Molecular and phenotypic analysis of Philadelphia chromosome-positive bilineage leukemia: possibility of a lineage switch from T-lymphoid leukemic progenitor to myeloid cells

CD371-positive pediatric B-cell acute lymphoblastic leukemia: propensity to lineage switch and slow early response to treatment

ABSTRACT

In the effort to improve immunophenotyping and minimal residual disease (MRD) assessment in acute lymphoblastic leukemia (ALL), the international Berlin-Frankfurt-Münster (iBFM) Flow Network introduced the myelomonocytic marker CD371 for a large prospective characterization with a long follow-up. In the present study, we aimed to investigate the clinical and biological features of CD371-positive (CD371pos) pediatric B-cell precursor ALL (BCP-ALL). From June 2014 to February 2017, 1812 pediatric patients with newly diagnosed BCP-ALLs enrolled in trial AIEOP-BFM ALL 2009 were evaluated as part of either a screening (n = 843, Italian centers) or validation cohort (n = 969, other iBFM centers). Laboratory assessment at diagnosis consisted of morphological, immunophenotypic, and genetic analysis. Response assessment relied on morphology, multiparametric flow cytometry (MFC), and polymerase chain reaction (PCR)-MRD. At diagnosis, 160 of 1812 (8.8%) BCP-ALLs were CD371pos. This correlated with older age, lower ETV6::RUNX1 frequency, immunophenotypic immaturity (all P < .001), and strong expression of CD34 and of CD45 (P < .05). During induction therapy, CD371pos BCP-ALLs showed a transient myelomonocytic switch (mm-SW: up to 65.4% of samples at day 15) and an inferior response to chemotherapy (slow early response, P < .001). However, the 5-year event-free survival was 88.3%. Among 420 patients from the validation cohort, 27 of 28 (96.4%) cases positive for DUX4-fusions were CD371pos. In conclusion, in the largest pediatric cohort, CD371 is the most sensitive marker of transient mm-SW, whose recognition is essential for proper MFC MRD assessment. CD371pos is associated to poor early treatment response, although a good outcome can be reached after MRD-based ALL-related therapies.

A rare case of Philadelphia-positive (P210BCR-ABL1) T-cell acute lymphoblastic leukemia/lymphoma associated with minimal residual disease persistence after intensive chemotherapeutic approaches

T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) is a rare and aggressive leukemia. Philadelphia chromosome-positive cytogenetic abnormality is most common in CML. It is difficult to differentiate between de novo Ph+ T-ALL/LBL and T-cell lymphoblastic crises of CML. We present a case of adult Ph+ T-ALL/LBL with a likely history of antecedent CML. Initially thought to be a case of chronic-phase CML, a diagnostic quandary led to the pursuit of a lymph node biopsy that established the diagnosis of Ph+ T-LBL or T lymphoblastic blast crisis of CML, a clinical presentation extremely rare and only the second of its kind from our review of the literature. The patient was treated with an intensive chemotherapy regimen for over a year due to persistent minimal residual disease (MRD) positivity indicating aggressive disease.

Recognizing Minor Leukemic Populations with Monocytic Features in Mixed-Phenotype Acute Leukemia by Flow Cell Sorting Followed by Cytogenetic and Molecular Studies: Report of Five Exemplary Cases

Mixed-phenotype acute leukemia (MPAL), a rare and heterogeneous category of acute leukemia, is characterized by cross-lineage antigen expression. Leukemic blasts in MPAL can be represented either by one population with multiple markers of different lineages or by several single-lineage populations. In some cases, a major blast population may coexist with a smaller population that has minor immunophenotypic abnormalities and may be missed even by an experienced pathologist. To avoid misdiagnosis, we suggest sorting doubtful populations and leukemic blasts and searching for similar genetic aberrations. Using this approach, we examined questionable monocytic populations in five patients with dominant leukemic populations of B-lymphoblastic origin. Cell populations were isolated either for fluorescence in situ hybridization or for clonality assessment by multiplex PCR or next-generation sequencing. In all cases, monocytic cells shared the same gene rearrangements with dominant leukemic populations, unequivocally confirming the same leukemic origin. This approach is able to identify implicit cases of MPAL and therefore leads to the necessary clinical management for patients.

Pediatric Mixed-Phenotype Acute Leukemia: What's New?

Simple Summary

Pediatric mixed-phenotype leukemia is a rare form of blood cancer in children. In this review, we cover both the evolution of treatment over the past several years and outline new emerging concepts in this disease.

Abstract

Mixed-phenotype acute leukemias (MPAL) are rare in children and often lack consensus on optimal management. This review examines the current controversies and emerging paradigms in the management of pediatric MPAL. We examine risk stratification, outcomes of recent retrospective and prospective collaborative trials, and the role of transplantation and precision genomics, and outline emerging targets and concepts in this rare entity.

Case Report: A Case With Philadelphia Chromosome Positive T-Cell Lymphoblastic Lymphoma and a Review of Literature

Philadelphia chromosome positive (Ph⁺) in T-lineage acute lymphoproliferative tumors is a rare event in both children and adults. In particular, it has not been reported in T-cell lymphoblastic lymphoma(T-LBL) yet. Here, we describe a patient with Ph⁺ T-LBL for both cytogenetic abnormality and BCR-ABL1 fusion transcript. Moreover, we review the published cases of Ph⁺ T-cell acute lymphoblastic leukemia (T-ALL) in the literature and summarize their clinical characteristics, management, and prognosis.

Myeloid Blast Crisis of Chronic Myeloid Leukemia Followed by Lineage Switch to B-Lymphoblastic Leukemia: A Case Report

Lineage switch is very rare in blastic crisis of chronic myeloid leukemia (CML-BC). Here, we report a case of CML-BC in which the blast lineage switched from myeloid to B-lymphoid. A 35-year-old male was initially admitted to our hospital because of abdominal distention for over a year and dizziness for one week. Prior to presentation at our hospital, he visited a local hospital because of abdominal distention where his white blood cell count and bone marrow (BM) smear indicated CML. Results from peripheral blood (PB) counts, bone marrow analysis, immunophenotyping by flow cytometry, and the detection of the Philadelphia chromosome were consistent with a diagnosis of myeloid blast crisis from CML. The patient received chemotherapy with imatinib for induction, which diminished the number of blasts. However, after three months, the blasts were increased in the PB and BM. The BM study and immunophenotyping by flow cytometry revealed B-lymphoblastic leukemia. In accordance with his first admission, a chromosome study revealed a karyotype of 46, XY, t(9; 22)(q34; q11) in all 20 cells analyzed, and B-lymphoblastic transformation from CML was diagnosed. Despite three months of treatment with DVCP (daunorubicin, vincristine, cyclophosphamide and prednisone) chemotherapy in combination with dasatinib, the patient did not achieve complete remission. The patient decided to stop treatment and was discharged from the hospital for financial reasons. This case implicates the Philadelphia chromosome with p210 BCR-ABL1 fusion proteins as a key molecule in CML-BC. Further research is needed to assess the frequency, treatment, and prognosis of CML-BC patients with lineage switch.

A Rare Case of Chronic Myelogenous Leukemia Presenting as T-Cell Lymphoblastic Crisis

Chronic Myelogenous Leukemia in blast crisis can manifest as either myeloid (more common) or lymphoid blast crisis. Most lymphoblastic crises are of B-cell lineage. T-cell blast crisis is extremely rare, with only a few reported cases. We present a case of a middle-aged man who was diagnosed with CML on peripheral blood and bone marrow biopsy. Because of a generalized lymphadenopathy noted at the time of diagnosis, a lymph node biopsy was also performed, which revealed a T-cell lymphoblastic leukemia/lymphoma, BCR/ABL1 positive, with clonal evolution. This is a very rare manifestation of CML in blast crisis with no standard treatment and with poor outcomes despite chemotherapy or allogeneic stem cell transplant. Given its rarity, it would be difficult to develop standard chemotherapy protocols. We believe the treatment for this condition should be similar to any lymphoid blast crisis. The patient was treated with induction chemotherapy (hyper-CVAD regimen) plus dasatinib for 3 cycles followed by sibling-donor allogeneic stem cell transplant and is currently on maintenance dasatinib and has minimal residual disease at this time.

Transcriptional and Microenvironmental Regulation of Lineage Ambiguity in Leukemia

Leukemia is characterized by the uncontrolled production of leukemic cells and impaired normal hematopoiesis. Although the combination of chemotherapies and hematopoietic stem cell transplantation has significantly improved the outcome of leukemia patients, a proportion of patients still suffer from relapse after treatment. Upon relapse, a phenomenon termed “lineage switch” is observed in a subset of leukemia patients, in which conversion of lymphoblastic leukemia to myeloid leukemia or vice versa is observed. A rare entity of leukemia called mixed-phenotype acute leukemia exhibits co-expression of markers representing two or three lineages. These two phenotypes regarding the lineage ambiguity suggest that the fate of some leukemia retain or acquire a certain degree of plasticity. Studies using animal models provide insight into how lineage specifying transcription factors can enforce or convert a fate in hematopoietic cells. Modeling lineage conversion in normal hematopoietic progenitor cells may improve our current understanding of how lineage switch occurs in leukemia. In this review, we will summarize the role of transcription factors and microenvironmental signals that confer fate plasticity to normal hematopoietic progenitor cells, and their potential to regulate lineage switching in leukemias. Future efforts to uncover the mechanisms contributing to lineage conversion in both normal hematopoiesis and leukemia may pave the way to improve current therapeutic strategies.

Lineage Switch Between B-Lymphoblastic Leukemia and Acute Myeloid Leukemia Intermediated by "Occult" Myelodysplastic Neoplasm: Two Cases of Adult Patients With Evidence of Genomic Instability and Clonal Selection by Chemotherapy

OBJECTIVES

Lineage switch occurs in rare leukemias, and the mechanism is unclear. We report two cases of B-lymphoblastic leukemia (B-ALL) relapsed as acute myeloid leukemia (AML).

METHODS

Retrospective review of clinical and laboratory data.

RESULTS

Complex cytogenetic abnormalities were detected in B-ALL for both cases with subclone heterogeneity. Postchemotherapy marrow biopsies showed trilineage hematopoiesis without detectable B-ALL. Cytogenetics in both showed stemline abnormalities. The cases were considered "occult" myelodysplastic syndrome (MDS) preceding B-ALL. The patients relapsed 6.5 and 9 months following induction, respectively. Case 1 relapsed as AML-M5 initially, was treated as such, and then relapsed again as B-ALL. Case 2 relapsed as AML-M6. Cytogenetics demonstrated persistent abnormalities. Both patients died soon after relapse.

CONCLUSIONS

Lineage switch between B-ALL and AML could be intermediated by occult MDS. A pluripotent progenitor likely undergoes neoplastic transformation, resulting in a genomically unstable clone. This leads to a repertoire of heterogeneous subclones that may be selected by chemotherapy. Lineage switch heralds a dismal clinical outcome.

Unusual cytogenetic abnormalities associated with Philadelphia chromosome

Cytogenetic abnormalities are the hallmark of leukemias. We report here two cases of unusual cytogenetic abnormalities associated with Philadelphia chromosome, one with mixed phenotypic acute leukemia showing monosomy 7 and t(9;22) (q34;q11.2) and the other with chronic myeloid leukemia and additional translocation involving chromosomes 10 and 13. Both patients achieved complete remission following imatinib based treatment.

Philadelphia chromosome positive pre-T cell acute lymphoblastic leukemia: a rare case report and short review

Pre-T cell acute lymphoblastic leukemia is a relatively rare leukemia. Twenty to 30 % of adult B cell leukemia cases are Philadelphia chromosome positive and it has a therapeutic and prognostic significance. Incidence and outcome of Ph+ T cell acute lymphoblastic leukemia (T cell ALL) is unknown. Only about 25 cases of de novo Ph+ T cell ALL and 44 cases of Ph+ T ALL in blastic phase of CML has been reported. Differentiation between Ph+ Pre-T ALL/LBL and T cell lymphoblastic crises of chronic myeloid leukemia may be difficult. We report a case of adult T cell ALL having Philadelphia chromosome as the cytogenetic abnormality. He was treated with acute lymphoblastic leukemia induction chemotherapy and Imatinib and achieved complete remission.

Clonal Relationships Between Malignant Lymphomas and Histiocytic/Dendritic Cell Tumors

Tumors of histiocytic or dendritic cell origin appear to occur with increased frequency in patients with lymphoma. Recent molecular data have demonstrated clonal relationships between the lymphoma and the histiocytic/dendritic cell tumor in some of these cases. Clinical, pathologic, and experimental data suggest that this phenomenon probably represents transdifferentiation of the lymphoma clone to a histiocytic/dendritic cell lineage in most cases. Awareness of this entity is necessary to prompt comparative molecular studies in appropriate cases.

Lineage switch in childhood acute leukemia: an unusual event with poor outcome

Although rarely, switches between lymphoid and myeloid lineages may occur during treatment of acute leukemias (AL). Correct diagnosis relies upon confirmation by immunophenotyping of the lineage conversion and certification that the same cytogenetic/molecular alterations remain despite the phenotypic changes. From a total of 1,482 AL pediatric patients, we report nine cases of lineage conversion (0.6%), seven from lymphoid (four Pro-B, two Pre-B, one Common) to myelo-monocytic, and two from myeloid (bilineal, with myeloid predominance) to Pro-B. Eight patients were infants. Switches were suggested by morphology and confirmed with a median of 15 days (range: 8 days-6 months) from initiation of therapy. Of note, in five cases switches occurred before day 15. Stability of the clonal abnormalities was assessed by cytogenetic, RT-PCR/Ig-TCR rearrangement studies in all patients. Abnormalities in 11q23/MLL gene were detected in seven cases. Treatment schedules were ALL (two pts), Interfant-99 (five pts) and AML (two pts) protocols. Despite changing chemotherapy according to the new lineage, all patients died. Our findings support the association of lineage switches with MLL gene alterations and the involvement of a common lymphoid B-myeloid precursor. New therapies should be designed to address these rare cases. Possible mechanisms implicated are discussed.

Lineage switch from precursor B cell acute lymphoblastic leukemia to acute monocytic leukemia at relapse

A lineage switch in leukemia, in which the leukemic cell lineage at onset converts to another lineage at a later time, is an uncommon type of hybrid (mixed) leukemia regarded as a variation of bilineage leukemia. We present a case of a 60-year-old female diagnosed with precursor B cell acute lymphoblastic leukemia (ALL), whose markers in flow cytometry shifted from their original status of CD19+, 22+, 79a+, 13+, HLA-DR+, and TdT+. Although her bone marrow achieved remission after induction therapy, there was a small residual population of leukemic cells in the liver. Residual disease was proved by biopsy and pathologically shown to have an immature phenotype of CD5+, CD10-, CD20-, CD79a- and myeloperoxidase negativity. Two weeks after liver biopsy, blast cells progressively appeared in the peripheral blood; these cells had a monocytoid morphology and phenotype (CD13, 14) but were accompanied by myeloid (CD33) and lymphoid (CD2, 4, 20) cells. Markers CD7, 10 and 19 were negative by flow cytometry. This phenotypical conversion from B-ALL to hybrid leukemia featuring monocytoid characteristics is known as a lineage switch. This case suggests that leukemic subclones tend to carry out dedifferentiation, occasionally in extramedullary sites, which serve as a hotbed for the selection of resistant clones.

Chronic myelogenous leukemia showing biphenotypic blast crisis followed by lineage switch to B lymphoblastic leukemia

Lineage switch is a very rare event in blastic crisis of chronic myelogenous leukemia (CML-BC). To our knowledge, only three cases of lineage switch between lymphoid and myeloid/myelomonocytic lineages have been reported in the literature. Here, we report a novel case of imatinib-resistant CML-BC, in which the blast lineage switched from biphenotypic to B-lymphoid.

Very early onset of an acute myeloid leukemia in an adult patient with B-cell lymphoblastic leukemia

We report on a case of a 30-year-old male with acute B-lymphoblastic leukemia (B-ALL) with immunophenotype CD19(+), CD22(+), CD20(+), CD10(+), with aberrant expression of CD13 and CD117, and IgH gene rearrangements. Three months after treatment with GMALL-2003 and Ida/FLAG protocols bone marrow showed predominance of blasts with myeloid morphology and phenotype MPO(+), CD13(+), CD33(+), CD64(+), CD15(+), CD56(+), EVI-1 gene overexpression and lack of IgH rearrangements. The case is the first report of a very early emergence of myeloid leukemia during the induction treatment for B-ALL in an adult patient. Different pathogenetic mechanisms are discussed - clonal evolution or selection, lineage switch or development of a de novo or therapy-induced leukemia.