A Significant Early Detection Of Poor Outcome In Acute Myeloid Leukemia Patients Having a Minimal Residual Disease Using Multiparameter Flow Cytomerty Combined To Mixed Chimerism At Three Months After Allogeneic Hematopoietic Stem Cell Transplantation

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4639-4639
Author(s):  
Florence Beckerich ◽  
Mohamad Sobh ◽  
Stephane Morisset ◽  
Adriana Plesa ◽  
Valerie Dubois ◽  
...  
Keyword(s):  
Myeloid Leukemia ◽  
Residual Disease ◽  
Progression Free Survival ◽  
Disease Recurrence ◽  
Mixed Chimerism ◽  
Hematopoietic Stem ◽  
Free Survival ◽  
Minimal Residual ◽  
Acute Myeloid

Background Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potential curative strategy for acute myeloid leukemia (AML) patients in complete remission (CR) presenting poor prognostic factors or with relapsed/refractory disease. However, the risk for disease recurrence following allo-HSCT remains significant and associated with poor outcomes. After transplantation, the early detection of minimal residual disease (MRD) using immunophenotyping combined to chimerism documentation before morphological relapse may allow for immediate interventions and can lead to better results. Immunophenotyping using Multiparameter Flow Cytometry (MFC) and chimerism documentation by PCR have been widely used to track disease recurrence, although a validated consensus on the use of these techniques in the post-allo-HSCT follow-up has not been established yet. The aim of our study was to evaluate the impact of positive MRD by MFC associated to chimerism documentation at 3 months after allo-HSCT on patients overall and progression-free survival (OS, PFS). Patients and Methods We evaluated 137 AML patients who received allo-HSCT in a single center between January 2005 and October 2012 at our department and for whom a 3 months MRD evaluation and chimerism documentation has been performed using MFC, and PCR analysis. There were 71 (52%) males and 66 females with a median age of 47 years (range: 19-66), 77% had de novo AML, 20% had secondary AML and 3% had biphenotypic AML. According to cytogenetics, 40% were normal, 51% were unfavorable (9% classified as failure). According to molecular markers, 9% were favorable, 31% intermediate, 44% unfavourable and 16% had no molecular markers. At allo-HSCT, 46% of patients were in first complete remission (CR1), 25% were in CR 2 and 29% had active disease; 40% received a full intensity conditioning and 60% got reduced intensity one. As cell source, 35% were bone marrow, 53% peripheral blood and 12% cord blood cells. Donors were related in 53% of the cases (45% were 10/10 HLA matched) and unrelated in 47% of cases (20% were 10/10 HLA matched). MFC was performed using BM samples with a sensitivity of 0.01%. Chimerism analysis was performed on marrow and/or blood samples using polymerase chain reaction (PCR) based on informative polymorphic short tandem repeat with an accuracy of ± 5%, a mixed chimerismwas defined by having 5% or more of recipient cells. Results After transplantation, all patients engrafted, the cumulative incidence of acute GVHD at 3 months was 19.9% (95% CI: 16.2-20.6) while the cumulative incidence of chronic GVHD reached 26.7% (95% CI: 22.9-30.5) at 1 year. After a median follow-up of 16 months (range: 3-77), the median OS was 66 months (65-NR) with a 3 years probability of 64% (95% CI: 56-73), the median PFS was 32 months (13-NR) with a 3 years probability of 50% (95% CI: 37-58) while the transplant related mortality rate reached 13.6% (95% CI: 10-16) at 2 years. The 3 months chimerism evaluation (n=137) showed a mixed chimerism in 12 (9%) patients, while the MFC (n= 62) detected 15 patients with leukemic cells. Sixty eight patients showed morphological relapse after a median time of 4.8 months (1-34.7); the correlation study between MRD positivity, mixed chimerism detection and morphological relapse showed a higher correlation for both chimerism and MFC (correlation=0.69, p<0.001) than if we consider chimerism or MFC alone. Multivariate analysis showed a significant worse OS for patients with 3 months positive MFC [1 year OS of 20% vs. 80%, HR= 4 (95% CI: 1.4-11.7), p=0.01] and patients with mixed chimerism [1 year OS of 21% vs. 70%, HR= 4 (95%CI: 1.3-12.1), p=0.01]; these results were still valid even after stratification on disease status at transplantation. These results applied also in terms of PFS for positive MFC [1 year PFS of 13% vs. 76%, HR= 3.6, p=0.02], and mixed chimerism[1 year PFS of 0% vs. 70%, HR= 7, p=0.001], Figure 1. Conclusion The 3 months MRD evaluation using MFC combined to chimerism documentation seems to be an independent prognostic factor on overall and progression-free survival for AML patients undergoing allo-HSCT. The standardisationof this evaluation may lead to the identification of patients with high relapse risk suggesting the need of early therapeutic intervention. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Prognostic Value of Minimal Residual Disease before Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Acute Myeloid Leukemia

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 5733-5733
Author(s):  
Olga Pérez-López ◽  
Teresa Caballero-Velázquez ◽  
Enrique Colado ◽  
Sara Alonso ◽  
José González-Campos ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Prognostic Value ◽  
Residual Disease ◽  
Hematopoietic Stem ◽  
Multiparametric Flow Cytometry ◽  
Minimal Residual ◽  
Acute Myeloid

Abstract Introduction Several studies have shown that the minimal residual disease (MRD) in acute myeloid leukemia (AML) patients has a prognostic value after induction and consolidation therapy. Nevertheless the relapse is the most important cause of treatment failure in these patients, although they achieved a negative MRD, and even after an allogeneic hematopoietic stem cell transplantation (allo-HSCT). Nowadays, the value of the MRD before allogeneic BMT is still controversial. Method Multicentric study where we have studied correlative AML patients who went under an allo-HSCT in a situation of complete response, between 2012 and April'18. The MRD was analyzed by 8-coloured multiparametric flow cytometry, at least with 2 tubes per patient and 1,000,000 events per tube. We evaluated the prognostic value of the MRD before allo-HSCT. Results Between January'12 and April'18 we have gathered 90 allogeneic BMT in AML patients who were in CR, with a median age of 45 years old (17 - 66). The pre-HSCT situation was 1st complete remission (CR) in 75 patients and 2nd CR in 15. In 45 patients the conditioning regimen was myeoablative. In the group of patients (67) where we could know the risk group at diagnosis, the distribution was: low risk 18%, intermediate risk 59.7% and high risk 22.4%. The 46.7% of the donors were not related. In the last follow-up after allo-HSCT 24 patients have suffered a relapse (26.7%) and 41 (45.5%) have died (17 cases of mortality related to the transplant and 24 not related). In the global analysis the median follow-up of the overall survival (OS) was 37.5 months. Among the 90 patients, MRD was valuable in 86. Ten of 59 patients (16.9%) with negative MRD relapsed vs 12/27 (44.4%) with positive MRD, p= 0.016. If we consider only patients in 1st CR, 9/50 (18%) patients with negative MRD relapsed vs 10/22 (45.5%) with positive MRD, p= 0.02. This statistically significant difference does not exist if we consider only patients in 2nd CR. The median follow-up of OS and event free survival (EFS) was not reached in the negative MRD group and 571 days and 299 days in the positive MRD group. OS and EFS at 2 years after transplantation were 65% and 64% in the negative MRD group and 42% and 37% in the positive MRD group, p= 0.03 and p= 0.008 respectively (figure 1). Conclusions The detected MRD by 8-colour multiparametric flow cytometry previous an allo-HSCT in patients with AML in 1st CR is a prognostic factor in terms of relapse. Patients with a positive MRD before the allo-HSCT have a poorer OS and EFS than the patients with a negative MRD. Figure 1. Figure 1. Disclosures No relevant conflicts of interest to declare.

scholarly journals Immunophenotyping Investigation of Minimal Residual Disease Is a Useful Approach for Predicting Relapse in Acute Myeloid Leukemia Patients

Blood ◽  
1997 ◽  
Vol 90 (6) ◽  
pp. 2465-2470 ◽  
Author(s):  
J.F. San Miguel ◽  
A. Martı́nez ◽  
A. Macedo ◽  
M.B. Vidriales ◽  
C. López-Berges ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Multidrug Resistance ◽  
Minimal Residual Disease ◽  
Myeloid Leukemia ◽  
Residual Disease ◽  
Leukemic Cells ◽  
Rhodamine 123 ◽  
Minimal Residual ◽  
Acute Myeloid

Abstract A high complete remission rate is currently achieved in patients with acute myeloid leukemia (AML). However, many patients eventually relapse due to the persistence of low numbers of residual leukemic cells that are undetectable by conventional cytomorphologic criteria (minimal residual disease [MRD]). Using immunophenotypic multiparametric flow cytometry, we have investigated in sequential studies (diagnosis and follow-up) the impact of MRD detection on the outcome of 53 AML patients that had achieved morphologic remission with standard AML protocols and displayed at diagnosis an aberrant phenotype. Patients were studied at diagnosis with a panel of 35 monoclonal antibodies in triple staining combinations for detection of aberrant or uncommon phenotypic features. According to these features, a patient's probe was custom-built at diagnosis for the identification of possible residual leukemic cells during follow-up. The level of MRD at the end of induction and intensification therapy correlated with the number of relapses and relapse-free survival (RFS). Thus, patients with more than 5 × 10−3 residual cells (5 residual cells among 1,000 normal bone marrow [BM] cells) identified as leukemic by immunophenotyping in the first remission BM showed a significant higher rate of relapse (67% v 20% for patients with less than 5 × 10−3 residual cells; P = .002) and a lower median RFS (17 months v not reached; P = .01). At the end of intensification, with a cut-off value of 2 × 10−3 leukemic cells, AML patients also separated into two distinct groups with relapse rates of 69% versus 32% (P = .02), respectively, and median RFS of 16 months versus not reached (P = .04). In addition, overall survival was also significantly related to the level of residual cells in the marrow obtained at the end of induction and particularly after intensification therapy (P = .008). Furthermore, we have explored whether residual disease was related with the functional expression of multidrug resistance (MDR-1) at diagnosis as assessed by the rhodamine-123 assay. Patients with ≥5 × 10−3 residual leukemic cells at the end of induction therapy had a significantly higher rhodamine-123 efflux (mean, 56% ± 24%) than those with less than 5 × 10−3 residual cells (mean, 32% ± 31%; P = .04). Finally, multivariate analysis showed that the number of residual cells at the end of induction or intensification therapy was the most important prognostic factor for prediction of RFS. Overall, our results show that immunophenotypical investigation of MRD strongly predicts outcome in patients with AML and that the number of residual leukemic cells correlates with multidrug resistance.

Minimal Residual Disease (MRD) Analysis in Acute Myeloid Leukemia (AML) with Favorable Cytogenetics [t(8;21) and inv(16)] by Real Time PCR(RT-PCR) and Flow Cytometry (FC).

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2989-2989
Author(s):  
Granada Perea ◽  
Adriana Lasa ◽  
Anna Aventin ◽  
Alicia Domingo ◽  
Neus Villamor ◽  
...  
Keyword(s):  
Myeloid Leukemia ◽  
Residual Disease ◽  
Fusion Transcript ◽  
Good Prognosis ◽  
Rt Pcr ◽  
Free Survival ◽  
End Of Treatment ◽  
The Mean ◽  
Minimal Residual

Abstract Objectives: To analyze MRD in 65 patients (pts) with good prognosis AML: 30 t(8;21) and 35 inv(16), using both FC and RT-PCR, and to investigate the prognostic value of MRD in the pts outcome. Methods: MRD was monitored in CR pts (n=55) by FC in 101 follow-up samples obtained after various cycles of treatment, as follows: 40 post-induction (ind), 30 post-intensification (int) and 31 at the end of treatment (ttm), and by RT-PCR in 76 samples: 31, 23 and 22, respectively. In 35 pts the two techniques were applied at the same time of the ttm. MRD by FC was assessed using fixed combinations of three monoclonal antibodies. AML1/ETO and CBFb/MYH11 were analyzed following the BIOMED protocol. Results: Twenty-seven percent (n=15) of CR pts relapsed: 6 with t(8;21) and 9 with inv(16). The mean MRD by FC was 1.1% after ind, 0.2% after int and 0.1% at the end of ttm. At the end of ttm, the MRD detected by FC in relapsed and not relapsed pts were significativaly different: 0.3% vs 0.08% (p=0.002). By RT-PCR, the mean of fusion transcript copies/ablx104 differed between relapsed and nonrelapsed pts: 2385 vs 122 (p=0.001) after ind, 56 vs 7.6 after int (p=0.0001) and 75 vs 3.3 (p=0.0001) at the end of ttm. Relapses were more commonly observed in those pts with FC MRD level >0.1% at the end of ttm than in pts with ≤0.1%: 50% vs 12% (p=ns); likewise, using RT-PCR, a cutoff level of >10 copies at the end of ttm correlated with high risk of relapse: 80% of pts with RT-PCR >10 relapsed compared to 12% of pts with levels <10 (p=0.009). The overall survival (OS) probability was 86% for pts with CF MRD ≤0.1 at the end of ttm and 0% for pts with MRD >0.1 (p=0.1) and the leukemia free survival (LFS) was 78% and 44%, respectively (p=0.05). For pts with RT-PCR ≤10 at the end of ttm, the OS was 100% and for pts with RT-PCR >10 it was 30% (p=0.007) and the LFS was 87% and 20%, respectively (p=0.001). MRD was identified after ind in 55% of relapsed pts and at the end of ttm in 83% of relapsed pts. Only 1 pt (1/13) with FC MRD <0.1 and RT-PCR <10 at the end of ttm relapsed. For patients in complete remission, the mean copy level of chimeric transcript was higher for pts with t(8;21) than for those with inv(16): 30.2 vs 17.4 (p=0.0001). Comments: In tandem analysis of MRD by FC and RT-PCR could improve MRD detection in AML pts.

Significance of Minimal Residual Disease in Patients with Chronic Myeloid Leukemia After Allogeneic Hematopoietic Stem Cell Transplantation.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3269-3269
Author(s):  
Iwona Solarska ◽  
Barbara Nasilowska-Adamska ◽  
Maria Bieniaszewska ◽  
Jan Maciej Zaucha ◽  
Piotr Rzepecki ◽  
...  
Keyword(s):  
Stem Cell ◽  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Residual Disease ◽  
Chronic Phase ◽  
Hematopoietic Stem ◽  
Free Survival ◽  
Low Level ◽  
High Level ◽  
Minimal Residual

Abstract Abstract 3269 Poster Board III-1 Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a potentially curative treatment for patients (pts) with chronic myeloid leukemia (CML). AlloHSCT is associated with long-term disease-free survival in 40% to 80% pts transplanted in early chronic phase of disease. The probability of relapse for pts transplanted in first chronic phase is 10% to 20% at 5 years, and is even higher (30% – 60%) for pts who received transplant in advanced phases of CML. The significance of minimal residual disease (MRD) in this clinical setting is uncertain. We enrolled 63 consecutive pts with CML who had received an alloHSCT between 1995 and 2007 and had BCR-ABL transcript quantity measured by RQ-PCR method on at least 2 occasions during follow-up in the period starting 6 months after alloHSCT. The reverse transcription was preformed using SuperScriptIII and random hexamers. Quantification of BCR-ABL was performed by RQ-PCR assay according to ‘Europe Against Cancer' protocol. BCR-ABL expression was normalized with endogenous control ABL gene and expressed as a ratio BCR-ABL/ABL. According to the amount of BCR-ABL transcript detected in blood or bone marrow after alloHSCT pts were allocated into 3 categories, including pts with no-detectable or stable very low-level of BCR-ABL transcripts (ratio BCR-ABL/ABL below 0.005%), pts with fluctuating-low level of BCR-ABL transcripts (0.005 – 0.01%) and pts with high-level of BCR-ABL transcripts (0.01 – 0.1%). We didn't find any relationships between different BCR-ABL levels after alloHSCT and clinical parameters at the time of CML diagnosis or transplantation, including Sokal, Hasford and Gratwohl scores. Median time from alloHSCT to molecular relapse (MR) was 38 months (range, 8.5 – 88.5 months). The 3-year progression rate into cytogenetic or hematological relapse of CML since MR was 70%. This progression occurred at a median time of 1.4 months (range, 0 – 3.2 months). We found strong correlation between the levels of BCR-ABL transcripts after alloHSCT and a risk of relapse. The incidence of MR was 0%, 26%, 71% for the low-level, fluctuating-low level and high-level of BCR-ABL transcript (p<.0001), respectively. Similarly the risk of cytogenetic and hematological relapse was 0%, 21%, 43% for these pts (p=.001), respectively. Five-year leukemia-free survival was 100%, 83.9% and 66.7% for the pts with low-level, fluctuating-low level and high-level BCR-ABL transcript (p=.003), respectively. There was no apparent relationship between the level of BCR-ABL transcript and overall survival. We conclude that pts with fluctuating-low and/or high levels of BCR-ABL transcripts are at higher risk of disease progression. Sequential RQ-PCR monitoring coupled with pre-emptive therapy can provide a valid strategy to reduce rates of relapse and development of a more individualized approach to management of pts with CML in major molecular response after alloHSCT. Disclosures: Warzocha: BMS: Consultancy, Honoraria; Celgene: Consultancy; Roche: Honoraria; Pfizer: Honoraria; Amgen: Honoraria.

Significance of Minimal Residual Disease Monitored by Quantitative Assessment of WT1gene in Patients in First Remission of Acute Myeloid Leukemia Before Allogeneic Stem Cell Transplantation

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4485-4485
Author(s):  
Veronika Válková ◽  
Jaroslav Polak ◽  
Marketa Markova ◽  
Hana Hájková ◽  
Antonin Vitek ◽  
...  
Keyword(s):  
Gene Expression ◽  
Myeloid Leukemia ◽  
Residual Disease ◽  
Conditioning Regimen ◽  
Wt1 Gene ◽  
Significant Difference ◽  
Induction Failure ◽  
Minimal Residual ◽  
Acute Myeloid

Abstract Abstract 4485 Purpose Thanks to the development of knowledge in the field of molecular biology, the great progress has been done in risk stratification of patients with acute myeloid leukemia (AML) at diagnosis, in recent years. Based on the recommendations of international expert groups there were identified the patients who may benefit from the allogeneic stem cell transplantation (allo-SCT) as a consolidation of first complete remission (CR). In the absence of an universal marker for minimal residual disease (MRD) measurements, there is still little information about the importance of MRD prior to allo-SCT. Our department has a very good experience with quantitative monitoring of WT1 gene expression as a marker of MRD during treatment of AML. The aim was to retrospectively evaluate the significance of MRD in patients indicated for allo-SCT in 1.CR. Patients and methods Overall 35 patients (pts) in the first morphological CR were transplanted from April 2005 - July 2011. Median age was 46 years (range; 20–63), mens 14, women 21, three good risk, intermediate risk 23, high risk 7 (NA 3). A total of 19 pts achieved CR after second induction (salvage), 11 pts were in 1st iCR. Induction 3+7 was given to 31 pts (4x other), as consolidation has been used HIDAC in 28 pts (7x other). As the graft, peripheral blood stem cells were used in 27 pts, bone marrow in 8 pts. The donor was identical sibling in 15 pts (1x mismatched sibling), matched unrelated donor (MUD) in 10 pts and mismatched UD in 9 pts. Conditioning regimen was myeloablative in 29 pts, reduced-intensity in 6 pts. Median follow-up was 18 months (range; 2–56). The expression of WT1 gene was measured by real-time polymerase chain reaction in peripheral blood according to the European Leukemia Net recommendations. The WT1 expression was related to the expression of a reference gene and the results were calculated with a number of WT1 copies related to 104 copies of ABL gene. The upper limit of normal WT1 expression was set as 50 copies of WT1 to 104 copies of ABL. Before allo-SCT, 25 pts were WT1-negative, ten pts were WT1-positive. Results When comparing the two groups according the MRD status, there was not significant difference in terms of age, risk groups, first induction failure, number of iCR, induction or consolidation type. Also, type of graft, conditioning regimen, or HSCT-CI was not significantly different. The group of WT1-positive pts had more unrelated donors, more aGVHD and shorter follow-up. In terms of cGVHD, the groups were comparable. When comparing the overall survival (OS) and cumulative relapse incidence (RI) of the entire group in terms of: risk group, first induction failure, iCR, consolidations number and incidence of aGVHD, we found no significant difference. Pts with cGVHD had a better OS, lower RI with comparable non-relapse mortality (NRM). In contrast, the MRD status measured by WT1 gene expression appears as clearly significant factor. The outcome of WT1-positive pts is significantly worse in terms of OS (55% vs 83% at 3 years, p = 0.03), RI (50% vs 11% at 3 years, p = 0.008), and there is a trend toward higher NRM (23% vs 5% in 3 years, p = 0.08). Conclusion Our results show that MRD status measured by WT1 gene expression in patients with AML in 1.CR significantly affects their future prognosis. Opportunities to influence the unfavorable prognosis of MRD-positive patients may be more intensive pre-transplantation therapy or earlier immunomodulatory intervention after allo-SCT (pre-emptive DLI). The larger prospective studies are necessary to confirm this hypothesis. The study was supported by scientific project MZ 00023736 granted by the Ministry of Health, Czech Republic. Disclosures: No relevant conflicts of interest to declare.

Decision-Making At The End Of Consolidation Of Acute Myeloid Leukemia: Negative Effect Of Minimal Residual Disease Detectable With Multiparametric Flowcytometry Combined With Gene Mutations Of FLT3 On Early Relapse

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3921-3921
Author(s):  
Yuichiro Ono ◽  
June Takeda ◽  
Hayato Maruoka ◽  
Yasuhiro Kazuma ◽  
Nobuhiro Hiramoto ◽  
...  
Keyword(s):  
Decision Making ◽  
Myeloid Leukemia ◽  
Residual Disease ◽  
Gene Mutations ◽  
Decision Making Process ◽  
Consolidation Therapy ◽  
Relapse Free Survival ◽  
Free Survival ◽  
Minimal Residual ◽  
Acute Myeloid

Abstract Background About 70-80% of adult patients (pts) with acute myeloid leukemia (AML) achieve complete remission (CR); however, around a half of them experience a relapse. For the purpose of creating accurate decision-making process of post-consolidation strategy, stratification system using karyotype and recurrent gene mutations have been widely utilized. As is confirmed in childhood acute lymphocytic leukemia, however, the information of minimal residual disease (MRD) status would substantially improve the reliance of decision-making process of adult AML pts. Unfortunately, approximately a half of AML patients lack molecular targets suitable for MRD monitoring. The aims of this study are to evaluate the applicability of MRD detection using multiparametric flow cytometry (MPFC) and to estimate the impact of MRD measured with MPFC at the end of consolidation therapy in improving decision-making process. Patients and Methods We retrospectively studied 81 consecutive pts with newly diagnosed AML who received induction therapies and achieved CR in our institute between January 2007 and March 2013. Pts with acute promyelocytic leukemia were excluded. We routinely analyzed the bone marrow specimens with MPFC for the detection of leukemia-associated immunophenotypes (LAIPs) at diagnosis. Since April 2010, RT-PCR assay examined FLT3-ITD mutation in the same specimens. In pts who had traceable LAIPs, the relationships of the levels of MRD at the end of consolidation therapy with relapse free survival were analyzed. Positive MRD was defined as the detection of 0.2% and more LAIPs-positive cells with MPFC. We compared two patient groups: those with MRD at the end of consolidation (MRDp group) and those without (MRDn group). Relapse-free survival (RFS) was analyzed using the Kaplan-Meier method and the log-rank test was used for comparison between each group. A multivariate Cox regression analysis for RFS was fit to assess the effect of the followings: age at diagnosis (≥ vs. < 65 years old), the number of induction regimens required for achieving CR (≥ vs. < 2 times), cytogenetic risk groups of SWOG (unfavorable vs. favorable/intermediate). Results In 57 / 81 pts, MPFC could detect LAIPs in the bone marrow specimens at diagnosis (70.4% of all subjects; 15-82 years-old; follow-up time [median] 98-2211[517] days). FLT-ITD mutations were found in 13 pts, but not in 39 pts (the remaining 5 pts were not examined). The rate of detection of LAIPs with 6-color MPFC was significantly superior to 3-color MPFC (82.1% vs. 61.0%, p<0.05). Induction chemotherapies the pts received were anthracyclin-containing regimens, such as idarubicin and cytarabin (3+7), in 52 pts (91.2%), low-dose cytarabin-based regimen in 4 pts (7.0%) and azacitidine in 1 pt. (1.8%). The MRDp and the MRDn groups were comprised of 20 and 37 pts (35.1% and 64.9%) , respectively. One-year RFS of the MRDp group was significantly inferior to the MRDn group (28.3% vs. 75.2%; log-rank p<0.0005). In the multivariable analysis using the model above, MRD positivity at the end of consolidation remains a significant predictor (HR, 2.93, 95% CI 1.16-7.45, p<0.05). In addition, the 1-year RFS in the MRDp group with FLT-ITD was significantly shorter than that in the MRDp group without FLT3-ITD (0% vs. 47.6% with positive and negative FLT3-ITD, log-rank p<0.05). In the MRDn group, however, the negative impact of FLT3-ITD was not documented (85.7% vs. 69.3% with positive and negative FLT3-ITD, log-rank p=0.954). Conclusion Our retrospective study confirmed that LAIPs as MRD targets were applicable to the majority of pts with AML; MRD positivity measured with LAIPs was a promising predictor for early relapses at the end of consolidation, as was previously reported. When combined with FLT-ITD status, it might become a more sensitive prognostic factor. Disclosures: Takahashi: celgene: Research Funding.

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