In acute myeloid leukemia (AML), assessment of minimal residual disease (MRD) by flow cytometry (flow MRD) after induction and consolidation therapy has been shown to provide independent prognostic information. However, data on the value of earlier flow MRD assessment are lacking. Therefore, the value of flow MRD detection was determined during aplasia in 178 patients achieving complete remission after treatment according to AMLCG (AML Cooperative Group) induction protocols. Flow MRD positivity during aplasia predicted poor outcome (5-year relapse-free survival (RFS) 16% vs 43%, P<0.001) independently from age and cytogenetic risk group (hazard ratio for MRD positivity 1.71; P=0.009). Importantly, the prognosis of patients without detectable MRD was neither impacted by morphological blast count during aplasia nor by MRD status postinduction. Early flow MRD was also evaluated in the context of existing risk factors. Flow MRD was prognostic within the intermediate cytogenetic risk group (5-year RFS 15% vs 37%, P=0.016) as well as for patients with normal karyotype and NPM1 mutations (5-year RFS 13% vs 49%, P=0.02) or FLT3-ITD (3-year RFS rates 9% vs 44%, P=0.016). Early flow MRD assessment can improve current risk stratification approaches by prediction of RFS in AML and might facilitate adaptation of postremission therapy for patients at high risk of relapse.
Background Immunophenotyping is essential for the diagnosis of chronic lymphocytic leukemia (CLL). The scoring proposed in the modified Matutes score has been the basis of diagnosis for the past 15 years and is defined by strong expression of CD5 and CD23, low or absent expression of CD79b, sIgM and FMC7. However, some markers within the current score such as sIgM display a high variability in staining patterns and thus the interpretation of expression intensity is not easily reproducible. Furthermore, the newly identified marker CD200 is not included in the current score in spite of its highly informative value in the differential diagnosis of B-cell disorders. In the study presented here we aimed to improve the current score through the addition of highly informative markers such as CD200 and the omission of sIgM as a less informative, error-prone marker. Methods Between February 2011 and May 2013, peripheral blood or bone marrow aspirates of patients with suspected B-cell lymphoproliferative disorders were subjected to evaluation by flow cytometry. Immunophenotyping was performed using a Navios flow cytometer (Beckman Coulter) and samples were stained by monoclonal antibodies targeting the antigens CD45, CD19, CD5, CD10, CD23, CD79b, CD200, FMC7, sIgM, kappa and lambda. Corresponding isotype controls were used. The modified Matutes score was calculated as described previously (Moreau et al., Am J Clin Pathol 1997) with positivity defined as ≥20% positive cells. Mean Fluorescence Intensity (MFI) ratio (MFI sample/MFI isotype) was calculated as a measure of expression intensity. For our new score, optimized cut-offs for positivity vs. negativity (CD5, CD23, CD200, FMC7) and low or absent expression (CD79b) as well as sensitivity and specificity were calculated by receiver operating characteristics (ROC). The final clinical diagnosis was defined as the diagnosis established by the treating physician taking into account clinical symptoms as well as all results from diagnostic procedures, including cytomorphology, flow cytometry, cytogenetics, molecular genetics and immunohistochemistry, if available. In order to perform an internal validation of our proposed score, we divided the patient cohort into an exploratory and a validation cohort by a 2:1 ratio based on the date of receipt of the samples. Result Flow cytometry data of 371 patients with B-cell disorders were available for analysis. 247 patients were assigned to the exploratory cohort and 124 patients were assigned to the validation cohort. 84.2% and 82.1% of patients, respectively, were diagnosed with CLL. In the exploratory cohort, sIgM-expression intensity on CD19+ B-cells (as measured by MFI ratio) was significantly lower in CLL versus non-CLL cases (p=0.001). However, low or absent sIgM-expression displayed poor specificity in distinguishing CLL from non-CLL cases (51,3%; sensitivity 83,7%). Absent or low CD79b-expression on CD19+ B-cells showed a higher sensitivity and specificity (94.2% and 71.8%, respectively). Positivity for CD200 as well as lack of FMC7-expression showed high diagnostic value (sensitivity and specificity all above 80%). Interestingly, positivity for CD5 on CD19+ B-cells did not have a strong diagnostic value (sensitivity and specificity 69.7% and 76.9%, respectively), but double positivity for CD5 and CD23 on CD19+ B-cells showed higher sensitivity and specificity (79.8% and 87.2%, respectively). Therefore, CD200+, CD23+/CD5+, FMC7- and low or absent CD79b on CD19+ B-cells were included in a new diagnostic score. The resulting score showed comparable sensitivity (97.1% for our score versus 98.6% for the Matutes score, McNemar’s test p=0.38), but markedly increased specificity (87.2% versus 53.8%, p<0.001). These results were confirmed in the internal validation cohort (sensitivity 97.0% versus 100%, p=N/A; specificity 86.4% versus 59.1%, p=0.03). Conclusion The data support the use of the improved score for the differential diagnosis of CLL. This novel scoring system exhibits significantly higher specificity while maintaining very high sensitivity and might therefore contribute to less false positive results. Finally, the surface markers contained in the novel score show more consistent staining patterns, which might further improve reproducibility. External validation of the proposed score will be pursued. Disclosures: No relevant conflicts of interest to declare.
1723 Background: Quantification of minimal residual disease (MRD) by multiparameter flowcytometry (MFC) in patients with acute myeloid leukemia (AML) provides significant prognostic information. Previous analyses have shown that positivity of leukemia-associated aberrant immunophenotype (LAIP) after induction and consolidation therapy is a risk factor concerning relapse and reflects over-all survival and relapse-free survival. Albeit molecular MRD monitoring has translated into therapeutic strategies in certain AML subgroups, e.g. APL, flowcytometric MRD assessment is still not integrated into therapeutic strategies. Methods: We performed a retrospective analysis of flowcytometric MRD data of 201 adult patients with AML. Patients were treated within the clinical study of the German AML cooperation group (AMLCG99 or sHAM); patients with APL were excluded. 165 patients were in the intermediate risk group according to karyotype; NPM1 and Flt3 positivity was present in 80 and 59 patients, respectively. 51% of patients relapsed in the course of disease, the median overall survival (OS) and relapse-free survival (RFS) were 518 and 292 days, respectively. MRD assessment by 3-color-flowcytometry was performed at initial diagnosis, during bone marrow aplasia (day 16 – 18 of induction therapy), after induction, after consolidation and at time of relapse. MRD flow was compared to molecular MRD assessment in patients with mutated NPM1. Results: Data on flowcytometric MRD assessment were available in 99% of patients at initial diagnosis, 74% on day16 of induction therapy, 80% post-induction, 42% post-consolidation and 62% at time of relapse. MRD positivity was defined as percentage of LAIP positive cells > 0,15%. In addition, the post-therapeutic degree of LAIP reduction compared to initial diagnosis was assessed: an indequate degree of LAIP reduction was set at a log difference (initial diagnosis/ day16) < 2. We could confirm that flowcytometric MRD predicts OS and RFS. The absolute level of MRD as well as the relative degree of MRD reduction on day16 of induction therapy defined significantly distinct risk groups concerning OS and RFS (OS: p = 0,03, RFS: p = 0,002). Discriminating the different types of LAIPs, we could demonstrate that cross-lineage phenotypes have the best sensitivity and specificity for predicting relapse (sensitivity 64%, specificity 88% on day16). The course of LAIP and NPM1 as assessed by rtPCR, highly correlates on day16 (correlation coefficient 0,84). Conclusion: Flowcytometric MRD assessment provides significant prognostic information at a very early point in induction therapy. In a subpopulation of NPM1+ AML patients we found a strong correleation of flowcytometric MRD and molecular MRD assessment. LAIP reduction on day 16 post-induction could therefore be integrated into prognostic models and can improve risk stratification especially in the absence of molecular MRD markers. Disclosures: No relevant conflicts of interest to declare.
934 Background: Induction chemotherapy in acute myeloid leukemia (AML) has been shown to successfully induce complete remission in over 70% of patients. However, a majority of patients experience subsequent relapse. Assessment of minimal residual disease (MRD) by flow cytometry at time of aplasia, after induction and after consolidation therapy has been shown to be of prognostic relevance for relapse free survival (RFS) and overall survival (OS). However, studies utilizing MRD diagnostics to guide therapeutic decisions in adult AML (excluding APL) are yet to be performed. Methods: From the database at the Laboratory of Leukemia Diagnostics at our clinic datasets of 583 patients with newly diagnosed AML treated between 2000 and 2011 were analyzed. Patients with biphenotypic acute leukemia, M3 according to FAB classification, as well as those not treated with intensive induction chemotherapy were excluded. To be eligible for further analysis, at least two samples of bone marrow blood (at primary diagnosis and at one further timepoint during or after treatment) had to be available for MRD assessment by 3-color-flow cytometry at our laboratory. Cytogenetic and molecular risk stratification was performed at our clinic and assigned in accordance to the European LeukemiaNet (ELN) guidelines. We used Cox Proportional Hazards Regression to determine prognostic factors for OS and RFS and Kaplan-Meier estimator to determine OS and RFS of the proposed score. Results: Data of 217 Patients fulfilled the inclusion criteria and were therefore eligible for further analysis. 171 (78,8%) patients achieved CR after induction therapy. Of these patients, 120 had flow cytometry data available at time of aplasia and were included in further analysis. The median age was 54,5 y and the median OS 1007 days. Here, only “favorable” ELN risk stratification was associated with significantly longer OS (favorable vs. intermediate-I, Intermediate-II & adverse, Hazard Ratio, HR 0,36, 95% CI 0,19–0,69, p=0,0019), whereas RFS did not yield a significant difference (HR 0,64, 0,37-1,13, p=0,125). Age > 60y was associated with significantly shorter OS (HR 2,07, 1,23-3,47, p=0,0058) and RFS (HR 1,83, 1,11-3,01, p=0,018). And though leukemia-associated phenotypes (LAIP) ≥0,15% at time of aplasia were not predictive of OS (HR 1,32, 0,79–2,23, p=0,293) they were highly predictive of shorter RFS (HR 2,15, 1,30–3,55, p=0,003). Combining these three factors in a simple prognostic score (ELN risk group “favorable” = 0 points, “intermediate-I”, “intermediate-II” or “adverse” = 1 point; age > 60y = 1 point; LAIP at time of aplasia ≥0,15% = 1 point, see table I) identified three distinct groups (0 points: good, 1 point: intermediate, 2–3 points: poor, see table II) which were predictive of both OS and RFS (see figures 1 and 2). Interestingly, this score was capable of identifying a small group of patients with a very good prognosis (n=18, median OS and RFS not reached after >6 years) while at the same time equally dividing up the remaining patients within the intermediate and poor prognosis group (n=52 vs. 50, median OS 1182 vs. 677 days, median RFS 1180 vs. 334 days). Conclusion: MRD based therapeutic decisions and risk-adapted therapy have long been suggested in management of adult AML. Here, we propose a prognostic score for patients with AML achieving CR under intensive induction chemotherapy. The addition of MRD Flow to established genetic prognostic markers as well as age improves the prediction of relapse free and overall survival. Application of this score in therapeutic decisions could assist the treating physician and avoid over-treatment. To further evaluate our proposed prognostic score, it has to be applied in a prospective study for further evaluation and determination of its clinical significance. These data will be the basis for therapeutic trials guided by MRD assessment. Disclosures: No relevant conflicts of interest to declare.
We report a case of a patient with thrombocytopenia. A sporadic MYH9-associated disease, May Hegglin anomaly, was identified by giant platelets, leucocyte inclusion bodies and the typical distribution of NMMHC-IIA in granulocytes in the absence of impaired renal function, cataract and hearing loss. MYH9-associated diseases are an underestimated differential diagnosis of idiopathic thrombocytopenia. The correct diagnosis is important to prevent unnecessary treatment of a patient with thrombocytopenia and to provide sufficient patient information and genetic counseling. Therefore, careful examination of the blood smear has to be the first diagnostic step in a case of unexplained thrombocytopenia.
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