Surrogate marker profiles for genetic lesions in acute leukemias

Measurable residual disease by flow cytometry in acute myeloid leukemia is prognostic, independent of genomic profiling

Measurable residual disease (MRD) assessment provides a potent indicator of the efficacy of anti-leukemic therapy. It is unknown, however, whether integrating MRD with molecular profiling better identifies patients at risk of relapse. To investigate the clinical relevance of MRD in relation to a molecular-based prognostic schema, we measured MRD by flow cytometry in 189 AML patients enrolled in ECOG-ACRIN E1900 trial (NCT00049517) in morphologic complete remission (CR) (28.8 % of the original cohort) representing 44.4 % of CR patients. MRD positivity was defined as ≥ 0.1 % of leukemic bone marrow cells. Risk classification was based on standard cytogenetics, fluorescence-in-situ-hybridization, somatic gene analysis, and sparse whole genome sequencing for copy number ascertainment. At 84.6 months median follow-up of patients still alive at the time of analysis (range 47.0-120 months), multivariate analysis demonstrated that MRD status at CR (p = 0.001) and integrated molecular risk (p = 0.0004) independently predicted overall survival (OS). Among risk classes, MRD status significantly affected OS only in the favorable risk group (p = 0.002). Expression of CD25 (α-chain of the interleukin-2 receptor) by leukemic myeloblasts at diagnosis negatively affected OS independent of post-treatment MRD levels. These data suggest that integrating MRD with genetic profiling and pre-treatment CD25 expression may improve prognostication in AML.

The immunophenotypic characteristics and flow cytometric scoring system of acute myeloid leukemia with t(8;21) (q22;q22); RUNX1-RUNX1T1

INTRODUCTION

The translocation t(8;21) is one of the most frequent chromosome translocations in AML. Molecular (cyto)genetics is regarded as the gold standard for diagnosis. However, due to the complicated variety of AML-related genetic abnormalities, comprehensive screening for all of these abnormalities may not be cost-effective. Therefore, a flow cytometric (FC) scoring system was generated in this study for rapid screening and diagnosis of t(8;21)AML.

METHODS

The immunophenotypic characteristics of leukemic cells and neutrophils in cases with t(8;21) AML or other subtypes of AML were analyzed to find a method for the flow diagnosis of t(8;21) AML.

RESULTS

In this study, we picked six FC features pointing to the diagnosis of t(8;21) AML: The blasts show high-intensity expression of CD34; aberrant expression of CD19, cCD79a, and CD56 in myeloblasts; co-expression of CD56 in neutrophils, especially in immature neutrophils; and a maturity disturbance in granulocytes. A six-point score was devised using these features. By ROC analysis, the AUC was 0.952, and the sensitivity, specificity, PPV, and NPV were 0.86, 0.90. 0.91, and 0.84 when the score was ≥3 points. The score was then prospectively validated on an independent cohort, and the AUC of the ROC curve for the validation cohort was 0.975. When the cutoff value was set at 3, the obtained sensitivity and specificity values were 0.91 and 0.94, respectively.

CONCLUSIONS

The FC score described can be used for the identification and rapid screening of t(8;21) AML.

Multiplex Approach in Classification, Diagnosis, and Prognostication in Acute Myeloid Leukemia: An Experience from Tertiary Cancer Center in South India

Introduction:

Acute myeloid leukemia (AML) is a heterogeneous group of disorders classified as per FAB subtypes and more recently by WHO by underlying genetic abnormalities.

Aims and Objectives:

This study aims to analyze the morphology, immunophenotype, cytogenetic and molecular abnormalities in around 200 patients of AML diagnosed over a period of 7 years at our institute and to determine relative frequency of various subtypes (based on FAB and WHO classification). An attempt to characterize the associations between hematological parameters, immunophenotype and these subtypes was also made.

Materials and Methods:

All cases diagnosed as AML on morphology, cytochemistry and/or immunophenotyping and tested for recurrent genetic abnormalities during period of Jan 2008-July 2014 were included in the study.

Results:

Age of presentation was younger in our AML patients as compared to western literature. Amongst FAB and WHO subtypes, M2 and t (15;17) PML-RARA were the most common groups respectively. As expected, CD33, CD13, were the most commonly expressed markers followed by HLA-DR, CD117, CD34 and CD14. Aberrant expression was seen in 62(41.6%) cases, most common was CD7 (15.4%), followed by CD56 (14.8%), CD19 (6.7%) and CD2 (4.7%). Significant associations between immunophenotypic markers and FAB subtypes as well as WHO subtypes were established.

Conclusion:

This is a hospital based study, giving a detailed account of frequencies of AML subtypes, hematological parameters and immunophenotypic markers in AML patients at our institute. Being a large and one of its kind study to establish significant associations between various haematological and immunophenotypic parameters with respective AML subtypes and genetic abnormalities, it might prove to be very useful in Indian setup where facilities for cytogenetic analysis are not available in many laboratories.

Optimal two-stage enrichment design correcting for biomarker misclassification

The enrichment design is an important clinical trial design to detect the treatment effect of the molecularly targeted agent (MTA) in personalized medicine. Under this design, patients are stratified into marker-positive and marker-negative subgroups based on their biomarker statuses and only the marker-positive patients are enrolled into the trial and randomized to receive either the MTA or a standard treatment. As the biomarker plays a key role in determining the enrollment of the trial, a misclassification of the biomarker can induce substantial bias, undermine the integrity of the trial, and seriously affect the treatment evaluation. In this paper, we propose a two-stage optimal enrichment design that utilizes the surrogate marker to correct for the biomarker misclassification. The proposed design is optimal in the sense that it maximizes the probability of correctly classifying each patient's biomarker status based on the surrogate marker information. In addition, after analytically deriving the bias caused by the biomarker misclassification, we develop a likelihood ratio test based on the EM algorithm to correct for such bias. We conduct comprehensive simulation studies to investigate the operating characteristics of the optimal design and the results confirm the desirable performance of the proposed design.

FLT3 mutations in early T-cell precursor ALL characterize a stem cell like leukemia and imply the clinical use of tyrosine kinase inhibitors

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) has been identified as high-risk subgroup of acute T-lymphoblastic leukemia (T-ALL) with a high rate of FLT3-mutations in adults. To unravel the underlying pathomechanisms and the clinical course we assessed molecular alterations and clinical characteristics in a large cohort of ETP-ALL (n = 68) in comparison to non-ETP T-ALL adult patients. Interestingly, we found a high rate of FLT3-mutations in ETP-ALL samples (n = 24, 35%). Furthermore, FLT3 mutated ETP-ALL was characterized by a specific immunophenotype (CD2+/CD5-/CD13+/CD33-), a distinct gene expression pattern (aberrant expression of IGFBP7, WT1, GATA3) and mutational status (absence of NOTCH1 mutations and a low frequency, 21%, of clonal TCR rearrangements). The observed low GATA3 expression and high WT1 expression in combination with lack of NOTCH1 mutations and a low rate of TCR rearrangements point to a leukemic transformation at the pluripotent prothymocyte stage in FLT3 mutated ETP-ALL. The clinical outcome in ETP-ALL patients was poor, but encouraging in those patients with allogeneic stem cell transplantation (3-year OS: 74%). To further explore the efficacy of targeted therapies, we demonstrate that T-ALL cell lines transfected with FLT3 expression constructs were particularly sensitive to tyrosine kinase inhibitors. In conclusion, FLT3 mutated ETP-ALL defines a molecular distinct stem cell like leukemic subtype. These data warrant clinical studies with the implementation of FLT3 inhibitors in addition to early allogeneic stem cell transplantation for this high risk subgroup.

CD117 expression is a sensitive but nonspecific predictor of FLT3 mutation in T acute lymphoblastic leukemia and T/myeloid acute leukemia

Others have suggested that CD117, or an immunophenotypic profile including CD117, can serve as surrogate for FLT3 mutation in T acute lymphoblastic leukemia (ALL), thereby guiding targeted therapy. We report the results of flow cytometry immunophenotypic analysis in 42 cases of T-ALL and T/myeloid acute leukemia also assessed for FLT3 mutation. CD117 was expressed in 21 (50%), and FLT3 was mutated in 8 cases (19%; 1 T-ALL and 7 T/myeloid). FLT3-mutated cases were terminal deoxynucleotidyl transferase (TdT)+/CD2+ (7/8), cytoplasmic CD3+/CD5+ (5/8), CD7+/CD13+/CD15+ (4/6), CD33+ (4/8), CD34+, and CD117+ (bright). Cytochemistry showed myeloperoxidase-positive cells in all T/myeloid acute leukemias (3%-50%). We conclude that FLT3 mutation is rare in T-ALL, and its presence supports T/myeloid lineage. CD117 expression alone is sensitive but not specific for FLT3 mutation. The immunophenotypic profile of TdT, CD7, CD13, CD34, and CD117 (bright) is helpful for predicting FLT3 mutation, with a sensitivity of 100% and specificity of 94%.

Prognostic significance of survivin and tumor necrosis factor-alpha in adult acute lymphoblastic leukemia

OBJECTIVES

Acute lymphoblastic leukemia (ALL) is an aggressive cancer especially in adults as only 20-40% are cured with current treatment regimens.

DESIGN AND METHODS

We measured survivin and tumor necrosis factor-alpha (TNF-α) in serum of 30 ALL patients before and after induction therapy and compared to 30 age and sex matched normal adults.

RESULTS

Survivin at cutoff value 15.18 pg/mL was detected in all ALL patients before therapy but in only 83.33% after therapy and not detected in the control group; P<0.001. However TNF-α at cutoff value 60.05 pg/mL was detected in 90% ALL patients before therapy and 86.6% after therapy that was significantly higher than the control group (20%); P<0.001. Survivin showed a significant positive correlation with TNF-α (P<0.05), bone marrow blast cells (P<0.01), peripheral blast cells (P<0.05) and Philadelphia chromosome (P<0.01).

CONCLUSIONS

Survivin may have an important role in the development of acute leukemia and it could serve as a significant prognostic marker.