Cell surface antigen expression in AML is becoming focus of investigation as it relates to progno... more Cell surface antigen expression in AML is becoming focus of investigation as it relates to prognostic impact as well as potential therapeutic implications. The CD117 (c-KIT) receptor tyrosine kinase is expressed on the cell surface of hematopoietic stem cells and its signaling is important in cell survival, proliferation and differentiation. CD117 is expressed in a majority of AML cases. In addition, mutations in c-KIT have been identified in a subset of patients, specifically those with CBF AML (inv(16)/t(16;16) and t(8;21)). As there is increasing interest in using tyrosine kinase inhibitors with anti-KIT activity based on surface CD117 expression as treatment in AML, we sought to evaluate the association of CD117 expression with biologic and clinical features in pediatric and young adult (YA) AML. A total of 1803 pediatric and YA patients (ages 0.01-29.2 years) treated on the Children's Oncology Group (COG) phase III trials AAML0531 (n=762) and AAML1031 (n=1041) with complete...
An accurate blast count is pivotal in the diagnosis, classification and prognosis of patients wit... more An accurate blast count is pivotal in the diagnosis, classification and prognosis of patients with myelodysplasia. Blast counts in all previous classification schemes are based on morphologic assessment of marrow aspirates with a poor correlation to blast counts determined by flow cytometry. A significant problem in blast enumeration by flow cytometry is the variable hemodilution of the marrow during collection for flow cytometric analysis. Blast counts can vary depending on which aspirate tube is used for flow analysis, e.g., 2.4%, 1st 5ml tube; 0.62%, 2nd 5ml tube; 0.58% 3rd 5ml tube. Morphologists circumvent this problem by selecting a region for assessment close to a spicule with minimal blood dilution. Cell surface antigens can be used to distinguish mature cells found in blood as distinct from immature cells identified in marrow. CD16 intensity on neutrophils reaches a maximum at the band/segmented stage of development with a low coefficient of variation, thereby becoming a marker for mature myeloid forms. A simple method to distinguish immature from mature myeloid cells was developed to assess extent of blood contamination in marrow aspirates using a combination of CD16, CD13, and CD45. The average mature neutrophil content of a marrow was determined from phenotypically normal bone marrow biopsy specimens, assumed to have minimal blood contamination. The proportion of dimCD16 cells gated on the myeloid cells based on CD45 and right angle light scatter in 31 biopsy specimens was 82% (range 69–93, SD=6.2) (Figure 1). A value of 80% (rather than 82%) was used for the subsequent calculations to correct for the excess mature neutrophils found in an aspirate as compared to the biopsies (Corrected Blasts = [80 / % dim CD16 myeloid] x determined blast count). To test this hypothesis bone marrow aspirates were diluted with blood at different ratios to mimic blood marrow hemodilution. Blasts (defined as CD45 dim, low right angle light scatter, HLA-DR positive, CD11b negative) were determined for the various dilutions, then corrected based solely on the proportion of dim CD16 myeloid cells (Figure 2). A marrow from an MDS case was also diluted (1:5 v/v) with blood for comparison. The original marrow contained 80% dim CD16 myeloid cells with a blast count of 9.2%. After dilution, only 12% dim CD16 cells were detected with 1.1% blasts, however upon correction (6.67), the blast count was 7.3%, close to the original determination. This approach may provide for more standardization and consistency in the determination of blast counts in MDS marrow specimens using flow cytometric analysis. Figure 1, CD16 of marrow myeloid cells. Figure 1,. CD16 of marrow myeloid cells. Figure 2, Uncorrected/Corrected Blast Count Figure 2,. Uncorrected/Corrected Blast Count
Introduction: CD74 is a type II transmembrane protein expressed on antigen-presenting cells and a... more Introduction: CD74 is a type II transmembrane protein expressed on antigen-presenting cells and an MHC class II chaperone. It has been associated with tumor progression and metastasis in solid tumors, and its expression has been suggested to serve as a prognostic factor in many cancers, with higher relative expression associated with oncogenesis. As the expression of CD74 has been associated with response to bortezomib in multiple myeloma, we inquired whether such correlation might be seen in pediatric AML. We prospectively evaluated CD74 expression by difference from normal (ΔN) flow cytometry and correlated expression with clinical characteristics and outcome as part of Children's Oncology Group protocol AAML1031 that randomized patients younger than 30 years of age with de novo AML to standard treatment with (Arm B) or without (Arm A) bortezomib. The addition of bortezomib to standard chemotherapy increased toxicity but did not improve survival. Given the association of CD74 ...
The aim of this study was to establish the therapeutic relevance of the CD33D2 isoform by develop... more The aim of this study was to establish the therapeutic relevance of the CD33D2 isoform by developing novel antibodies targeting the IgC domain of CD33. Two novel IgC-targeting antibodies, HL2541 and 5C11-2, were developed, and CD33 isoforms were assessed using multiple assays in cells overexpressing either CD33FL or CD33D2 isoforms, unmodified acute myeloid leukemia (AML) cell lines and primary AML specimens representing different genotypes for the CD33 splicing single nucleotide polymorphism. CD33D2 was recognized on cells overexpressing CD33D2 and unmodified AML cell lines; however, minimal/no cell surface detection of CD33D2 was observed in primary AML specimens. Both isoforms were detected intracellularly using novel antibodies. Minimal cell surface expression of CD33D2 on primary AML/progenitor cells warrants further studies on anti-CD33D2 immunotherapeutics.
Five-dimensional flow cytometry was used to identify the 5 lineages of peripheral blood leukocyte... more Five-dimensional flow cytometry was used to identify the 5 lineages of peripheral blood leukocytes simultaneously in a single cell preparation. This technique was then used to compare quantitatively the distribution of cell surface antigens on each of these lineages of cells. Neutrophils, eosinophils, basophils, lymphocytes, and monocytes were uniquely identified by correlating their forward and orthogonal light scattering signals with the amount of cell surface-bound IgE. These three cellular characteristics were combined with two additional immunofluorescence labels to create a 5-dimensional space in which each leukocyte population occupied a unique position. The relative quantities of antigens on each cell type were determined for the monoclonal antibodies CD11b, CD13, CD14, CD15, CD16, CD33, CD38, CD45, CD45R, anti-HLA-DR, and anti-Leu-8 labeled with either fluorescein or phycoerythrin. The amount of antigen was described by the mean fluorescence intensity in comparison with the...
After demonstrating that hemoglobin function (p50 and 2,3-DPG) was better maintained with blood s... more After demonstrating that hemoglobin function (p50 and 2,3-DPG) was better maintained with blood stored in CPD as compared to ACD, the senior author showed that the higher pH of CPD was the reason for its better maintenance of hemoglobin function. In the present study a wider ...
Blut Zeitschrift für die Gesamte Blutforschung, 1972
oxygen dissociation curves were performed on blood units preserved in acid-citrate-dextrose (ACD)... more oxygen dissociation curves were performed on blood units preserved in acid-citrate-dextrose (ACD), ACD-adenine, and ACD-adenine-inosine. Dividing blood from a single donor into two or more bags allowed direct comparison between preservatives. During the 1st wk of storage in ACD, a progressive increase in oxygen affinity was observed. Thereafter, little further change was noted. Oxygen affinity increased even more rapidly during initial storage in ACD-adenine. However, with the inclusion of inosine as a preservative, oxygen affinity remained unaltered during the first 2 wk. Increases in oxygen affinity correlated well with falling levels of red cell 2,3-diphosphoglycerate (2,3-DPG) during storage. No significant changes in glutathione, reduced form (GSH), or A3 (AI) hemoglobin levels were noted during the first 3 wk of storage. No significant accumulation of ferrihemoglobin was detected. When blood stored 20 days in ACD or ACD-adenine was incubated with inosine for 60 min at 37'C, 2,3-DPG and adenosine triphosphate (ATP) were resynthesized, and oxygen affinity was decreased. The distribution of 2,3-DPG in fresh and stored red cells appeared to influence experimental values for Hill's n, a measure of heme-heme interaction.
INTRODUCTION Sorafenib, a multi-kinase tyrosine kinase inhibitor (TKI) targets FLT3 internal tand... more INTRODUCTION Sorafenib, a multi-kinase tyrosine kinase inhibitor (TKI) targets FLT3 internal tandem duplication (FLT3/ITD) mutations and has efficacy in adult FLT3/ITD+ AML. High allelic ratio (HAR) FLT3/ITD mutations (allelic ratio of > 0.4, referred to as FLT3/ITD+) confer poor prognosis in de novo pediatric AML. COG AAML1031 Arm C studied the feasibility and efficacy of adding sorafenib to standard chemotherapy and as a single agent maintenance therapy in pediatric HAR FLT3/ITD+ patients. METHODS The AAML1031 primary randomization (Arm A vs. B) has been previously reported (Aplenc et al. Blood 2016;128:899). Patients with FLT3/ITD+ AML were offered secondary enrollment on Arm C and toxicities were monitored on respective treatment arms. An initial safety phase (Cohort 1, C1; N=12) defined the maximum tolerated dose (MTD) of sorafenib when added to induction II chemotherapy and subsequent courses. Following completion, the study was amended (Cohort 2; C2) to start sorafenib on ...
The optimal number of chemotherapy courses for low‐risk (LR) pediatric acute myeloid leukemia (AM... more The optimal number of chemotherapy courses for low‐risk (LR) pediatric acute myeloid leukemia (AML) is not known.
International Working Group (IWG) and European LeukemiaNet (ELN) response definitions are utilize... more International Working Group (IWG) and European LeukemiaNet (ELN) response definitions are utilized to evaluate the efficacy of new agents for childhood acute myeloid leukemia (AML) for regulatory purposes. However, these criteria are not consistent with definitions used in pediatric AML trials or with standard pediatric practice to proceed with subsequent therapy cycles prior to IWG/ELN-defined count recovery. We retrospectively analyzed data from the two most recent Phase 3 pediatric AML clinical trials conducted by the Children’s Oncology Group (COG) to assess the incidence, timing, and prognostic significance of count recovery following induction chemotherapy. Of the patients with fewer than 5% bone marrow blasts at the end of first induction, 21.5% of patients proceeded to a second induction cycle prior to achieving ANC ≥ 500 cells/μL and platelets ≥ 50,000 cells/μL, both well below the IWG/ELN thresholds of ANC > 1000 cells/μL and platelets > 100,000 cells/μL. In these tw...
Infant Acute Myeloid Leukemia (AML) is a poorly-addressed, heterogeneous malignancy distinguished... more Infant Acute Myeloid Leukemia (AML) is a poorly-addressed, heterogeneous malignancy distinguished by surprisingly few mutations per patient but accompanied by myriad age-specific translocations. These characteristics make treatment of infant AML challenging. While infant AML is a relatively rare disease, it has enormous impact on families, and in terms of life-years-lost and life limiting morbidities. To better understand the mechanisms that drive infant AML, we performed integrative analyses of genome-wide mRNA, miRNA, and DNA-methylation data in diagnosis-stage patient samples. Here, we report the activation of an onco-fetal B-cell developmental gene regulatory network in infant AML. AML in infants is genomically distinct from AML in older children/adults in that it has more structural genomic aberrations and fewer mutations. Differential expression analysis of ~1500 pediatric AML samples revealed a large number of infant-specific genes, many of which are associated with B cell de...
10002 Background: Patients with residual acute myeloid leukemia (AML) after induction fare poorly... more 10002 Background: Patients with residual acute myeloid leukemia (AML) after induction fare poorly. The recently completed AAML1031 Phase III clinical trial intensified Induction II chemotherapy, altered the stem cell transplant (SCT) conditioning regimen, and liberalized SCT donor source criteria. We sought to test whether these practice changes improved clinical outcomes. Methods: Patients on AAML0531 and AAML1031, sequential Phase III trials for AML with shared high risk features of both > 15% residual blasts by morphology and ≥ 0.1% minimal residual disease (MRD) by flow cytometry with uninformative cytogenetics or high risk cytogenetic features (-7 or -5/5q-) were included. Gemtuzmab exposed and patients with high allelic ratio FLT3 ITD were excluded. Patients were observed from the start of Induction II through last available follow up. Induction II chemotherapy (ADE or AraC/Mito) was the exposure of interest. Disease free and overall survival (DFS, OS) were the primary outc...
We analyzed the safety and efficacy of Mylotarg (gemtuzumab ozogamicin, an antibody-targeted chem... more We analyzed the safety and efficacy of Mylotarg (gemtuzumab ozogamicin, an antibody-targeted chemotherapy consisting of a humanized anti-CD33 antibody linked to calicheamicin, a potent antitumor antibiotic) in the treatment of 101 patients Ն60 years of age with acute myeloid leukemia (AML) in untreated first relapse in three open-label trials. Mylotarg is administered as a 2-h intravenous infusion at 9 mg/m 2 for two doses with 14 days between doses. The overall remission rate was 28%, with complete remission (CR) in 13% of patients and complete remission with incomplete platelet recovery (CRp) in 15%. Median survival was 5.4 months for all patients and 14.5 months and 11.8 months for patients achieving CR and CRp, respectively. CD33 antigen is present on normal hematopoietic progenitor cells; thus, an expected high incidence of grade 3 or 4 neutropenia (99%) and thrombocytopenia (99%) was observed. The incidences of grade 3 or 4 elevations of bilirubin and hepatic transaminases were 24% and 15%, respectively. There was a low incidence of grade 3 or 4 mucositis (4%) and infections (27%) and no treatment-related cardiotoxicity, cerebellar toxicity, or alopecia. Mylotarg is an effective treatment for older patients with CD33-positive AML in first relapse and has acceptable toxicity.
MYD88 L265P, a diagnostic marker for lymphoplasmacytic lymphoma (LPL)/Waldenström macroglobulinem... more MYD88 L265P, a diagnostic marker for lymphoplasmacytic lymphoma (LPL)/Waldenström macroglobulinemia (WM) can also be detected in other hematopoietic malignancies. We demonstrate a novel approach to increase the specificity of this marker for WM/LPL diagnosis by combining flow cytometric cell sorting with molecular analysis. Clonal B-lymphocyte and co-occurring clonal plasma cell populations of low-grade B-cell lymphomas were sorted by flow cytometry and analyzed for immunoglobulin gene rearrangements (PCR), and for MYD88 and CXCR4 mutations. Identical clonal origin was confirmed by PCR for 21 LPL/WM cases and MYD88 L265P was detected in both B-cell and plasma cell fractions. 9/20 other B-cell lymphomas with identical light chain restriction on B-cells and plasma cells were genotypically identical by PCR and MYD88 L265P was detected in both cell fractions in 7/9 whereas in 11/20 specimens with different clonal origin, MYD88 L265P was absent (5/11), or only found in B-lymphocytes (4/1...
Three rat anti-mouse monoclonal antibodies reactive with different populations of cells in mouse ... more Three rat anti-mouse monoclonal antibodies reactive with different populations of cells in mouse bone marrow have been extensively characterized with respect to their binding to cells in the lymphohemopoietic system. One antibody identifies lymphocytes committed exclusively to the B lineage. A second antibody identifies cells of the myeloid lineage including granulocytes and macrophages. The third antibody binds to nearly all of the bone marrow cells including erythrocytes, however, quantitative differences in antigenic expression allows the discrimination between early and late erythroid cells and can be used to purify eosinophils. The differential binding of these three monoclonal antibodies to mature cells, immature cells and progenitor cells (CFU-S, CFU-C (GM), BFU-E, and CFU-E) permits the construction of a scheme of lymphohemopoietic differentiation based on the expression of three cell surface antigens.
Cell surface antigen expression in AML is becoming focus of investigation as it relates to progno... more Cell surface antigen expression in AML is becoming focus of investigation as it relates to prognostic impact as well as potential therapeutic implications. The CD117 (c-KIT) receptor tyrosine kinase is expressed on the cell surface of hematopoietic stem cells and its signaling is important in cell survival, proliferation and differentiation. CD117 is expressed in a majority of AML cases. In addition, mutations in c-KIT have been identified in a subset of patients, specifically those with CBF AML (inv(16)/t(16;16) and t(8;21)). As there is increasing interest in using tyrosine kinase inhibitors with anti-KIT activity based on surface CD117 expression as treatment in AML, we sought to evaluate the association of CD117 expression with biologic and clinical features in pediatric and young adult (YA) AML. A total of 1803 pediatric and YA patients (ages 0.01-29.2 years) treated on the Children's Oncology Group (COG) phase III trials AAML0531 (n=762) and AAML1031 (n=1041) with complete...
An accurate blast count is pivotal in the diagnosis, classification and prognosis of patients wit... more An accurate blast count is pivotal in the diagnosis, classification and prognosis of patients with myelodysplasia. Blast counts in all previous classification schemes are based on morphologic assessment of marrow aspirates with a poor correlation to blast counts determined by flow cytometry. A significant problem in blast enumeration by flow cytometry is the variable hemodilution of the marrow during collection for flow cytometric analysis. Blast counts can vary depending on which aspirate tube is used for flow analysis, e.g., 2.4%, 1st 5ml tube; 0.62%, 2nd 5ml tube; 0.58% 3rd 5ml tube. Morphologists circumvent this problem by selecting a region for assessment close to a spicule with minimal blood dilution. Cell surface antigens can be used to distinguish mature cells found in blood as distinct from immature cells identified in marrow. CD16 intensity on neutrophils reaches a maximum at the band/segmented stage of development with a low coefficient of variation, thereby becoming a marker for mature myeloid forms. A simple method to distinguish immature from mature myeloid cells was developed to assess extent of blood contamination in marrow aspirates using a combination of CD16, CD13, and CD45. The average mature neutrophil content of a marrow was determined from phenotypically normal bone marrow biopsy specimens, assumed to have minimal blood contamination. The proportion of dimCD16 cells gated on the myeloid cells based on CD45 and right angle light scatter in 31 biopsy specimens was 82% (range 69–93, SD=6.2) (Figure 1). A value of 80% (rather than 82%) was used for the subsequent calculations to correct for the excess mature neutrophils found in an aspirate as compared to the biopsies (Corrected Blasts = [80 / % dim CD16 myeloid] x determined blast count). To test this hypothesis bone marrow aspirates were diluted with blood at different ratios to mimic blood marrow hemodilution. Blasts (defined as CD45 dim, low right angle light scatter, HLA-DR positive, CD11b negative) were determined for the various dilutions, then corrected based solely on the proportion of dim CD16 myeloid cells (Figure 2). A marrow from an MDS case was also diluted (1:5 v/v) with blood for comparison. The original marrow contained 80% dim CD16 myeloid cells with a blast count of 9.2%. After dilution, only 12% dim CD16 cells were detected with 1.1% blasts, however upon correction (6.67), the blast count was 7.3%, close to the original determination. This approach may provide for more standardization and consistency in the determination of blast counts in MDS marrow specimens using flow cytometric analysis. Figure 1, CD16 of marrow myeloid cells. Figure 1,. CD16 of marrow myeloid cells. Figure 2, Uncorrected/Corrected Blast Count Figure 2,. Uncorrected/Corrected Blast Count
Introduction: CD74 is a type II transmembrane protein expressed on antigen-presenting cells and a... more Introduction: CD74 is a type II transmembrane protein expressed on antigen-presenting cells and an MHC class II chaperone. It has been associated with tumor progression and metastasis in solid tumors, and its expression has been suggested to serve as a prognostic factor in many cancers, with higher relative expression associated with oncogenesis. As the expression of CD74 has been associated with response to bortezomib in multiple myeloma, we inquired whether such correlation might be seen in pediatric AML. We prospectively evaluated CD74 expression by difference from normal (ΔN) flow cytometry and correlated expression with clinical characteristics and outcome as part of Children's Oncology Group protocol AAML1031 that randomized patients younger than 30 years of age with de novo AML to standard treatment with (Arm B) or without (Arm A) bortezomib. The addition of bortezomib to standard chemotherapy increased toxicity but did not improve survival. Given the association of CD74 ...
The aim of this study was to establish the therapeutic relevance of the CD33D2 isoform by develop... more The aim of this study was to establish the therapeutic relevance of the CD33D2 isoform by developing novel antibodies targeting the IgC domain of CD33. Two novel IgC-targeting antibodies, HL2541 and 5C11-2, were developed, and CD33 isoforms were assessed using multiple assays in cells overexpressing either CD33FL or CD33D2 isoforms, unmodified acute myeloid leukemia (AML) cell lines and primary AML specimens representing different genotypes for the CD33 splicing single nucleotide polymorphism. CD33D2 was recognized on cells overexpressing CD33D2 and unmodified AML cell lines; however, minimal/no cell surface detection of CD33D2 was observed in primary AML specimens. Both isoforms were detected intracellularly using novel antibodies. Minimal cell surface expression of CD33D2 on primary AML/progenitor cells warrants further studies on anti-CD33D2 immunotherapeutics.
Five-dimensional flow cytometry was used to identify the 5 lineages of peripheral blood leukocyte... more Five-dimensional flow cytometry was used to identify the 5 lineages of peripheral blood leukocytes simultaneously in a single cell preparation. This technique was then used to compare quantitatively the distribution of cell surface antigens on each of these lineages of cells. Neutrophils, eosinophils, basophils, lymphocytes, and monocytes were uniquely identified by correlating their forward and orthogonal light scattering signals with the amount of cell surface-bound IgE. These three cellular characteristics were combined with two additional immunofluorescence labels to create a 5-dimensional space in which each leukocyte population occupied a unique position. The relative quantities of antigens on each cell type were determined for the monoclonal antibodies CD11b, CD13, CD14, CD15, CD16, CD33, CD38, CD45, CD45R, anti-HLA-DR, and anti-Leu-8 labeled with either fluorescein or phycoerythrin. The amount of antigen was described by the mean fluorescence intensity in comparison with the...
After demonstrating that hemoglobin function (p50 and 2,3-DPG) was better maintained with blood s... more After demonstrating that hemoglobin function (p50 and 2,3-DPG) was better maintained with blood stored in CPD as compared to ACD, the senior author showed that the higher pH of CPD was the reason for its better maintenance of hemoglobin function. In the present study a wider ...
Blut Zeitschrift für die Gesamte Blutforschung, 1972
oxygen dissociation curves were performed on blood units preserved in acid-citrate-dextrose (ACD)... more oxygen dissociation curves were performed on blood units preserved in acid-citrate-dextrose (ACD), ACD-adenine, and ACD-adenine-inosine. Dividing blood from a single donor into two or more bags allowed direct comparison between preservatives. During the 1st wk of storage in ACD, a progressive increase in oxygen affinity was observed. Thereafter, little further change was noted. Oxygen affinity increased even more rapidly during initial storage in ACD-adenine. However, with the inclusion of inosine as a preservative, oxygen affinity remained unaltered during the first 2 wk. Increases in oxygen affinity correlated well with falling levels of red cell 2,3-diphosphoglycerate (2,3-DPG) during storage. No significant changes in glutathione, reduced form (GSH), or A3 (AI) hemoglobin levels were noted during the first 3 wk of storage. No significant accumulation of ferrihemoglobin was detected. When blood stored 20 days in ACD or ACD-adenine was incubated with inosine for 60 min at 37'C, 2,3-DPG and adenosine triphosphate (ATP) were resynthesized, and oxygen affinity was decreased. The distribution of 2,3-DPG in fresh and stored red cells appeared to influence experimental values for Hill's n, a measure of heme-heme interaction.
INTRODUCTION Sorafenib, a multi-kinase tyrosine kinase inhibitor (TKI) targets FLT3 internal tand... more INTRODUCTION Sorafenib, a multi-kinase tyrosine kinase inhibitor (TKI) targets FLT3 internal tandem duplication (FLT3/ITD) mutations and has efficacy in adult FLT3/ITD+ AML. High allelic ratio (HAR) FLT3/ITD mutations (allelic ratio of > 0.4, referred to as FLT3/ITD+) confer poor prognosis in de novo pediatric AML. COG AAML1031 Arm C studied the feasibility and efficacy of adding sorafenib to standard chemotherapy and as a single agent maintenance therapy in pediatric HAR FLT3/ITD+ patients. METHODS The AAML1031 primary randomization (Arm A vs. B) has been previously reported (Aplenc et al. Blood 2016;128:899). Patients with FLT3/ITD+ AML were offered secondary enrollment on Arm C and toxicities were monitored on respective treatment arms. An initial safety phase (Cohort 1, C1; N=12) defined the maximum tolerated dose (MTD) of sorafenib when added to induction II chemotherapy and subsequent courses. Following completion, the study was amended (Cohort 2; C2) to start sorafenib on ...
The optimal number of chemotherapy courses for low‐risk (LR) pediatric acute myeloid leukemia (AM... more The optimal number of chemotherapy courses for low‐risk (LR) pediatric acute myeloid leukemia (AML) is not known.
International Working Group (IWG) and European LeukemiaNet (ELN) response definitions are utilize... more International Working Group (IWG) and European LeukemiaNet (ELN) response definitions are utilized to evaluate the efficacy of new agents for childhood acute myeloid leukemia (AML) for regulatory purposes. However, these criteria are not consistent with definitions used in pediatric AML trials or with standard pediatric practice to proceed with subsequent therapy cycles prior to IWG/ELN-defined count recovery. We retrospectively analyzed data from the two most recent Phase 3 pediatric AML clinical trials conducted by the Children’s Oncology Group (COG) to assess the incidence, timing, and prognostic significance of count recovery following induction chemotherapy. Of the patients with fewer than 5% bone marrow blasts at the end of first induction, 21.5% of patients proceeded to a second induction cycle prior to achieving ANC ≥ 500 cells/μL and platelets ≥ 50,000 cells/μL, both well below the IWG/ELN thresholds of ANC > 1000 cells/μL and platelets > 100,000 cells/μL. In these tw...
Infant Acute Myeloid Leukemia (AML) is a poorly-addressed, heterogeneous malignancy distinguished... more Infant Acute Myeloid Leukemia (AML) is a poorly-addressed, heterogeneous malignancy distinguished by surprisingly few mutations per patient but accompanied by myriad age-specific translocations. These characteristics make treatment of infant AML challenging. While infant AML is a relatively rare disease, it has enormous impact on families, and in terms of life-years-lost and life limiting morbidities. To better understand the mechanisms that drive infant AML, we performed integrative analyses of genome-wide mRNA, miRNA, and DNA-methylation data in diagnosis-stage patient samples. Here, we report the activation of an onco-fetal B-cell developmental gene regulatory network in infant AML. AML in infants is genomically distinct from AML in older children/adults in that it has more structural genomic aberrations and fewer mutations. Differential expression analysis of ~1500 pediatric AML samples revealed a large number of infant-specific genes, many of which are associated with B cell de...
10002 Background: Patients with residual acute myeloid leukemia (AML) after induction fare poorly... more 10002 Background: Patients with residual acute myeloid leukemia (AML) after induction fare poorly. The recently completed AAML1031 Phase III clinical trial intensified Induction II chemotherapy, altered the stem cell transplant (SCT) conditioning regimen, and liberalized SCT donor source criteria. We sought to test whether these practice changes improved clinical outcomes. Methods: Patients on AAML0531 and AAML1031, sequential Phase III trials for AML with shared high risk features of both > 15% residual blasts by morphology and ≥ 0.1% minimal residual disease (MRD) by flow cytometry with uninformative cytogenetics or high risk cytogenetic features (-7 or -5/5q-) were included. Gemtuzmab exposed and patients with high allelic ratio FLT3 ITD were excluded. Patients were observed from the start of Induction II through last available follow up. Induction II chemotherapy (ADE or AraC/Mito) was the exposure of interest. Disease free and overall survival (DFS, OS) were the primary outc...
We analyzed the safety and efficacy of Mylotarg (gemtuzumab ozogamicin, an antibody-targeted chem... more We analyzed the safety and efficacy of Mylotarg (gemtuzumab ozogamicin, an antibody-targeted chemotherapy consisting of a humanized anti-CD33 antibody linked to calicheamicin, a potent antitumor antibiotic) in the treatment of 101 patients Ն60 years of age with acute myeloid leukemia (AML) in untreated first relapse in three open-label trials. Mylotarg is administered as a 2-h intravenous infusion at 9 mg/m 2 for two doses with 14 days between doses. The overall remission rate was 28%, with complete remission (CR) in 13% of patients and complete remission with incomplete platelet recovery (CRp) in 15%. Median survival was 5.4 months for all patients and 14.5 months and 11.8 months for patients achieving CR and CRp, respectively. CD33 antigen is present on normal hematopoietic progenitor cells; thus, an expected high incidence of grade 3 or 4 neutropenia (99%) and thrombocytopenia (99%) was observed. The incidences of grade 3 or 4 elevations of bilirubin and hepatic transaminases were 24% and 15%, respectively. There was a low incidence of grade 3 or 4 mucositis (4%) and infections (27%) and no treatment-related cardiotoxicity, cerebellar toxicity, or alopecia. Mylotarg is an effective treatment for older patients with CD33-positive AML in first relapse and has acceptable toxicity.
MYD88 L265P, a diagnostic marker for lymphoplasmacytic lymphoma (LPL)/Waldenström macroglobulinem... more MYD88 L265P, a diagnostic marker for lymphoplasmacytic lymphoma (LPL)/Waldenström macroglobulinemia (WM) can also be detected in other hematopoietic malignancies. We demonstrate a novel approach to increase the specificity of this marker for WM/LPL diagnosis by combining flow cytometric cell sorting with molecular analysis. Clonal B-lymphocyte and co-occurring clonal plasma cell populations of low-grade B-cell lymphomas were sorted by flow cytometry and analyzed for immunoglobulin gene rearrangements (PCR), and for MYD88 and CXCR4 mutations. Identical clonal origin was confirmed by PCR for 21 LPL/WM cases and MYD88 L265P was detected in both B-cell and plasma cell fractions. 9/20 other B-cell lymphomas with identical light chain restriction on B-cells and plasma cells were genotypically identical by PCR and MYD88 L265P was detected in both cell fractions in 7/9 whereas in 11/20 specimens with different clonal origin, MYD88 L265P was absent (5/11), or only found in B-lymphocytes (4/1...
Three rat anti-mouse monoclonal antibodies reactive with different populations of cells in mouse ... more Three rat anti-mouse monoclonal antibodies reactive with different populations of cells in mouse bone marrow have been extensively characterized with respect to their binding to cells in the lymphohemopoietic system. One antibody identifies lymphocytes committed exclusively to the B lineage. A second antibody identifies cells of the myeloid lineage including granulocytes and macrophages. The third antibody binds to nearly all of the bone marrow cells including erythrocytes, however, quantitative differences in antigenic expression allows the discrimination between early and late erythroid cells and can be used to purify eosinophils. The differential binding of these three monoclonal antibodies to mature cells, immature cells and progenitor cells (CFU-S, CFU-C (GM), BFU-E, and CFU-E) permits the construction of a scheme of lymphohemopoietic differentiation based on the expression of three cell surface antigens.
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Papers by Michael Loken