Database-Guided Analysis for Immunophenotypic Diagnosis and Follow-Up of Acute Myeloid Leukemia With Recurrent Genetic Abnormalities

Acute myeloid leukemias (AMLs) are hematologic malignancies with varied molecular and immunophenotypic profiles, making them difficult to diagnose and classify. High-dimensional analysis algorithms might increase the utility of multicolor flow cytometry for AML diagnosis and follow-up. The objective of the present study was to assess whether a Compass database-guided analysis can be used to achieve rapid and accurate diagnoses. We conducted this study to determine whether this method could be employed to pilote the genetic and molecular tests and to objectively identify different-from-normal (DfN) patterns to improve measurable residual disease follow-up in AML. Three Compass databases were built using Infinicyt 2.0 software, including normal myeloid-committed hematopoietic precursors (n = 20) and AML blasts harboring the most frequent recurrent genetic abnormalities (n = 50). The diagnostic accuracy of the Compass database-guided analysis was evaluated in a prospective validation study (125 suspected AML patients). This method excluded AML associated with the following genetic abnormalities: t(8;21), t(15;17), inv(16), and KMT2A translocation, with 92% sensitivity [95% confidence interval (CI): 78.6%–98.3%] and a 98.5% negative predictive value (95% CI: 90.6%–99.8%). Our data showed that the Compass database-guided analysis could identify phenotypic differences between AML groups, representing a useful tool for the identification of DfN patterns.

Advanced Flow Cytometry Analysis Algorithms for Optimizing the Detection of "Different From Normal" Immunophenotypes in Acute Myeloid Blasts

Acute myeloid leukemias (AMLs) are a group of hematologic malignancies that are heterogeneous in their molecular and immunophenotypic profiles. Identification of the immunophenotypic differences between AML blasts and normal myeloid hematopoietic precursors (myHPCs) is a prerequisite to achieving better performance in AML measurable residual disease follow-ups. In the present study, we applied high-dimensional analysis algorithms provided by the Infinicyt 2.0 and Cytobank software to evaluate the efficacy of antibody combinations of the EuroFlow AML/myelodysplastic syndrome panel to distinguish AML blasts with recurrent genetic abnormalities (n = 39 AML samples) from normal CD45low CD117+ myHPCs (n = 23 normal bone marrow samples). Two types of scores were established to evaluate the abilities of the various methods to identify the most useful parameters/markers for distinguishing between AML blasts and normal myHPCs, as well as to distinguish between different AML groups. The Infinicyt Compass database-guided analysis was found to be a more user-friendly tool than other analysis methods implemented in the Cytobank software. According to the developed scoring systems, the principal component analysis based algorithms resulted in better discrimination between AML blasts and myHPCs, as well as between blasts from different AML groups. The most informative markers for the discrimination between myHPCs and AML blasts were CD34, CD36, human leukocyte antigen-DR (HLA-DR), CD13, CD105, CD71, and SSC, which were highly rated by all evaluated analysis algorithms. The HLA-DR, CD34, CD13, CD64, CD33, CD117, CD71, CD36, CD11b, SSC, and FSC were found to be useful for the distinction between blasts from different AML groups associated with recurrent genetic abnormalities. This study identified both benefits and the drawbacks of integrating multiple high-dimensional algorithms to gain complementary insights into the flow-cytometry data.

HSP90 inhibition results in apoptosis of Philadelphia acute lymphoblastic leukaemia cells: an attractive prospect of new targeted agents

PURPOSE

HSP90 targeting is a promising therapeutic approach in cancer. 17-AAG is an HSP90 inhibitor with completed Phase I trials in patients with advanced cancer and recently published Phase II trials. The aim of this work was to study the expression of HSP 90 and apoptotic proteins, the effects in culture of 17-AAG on cell survival and apoptosis and to compare Philadelphia-positive (Ph+) ALL to common B cell ALL, in ALL cell lines and in patients' cells collected at ALL diagnosis.

METHODS

We analysed 2 ALL cell lines and 63 leukaemic samples from patients treated in our institution (44 common B cell ALL and 19 Ph+ ALL). We performed flow cytometry analysis of bone marrow aspiration and cell lines with a combination of anti-HSP90, Bax, Bcl-2 and Bcl-xl antibodies. Apoptosis after cell culture (in presence or not of 17-AAG) was assessed using Annexin V and activated caspase-3 staining.

RESULTS

Ph+ ALL cells appeared to be more sensitive to 17-AAG cytotoxicity with a 100 % mortality rate after exposure to 10 μM for 24 h (vs. 62 % for B-common ALL). A high percentage of HSP90-positive cells (in Ph+ ALL samples) was associated with high sensitivity to 17-AAG. 17-AAG induced apoptosis in a dose-dependent manner and was associated with down-regulation of Bcl-2 and Bcl-Xl expression and up-regulation of Bax expression.

CONCLUSION

Considering that Bcr-Abl constitutes HSP 90 substrates, HSP 90 inhibition could be of particular interest for Ph+ ALL disease, even in patients harbouring resistance to tyrosine kinase inhibitor therapy.