Prognostic implications of the immunophenotype in biphenotypic acute leukemia

COMBINED CENTRAL RETINAL ARTERIAL AND VENOUS OCCLUSIONS DUE TO LEUKEMIC INFILTRATION

PURPOSE

To report combined central arterial and venous occlusions secondary to bilateral leukemic interfascicular optic nerve infiltration in a 56-year-old man. This was the sole presentation of a relapse in T/myeloid mixed-phenotype acute leukemia after 5 months of remission.

METHODS

Case report with clinical photography.

RESULTS

A 56-year-old man reported to be in complete remission of T/myeloid mixed-phenotype acute leukemia presented with sudden painless loss of vision in his left eye. Fundoscopy showed unilateral severe optic disk swelling with characteristic findings of a central retinal vein occlusion, namely, intraretinal and preretinal hemorrhages and cotton-wool spots, as well as the features of a central retinal artery occlusion resulting in a pale, edematous retina and a characteristic cherry-red spot. Blood analysis, cerebrospinal fluid evaluation, and bone marrow analysis were performed in combination with medical imaging. No evidence of leukemic relapse was found. An optic nerve biopsy was indicated because of decompensation of the contralateral eye and ultimately confirmed leukemic infiltration.

CONCLUSION

Regardless of no hematological and nonspecific imaging findings, optic nerve biopsy may be crucial for clinical decision-making in a patient with acute complete vision loss and a history of leukemia.

Prognostic impact of Philadelphia chromosome in mixed phenotype acute leukemia (MPAL): A cancer registry analysis on real-world outcome

Mixed phenotype acute leukemia (MPAL) is thought to have poor outcome, and presence of the Philadelphia chromosome (Ph+) has been considered to be an adverse prognostic marker. However, most of these reports were in the pre-tyrosine kinase inhibitors (TKIs) era. Recent limited reports indicate improved outcomes for MPAL with the addition of TKIs. We examined the outcomes of 241 cases of MPAL according to the 2008 WHO classification from the Surveillance, Epidemiology, and End Results registry. The MLL+ patients had a median age of 6 years while other subtypes occurred mostly in adults and had comparable age. On multivariate analyses and after adjustment for age, year of diagnosis and chemotherapy status, Ph+ MPAL patients had reduced risk of death in comparison to Ph(-) MPAL patients (hazard ratio [HR] = 0.28, P = .002). So, MLL+ MPAL had the worst outcome with a 10-fold increased risk of death in comparison to Ph+ MPAL patients (HR = 10.2, P < .001). Importantly, the outcome of Ph+ MPAL was comparable to Ph+ acute lymphoblastic leukemia in a 1:1 matched case-control analysis. In conclusion, this is the largest registry study which examines the outcomes of MPAL subtypes. We confirm that MPAL is a heterogenous disease. Note, Ph+ MPAL nowadays has a better OS in comparison to other subtypes and is comparable to Ph+ ALL patients. This is most likely secondary to changes in practice and more utilization of TKIs. On the other hand, MLL rearrangement is associated with infantile MPAL and has a dismal prognosis.

Acute Leukemias of Ambiguous Lineage: Clarification on Lineage Specificity

Acute leukemias of ambiguous lineage (ALAL) include acute undifferentiated leukemia and mixed-phenotype acute leukemia (MPAL). This article provides an overview of the diagnosis of ALAL and focuses on the data accounting for the current lineage-assignment criteria for blasts harboring more than one lineage-associated marker. In addition, the currently known molecular data are reviewed, which show that MPAL-associated gene mutations, methylation signatures, and expression profiles are a mixture of those seen in both acute myeloid leukemia and acute lymphoblastic leukemia. Finally, the prognosis and current treatments of MPAL are briefly discussed.

PHF6 and DNMT3A mutations are enriched in distinct subgroups of mixed phenotype acute leukemia with T-lineage differentiation

The genetic aberrations that drive mixed phenotype acute leukemia (MPAL) remain largely unknown, with the exception of a small subset of MPALs harboring BCR -ABL1 and MLL translocations. We performed clinicopathologic and genetic evaluation of 52 presumptive MPAL cases at Memorial Sloan Kettering Cancer Center. Only 29 out of 52 (56%) cases were confirmed to be bona fide MPAL according to the 2016 World Heath Organization classification. We identified PHF6 and DNMT3A mutations as the most common recurrent mutations in MPAL, each occurring in 6 out of 26 (23%) cases. These mutations are mutually exclusive of each other and BCR-ABL1/MLL translocations. PHF6- and DNMT3A-mutated MPAL showed marked predilection for T-lineage differentiation (5/6 PHF6 mutated, 6/6 DNMT3A mutated). PHF6-mutated MPAL occurred in a younger patient cohort compared with DNMT3A-mutated cases (median age, 27 years vs 61 years, P < .01). All 3 MPAL cases with both T- and B-lineage differentiation harbored PHF6 mutations. MPAL with T-lineage differentiation was associated with nodal or extramedullary involvement (9/15 [60%] vs 0, P = .001) and a higher relapse incidence (78% vs 22%, P = .017) compared with those without T-lineage differentiation. Sequencing studies on flow-cytometry-sorted populations demonstrated that PHF6 mutations are present in all blast compartments regardless of lineage differentiation with high variant allele frequency, implicating PHF6 as an early mutation in MPAL pathogenesis. In conclusion, PHF6 and DNMT3A mutations are the most common somatic alterations identified in MPAL and appear to define 2 distinct subgroups of MPAL with T-lineage differentiation with inferior outcomes.

Biphenotypic acute leukemia or acute leukemia of ambiguous lineage in childhood: clinical characteristics and outcome

Background

Acute leukemia (AL), not clearly assigned to myeloid, B-lymphoid, or T-lymphoid lineage, is classified as either biphenotypic acute leukemia (BAL) based on the European Group for Immunological Classification of Leukemias (EGIL) or acute leukemia of ambiguous lineage (ALAL) encompassing acute undifferentiated leukemia (AUL) and mixed-phenotype acute leukemia (MPAL) based on the World Health Organization (WHO) criteria.

Methods

Medical records of children newly diagnosed with BAL or ALAL, based on the EGIL or the 2008/2016 WHO criteria, respectively, admitted at Chonnam National University Hospital in 2001-2017 were retrospectively reviewed.

Results

Twelve (3.2%) of 377 AL patients satisfied the BAL or ALAL definitions based on the EGIL or the WHO criteria, respectively. Among 12 patients including 11 with BAL and another with undefined case based on the EGIL criteria, 7 (1.9%) had ALAL based on more stringent 2016 WHO criteria (AUL, 2; MPAL, 5). One patient had MPAL with t(9;22)(q34;q11.2), BCR-ABL+, and two had MLL gene abnormality. ALL-directed regimen was associated with better complete remission rate compared with AML-directed regimen (100.0% vs. 16.7%; P=0.015). The 5-year overall survival (OS) and event-free survival (EFS) were 51.1±15.8% and 51.9±15.7%, respectively. AUL was associated with poor OS and EFS compared with MPAL (0.0% vs. 75.0±21.7%; P=0.008).

Conclusion

Due to the rarity of the cases, future multicenter, prospective studies incorporating large number of cases are urgently warranted to identify the clinical, biologic, and molecular markers for the prediction of prognosis and determine the best tailored therapy for each patient.

An update on classification, genetics, and clinical approach to mixed phenotype acute leukemia (MPAL)

Mixed phenotype acute leukemia (MPAL) is an uncommon diagnosis, representing only about 2-5% of acute leukemia cases. The blast cells of MPAL express multilineage immunophenotypic markers and may have a shared B/T/myeloid phenotype. Due to historical ambiguity in the diagnosis of MPAL, the genetics and clinical features of this disease remain poorly characterized. Based on the 2008 and 2016 World Health Organization classifications, myeloid lineage is best determined by presence of myeloperoxidase, while B and T lymphoid lineages are demonstrated by CD19 and cytoplasmic CD3 expression. MPAL typically carries a worse prognosis than either acute myeloid leukemia (AML) or acute lymphoid leukemia (ALL). Given the rarity of MPAL, there is a lack of prospective trial data to guide therapy; treatment generally relies on ALL-like regimens followed by consolidation chemotherapy or hematopoietic stem cell transplant (HSCT). Here, we review the updated classification, biology, clinical features, and treatment approach to MPAL.

Therapy for children and adults with mixed phenotype acute leukemia: a systematic review and meta-analysis

The rarity of mixed-phenotype acute leukemia (MPAL) has resulted in diffuse literature consisting of small case series, thus precluding a consensus treatment approach. We conducted a meta-analysis and systematic review to investigate the association of treatment type (acute lymphoblastic leukemia [ALL], acute myeloid leukemia [AML], or "hybrid" regimens), disease response, and survival. We searched seven databases from inception through June 2017 without age or language restriction. Included studies reported sufficient treatment detail for de novo MPAL classified according to the well-established European Group for Immunological Characterization of Acute Leukemias (EGIL) or World Health Organization (WHO2008) criteria. Meta-analyses and multivariable analyses of a patient-level compiled case series were performed for the endpoints of complete remission (CR) and overall survival (OS). We identified 97 reports from 33 countries meeting criteria, resulting in 1,499 unique patients with data, of whom 1,351 had sufficient detail for quantitative analysis of the study endpoints. Using either definition of MPAL, meta-analyses revealed that AML induction was less likely to achieve a CR as compared to ALL regimens, (WHO2008 odds ratio [OR] = 0.33, 95% confidence interval [95% CI] 0.18-0.58; EGIL, OR = 0.18, 95% CI 0.08-0.40). Multivariable analysis of the patient-level data supported poorer efficacy for AML induction (versus ALL: OR = 0.45 95% CI 0.27-0.77). Meta-analyses similarly found better OS for those beginning with ALL versus AML therapy (WHO2008 OR = 0.45, 95% CI 0.26-0.77; EGIL, OR = 0.43, 95% CI 0.24-0.78), but multivariable analysis of patient-level data showed only those starting with hybrid therapy fared worse (hazard ratio [HR] = 2.11, 95% CI 1.30-3.43). MPAL definition did not impact trends within each endpoint and were similarly predictive of outcome. Using either definition of MPAL, ALL-therapy is associated with higher initial remission rates for MPAL and is at least equivalent to more intensive AML therapy for long-term survival. Prospective trials are needed to establish a uniform approach to this heterogeneous disease.

Haematological profile of patients with mixed-phenotype acute leukaemia from a tertiary care centre of north India

Background & objectives:

Mixed-phenotype acute leukaemia (MPAL) is a rare neoplasm with no definite treatment protocols and a distinctly poor outcome. Advancement in polychromatic flow cytometry has made its identification easier. This prospective study was designed to identify cases of MPAL and study their clinical presentation and haematological profile in a tertiary care hospital in north India.

Methods:

Ethylenediaminetetraacetic acid (EDTA)-anticoagulated bone marrow aspirate samples of patients diagnosed as acute leukaemia (AL) on the basis of morphology were utilized for immunophenotyping. A comprehensive panel of fluorochrome-labelled monoclonal antibodies targeting myeloid, B-cell, T-cell and immaturity markers was utilized. The patients diagnosed to have MPAL, on the basis of the World Health Organization 2008 classification, were selected for further analyses.

Results:

There were 15 (2.99%) patients with MPAL of the total 501 cases of AL. Seven were children, all males and mean age of 5.08±3.88 yr. Eight were adults, male:female=6:2 and mean age of 21.43±5.74 yr. Eight were diagnosed as B/myeloid and seven were T/myeloid. No association was observed between age and immunophenotype of MPAL. On morphology, 11 were diagnosed as AML and four as ALL, and no specific morphology of blasts was predictive of a MPAL.

Interpretation & conclusions:

MPAL appeared to be a rare neoplasm (2.99% of AL cases). A comprehensive primary panel of monoclonal antibodies should be used to identify this neoplasm known to have a poor outcome.

Mixed-phenotype acute leukemia: suboptimal treatment when the 2008/2016 WHO classification is used

Background

Different criteria have been used to diagnose mixed-phenotype acute leukemia (MPAL), which has impacted the number of individuals diagnosed with this pathology. Better outcomes have been reported when using acute lymphoblastic leukemia (ALL)-type chemotherapy in the treatment of MPAL.

Methods

We compared the outcome of 4 groups of patients with MPAL. Group 1 included patients diagnosed using the 2008/2016 World Health Organization (WHO) classification; group 2 included patients diagnosed using the European Group for the Immunological Characterization of Leukemias (EGIL) criteria; group 3 included patients diagnosed using either the EGIL or the 2008/2016 WHO criteria; and group 4 was comprised of patients diagnosed with MPAL using the EGIL classification only.

Results

We found a significantly worse disease-free survival (groups 1-4) and overall survival (OS) (groups 2 and 3) when comparing MPAL patients to other acute leukemia (AL) patients. A significantly better OS was obtained in patients (groups 2-4) treated with ALL-type chemotherapy compared to acute myeloid leukemia (AML)-type regimens.

Conclusion

In light of these results, and because a trend (P=0.06) was found with regard to a better OS in group 4 when compared to other AL patients, an argument can be made that the 2008/2016 WHO classification is underpowered to diagnose all MPAL cases, potentially resulting in the suboptimal treatment of some individuals with AL.

Bilineal Acute Leukemia Associated With Fanconi Syndrome: The First Case Report

Fanconi syndrome is a metabolic disorder involving dysfunction of the renal proximal tubules, resulting in excessive urinary excretion of several metabolites. Various factors may lead to Fanconi syndrome, as it may be a genetic disease with primary or secondary etiologies, or may be acquired. In this study, we report a unique case of Fanconi syndrome with development of a relatively rare acute leukemia, a condition that has not been reported before. The case was an 8-year-old boy with familial occurrence of Fanconi syndrome, presenting with pallor, asthenia, recurrent infections, growth failure, and a variety of biochemical and hematological abnormalities. After physical examination, radiographic studies, and comprehensive laboratory analyses, Fanconi syndrome associated with bilineal acute leukemia, of myeloid and T-lymphoid lineages, was diagnosed.

How I treat mixed-phenotype acute leukemia

Mixed-phenotype acute leukemia (MPAL) encompasses a heterogeneous group of rare leukemias in which assigning a single lineage of origin is not possible. A variety of different terms and classification systems have been used historically to describe this entity. MPAL is currently defined by a limited set of lineage-specific markers proposed in the 2008 World Health Organization monograph on classification of tumors of hematopoietic and lymphoid tissues. In adult patients, MPAL is characterized by relative therapeutic resistance that may be attributed in part to the high proportion of patients with adverse cytogenetic abnormalities. No prospective, controlled trials exist to guide therapy. The limited available data suggest that an "acute lymphoblastic leukemia-like" regimen followed by allogeneic stem-cell transplant may be advisable; addition of a tyrosine kinase inhibitor in patients with t(9;22) translocation is recommended. The role of immunophenotypic and genetic markers in guiding chemotherapy choice and postremission strategy, as well as the utility of targeted therapies in non-Ph-positive MPALs is unknown.

Hacking cell differentiation: transcriptional rerouting in reprogramming, lineage infidelity and metaplasia

Initiating neoplastic cell transformation events are of paramount importance for the comprehension of regeneration and vanguard oncogenic processes but are difficult to characterize and frequently clinically overlooked. In epithelia, pre-neoplastic transformation stages are often distinguished by the appearance of phenotypic features of another differentiated tissue, termed metaplasia. In haemato/lymphopoietic malignancies, cell lineage ambiguity is increasingly recorded. Both, metaplasia and biphenotypic leukaemia/lymphoma represent examples of dysregulated cell differentiation that reflect a history of trans-differentiation and/or epigenetic reprogramming. Here we compare the similarity between molecular events of experimental cell trans-differentiation as an emerging therapeutic concept, with lineage confusion, as in metaplasia and dysplasia forecasting tumour development.

Mixed phenotypic acute leukemia with two immunophenotypically distinct blast populations: report of an unusual case

Mixed phenotypic acute leukemia (MPAL) is a rare disorder with an incidence of less than 2% of all acute leukemia using the recent 2008 WHO criteria. Common subtypes encountered are the B/myeloid and T/myeloid; B/T or trilineage MPAL being an exception. We discuss here a case of 20-year-male patient who presented with pallor and generalised lymphadenopathy. Peripheral blood smear examination showed presence of 61% blasts of lymphoid morphology. Immunophenotyping by multicolor flow cytometry showed two distinct populations of blasts with T and B phenotype respectively. He was diagnosed as MPAL with two distinct blast lineages. Conventional karyotyping done on bone marrow sample showed t(9;22)(q34;q11)(Ph +). Induction was started using ALL based protocol. The patient is on follow up with post induction marrow being in morphological remission.

MicroRNA profiling can classify acute leukemias of ambiguous lineage as either acute myeloid leukemia or acute lymphoid leukemia

PURPOSE

Classification of acute leukemia is based on the commitment of leukemic cells to the myeloid or the lymphoid lineage. However, a small percentage of acute leukemia cases lack straightforward immunophenotypical lineage commitment. These leukemias of ambiguous lineage represent a heterogeneous category of acute leukemia that cannot be classified as either acute myeloid leukemia (AML) or acute lymphoid leukemia (ALL). The lack of clear classification of acute leukemias of ambiguous lineage as either AML or ALL is a hurdle in treatment choice for these patients.

EXPERIMENTAL DESIGN

Here, we compared the microRNA (miRNA) expression profiles of 17 cases with acute leukemia of ambiguous lineage and 16 cases of AML, B-cell acute lymphoid leukemia (B-ALL), and T-cell acute lymphoid leukemia (T-ALL).

RESULTS

We show that leukemias of ambiguous lineage do not segregate as a separate entity but exhibit miRNA expression profiles similar to AML, B-ALL, or T-ALL. We show that by using only 5 of the most lineage-discriminative miRNAs, we are able to define acute leukemia of ambiguous lineage as either AML or ALL.

CONCLUSION

Our results indicate the presence of a myeloid or lymphoid lineage-specific genotype, as reflected by miRNA expression, in these acute leukemias despite their ambiguous immunophenotype. miRNA-based classification of acute leukemia of ambiguous lineage might be of additional value in therapeutic decision making.

Clinical and laboratory features of adult biphenotypic acute leukemia

AIM

To analyze the clinical and biological characteristics of adult BAL.

METHODS

We identified 22 cases (4.4%) of BAL from 496 newly diagnosed acute leukemia patients and compared them with patients with acute myloid leukemia (AML) and acute lymphoblastic leukemia (ALL).

RESULTS

CD34 positivity was higher in BAL (87%) than in ALL (60%, P = 0.04) and AML patients (63%, P = 0.05). The median age in the BAL group was greater than in ALL (43 vs 31 years, P = 0.04). Enlargement of liver, spleen and lymphonodes was more common in BAL (81.8%) than AML (46%, P = 0.003). Cytogenetic analysis revealed abnormal karyotypes in 56% of BAL patients. The overall completed remission rate in the BAL group (65%) was lower than in ALL (86%, P = 0.04).

CONCLUSION

BAL patients showed a much higher incidence of older age, CD34 antigen expression, presence of Philadelphia chromosome, liver, spleen and lymphonodes infiltration and resistance to therapy.

A Study on the Expression of BCR-ABL Transcript in Mixed Phenotype Acute Leukemia (MPAL) Cases Using the Reverse Transcriptase Polymerase Reaction Assay (RT-PCR) and its Correlation with Hematological Remission Status Post Initial Induction Therapy

Introduction:

The MPAL comprise 2–5% of all acute leukemia. The present WHO 2008 classification has separated two groups in MPAL based on t(9;22) positivity and MLL rearrangement.

Aims & Objectives:

The aim of the present pilot study is to note the frequency of BCR-ABL transcript in MPAL cases using the RT-PCR assay and to correlate the status with hematological remission post induction.

Materials & Methods:

A total of 10 MPAL cases classified on Flow-cytometry based on the current WHO 2008 criteria were enrolled. In all the cases Bone marrow or peripheral blood sample in EDTA was processed for molecular studies and the RT-PCR reaction carried out using primers specific to the t (9;22) and t(4;11) translocation. The post induction check marrow slides were also reviewed.

Results:

Out of the total 10 MPAL cases, 7/10 (70%) were adult and 3/10 (30%) pediatric cases. A total of 4/10 (40%) cases showed positivity for the t(9;22) transcript and none for t (4;11). Of the 4 positive cases, 3/10(30%) were adult cases and 1/10(10%) pediatric case. The BCR-ABL transcript type in adult cases was b3a2 (p210) in 2/3 (66%) and e1a2 (p190) in 1/3 (33.3%) case. The single pediatric case was positive for b3a2 transcript.

Discussion & Conclusion:

All the 4 positive MPAL cases presented with high TLC and low platelet count (p<0.05). The positive cases also showed hematological remission at post induction check marrow (blasts<5%). This could partly be explained due to good response to the imatinib added to the treatment protocol.

Clinical characteristics, biological profile, and outcome of biphenotypic acute leukemia: a case series

BACKGROUND

Biphenotypic acute leukemia (BAL) is a rare type of acute leukemia that presents with a high degree of heterogeneity and is not well defined.

METHODS

We identified 51 cases (3%) of BAL from 1,693 newly diagnosed acute leukemia patients according to the EGIL scoring system. The immunophenotyping, cytogenetics, treatment, and outcome of 39 BAL patients were retrospectively analyzed.

RESULTS

There were 23 (59%) cases of the myeloid and B-lymphoid phenotype, 14 (36%) cases of the myeloid and T-lymphoid phenotype, and 1 case (3%) of the trilineage phenotype or B/T phenotype. Abnormal karyotypes were detected in 76% of the 37 validated patients and displayed a high degree of heterogeneity. Combined regimens for both acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL), as well as ALL type regimens, appeared to achieve a better complete remission rate than AML type regimens (71 and 64 vs. 33%, respectively). BAL patients with complex karyotypes or a rearrangement of chromosome 11 had a significantly reduced survival rate in comparison to patients with normal, t(8; 21), or t(9; 22) karyotypes. The probability of overall survival and disease-free survival at 2 years was 26 and 18%, respectively.

CONCLUSIONS

Our findings indicate that BAL shows a high incidence of abnormal karyotypes and a poor prognosis. Combined-type regimens or ALL-based protocols are effective for the treatment of BAL.

Mixed-phenotype acute leukemia: historical overview and a new definition

Acute leukemia with a mixed phenotype is a rare disease and comprises 2-5% of all acute leukemias. These disorders have been known historically by a variety of names, such as mixed lineage leukemia, bilineal leukemia and biphenotypic leukemia, and the criteria for diagnosis have often been arbitrary. The scoring criteria proposed by the European Group for the Immunological Characterization of Leukemias represented a major attempt to define this disorder. However, the relative weight given to some markers and the lack of lineage specificity of most markers have raised questions regarding the significance of this approach. In 2008, the World Health Organization classification of hematopoietic and lymphoid tumors proposed a simpler diagnostic algorithm, which relies on fewer and more lineage-specific markers to define mixed-phenotype acute leukemia (MPAL). MPAL with t(9;22) and MLL rearrangement have been separated. Several studies have suggested that patients with acute leukemia of mixed phenotype have a worse clinical outcome when compared with matched controls with acute myeloid leukemia or acute lymphoblastic leukemia. Further studies are needed to confirm the significance of MPAL as currently defined, to determine a standardized treatment approach and to better understand the biological and clinical aspects of this disease.

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].

Biological features and outcome of biphenotypic acute leukemia: a case series

BACKGROUND

Biphenotypic acute leukemia (BAL) is a distinct entity that is immunophenotypically defined by the European Group for the Immunological Classification of Leukemia (EGIL) scoring system and accounts for less than 5% of all acute leukemia cases. Since it is a rare and heterogeneous form of acute leukemia with an allegedly poor outcome, there is no consensus on the best treatment approach in these patients. Our objective was to analyze the biological features and outcome of patients diagnosed with BAL in our institution.

PATIENTS AND METHODS

Using the EGIL system, we identified 21 cases (3.9%) of BAL from 535 newly diagnosed acute leukemia patients in an 11-year period.

RESULTS

There were ten cases of myeloid+B-lymphoid leukemia, eight cases of myeloid+T-lymphoid, one case of B+T-lymphoid and two cases of trilineage (myeloid+B+T-lymphoid leukemia). The complete remission (CR) rate with high-dose chemotherapy was 72% and overall survival at 5 years was 21%. Patients that received acute lymphoblastic leukemia-oriented chemotherapy had a higher CR rate compared with those who received acute myeloid leukemia-oriented chemotherapy (100% vs. 60%, P = .007). The white blood cell count at diagnosis was found to have statistically significant impact on survival.

CONCLUSION

Despite the progress in the treatment of acute leukemia, the prognosis of BAL remains poor and treatment protocols devised explicitly for this entity should be investigated in prospective collaborative studies.

Stem cell transplant in the treatment of childhood biphenotypic acute leukemia

BACKGROUND

Many studies have found that biphenotypic acute leukemia (BAL) is associated with a poor outcome.

METHODS

We retrospectively reviewed the medical records and analyzed clinicopathological data on 25 children with BAL, and correlated outcomes with prognostic factors.

RESULTS

BAL constituted 4.4% of all acute childhood leukemia cases. In terms of immunophenotype, 14 patients had leukemia with myeloid plus B-lymphoid (M + B) marker, 7 with myeloid plus T-lymphoid (M + T) marker, and 4 with myeloid plus B-lymphoid and T-lymphoid (M + B + T) markers. Overall survival was superior in patients with the M + B immunophenotype (P = 0.004). Hematopoietic stem cell transplantation (HSCT) did not improve either overall survival or event-free survival compared to chemotherapy alone (hazard ratio 0.98, 95% CI 0.35-2.76, P = 0.966; hazard ratio 1.07, 95% CI 0.41-2.78, P = 0.88). Each of four patients with high-hyperdiploidy (>50 chromosomes) displayed a good treatment response and long-term overall survival even though these patients were treated with chemotherapy alone.

CONCLUSIONS

Treatment outcomes in childhood BAL patients differed by immunophenotype and cytogenetics. HSCT did not offer a significantly greater survival advantage compared to chemotherapy. While these data suggest that treatment should be individualized and stratified according to biologic characteristics and prognostic factors in BAL, prospective trial data are still needed.

Clinical and biological characteristics of adult biphenotypic acute leukemia in comparison with that of acute myeloid leukemia and acute lymphoblastic leukemia: a case series of a Chinese population

BACKGROUND

Biphenotypic acute leukemia is a rare disorder that is difficult to diagnose. It displays features of both myeloid and lymphoid lineage. There is still a lack of studies in biphenotypic acute leukemia in a Chinese population. We present here a comprehensive investigation of the clinical and biological characteristics, and outcome of biphenotypic acute leukemia in our hospital in over a seven year period.

DESIGN AND METHODS

We retrospectively analyzed 452 adult acute leukemia patients diagnosed according to French-American-British (FAB) classification and biphenotypic acute leukemia diagnosed according to European Group for the Immunological Characterization of Leukemias (EGIL) classification, respectively. Biological characteristics, response to treatment, and outcome were examined in biphenotypic acute leukemia patients and compared with that in acute myeloid leukemia and acute lymphoblastic leukemia patients with complete follow-up profiles diagnosed in the same period.

RESULTS

Of 452 acute leukemia patients, 21 cases (4.6%) were diagnosed as biphenotypic acute leukemia. Among them, 14 (66.7%) were B lymphoid and myeloid, 5 (23.8%) were T lymphoid and myeloid, one (4.8%) was T/B lymphoid and one (4.8%) was trilineage differentiation. When compared with acute myeloid leukemia and acute lymphoblastic leukemia, patients with biphenotypic acute leukemia showed significantly higher incidence of CD34 antigen expression, unfavorable karyotypes, and extramedullary infiltration (p<0.05). In this cohort of patients with biphenotypic acute leukemia, t(9;22) was the most common abnormality in chromosome structure. The median disease-free survival and overall survival in biphenotypic acute leukemia patients was five months and ten months, respectively, significantly shorter than those in acute myeloid leukemia and acute lymphoblastic leukemia patients (p<0.05).

CONCLUSIONS

The prognosis of biphenotypic acute leukemia patients is poor when compared with de novo acute myeloid leukemia or acute lymphoblastic leukemia. Biphenotypic acute leukemia patients showed a much higher incidence of CD34 antigen expression, complex abnormal karyotype, extramedullary infiltration, relapse, and resistance to therapy after relapse.