcomes in patients with chronic myeloid leukemia (CML) and Philadelphia-positive acute lymphoblastic leukemia (Ph + ALL), allogeneic hematopoietic stem cell transplantation (HSCT) continues to be an important and potentially curative option for selected patients with either disease. After HSCT, TKIs are increasingly being used to treat or prevent disease relapse, and practice patterns suggest that these TKIs are often chosen empirically without regard to pre-HSCT mutation status. We investigated whether ABL kinase domain mutations persist after transplantation and, thus, whether pre-HSCT mutation status should inform the selection of post-HSCT TKIs in these patients. We retrospectively analyzed adults who underwent allogeneic HSCT for CML and Ph + ALL at our institution between 2000 and 2010, and we identified subjects who had detectable BCR-ABL transcripts by polymerase chain reaction (PCR), as well as available RNA for Sanger sequencing of the ABL kinase domain, in both the pre- and post-HSCT settings. In total, 95 CML and 20 Ph + ALL patients with positive PCR transcripts were identified, of which 10 (10.5%) and 4 (20.0%), respectively, were found to have pre-HSCT ABL kinase mutations known to confer TKI resistance. In 9 (64.2%) of these 14 patients, the same kinase mutation was also detectable at an average time of 191 days after HSCT. Seven (50.0%) of the 14 harboring mutations had relapsed/refractory disease by last follow-up, of which, in retrospect, 6 had received a predictably ineffective TKI within the first 100 days after transplantation based on our mutation analysis. These data support the idea that pre-existing mutations in the ABL kinase domain, frequently associated with resistance to TKIs and prevalent in a transplantation population, are persistently detectable in the majority of patients after transplantation. We propose that such resistance patterns should be considered when selecting TKIs in the post-HSCT setting, including clinical trials of post-HSCT TKI prophylaxis.

Deep molecular responses achieved in patients with CML-CP who are switched to nilotinib after long-term imatinib

Patients in complete cytogenetic response (CCyR) with detectable BCR-ABL1 after ≥2 years on imatinib were randomized to nilotinib (400 mg twice daily, n = 104) or continued imatinib (n = 103) in the Evaluating Nilotinib Efficacy and Safety in clinical Trials-Complete Molecular Response (ENESTcmr) trial. By 1 and 2 years, confirmed undetectable BCR-ABL1 was achieved by 12.5% vs 5.8% (P = .108) and 22.1% vs 8.7% of patients in the nilotinib and imatinib arms, respectively (P = .0087). Among patients without molecular response 4.5 (BCR-ABL1(IS) ≤0.0032%; MR(4.5)) and those without major molecular response at study start, MR(4.5) by 2 years was achieved by 42.9% vs 20.8% and 29.2% vs 3.6% of patients in the nilotinib and imatinib arms, respectively. No patient in the nilotinib arm lost CCyR, vs 3 in the imatinib arm. Adverse events were more common in the nilotinib arm, as expected with the introduction of a new drug vs remaining on a well-tolerated drug. The safety profile of nilotinib was consistent with other reported studies. In summary, switching to nilotinib enabled more patients with chronic myeloid leukemia in chronic phase (CML-CP) to sustain lower levels of disease burden vs remaining on imatinib. This trial was registered at www.clinicaltrials.gov as #NCT00760877.

Autologous Hematopoietic Stem Cell Transplantation for High-risk Acute Lymphoblastic Leukemia: non-Randomized Study with a maximum Follow-up of more than 22 Years.

ObjectiveTo evaluate the efficacy and toxicity of autologous hematopoietic stem cell transplantation (AHSCT) for high-risk acute lymphoblastic leukemia (ALL).Material and methodsOverall, 128 high-risk ALL patients at a median age of 26 years (range 18–56 years) at diagnosis received AHSCT between 1991–2008. Induction treatment was anthracycline-based in all patients. Conditioning regimen consisted of CAV (cyclophosphamide, cytarabine, etoposide) in 125 patients whereas 3 subjects received cyclophosphamide and TBI (total body irradiation). Bone marrow was stored for 72 hours in 4°C and re-infused 24 hours after conditioning completion. Bone marrow was a source of stem cells in 119 patients, peripheral blood in 2 and 7 subjects received both bone marrow and peripheral blood.ResultsWith a median follow-up after AHSCT of 1.6 years (range 0.1–22.3 years), the probability of leukemia-free survival (LFS) for the whole group at 10 years was 27% and 23% at 20 years. Transplant-related mortality at 100 days after AHSCT was 3.2%. There was a strong tendency for better LFS for MRD-negative patients if compared with patients who had positive or unknown MRD status at AHSCT (32% vs 23% and 25%, respectively; p=0.06). There was no difference in LFS between B- and T-lineage ALL as well as between patients transplanted in first complete remission (CR1) and CR2. LFS at 10 years for patients with Philadelphia-positive (Ph+) ALL at transplant was 20% and this was comparable with subjects with negative and missing Ph status (26% and 28%; p=0.97).ConclusionsThe results of AHSCT for high-risk ALL remains unsatisfactory with low probability of long-term LFS.

Effect of continued imatinib (IM) in pts with detectable BCR-ABL after ≥ 2 years on study on deep molecular responses (MR): 36-month update from ENESTcmr.

7025 Background: With 24 mo f/u, ENESTcmr demonstrated higher rates of stable, deep MRs with nilotinib (NIL) vs IM in pts on long-term (≥ 2 y) IM with residual disease. Here, we present 36-mo resul...