Precursor B-acute lymphoblastic leukemia occurring in patients with a history of prior malignancies: is it therapy-related?

Mutational patterns in therapy-related acute lymphoblastic leukemia subgroups: one step closer to unveiling the genetic odyssey

There is increasing evidence that therapy-related acute lymphoblastic leukemia (trALL) resulting from chemo- and/or radiotherapy represents a distinct entity. However, apart from KMT2A rearrangements, which have been repeatedly reported in this subgroup, the relevance of other aberrations remains controversial due to divergent study results and sparse molecular analyses. Within our ALL patient cohort, 15% (n = 19/131) met the criteria for trALL with a high proportion of Ph + and KMT2A rearrangements. On the molecular level, the most frequently observed mutation was KMT2D, followed by CDKN2A, KRAS and DNMT3A. No TP53 mutation was detected. Outcome was particularly poor in Ph + trALL compared to Ph+ de novo ALL, which seemed to be mitigated by allogeneic stem cell transplantation. Our findings further define trALL as a distinct entity but highlight the need for further molecular genome sequencing of somatic and germline variants to advance our understanding of trALL.

Allogeneic hematopoietic cell transplantation is equally effective in secondary acute lymphoblastic leukemia (ALL) compared to de-novo ALL-a report from the EBMT registry

Secondary acute lymphoblastic leukemia (s-ALL) comprises up to 10% of ALL patients. However, data regarding s-ALL outcomes is limited. To answer what is the role of allogeneic hematopoietic cell transplantation (HCT) in s-ALL, a matched-pair analysis in a 1:2 ratio was conducted to compare outcomes between s-ALL and de novo ALL (dn-ALL) patients reported between 2000-2021 to the European Society for Blood and Marrow Transplantation registry. Among 9720 ALL patients, 351 (3.6%) were s-ALL, of which 80 were in first complete remission (CR1) with a known precedent primary diagnosis 58.8% solid tumor (ST), 41.2% hematological diseases (HD). The estimated 2-year relapse incidence (RI) was 19.1% (95%CI: 11-28.9), leukemia-free survival (LFS) 52.1% (95%CI: 39.6-63.2), non-relapse mortality (NRM) 28.8% (95%CI: 18.4-40), GvHD-free, relapse-free survival (GRFS) 39.4% (95%CI: 27.8-50.7), and overall survival (OS) 60.8% (95%CI: 47.9-71.4), and did not differ between ST and HD patients. In a matched-pair analysis, there was no difference in RI, GRFS, NRM, LFS, or OS between s-ALL and dn-ALL except for a higher incidence of chronic GvHD (51.9% vs. 31.4%) in s-ALL. To conclude, patients with s-ALL who received HCT in CR1 have comparable outcomes to patients with dn-ALL.

'Secondary' acute lymphoblastic/lymphocytic leukemia - done playing second fiddle?

Acute lymphoblastic/lymphocytic leukemia (ALL) occurring post-cancer diagnosis (secondary ALL - sALL) is increasingly recognized as a discrete entity, constituting up to as much as 5-10% of all new ALL diagnoses, and carrying its own biologic, prognostic and therapeutic significance. In this review, we will outline the history and current state of research into sALL. We will explore the evidence for differences underlining its existence as a distinct subgroup, as well as examining what might be driving such differences etiologically, including prior chemotherapy. We will examine these distinctions on population-, chromosomal-, and molecular-levels, and we will consider whether they translate to differences in clinical outcome, and whether they do - or should - warrant differences in treatment selection.

Distinct clonal identities of B-ALLs arising after lenolidomide therapy for multiple myeloma

Patients with multiple myeloma (MM) who are treated with lenalidomide rarely develop a secondary B-cell acute lymphoblastic leukemia (B-ALL). The clonal and biological relationship between these sequential malignancies is not yet clear. We identified 17 patients with MM treated with lenalidomide, who subsequently developed B-ALL. Patient samples were evaluated through sequencing, cytogenetics/fluorescence in situ hybridization (FISH), immunohistochemical (IHC) staining, and immunoglobulin heavy chain (IgH) clonality assessment. Samples were assessed for shared mutations and recurrently mutated genes. Through whole exome sequencing and cytogenetics/FISH analysis of 7 paired samples (MM vs matched B-ALL), no mutational overlap between samples was observed. Unique dominant IgH clonotypes between the tumors were observed in 5 paired MM/B-ALL samples. Across all 17 B-ALL samples, 14 (83%) had a TP53 variant detected. Three MM samples with sufficient sequencing depth (>500×) revealed rare cells (average of 0.6% variant allele frequency, or 1.2% of cells) with the same TP53 variant identified in the subsequent B-ALL sample. A lack of mutational overlap between MM and B-ALL samples shows that B-ALL developed as a second malignancy arising from a founding population of cells that likely represented unrelated clonal hematopoiesis caused by a TP53 mutation. The recurrent variants in TP53 in the B-ALL samples suggest a common path for malignant transformation that may be similar to that of TP53-mutant, treatment-related acute myeloid leukemia. The presence of rare cells containing TP53 variants in bone marrow at the initiation of lenalidomide treatment suggests that cellular populations containing TP53 variants expand in the presence of lenalidomide to increase the likelihood of B-ALL development.

Comparative study of therapy-related and de novo adult b-cell acute lymphoblastic leukaemia

We report a comparative analysis of patients with therapy‐related acute lymphoblastic leukaemia (tr‐ALL) vs de novo ALL. We identified 331 patients with B‐ALL; 69 (21%) were classified as tr‐ALL. The most common prior malignancies were breast (23·2%) and plasma cell disorders (20·3%). Patients with tr‐ALL were older (median 63·2 vs. 46·2 years, P < 0.001), more often female (66·7% vs. 43·5%, P < 0·001), and more likely to have hypodiploid cytogenetics (18·8% vs. 5·0%, P < 0·001). In multivariable analysis, patients with tr‐ALL were less likely to achieve complete remission [odds ratio (OR) = 0·16, P < 0·001] and more likely to be minimal residual disease‐positive (OR = 4·86, P = 0·01) but had similar OS after diagnosis and allo‐haematopoietic cell transplantation.

Allogeneic Hematopoietic Stem Cell Transplantation in Therapy Related Acute Leukemia

Therapy related acute leukemia consists of a unique subset of acute leukemia with an increased frequency of high risk cytogenetic and molecular abnormalities, dismal response to therapy, higher relapse rates and poor overall survival. Therapy related acute myeloid leukemia (t-AML) is a better defined disease entity than therapy related acute lymphoid leukemia (t-ALL). However, in recent times, t-ALL is also being increasingly recognized and extensively studied. Therapy related acute myeloid leukemia is usually classified together with therapy related myelodysplastic syndrome. However, the management of these two diseases maybe different regarding needs of induction chemotherapy and eligibility for upfront allogeneic hematopoietic stem cell transplantation (Allo HSCT). There is also evidence regarding differences in prognosis and outcomes between these two entities. Allo HSCT offers a potential for cure in t-AML and t-ALL. However, existing literature on the same is confounded by inclusion of t-MDS and secondary acute leukemias. Here we review the current evidence on the outcomes and predictors of outcomes of Allo HSCT in the management of therapy related acute leukemias. We also shed light into the under-representation of therapy related leukemias in clinical trials. This stresses the need for prospective trials incorporating measurable residual disease monitoring and sequential next generation sequencing based genomic data for accurate prognostication and management of therapy related acute leukemia.

Synchronous B-Cell Acute Lymphoblastic Leukemia and Serous Ovarian Carcinoma: A Case Report

Adult patients with B-cell acute lymphoblastic leukemia (ALL) have higher rates of antecedent and subsequent malignancies. However, synchronous identification of ALL and ovarian cancer is exceedingly rare. We report the unique case of a 65-year-old woman with synchronous B-cell ALL and low-grade serous ovarian carcinoma diagnosed after surgical intervention for a small bowel obstruction. Treatment with inotuzumab ozogamicin followed by adnexal mass resection and postoperative letrozole was successful in achieving complete remission for both her leukemia and ovarian cancer.

Preventive Healthcare and Management for Acute Lymphoblastic Leukaemia in Adults: Case Report and Literature Review

Acute lymphoblastic leukaemia (ALL) is diagnosed by the presence of at least 20% lymphoblasts in the bone marrow. ALL may be aggressive and include the lymph nodes, liver, spleen, central nervous system (CNS), and other organs. Without early recognition and timely treatment, ALL will progress quickly and may have poor prognosis in clinical scenarios. ALL is a rare type of leukaemia in adults but is the most common type in children. Precipitating factors such as environmental radiation or chemical exposure, viral infection, and genetic factors can be associated with ALL. We report a rare case of ALL with symptomatic hypercalcaemia in an adult woman. The patient presented with general weakness, poor appetite, bilateral lower limbs oedema, consciousness disturbance, and lower back pain for 3 weeks. She had a history of cervical cancer and had undergone total hysterectomy, chemotherapy, and radiation therapy. Her serum calcium level was markedly increased, at 14.1 mg/dl at admission. Neck magnetic resonance imaging, abdominal sonography, abdominal computed tomography, and bone marrow examination were performed. Laboratory data, including intact parathyroid hormone (i-PTH), peripheral blood smear, and 25-(OH) D3, were checked. Bone marrow biopsy showed B cell lymphoblastic leukaemia. Chemotherapy was initiated to be administered but was discontinued due to severe sepsis. Finally, the patient died due to septic shock. This was a rare case of B cell ALL in an adult complicated by hypercalcaemic crisis, which could be a life-threatening emergency in clinical practice. Physicians should pay attention to the associated risk factors. Early recognition and appropriate treatment may improve clinical outcomes.

Therapy-induced Deletion in 11q23 Leading to Fusion of KMT2A With ARHGEF12 and Development of B Lineage Acute Lymphoplastic Leukemia in a Child Treated for Acute Myeloid Leukemia Caused by t(9;11)(p21;q23)/KMT2A-MLLT3

BACKGROUND/AIM

Fusion of histone-lysine N-methyltransferase 2A gene (KMT2A) with the Rho guanine nucleotide exchange factor 12 gene (ARHGEF12), both located in 11q23, was reported in some leukemic patients. We report a KMT2A-ARHGEF12 fusion occurring during treatment of a pediatric acute myeloid leukemia (AML) with topoisomerase II inhibitors leading to a secondary acute lymphoblastic leukemia (ALL).

MATERIALS AND METHODS

Multiple genetic analyses were performed on bone marrow cells of a girl initially diagnosed with AML.

RESULTS

At the time of diagnosis with AML, the t(9;11)(p21;q23)/KMT2A-MLLT3 genetic abnormality was found. After chemotherapy resulting in AML clinical remission, a 2 Mb deletion in 11q23 was found generating a KMT2A-ARHGEF12 fusion gene. When the patient later developed B lineage ALL, a t(14;19)(q32;q13), loss of one chromosome 9, and KMT2A-ARHGEF12 were detected.

CONCLUSION

The patient sequentially developed AML and ALL with three leukemia-specific genomic abnormalities in her bone marrow cells, two of which were KMT2A-rearrangements.

Therapy-related acute lymphoblastic leukemia is a distinct entity with adverse genetic features and clinical outcomes

Patients with therapy-related acute lymphoblastic leukemia (t-ALL) represent a small subset of acute lymphoblastic leukemia (ALL) patients who received genotoxic therapy (ie, chemotherapy or radiation) for a prior malignancy. These patients should be distinguished from patients with de novo ALL (dn-ALL) and ALL patients who have a history of prior malignancy but have not received cytotoxic therapies in the past (acute lymphoblastic leukemia with prior malignancy [pm-ALL]). We report a retrospective multi-institutional study of patients with t-ALL (n = 116), dn-ALL (n = 100), and pm-ALL (n = 20) to investigate the impact of prior cytotoxic therapies on clinical outcomes. Compared with patients with pm-ALL, t-ALL patients had a significantly shorter interval between the first malignancy and ALL diagnosis and a higher frequency of poor-risk cytogenetic features, including KMT2A rearrangements and myelodysplastic syndrome-like abnormalities (eg, monosomal karyotype). We observed a variety of mutations among t-ALL patients, with the majority of patients exhibiting mutations that were more common with myeloid malignancies (eg, DNMT3A, RUNX1, ASXL1), whereas others had ALL-type mutations (eg, CDKN2A, IKZF1). Median overall survival was significantly shorter in the t-ALL cohort compared with patients with dn-ALL or pm-ALL. Patients who were eligible for hematopoietic cell transplantation had improved long-term survival. Collectively, our results support t-ALL as a distinct entity based on its biologic and clinical features.

Inv(11)(q21q23); KMT2A-MAML2, a Recurrent Genetic Abnormality in T-Cell Therapy-related Acute Lymphoblastic Leukemia

T-cell therapy-related acute lymphoblastic leukemia (T-t-ALL) is a rare condition associated with previous cytotoxic therapy for another disease. Here we report T-t-ALL with inv(11)(q21q23), which involves KMT2A and MAML2, a transcriptional coactivator of NOTCH proteins, that occurred after chemotherapy for Philadelphia chromosome-positive B-cell acute lymphoblastic leukemia. This case describes the youngest patient with T-t-ALL harboring inv(11)(q21q23) and is the first independent report following an initial series also occurring in children. Our results lend further support to the observation that the KMT2A-MAML2 fusion gene resulting from inv(11)(q21q23) is likely a recurrent cytogenetic abnormality in T-t-ALL and appears to be associated with pediatric cases.

Outcomes of therapy-related acute lymphoblastic leukemia in adults after allogeneic stem cell transplantation

INTRODUCTION

Therapy-related acute lymphoblastic leukemia (t-ALL) is an increasingly recognized subset of therapy-related acute leukemia. There are limited data on the role of allogeneic hematopoietic stem cell transplantation (HSCT) in t-ALL. Recent reports suggest comparable outcomes of t-ALL with de novo ALL after HSCT.

PATIENTS AND METHODS

We retrospectively reviewed all patients of t-ALL who underwent HSCT at our center. Patients were analyzed for prior malignancy, therapy, time to diagnosis of t-ALL, clinical, laboratory characteristics, transplant details, relapse-free survival (RFS), and overall survival (OS).

RESULTS

Eighteen patients (M:F ratio 1:1; Median age 44 years) underwent HSCT for t-ALL. Median latent period from primary malignancy to t-ALL was 44.8 months. 11q23 rearrangement and t(9;22) were present in 33.3% and 22.2% patients, respectively. Stem cell donors were matched related, matched unrelated, and haploidentical in 27.8% (n = 5), 55.6% (n = 10), and 16.7% (n = 3) patients, respectively. Five patients died before D+ 100 (27.8%). Estimated 2-year RFS and OS were 47.1% and 51.8%, respectively. We did not find any pretransplant and post-transplant risk factors that were predictive of improved OS or RFS after multivariate analysis.

CONCLUSIONS

Allogeneic HSCT outcomes in t-ALL were comparable to HSCT outcomes in de novo ALL. Multicenter studies with more patients and longer follow-up may provide factors affecting outcome and survival.

Development of acute lymphoblastic leukemia following treatment for acute myeloid leukemia in children with Down syndrome: A case report and retrospective review of Children's Oncology Group acute myeloid leukemia trials

Children with Down syndrome have a 150-fold increased risk of developing acute myeloid leukemia (AML) and 20-fold increased risk of developing acute lymphoblastic leukemia (ALL). Although the risk of developing AML and ALL is significantly increased in children with Down syndrome, the development of both malignancies in the same patient is very rare. We describe a patient with Down syndrome who developed ALL 6 years after being diagnosed with AML. We performed a literature review and Children's Oncology Group query and discovered eight published cases and five cases of ALL following AML in pediatric patients with Down syndrome, as well as six cases of ALL following AML in non-Down syndrome patients. There was a similar cumulative incidence of ALL after treatment for AML in the Down syndrome and non-Down syndrome populations. Overall survival in patients with Down syndrome who developed ALL after treatment for AML was comparable to overall survival for patients with Down syndrome with de novo ALL with an average follow-up of 7 years after ALL diagnosis. Clinical data collected were used to discuss whether this phenomenon represents a secondary leukemia, second primary cancer, or mixed-lineage leukemia.

B-cell acute lymphoblastic leukemia as a secondary malignancy following diffuse large B-cell lymphoma

Secondary acute lymphoblastic leukemia (ALL) is a rare disease that has not been well characterized compared with secondary myelodysplastic syndrome or secondary acute myeloid leukemia. We present a report of two patients who developed ALL following complete remission of diffuse large B-cell lymphoma (DLBCL). The first case is more consistent with a therapy- related ALL as a PCR analysis of bone marrow aspirate revealed a distinct clone and the mixed-lineage leukemia gene rearrangement, commonly associated with exposure to topoisomerase II inhibitors. The second case is more consistent with clonal evolution given positive MYC and BCL2 fusion signals in the original diagnosis of DLBCL and the secondary ALL.

Secondary acute lymphoblastic leukemia, a retrospective analysis from Washington University and meta-analysis of published data

Secondary acute lymphoblastic leukemia (s-ALL) is rare and poorly defined and data regarding outcomes post-transplant are lacking. Here, we report a detailed analysis of s-ALL at our Institution. Among 211 eligible patients with ALL from 2006 to 2017, 30 (14%) were defined as s-ALL and the remaining as primary ALL (p-ALL). s-ALL patients were older and had higher incidence of adverse risk factors. Overall response (OR) after induction was not different between s-ALL and p-ALL (79% versus 90% respectively, p = 0.106). S-ALL group had a higher risk of relapse (RFS) and death (RFS HR = 1.93, 95% CI 1.2-3.12, p = 0.007. OS HR: =1.95, 95% CI 1.18-3.23, p = 0.01). In multivariate analysis, the adverse effect of s-ALL on RFS and OS was no longer significant, however a pooled meta-analysis of our and published data indicated that s-ALL is an independent risk factor for lower OS (HR: 1.30, 95% CI: 1.11-1.52, p < 0.01). Myeloablative allogeneic transplantation in s-ALL was associated with lower rates of relapse and higher transplant related mortality without improvement in OS. These data indicate that s-ALL status should be considered for risk- stratification of newly diagnosed ALL. The optimal conditioning regimen for s-ALL patients undergoing allogeneic stem cell transplantation needs to be evaluated in a larger study.

Therapy-related acute lymphoblastic leukemia has distinct clinical and cytogenetic features compared to de novo acute lymphoblastic leukemia, but outcomes are comparable in transplanted patients

Therapy-related acute lymphoblastic leukemia remains poorly defined due to a lack of large data sets recognizing the defining characteristics of this entity. We reviewed all consecutive cases of adult acute lymphoblastic leukemia treated at our institution between 2000 and 2017 and identified therapy-related cases - defined as acute lymphoblastic leukemia preceded by prior exposure to cytotoxic chemotherapy and/or radiation. Of 1022 patients with acute lymphoblastic leukemia, 93 (9.1%) were classified as therapy-related. The median latency for therapy-related acute lymphoblastic leukemia onset was 6.8 years from original diagnosis, and this was shorter for patients carrying the MLL gene rearrangement compared to those with other cytogenetics. When compared to de novo acute lymphoblastic leukemia, therapy-related patients were older (P<0.01), more often female (P<0.01), and had more MLL gene rearrangement (P<0.0001) and chromosomes 5/7 aberrations (P=0.02). Although therapy-related acute lymphoblastic leukemia was associated with inferior 2-year overall survival compared to de novo cases (46.0% vs 68.1%, P=0.001), prior exposure to cytotoxic therapy (therapy-related) did not independently impact survival in multivariate analysis (HR=1.32; 95% CI: 0.97-1.80, P=0.08). There was no survival difference (2-year = 53.4% vs 58.9%, P=0.68) between the two groups in patients who received allogenic hematopoietic cell transplantation. In conclusion, therapy-related acute lymphoblastic leukemia represents a significant proportion of adult acute lymphoblastic leukemia diagnoses, and a subset of cases carry clinical and cytogenetic abnormalities similar to therapy-related myeloid neoplasms. Although survival of therapy-related acute lymphoblastic leukemia was inferior to de novo cases, allogeneic hematopoietic cell transplantation outcomes were comparable for the two entities.

Second primary acute lymphoblastic leukemia in adults: a SEER analysis of incidence and outcomes

We conducted a surveillance epidemiology and end results (SEER)-based analysis to describe the incidence and characteristics of second primary acute lymphoblastic leukemia (sALL) among adults (≥18 years) with a history of primary malignancies (1M). Standardized incidence ratios (SIRs) of sALL cases were calculated by site and 1M stage. We also evaluated the differences in 5-year sALL survival by age, site, and extent of 1M, latency of sALL after 1M, and evidence of underlying racial/ethnic disparity. We identified 10,956 patients with de-novo/primary acute lymphoblastic leukemia (1ALL) and 772 with sALL. Women (49.1% vs. 42.9%), white patients (72.0% vs. 59.5%), older patients (58.8% vs. 25.2%; age ≥65 years), and patients diagnosed between 2003 and 2012 (66.8% vs. 53.9%) had a higher proportion of sALL compared with 1ALL. There was a significantly inferior median 5-year survival for sALL patients compared to 1ALL (6 vs. 15 months; HR 1.20, 95% CI 1.10-1.31, P < 0.001). The median latency period was 60.0 months; the most common 1M among sALL patients were breast (17.9%) and prostate (17.4%). Patients with any 1M were at increased risk of developing sALL (SIR 1.76, 95% CI 1.58-1.95, P < 0.001). Hematological-1M sites had significantly higher SIRs (hematological-SIR 7.35; solid-SIR 1.33; P < 0.001). We observed a significant increase in sALL incidence after a 1M and a significantly worse 5-year survival with different demographic characteristics from 1ALL. There is a need to define appropriate screening methods for patients surviving their primary cancer.

Secondary acute lymphoblastic leukemia is a distinct clinical entity with prognostic significance

The effect of prior malignancy on the risk of developing, and prognosis of, acute lymphoblastic leukemia (ALL) is unknown. This observational study utilized the California Cancer Registry to estimate the risk of developing ALL after a prior malignancy using standardized incidence ratios (SIRs, 95% confidence intervals). ALL occurring after a malignancy with an SIR>1 (increased-risk (IR) malignancies) was considered secondary ALL (s-ALL). Adjusted hazard ratios (aHRs, 95% confidence intervals) compared the effect of s-ALL with de novo ALL on overall survival. A total of 14 481 patients with ALL were identified (1988–2012) and 382 (3%) had a known prior malignancy. Any prior malignancy predisposed patients to developing ALL: SIR 1.62 (1.45–1.79). Hematologic malignancies (SIR 5.57, 4.38–6.98) and IR-solid tumors (SIR 2.11, 1.73–2.54) increased the risk of developing ALL. s-ALL increased the risk of death compared with de novo ALL (aHR 1.38 (1.16–1.63)) and this effect was more pronounced among younger patients (age<40 years: aHR 4.80 (3.15–7.30); age⩾40 years: aHR 1.40 (1.16–1.69)) (interaction P<0.001). This population-based study demonstrates that s-ALL is a distinct entity that occurs after specific malignancies and carries a poor prognosis compared with de novo ALL, particularly among patients <40 years of age.

Acquired 11q23/MLL rearrangement of unknown clinical significance

Newly emerged 11q23/MLL rearrangements in patients with a prior history of cytotoxic therapies are almost always associated with therapy-related hematological malignancies. Here we report a patient who had received various chemotherapies for his chronic lymphocytic leukemia (CLL). An abnormal clone of t(3;11)(p13;q23) was detected in 7 out of 20 metaphases in the bone marrow (BM) in the 15^th year of disease. MLL rearrangement was detected in myeloid and erythroid cells, not in CLL cells by combined morphologic and fluorescence in situ hybridization. BM showed no evidence of myelodysplasia or increased blasts. Patient had been closely followed for 3 years, the abnormal clone was persistently detected but the patient had normal blood counts and normal BM examinations. This is the first case to show MLL rearrangement of unknown clinical significance in the setting of post cytotoxic chemotherapy.

B-acute lymphoblastic leukemia/lymphoblastic lymphoma

OBJECTIVES

This session of the 2013 Society of Hematopathology/European Association for Haematopathology Workshop was dedicated to B-acute lymphoblastic leukemia (B-ALL)/lymphoblastic lymphoma (LBL) with recurrent translocations and not otherwise specified.

METHODS

In this review, we summarize the cases discussed during the workshop, review the pertinent and most recent literature on the respective topics, and provide a few key points that may aid in the workup of patients with B-ALL/LBL.

RESULTS

Many of the submitted cases showed interesting diagnostic, immunophenotypic, or clinical aspects of B-ALL with BCR/ABL1, MLL-associated, and other recurrent chromosomal abnormalities. Several cases showed rare aberrancies such as coexistent IGH/BCL2 and MYC rearrangements and raised issues in classification. Other cases had unusual clinical presentations, including B-ALL with hypereosinophilia and therapy-related B-ALL. Several cases highlighted the role of flow cytometry immunophenotyping in distinguishing benign B-cell precursors from aberrant lymphoblasts, and other cases raised questions regarding the clinical importance of myeloperoxidase positivity in acute lymphoblastic leukemia.

CONCLUSIONS

The complexity and spectrum of cases presented in this review highlight the importance of clinicopathologic correlation and the value of ancillary studies in the classification and workup of patients with B-ALL/LBL.

Acute leukemias of ambiguous origin

OBJECTIVES

This session of the Society for Hematopathology/European Association for Haematopathology Workshop focused on acute leukemias of ambiguous origin.

METHODS

We provide an overview of mixed-phenotype acute leukemia (MPAL) as recognized in the current World Health Organization classification and summarize diagnostic criteria for major categories of MPAL: B/myeloid, T/myeloid, B/T, and B/T/myeloid.

RESULTS

Most MPAL cases submitted were B/myeloid and T/myeloid MPAL, the most frequent types, but three cases of B/T MPAL were also submitted, and examples of all categories are illustrated. We emphasize that a comprehensive approach to immunophenotyping is required to accurately establish the diagnosis of MPAL. Flow cytometry immunophenotyping using a large panel of antibodies is needed as well as confirmatory immunohistochemical analysis and cytochemistry studies for myeloperoxidase and nonspecific esterase. We discuss technical issues in determining blast lineage and possible pitfalls in MPAL diagnosis. In particular, rare cases of B-acute lymphoblastic leukemia (B-ALL) can express myeloperoxidase but are otherwise consistent with B-ALL and should be treated as such. Last, we review the differential diagnosis between acute undifferentiated leukemia and acute myeloid leukemia with minimal differentiation.

CONCLUSIONS

There was an agreement that diagnosis of MPAL can be challenging, especially if applied flow cytometry panels are not comprehensive enough.

Incidence, clinical and biological characteristics and outcome of secondary acute lymphoblastic leukemia after solid organ or hematologic malignancy

Acute lymphoblastic leukemia (ALL) following solid organ or hematologic malignancy (secondary ALL, s-ALL) is not well characterized. We analyzed the characteristics and outcome of patients with s-ALL and compared them with those of patients with de novo- ALL. Of 448 patients, 24 (5%) had previous neoplasia. Sixteen patients had received previous cytotoxic therapy (therapy-associated ALL, t-ALL), and eight had not (antecedent-malignancy ALL, am-ALL). Except for more advanced age in patients with s-ALL, no statistically significant differences were observed in WBC count, CNS involvement, immunophenotype or cytogenetics between the groups, nor in complete remission (t-ALL: 94%; am-ALL: 75%; de novo-ALL: 85%), 3-year remission duration (58%; 50%; 72%), overall survival (71%; 38%; 60%) or event-free survival (53%, 38%; 53%). Our study did not show poor clinical or cytogenetic features or inferior outcome in ALL patients with antecedent neoplastic disease, irrespective of the type of treatment received for the neoplasia.

Secondary acute lymphoblastic leukaemia is constitutional and probably not related to prior therapy

Very little is known about secondary acute lymphoblastic leukaemia (s-ALL). This retrospective analysis studied a cohort of s-ALL patients treated at a single centre between 1994 and 2013, while comparing therapy-associated ALL (t-ALL) and antecedent malignancy ALL (am-ALL) patients. Thirty-two patients with s-ALL were identified. The overall incidence was 9.4% among ALL adults while T-cell s-ALL was rare (12% of s-ALLs). The median time interval between two malignant diagnoses was 5.3 years (range: 0.1-28). In contrast to previous reports, most of the s-ALLs were CD10 + and without KMT2A (MLL) abnormalities. The overall survival (OS) rates of the entire cohort at 12 and 24 months from ALL diagnosis was 49% and 25%, respectively. Most patients (n = 23, 72%) received prior chemo-/radio-therapy for their first malignancy (t-ALL) and only 9 (28%) did not (am-ALL). No significant difference was found in the incidence of B-/T- lineage ALL, extramedullary disease, blood count, and the rate of Philadelphia-positive ALL, nor in the rates of complete remission (P = 0.55) and OS (P = 0.97). This similarity, together with high incidence of family malignancy in both groups, raise the possibility that s-ALL patients may have an inherent predisposition to malignancies and a history of previous therapy may be of lesser importance in the pathogenesis of s-ALL.

MLL partner genes in secondary acute lymphoblastic leukemia: report of a new partner PRRC1 and review of the literature

Secondary acute lymphoblastic leukemia (sALL) following chemotherapy and/or radiotherapy of previous malignancies represents 2-10% of all cases of ALL. A 72-year-old female patient was diagnosed with acute lymphoblastic leukemia following chemotherapy for a diffuse large B cell lymphoma. Banding cytogenetics showed a t(t(5;11)(q23-31;q23) in 20 of the 21 metaphases examined and fluorescent in situ hybridization confirmed rearrangement of MLL. Long distance inverse-polymerase chain reaction revealed an in-frame fusion between 5'MLL and 3'PRRC1. Sixty-five cases of sALL associated with 11q23/MLL rearrangement, including 47 with a t(4;11)(q21;q23), were retrieved from the literature. Drug regimen used to treat the primary neoplasm was available for 54 patients; 52 had received a topoisomerase II inhibitor, known to induce MLL rearrangement.

A focused review of hematopoietic neoplasms occurring in the therapy-related setting

Hematological neoplasms developed in patients with a history of cytotoxic therapies comprise a group of diseases with a poor clinical outcome, and collectively categorized as "therapy-related myeloid neoplasms" (t-MN) in the 2008 World Health Organization (WHO) Classification. In recent years, numerous publications have emerged, and these studies have greatly expanded the scope of our understanding in this field. We here focused our review on several selected areas including secondary malignancies occurring in patients with autoimmune diseases; radiation therapy alone as a causative agent; the similarity and differences between therapy-related myelodysplastic syndromes (t-MDS) and acute myeloid leukemia (t-AML); clinical behavior and treatment outcome of t-AML patients with favorable cytogenetics; the incidence and clinical features of myelodysplastic/myeloproliferative neoplasms, as well as acute lymphoblastic leukemia and myeloproliferative neoplasms in patients with prior cytotoxic exposure. These recent studies have shown that therapy-related hematopoietic neoplasms are heterogeneous, and may manifest in various forms, more complex than we have recognized previously. Cytogenetic abnormalities and underlying mutations are likely to be the major factors dictating prognosis.

Therapy-related B lymphoblastic leukemia with t(4;11)(q21;q23)/AF4-MLL in a patient with mantle cell lymphoma after recent aggressive chemotherapy: a unique case report

Mantle cell lymphoma (MCL) is a mature B-cell lymphoma associated with the hallmark translocation t(11;14)(q13;32), which involves the cyclin D1 (CCND1) and immunoglobin heavy chain (IgH) genes. It may transform to a more aggressive blastoid or pleomorphic variant, with or without acquisition of chromosomal abnormalities. MCL could also present with a leukemic phase with marked lymphocytosis. A literature search did not reveal any prior reports of MCL transforming to or followed by a B-cell lymphoblastic leukemia (B-ALL).

Therapy-related pro-B cell acute lymphoblastic leukemia: report of two patients with MLL amplification

Improvements in chemotherapy and medical support of patients treated with chemotherapy and radiation have led to an ever-increasing number of cancer survivors. Unfortunately, a small fraction of these patients develop secondary hematologic malignancies as a consequence of their exposure to genotoxic anti-cancer regimens. Most of these are myeloid malignancies, therapy-related acute myeloid leukemia (t-AML) or myelodysplasia (t-MDS); however, a small but growing body of literature exists, which describes therapy-related acute lymphoblastic leukemias (t-ALL). Nearly all these cases are reportedly associated with translocations involving chromosome 11q23, the site of the MLL gene. We herein report two cases of ALL occurring after chemotherapy for other malignancies that showed complex karyotypic abnormalities and distinct MLL amplification by fluorescence in situ hybridization analysis. Immunophenotypic analysis showed that both cases expressed a pro-B cell (CD10-) phenotype with aberrant myeloid antigen expression. Although MLL amplification has been reported in therapy-related myeloid disease, to our knowledge this is the first report of MLL amplification occurring in therapy-related B cell ALL.