Coexpression Of Myeloid Antigens Research Articles

Project Evolve, Evaluation of Lineage Switch (LS), an International Initiative: Preliminary Results Reveal Dismal Outcomes in Patients with LS

Introduction: Lineage switch (LS) refers to the transformation of acute leukemia from one cell lineage to another (e.g., lymphoid (ALL) to myeloid (AML)). This rare phenomenon, distinct from treatment induced malignancy (i.e., t-AML) and mixed phenotype acute leukemia (MPAL), is increasingly being observed following cell surface antigen targeting. Given challenges in the diagnosis and treatment of LS, Project EVOLVE was developed to globally identify cases of LS following immunotherapy. Methods: A protocol and data collection form for this IRB exempt study was widely disseminated to capture deidentified LS case information across multiple centers and cancer consortia. This included collection of data from published reports of LS, with authors contacted to obtain additional information. For this analysis, LS was defined by the emergence of cell-surface markers warranting reclassification of the original leukemia as a different lineage derivation based on the immunophenotype, including cases of AML emerging alongside the original ALL. “Confirmed” LS cases included those where retention of original cytogenetic or molecular aberrations and/or the clonal immunoglobulin rearrangement patterns were verified to confirm the clonal relationship. “Suspected” LS cases included those where samples to confirm clonality marker retention could not be obtained, but the clinical presentation was consistent with LS. The term “transition” was applied when immunophenotypic shifts were transient. Cases with new cytogenetic abnormalities unrelated to the original diagnosis and compatible with t-AML were excluded. Statistical analysis was primarily descriptive. Data cut-off was July 26, 2023. Results: A total of 58 cases were identified, including 19 cases referenced in prior publications. Of the 58, 11 cases were excluded from this initial analysis, including: 4 cases of t-AML, 2 cases of T-ALL to AML, and 5 “transition” cases. Collectively, 47 cases of LS (43 “confirmed”; 4 “suspected”), spanning across 3 continents and 8 countries, were analyzed. (Fig. 1A) Cases included transition from B-ALL to AML in 36 (76.6%) and to MPAL/biphenotypic/ambiguous lineage in 11 (23.4%). Two likely had MPAL at diagnosis and a third with chronic myeloid leukemia. The median age at initial diagnosis was 8.4 years (range, 1 day-76.5 years); median age at LS presentation was 11.0 years (range 0.4-77.3 years). Twenty-three (48.9%) were male and 19 (40.4%) had prior stem cell transplant (SCT). Baseline cytogenetics showed KMT2A rearrangement in 27 (57.4%). Baseline myeloid antigen co-expression was seen in 22 of 23 patients with submitted data, but variation in degree of expression across patients and antigens was substantial. The most proximal immunotherapy prior to development of LS was CAR T-cells in 23 (48.9%) and blinatumomab in 24 (51.1%). The median time from the most proximal immunotherapy to development of LS was 1.6 months (range, 7 days-36.5 months). In 7 (29.2%) patients receiving blinatumomab, LS developed during the infusion. LS presented as isolated marrow relapse in 27 (57.4%), isolated CNS in 2 (4.3%), isolated non-CNS extramedullary disease in 3 (6.4%), combined relapse in 14 (29.8%) and unreported in 1. First line treatment for LS was chemotherapy induction in 31 (66.0%), palliative care/no therapy in 8 (17.0%), and alternative therapies in the remaining 8 (17.0%). In 35 (74.5%) patients, remission induction was the goal of first line therapy. Fifteen (31.9%) achieved a complete remission (CR) of whom 2 were treated with palliative intent. Across all patients, 8 (17.0%) are alive in remission, the longest being 4.7 years from LS diagnosis; 2 (4.3%) are alive with active LS and 37 (78.7%) died from LS, their original disease, or complications of treatment of LS (Fig 1B). For those alive in CR (n=8), 7 (87.5%) proceeded to a consolidative SCT for treatment of LS and 1 patient, an octogenarian remains in remission after AML directed therapy. Conclusions: LS is emerging as an important mechanism of immune escape following immunotherapy. Project EVOLVE provides the largest dataset of patients with LS to date. This systematic, international effort reveals substantial complexity and variability in diagnosing and managing LS. Unfortunately, outcomes following LS are grim, underscoring the critical need to identify risk factors of and optimal therapies for this leukemia transformation.

Comparison of flowcytometry-based scoring system for the diagnosis of early T precursor-acute lymphoblastic leukemia.

Early T cell precursor-acute lymphoblastic leukemia (ETP-ALL) is a hematolymphoid malignancy where the blasts demonstrate T cell differentiation markers along with stem cell and myeloid antigen expression. The differential diagnosis of ETP-ALL from non-ETP ALL and mixed phenotype acute leukemia is often challenging due to its overlapping immunophenotypic picture with co-expression of myeloid antigens. In this study, we endeavored to describe the immune-phenotype profile of ETP-ALL in our patients and compared the utility of four different scoring systems for better discrimination of these entities. This retrospective analysis included 31 ETP-ALL out of 860 acute leukemia cases consecutively diagnosed at the two tertiary care centers. Flowcytometry-based immunophenotype was reviewed for all the cases, and the utility of four flow-based objective scorings was assessed for the diagnosis of ETP-ALL. Receiver operating curves were drawn to compare the different flow-based scoring systems. The prevalence of ETP-ALL was 40% (n=31/77 T-ALL) in our study group, comprised mainly of adults with a median age of 20 years. The five-marker scoring system had the maximum area under the curve, followed by the seven-marker scoring system. A cut-off of ≥2.5 was more specific (sensitivity: 91%; specificity: 100%), while a score of ≥1.5 was more sensitive but slightly less specific (sensitivity: 94%, specificity: 96%). The WHO criteria for the diagnosis of ETP-ALL should be followed across all laboratories to avoid confusion and for better treatment stratification. Flow-based scoring systems can be objectively employed for better detection of cases.

Mixed phenotype acute leukemia and lineage switch from lymphoblastic leukemia to myeloid leukemia in the course of Philadelphia-negative myeloproliferative neoplasm – case reports and literature review

AbstractPhiladelphia-negative myeloproliferative neoplasms (Ph-neg MPNs) are characterized by clonal hematopoiesis derived from a mutated hematopoietic stem cell. Ph-neg MPNs rarely transforms into acute leukemia, and in most cases, the transformation leads to the development of acute myeloid leukemia (AML). The incidence of mixed-phenotype leukemia (MPAL) or acute lymphoblastic leukemia (ALL) with lineage switch is much rarer. The unidentified lineage of blast cells is due to the immaturity of their undifferentiated progenitors with co-expression of myeloid and lymphoid antigens. The prognosis of secondary acute leukemia transformed from Ph-neg MPN is very unfavorable, especially in MPAL or lineage switch from ALL to AML cases. Moreover, there are no therapeutic protocols for these specific leukemia subtypes. Therefore, we believe that all cases of MPAL or lineage switch leukemia should be reported. This article presents the case of a patient with JAK2-positive essential thrombocythemia (ET) transformed to MPAL, and a patient with triple-negative primary myelofibrosis (PMF) (negative for JAK2, CALR, and MPL) transformed to ALL with subsequent lineage switch to AML.

A study on clinical, immunophenotypic pattern in pediatric acute leukemias in a teaching hospital

Background: Acute leukemia contributes to nearly one third of the pediatric malignancies. For effective management of a curable malignancy, the epidemiology of childhood leukemias and audit of previously treated patients would be required. The objective was to study the clinical and immunophenotypic pattern of acute leukemia in children <12 years of age admitted in a tertiary centre. Methods: Prospective study done on 31 children, diagnosed as leukemia and treated over a period of 3 years in GRH, Madurai. Detailed history analysis, clinical examination, lab investigations including flowcytometry were done.Results: ALL was the most common acute leukemia in children (90.3%). 85.7% were identified as B-cell and 14.3% as T-cell. Of the B-ALL, 87.5% was pre-B, 8.3% pro-B and 4.2% mature B ALL. Myeloid antigen co-expression was seen in 35.7%. Fever was the most common symptom (87%) and hepatosplenomegaly was the most common sign (>90%). Poor outcome was noted in 42.3%. T-cell appeared to have worse prognosis than B-cell but did not retain independent prognostic significance in univariate analysis.Conclusions: B-ALL was more common than T-ALL. Extra medullary organ involvement indicates increased tumor burden and poor outcome. None of the clinical or laboratory parameters appeared to predict poor outcomes in our study and this may be due to small sample size. This study provides an insight into the data regarding the epidemiology, clinicopathologic feature and outcome of acute leukemia in a center with low resource settings.

Aberrant myeloid antigen co-expression is correlated with high percentages of CD34-positive cells among blasts of acute lymphoblastic leukemia patients: an Indian tertiary care center perspective.

BackgroundAberrant myeloid antigen (MA) co-expression and high expression of CD34 antigen on the blasts of acute lymphoblastic leukemia (ALL) patients are independently reported to have a role in pathogenesis and prognosis. This study was conducted to determine whether these two parameters are related.MethodsA total of 204 cases of ALL were included in an analysis of blast immunophenotypic data. CD34 expression was categorized as low when less than 50% of blasts were CD34-positive (CD34low) and as high when 50% or more were CD34-positive (CD34high).ResultsOf 204 cases of ALL, 163 and 41 were of B-cell origin (B-ALL) and T-cell origin (T-ALL), respectively. Of all cases, 132 (64.7%) showed co-expression of MA and among these, 101 (76.51%) were CD34high, while the remaining 31 (23.48%) were CD34low. Of 72 cases without MA co-expression, 25 (34.72%) were CD34high and 47 (67.25%) were CD34low. Furthermore, of 163 cases of B-ALL, 111 showed co-expression of MA and 84 of these were CD34high. Of 52 cases of B-ALL without MA expression, 22 were CD34high. Among 41 cases of T-ALL, 21 co-expressed MA, 17 of which were CD34high. Moreover, all 20 cases of T-ALL without co-expression of MA were CD34low. These differences were statistically significant.ConclusionWe observed a strong correlation between aberrant MA expression and CD34high expression on the blasts of ALL. We hypothesize that these different patient subsets may represent unique prognostic characteristics.

The clinical importance of myeloid antigen coexpression and TEL-AML1 mutation in patients with childhood acute lymphoblastic leukemia

Objective: In this study, we aim to investigate the relation­ship, if any, between clinical features, prognosis, and the coexpressions and TEL-AML1 mutation in patients with acute lymphoblastic leukemia (ALL). Methods: Eigthy-three patients with acute lymphoblastic leukemia were retrospectively examined. Age, gender, White blood cell count, hemoglobin level, platelet count, ALL subtypei (B or T ALL), risk groups, surface antigens deteceted by flow cytometry, existence of TEL-AML1 mu­tations, response, remission and relapse status at 8., 15. ve 33. Days of treatment were recorded and analyzed. Results: 15 (18%) out of 83 were identified with aberrant antigen expression. Of these patients, twelve (14.4%) had myeloid antigen coexpression (CD13 and/or CD33), two with B cell ALL had CD2 and CD7 coexpressions re­spectively, one with T cell ALL had CD19 coexpression. No significant differences were found between patients with and without myeloid antigen coexpression in terms of hemoglobin levels, white blood cells and platelet counts, responses given on the 8th, 15th, and 30th days on the treat­ment, risk groups, and relapse (p>0.05). Myeloid antigen coexpression was found in 4 of 13 patients who were iden­tified with TEL-AML1 mutation. No significant relationship was found between this mutation and coexpressions. No relapse and exitus were observed in four patients with co­expression and TEL-AML1. Conclusion: The prognosis and clinical features shows no statistically significant relationship with the presence of neither Myeloid antigen expression nor TEL-AML1 muta­tion. We believe, however, the future studies involving big­ger sample sizes will prove to be useful in terms of more convincing results.

Exome Sequencing Identifies Recurring DNMT3A Mutations in Adult ETP-ALL

AbstractAbstract 1377 Introduction:Early T-cell precursor (ETP) ALL accounting for 10% of all T-ALL cases is of special interest because of its proposed origin from early thymic progenitors with multilineage differentiation potential. ETP-ALL is associated with a poorer outcome in pediatric and adult patients. On the molecular level, ETP-ALL is characterized by a specific immunophenotype (CD1-, CD5weak, CD8-, co-expression of stem cell and/or myeloid antigens) and distinct molecular features (expression of stem cell genes, high frequency of FLT3 mutations with absence of NOTCH1 mutations). Whereas a highly heterogeneous genetic pattern was revealed by whole genome sequencing in pediatric patients, the genetic background of adult ETP-ALL remains largely unknown. Here we investigated genetic alterations in adult ETP-ALL by whole exome sequencing and subsequently analyzed specific target genes. Patients and methods:We performed whole exome sequencing of five paired (diagnosis/remission) adult ETP-ALL patients enrolled in German Acute Lymphoblastic Leukemia Multicenter Study Group (GMALL) trials. Using exon capturing from genomic DNA, followed by 76-bp paired-end sequencing on an Illumina Genome Analyzer IIx platform, we generated at least 5 Gb of exome sequence from each ETP-ALL and remission samples. Somatic mutations were identified by comparing the ETP-ALL with the remission exome sequence, excluding all annotated polymorphisms (dbSNP130), non-coding positions and positions with evidence of a variant in the corresponding remission samples. Candidate variants were confirmed by capillary sequencing of genomic DNA. The DNMT3A mutations status was analyzed by Sanger sequencing of exons 11–23 in additional 68 adult ETP-ALL (55 male, 13 female, median age: 38 years) as well as the mutation status of the polycomb repressor complex (PRC) genes EZH2 and SUZ12. For 52 of 68 patients clinical follow-up data were available. Results:Using whole exome sequencing we found a total of 56 non-synonymous somatic mutations or indels in the five ETP-ALL patients (range: 6 to 16 per patient). Eleven mutations/indels affected cancer genes. DNMT3A (2/5) and FAT3 (2/5) were recurrently mutated in the five patients. The DNA-methyl-transferase DNMT3A is a frequent mutational target in acute myeloid leukemia (AML; 20%), whereas FAT3 (FAT, tumor suppressor homolog 3) mutations were recently reported in ovarian carcinoma (TCGA, Nature 2011). Novel mutations identified in adult ETP-ALL involved genes in epigenetic regulation (e.g. MLL2, MLL3, BMI1), and in genes previously reported to be mutated in ETP-ALL (e.g. in JAK1, ETV6, NOTCH1, DNM2).By Sanger sequencing, we screened for DNMT3A mutations in a larger cohort of adult ETP-ALL. DNMT3A mutations were present in 11 of the 68 (16%) patients, a mutation rate similar to AML. Amino acid R882 (exon 23), the most frequently mutated amino acid in AML, was mutated in five ETP-ALL. The remaining six mutations occurred in single spots, with one exception in the ZNF or the MTF domain. Patients with a DNMT3A mutation were significantly older (median: 63 vs 37 years, P=0.016). No correlation was found between DNMT3A and FLT3 mutations (27% in DNMT3A mut pts. vs. 37% in DNMT3A wt pts., P=0.41) or NOTCH1 mutations (10% in DNMT3A mut pts. vs. 16% in DNMT3A wt pts., P=0.47).In addition, we investigated genetic alterations in epigenetic regulators including members of the polycomb repressor complex (PRC). Mutations were seen in EZH2 in 4/68 (6%), SUZ12 in 1/68 (1%) and SH2B3 in 4/69 (6%) of ETP-ALL. Interestingly, patients with at least one mutation in an epigenetic regulator gene (DNMT3A, SUZ12, SH2B3, MLL2, or EZH2) showed a trend towards an inferior survival (one-year-survival: 50% vs. 85%, P=0.08). Conclusion:Adult ETP-ALL patients display a heterogenous spectrum of mutations, particularly affecting genes involved in epigenetic regulation. The spectrum is different to pediatric patients with a lower rate of polycomb repressor complex and a higher rate of DNMT3A mutations. The higher rate of DNMT3A mutations in older patients might point to a different pathogenesis compared to pediatric ETP-ALL. Like in AML, DNMT3A mutations in adult ETP-ALL show a similar frequency, within the same hot spots and are correlated with an adverse prognostic value, underscoring the myeloid character of ETP-ALL. Thus, these data may provide a rationale to use epigenetic therapy in ETP-ALL. Disclosures:Krebs:Illumina: Honoraria. Greif:Illumina: Honoraria.

Clonal evolution in UKE-1 cell line leading to an increase in JAK2 copy number

Clonal evolution in UKE-1 cell line leading to an increase in JAK2 copy number

Prognostic Value of Immunophenotype In Infant ALL – Results of the INTERFANT'99 Study

AbstractAbstract 2700 Objective:Infant acute lymphoblastic leukemia (ALL) is characterized by distinct biological and clinical features. In this study, we aimed at detailed evaluation of infant ALL immunophenotype based on the large cohort of patients treated homogeneously on INTERFANT'99 protocol. Patients and Methods:We were able to obtain sufficient flow cytometry based immunophenotypic data from 286 (130 boys and 156 girls) of 483 infant ALL cases treated on INTERFANT'99 protocols. The distribution of patient and leukemia characteristics as well as clinical outcome were very similar to the entire study cohort (Pieters et al, Lancet 2007; 370: 240–250). The positivity for a certain antigen was defined at the cut-off value of >20% of cells expressing this antigen. In B-cell precursor ALL (BCP-ALL), evaluated antigens included CD10, CD20, CD34, myeloid markers (CD13, CD33, CD15 and/or CD65) and NG2 antigen assessed with 7.1 antibody. The strength of association between characteristics (patient's age and gender, initial white blood count [WBC], CNS involvement, presence of MLL gene rearrangements, prednisone response [PR]) and antigen expression was analyzed with Fisher exact test adjusted for multiple comparisons. Univariate analysis of outcome by immunophenotype was based on event free survival (EFS) and compared by log-rank test. Multivariate analysis was performed using Cox model in MLL-rearranged cases. P values < 0.05 were considered to be significant. Results:Altogether, 272 cases of infant BCP-ALL and 14 of infant T-ALL were analyzed. Most BCP-ALL cases were CD10 negative (66%), CD20 negative (88%), CD34 positive (60%), and NG2 positive (58%). Co-expression of myeloid antigens was less frequent and concerned CD13 in 8%, CD33 in 17%, CD15 in 31%, and CD65 in 28%. CD10 negativity and NG2 expression were significantly more frequent in younger infants, patients with initial high leukocytosis and with MLL rearrangements. CD34 expression was observed more frequently in younger infants, while CD20 positivity was significantly associated with lower initial leukocytosis and absence of MLL rearrangement. For myeloid antigen expression, the only significant association was more frequent CNS involvement in infants with CD13+ and/or CD33+ BCP-ALL. Analysis of outcome showed significantly better prognosis for CD10 positivity (4-year EFS of 56.3 as compared to 37.2 for CD10 negative BCP-ALL), absence of NG2 expression (4-year EFS of 63.9 as compared to 34.9 for NG2 positive BCP-ALL) and CD33 negativity (4-year EFS of 47.6 as compared to 27.7 for CD33 positive BCP-ALL). There was also a trend towards better outcome in CD20 positive infant BCP-ALL. While CD10 negativity and NG2 positivity were associated with well-known high-risk features, prognostic significance of CD33 expression is somewhat more difficult to explain. Of note, CD10 negativity was not associated to a worst outcome in MLL-rearranged patients. Moreover, in this subset, multivariate analysis showed that none of the markers analyzed had independent prognostic significance, after adjustment for sex, age at diagnosis, WBC and PR. In rare infant T-ALL cases, we observed equal distribution to different immunophenotypic subgroups as defined by EGIL classification. Conclusion:Infant BCP-ALL has distinct immunophenotypic features. However, immunophenotype has no independent prognostic relevance when MLL, age, WBC, PR and other factors are included. Disclosures:No relevant conflicts of interest to declare.

Mixed phenotype acute leukemia with t(11;19)(q23;p13.3)/ MLL‐MLLT1(ENL), B/T‐lymphoid type: A first case report

The majority of cases of acute leukemia belong to a specific lineage origin, either lymphoid or myeloid, and therefore are classified as acute lymphoblastic leukemia (ALL) or acute myelogenous leukemia (AML), based on morphologic features and cytochemical and immunophenotypic profile of the blast cells. A minority of acute leukemias however, show no clear evidence of differentiation along a single lineage. These are now classified under acute leukemias of ambiguous lineage by the most recent WHO classification and account for <4% of all cases of acute leukemia [1]. They include leukemias with no lineage specific antigens (acute undifferentiated leukemias) and those with blasts that express antigens of more than one lineage to such degree that it is not possible to assign the leukemia to any one particular lineage with certainty (mixed phenotype acute leukemias). The latter can either be leukemias with two distinct populations of blasts, each expressing antigens of a different lineage (historically referred to as "bilineal" leukemias) or a single blast population expressing antigens of multiple lineages (historically referred to as "biphenotypic" acute leukemias) [2]. Acute leukemias of ambiguous lineage may harbor a variety of genetic lesions. Those with t(9;22)(q34;q11) or translocations associated with mixed lineage leukemias (MLL) gene, i.e., t(11;V)(q23;V), occur frequently enough and are associated with distinct features, that are considered as separate entities according to the recent WHO classification. Co-expression of myeloid and B-lymphoid antigens is most common in mixed phenotype acute leukemia (MPAL), followed by co-expression of myeloid and T-lymphoid antigens, accounting for 66-70% and 23-24% of MLLs, respectively. Coexpression of B- and T-lineage associated antigens or antigens of all three lineages is exceedingly rare, accounting for <5% of MLLs [3,4]. The requirements for assigning more than one lineage to a single blast population has been established by current WHO classification [1].

Promising Outcome of Imatinib-Combined Chemotherapy Followed by Allogeneic Hematopoietic Stem Cell Transplantation for Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia: Results of the Japan Adult Leukemia Study Group (JALSG) Ph+ALL202 Regimen.

Abstract 3090Poster Board III-27The outcome of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) has dramatically improved since the start of treatment with imatinib. The Japan Adult Leukemia Study Group (JALSG) has reported a high complete remission (CR) rate for Ph+ALL treated with imatinib-combined chemotherapy (Yanada et al, J Clin Oncol 2006). Here we report a follow-up analysis of the results of the JALSG imatinib-combined chemotherapy. In the study, remission was induced by administering imatinib from day 8 to day 62 in combination with cyclophosphamide, daunorubicin, vincristine (VCR), and prednisolone (PSL). Consolidation regimen consisted of an odd course comprising high-dose methotrexate and high-dose cytarabine and an even course with 28 days administration of single-agent imatinib. The consolidation regimens were alternated for four courses each. Maintenance consisting of VCR, PSL, and imatinib was continued for two years after a CR. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) was recommended if HLA identical sibling donor was available and was allowed from an alternative donor.A total of 103 newly diagnosed Ph+ALL patients were enrolled in the study between August 2002 and August 2004. Median age of the patients was 45 years (range, 15-64 years), and there were 57 males and 46 females. Median follow-up period was 2.6 years (range, 0.1-5.1 years). A CR was achieved in 100 (97.1%) of the 103 patients and not achieved in a patient in whom imatinib was discontinued because of ileus. There were two early deaths during induction.The probability of overall survival (OS) rate for the entire group at three years was 56.8%. No severe adverse effects were observed. Allo-HSCT was performed in the 1st CR (CR1) in 54 of the 74 CR patients under 55 years of age. Relapse occurred in 18 of 20 patients (90.0%) in whom allo-HSCT was not performed in CR1, but in only seven of the 54 patients (13.0%) who underwent allo-HSCT. At three years, the probability of OS rate for patients under 55 years of age was 75.0% in the transplanted group and 36.4% in the non-transplanted group. Allo-HSCT was performed in CR1 in eight of the 25 patients over 55 years of age. Two were myeloablative and six reduced intensity conditionings. Seven of eight patients who underwent HSCT are still alive in a CR. However, the probability of OS rate at three years in the non-transplanted group was 43.2%.In the group that did not receive allo-HSCT in CR1, age (55< years or 55> years), WBC count, bcr/abl transcript level, bcr/abl transcript type (major or minor), co-expression of myeloid antigens (CD13 and/or CD33), and additional chromosomal abnormalities at diagnosis were not associated with OS.The results demonstrated that the imatinib-combined chemotherapy regimen was effective and feasible. The regimen provided a better chance to receive allo-HSCT which resulted in an excellent outcome. However, relapse still remains a problem, especially in patients who are not candidates for allo-HSCT. DisclosuresNo relevant conflicts of interest to declare.

Clinical Significance of Co-expression of Aberrant Antigens in Acute Leukemia

Background: Acute leukemias co-expressing myeloid and lymphoid antigens but does not meet the criteria for biphenotypic acute leukemia (BAL) is common, however its clinical significance is not fully defined. Methods: In this study, clinical features of 68 co-expressing (myeloid and lymphoid) acute leukemias diagnosed between January 2000 and December 2006 were studied and compared with those of a control group of patients (pure AML or ALL). Results: Age, gender, initial Lactate dehydrogenase (LDH) level and cytogenetics were not different between the co-expressing group and the control group. But, the initial bone marrow blast percent was significantly higher in the co-expressing group (70% vs. 54.5%, P=0.003). Fifty five percent (16/29) of ALL and 30% (52/172) of AML patients showed myeloid and lymphoid markers concomitantly. The lymphoid antigen positive AML (Ly+ AML) patients showed significantly shorter survival rates than pure AML patients (4 year survival rate, 17.6% vs. 45.6%, P=0.002). However hematopoietic stem cell transplantation (HST) abrogated the difference (4 year survival rate, 54.7% vs. 50.6%, P=0.894). In ALL patients, survival rate was not affected by myeloid antigen co-expression (4 year survival rate 26.1% vs. 20%, P=0.954). Conclusion: Co-expression of lymphoid markers in AML should be regarded as a poor prognostic factor and more aggressive treatment such as HST should be considered.

164: Clinical Features of Acute Leukemia with Co-Expression of Myeloid and Lymphoid Antigens

164: Clinical Features of Acute Leukemia with Co-Expression of Myeloid and Lymphoid Antigens

6021 POSTER Clinical features and treatment outcome of patients with myeloid antigen coexpression in acute lymphoblastic leukemia: a study of 214 Peruvian patients

Acute myeloid leukemia with mutated nucleophosmin (NPM1m+AML) is a heterogeneous entity. We investigated whether NPM1m+AML with monocytic or myeloid differentiation have distinct immunophenotype. The study included 160 NPM1m+AMLpatients and 178 AML patients without NPM1 mutation and recurrent cytogenetic abnormality (NPM1wt−AML). We analyzed the immunophenotype by flow cytometry. NPM1 mutation was detected by PCR. Compared with NPM1wt−AML patients, NPM1m+AML patients showed higher positive rates of CD33 and CD9 and lower positive rates of CD34, HLA-DR, CD7, CD15 and CD117 (all P < 0.05). HLA-DR, CD64, CD14, CD11b, CD15, CD4, CD9 and CD10 were higher (P < 0.001) and CD117 was lower (P < 0.01) in monocytic NPM1m+AML compared with myeloid NPM1m+AML. Similar rates of lymphoid antigen (CD19, CD2, and CD7) and myeloid antigen (CD13, CD33) positivity were detected in monocytic and myeloid NPM1m+AML. Compared with NPM1wt−AML, CD34 expression was lower both in myeloid and monocytic NPM1m+AML subgroups, although HLA-DR was lower in NPM1m+AML compared with NPM1wt−AML only in myeloid subgroup. Comparisons of NPM1m+AML and NPM1wt−AML showed no differences in monocyte-associated markers such as CD14 and CD11b in myeloid and monocytic subgroup. Myeloid NPM1m+AML correlated with the female gender (P = 0.001), lower WBC counts (P = 0.04) and higher WT1 transcripts (P = 0.006) compared with monocytic NPM1m+AML.These results suggested monocytic and myeloid-derived NPM1m+AML exhibit distinct immunophenotypes.

Prognostic significance of myeloid associated antigen expression in childhood acute lymphoblastic leukemia in Peru

9030 Background: The prognostic significance of coexpression of myeloid antigens in pediatric patients with acute lymphoblastic leukemia (ALL) has been reported by several authors, with a frequency that has ranged widely. All of these authors are from developed countries, the aim of this study is to evaluate the prognostic significance of these antigens in childhood ALL in a developing country. Methods: We retrospectively reviewed 729 newly diagnosed patients with ALL under 14 years of age, who had a bone marrow flow cytometry performed at our institution, between 1996–2002. Clinical data and treatment outcomes were reviewed and compared between patients with ALL who expressed myeloid antigens and those who did not using chi-square test. Results: 729 medical charts were studied, 81.6% of them were B-common, 8.2% were pro-B, 8.2% were T-cell and 2.1% were pre-B ALL patients. Overall frequency of myeloid antigen expression was 36.6%. The most frequent specific antigens found were: CD13, 15.5%; CD15, 6.0% and CD33, 4.5%. Evaluating the B-common ALL patients the presence of myeloid antigens rises to 43%. Patients who had coexpression of myeloid antigens had a relapse rate (any site) of 49.2% while 36.3% who had no coexpression had a relapse (p=0.001). There has also been statistical significance in bone marrow response on day 14 of induction with 64.9% having less than 5% blasts in the group without coexpression and 46.4% in the group with coexpression (p&lt;0.0001). Conclusions: The present retrospective review shows the presence of associated myeloid antigens in our ALL patients in 36.6%. We have shown that it is an adverse prognostic factor for childhood ALL in a developing country, unlike reports from other centers in developed countries. No significant financial relationships to disclose.

Myeloid/natural killer cell precursor acute leukemia with tetraploidy

Myeloid/natural killer (NK) cell precursor acute leukemia is characterized by coexpression of myeloid and natural killer cell antigens and an aggressive clinical course. Here we report a case of myeloid/NK precursor acute leukemia in a 37-year-old woman. Clinical presentation was correlated with leukemic blast morphology, immunophenotype, and cytogenetic analysis. The patient had noted fever, weakness, purpura, peripheral lymphadenopathy, and moderate hepatosplenomegaly. Peripheral blood smears and bone marrow aspirate smears at presentation revealed blastic cells, which were generally L2 shaped, with variation in cell size, round to moderately irregular nuclei and prominent nucleoli, pale cytoplasm, and a lack of azurophilic granules. Immunophenotypic analysis of the blasts displayed coexpression of myeloid and natural killer cell antigens with relatively immature phenotype: CD7 +, CD33 +, CD34 +, CD56 +, CD57 +, CD16 −, MPO −. Cytogenetic analysis of marrow cells showed 62% of cells with a normal female karyotype; in the remaining 38%, tetraploid changes were detected, where the chromosome number was 92, with no preferential losses or gains of chromosomes. Fluorescence in situ hybridization analysis revealed the same abnormality. The patient did not respond to chemotherapy (cytosine arabinoside and idarubicin) and died of a septic complication on the 34th day after admission. To our knowledge, this is the first description of tetraploidy in myeloid/NK cell precursor acute leukemia.

Clinical Significance of the Philadelphia Chromosome Positive Pediatric Acute Lymphoblastic Leukemia in Chinese.

Objective To explore the incidence, clinical characteristics and prognosis of childhood acute lymphoblastic leukemia (ALL) with t(9; 22).Methods All of the clinical characteristics of the 325 childhood ALL patients from November, 1998 to November, 2003 were analysised. The statistics was done by SPSS 10.0.Results There were 129 cases of high-risk ALLs in 325 Childhood ALL patients, with 95 males and 34 females. BCR-ABL fusion gene was found in 16 cases by RT-PCR, accounting for 4.9%. All of them were m-BCR-ABL. There were 12 males and 4 females among 16 Ph positive ALLs. The mean age at diagnosis was 8.54±3.36 (3.5 to 12.5) years, 50.0% of which were older than 10 years. The percents of patients who had initial WBC count more than 100×109/L, myeloid antigen coexpression, hypodiploidy, and ALL-L2 were 37.5%, 53.8%, 33.3%, and 62.5%, respectively. By comparison, the percents of age (older than 10 years), initial WBC count (more than 100×109/L), myeloid antigen coexpression, prednisone poor response (PPR), and CR over 35 days in the Ph positive ALLs were higher than that in the negative ALLs. No statistic difference was found in sex and L2 proportion between them. Moreover, no difference was found between Ph positive ALLs and negative high-risk ALLs in the mentioned parameters, except for the myeloid antigen coexpression. Four-year event-free survivals (EFS) and disease-free survivals (DFS) were 77.4% and 79.4, respectively, in Ph negative ALLs, but were 33.0% and 47.7%, respectively, in Ph positive ALLs (P<0.01). In Ph negative high-risk ALLs, the four-year EFS and DFS were 51.2% and 54.6%, respectively, both of which had no statistic difference between Ph positive cases. Only one Ph positive child received allogeneic BM transplantation, who remained in EFS at the time of this analysis.Conclusion The percent of t(9; 22) in Chinese childhood ALLs had no difference with the report abroad. There were statistic differences between Ph positive and negative childhood ALLs in age, initial WBC count, early response to therapy, and four-year EFS and DFS, but no difference was found between Ph positive ALLs and Ph negative high-risk ALLs, except for the immunophnotype. Aggressive treatment, such as high-dose chemotherapy with allogeneic BM transplantation should be considered for these patients to improve survival. [Display omitted]

Extramedullary presentation of acute leukaemia: a case of myeloid/natural killer cell precursor leukaemia

Myeloid/natural killer (NK) cell leukaemia is characterised by coexpression of myeloid with natural killer cell antigens, a high incidence of extramedullary disease and an aggressive clinical course. We report a case of a 28-year-old woman with myeloid/NK cell precursor acute leukaemia. Clinical presentation was correlated with leukaemic blast morphology, immunophenotype, cytogenetic analysis, molecular studies for clonal rearrangements and histological review. The patient had noted skin lesions and a breast infiltrate 4 months prior to the diagnosis. Bone marrow biopsy at the time of presentation revealed characteristic morphological features with a dense infiltrate of bizarre, pleomorphic blast cells with marked nuclear invagination and reniform shapes. Immunophenotypic analysis of the blasts displayed coexpression of myeloid and natural killer cell antigens with a relatively immature phenotype: CD34-,HLADR+, CD33+, CD56+, CD16-, CD57-, MPO-. Cyto- genetic analysis revealed a complex karyotype: del(6)(q21);-12 and add(19)(p13). Histological review of the previous breast biopsy was consistent with granulocytic sarcoma of the breast with a phenotype corresponding to the circulating blasts (positive cytoplasmic staining for myeloid markers, CD68 and CD31, and the NK cell marker CD56, with negative staining for MPO). Skin biopsy confirmed leukaemia cutis. Although nodal extramedullary disease is common in the myeloid/NK cell leukaemias, this is the first description of myeloid/NK cell leukemia primarily involving breast and skin. We speculate that CD56 may predispose to extramedullary localisation of tumour.

The immunophenotype of 325 adult acute leukemias: relationship to morphologic and molecular classification and proposal for a minimal screening program highly predictive for lineage discrimination.

Bone marrow cells of 325 adults with acute leukemia were immunophenotyped using a panel of monoclonal antibodies proposed by the European Group for the Immunological Characterization of Leukemias (EGIL). Of these, 97.2% could be assigned clearly to myeloid or lymphoid lineage (254 acute myeloid leukemias [AMLs], 48 B-cell lineage acute lymphoblastic leukemias [ALLs], 14 T-cell lineage ALLs), 1.8% as biphenotypic, and less than 1% as undifferentiated. Immunologic subtyping of ALLs revealed an association between early precursor phenotypes and coexpression of myeloid antigens, particularly CD15/CD65s coexpression and pre-pre-B cell-specific phenotypes and genotypes. The common ALL phenotype was associated with BCR-ABL translocation. Among AMLs, CD2 coexpression was almost exclusively restricted to French-American-British subtypes M3 variant and M4Eo and related molecular aberrations. The most valuable markers to differentiate between myeloperoxidase-negative AML subtypes M0 and ALLs were CD13, CD33, and CD117, typical of M0, and intracytoplasmic CD79a, intracytoplasmic CD3, CD10, and CD2, typical of B cell- or T cell-lineage ALL. Our results confirm excellent practicability of the EGIL proposalfor immunologic classification of acute leukemias. For myeloperoxidase-negative AMLs, we suggest a scoring system based on markers most valuable to distinguish between AML-M0 and ALLs.

Induction of apoptosis and bcl-2 expression in acute lymphoblastic leukaemia and non-Hodgkin's lymphoma in children.

bcl-2 expression is associated with the expression of the multidrug resistance molecule (p-gp) and the resistance of leukaemia cells to the induction of apoptosis. The activity of p-gp is the main mechanism of resistance of leukaemia cells to chemotherapy. This study assessed the induction of apoptosis of acute lymphoblastic leukaemia (ALL) and non-Hodgkin's lymphoma (NHL) blastic cells following in vitro treatment with dexamethasone (DXM), vincristine (VCR), and tumour necrosis factor (TNF) in relation to the expression of bcl-2 and p-gp. Common ALL (cALL; n = 24 patients), common ALL with co-expression of myeloid antigens (cALL + My; n = 9), ALL-T (n = 9), and NHL [n = 6 (T type, n = 2; B type, n = 4)] were included. The expression of bcl-2 and p-gp and apoptosis were assayed by flow cytometry. Spontaneous apoptosis was low (< 5%) in cALL and ALL-T and higher (> 8%) in NHL and cALL + My. A high frequency of bcl-2 expression was noted in cALL and cALL + My. A high frequency of p-gp expression was observed in cALL + My, ALL-T, and NHL. There was a reverse association between bcl-2 expression and spontaneous apoptosis. DXM-induced apoptosis was observed in 52.63%, TNF-induced in 42.85%, VCR-induced in 36.36%, and GM-CSF-induced in 33.3% of leukaemia and lymphoma cases. DXM and GM-CSF-driven apoptosis was reversibly associated with bcl-2-expression (bcl-2-dependent mechanism). VCR and TNF-driven apoptosis was not associated with bcl-2 expression, suggesting a different, bcl-2-independent, mechanism(s) of its induction. The in vitro induction of apoptosis was not associated with expression of p-gp.