The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia.

The World Health Organization (WHO) classification of tumors of the hematopoietic and lymphoid tissues was last updated in 2008. Since then, there have been numerous advances in the identification of unique biomarkers associated with some myeloid neoplasms and acute leukemias, largely derived from gene expression analysis and next-generation sequencing that can significantly improve the diagnostic criteria as well as the prognostic relevance of entities currently included in the WHO classification and that also suggest new entities that should be added. Therefore, there is a clear need for a revision to the current classification. The revisions to the categories of myeloid neoplasms and acute leukemia will be published in a monograph in 2016 and reflect a consensus of opinion of hematopathologists, hematologists, oncologists, and geneticists. The 2016 edition represents a revision of the prior classification rather than an entirely new classification and attempts to incorporate new clinical, prognostic, morphologic, immunophenotypic, and genetic data that have emerged since the last edition. The major changes in the classification and their rationale are presented here.

Brca1 deficiency causes bone marrow failure and spontaneous hematologic malignancies in mice.

BRCA1 is critical for maintenance of genomic stability and interacts directly with several proteins that regulate hematopoietic stem cell function and are part of the Fanconi anemia (FA) double-strand break DNA repair pathway. The effects of complete BRCA1 deficiency on bone marrow (BM) function are unknown. To test the hypothesis that Brca1 is essential in hematopoiesis, we developed a conditional mouse model with Mx1-Cre-mediated Brca1 deletion. Mice lacking Brca1 in the BM have baseline cytopenias and develop spontaneous bone marrow failure or diverse hematologic malignancies by 6 months of age. Brca1(-/-) BM cells have a reduced capacity to form hematopoietic colonies in vitro and to reconstitute hematopoiesis in irradiated recipients, consistent with a hematopoietic progenitor functional defect. Brca1(-/-) BM cells also show FA-like hypersensitivity to the DNA crosslinking agent mitomycin C, and karyotypes feature genomic instability. Taken together, our results show that loss of Brca1 in murine BM causes hematopoietic defects similar to those seen in people with FA, which provides strong evidence that Brca1 is critical for normal hematopoiesis and that Brca1 is a bona fide FA-like gene.

Complex or monosomal karyotype and not blast percentage is associated with poor survival in acute myeloid leukemia and myelodysplastic syndrome patients with inv(3)(q21q26.2)/t(3;3)(q21;q26.2): a Bone Marrow Pathology Group study.

Acute myeloid leukemia and myelodysplastic syndrome with inv(3)(q21q26.2)/t(3;3)(q21;q26.2) have a poor prognosis. Indeed, the inv(3)(q21q26.2)/t(3;3)(q21;q26.2) has been recognized as a poor risk karyotype in the revised International Prognostic Scoring System. However, inv(3)(q21q26.2)/t(3;3)(q21;q26.2) is not among the cytogenetic abnormalities pathognomonic for diagnosis of acute myeloid leukemia irrespective of blast percentage in the 2008 WHO classification. This multicenter study evaluated the clinico-pathological features of acute myeloid leukemia/myelodysplastic syndrome patients with inv(3)(q21q26.2)/t(3;3)(q21;q26.2) and applied the revised International Prognostic Scoring System to myelodysplastic syndrome patients with inv(3)(q21q26.2)/t(3;3)(q21;q26.2). A total of 103 inv(3)(q21q26.2)/t(3;3)(q21;q26.2) patients were reviewed and had a median bone marrow blast count of 4% in myelodysplastic syndrome (n=40) and 52% in acute myeloid leukemia (n=63) (P<0.001). Ninety-one percent of patients showed characteristic dysmegakaryopoiesis. There was no difference in overall survival between acute myeloid leukemia and myelodysplastic syndrome patients with inv(3)(q21q26.2)/t(3;3)(q21;q26.2) (12.9 vs. 7.9 months; P=0.16). Eighty-three percent of patients died (median follow up 7.9 months). Complex karyotype, monosomal karyotype and dysgranulopoiesis (but not blast percentage) were independent poor prognostic factors in the entire cohort on multivariable analysis. The revised International Prognostic Scoring System better reflected overall survival of inv(3)(q21q26.2)/t(3;3)(q21;q26.2) than the International Prognostic Scoring System but did not fully reflect the generally dismal prognosis. Our data support consideration of myelodysplastic syndrome with inv(3)(q21q26.2)/t(3;3)(q21;q26.2) as an acute myeloid leukemia with recurrent genetic abnormalities, irrespective of blast percentage.

Dose intensification of daunorubicin and cytarabine during treatment of adult acute lymphoblastic leukemia: results of Cancer and Leukemia Group B Study 19802.

BACKGROUND: Cancer and Leukemia Group B (CALGB) Study 19802, a phase 2 study, evaluated whether dose intensification of daunorubicin and cytarabine could improve disease-free survival (DFS) in adults with acute lymphoblastic leukemia (ALL) and whether high-dose systemic and intrathecal methotrexate could replace cranial radiotherapy for central nervous system (CNS) prophylaxis. METHODS: One hundred sixty-one eligible, previously untreated patients ages 16 to 82 years (median age, 40 years) were enrolled, and 33 (20%) were aged ≥60 years. RESULTS: One hundred twenty-eight patients (80%) achieved complete remission (CR). Dose intensification of daunorubicin and cytarabine was feasible. At a median follow-up of 10.4 years for surviving patients, the 5-year DFS rate was 25% (95% confidence interval, 18%-33%), and the overall survival (OS) rate was 30% (95% confidence interval, 23%-37%). Patients aged <60 years who received the 80 mg/m(2) dose of daunorubicin had a DFS of 33% (95% confidence interval, 22%-44%) and an OS of 39% (95% confidence interval, 29%-49%) at 5 years. Eighty-four patients (52%) relapsed, including 9 patients (6%) who had isolated CNS relapses. The omission of cranial irradiation did not result in higher than historic CNS relapse rates. CONCLUSIONS: Intensive systemic, oral, and intrathecal methotrexate dosing permitted the omission of CNS irradiation in adult patients with ALL. This intensive approach using higher doses of daunorubicin and cytarabine failed to result in an overall improvement in DFS or OS compared with historic CALGB studies. Future therapeutic strategies for adults with ALL should be tailored to specific age and molecular genetic subsets.

P-glycoprotein inhibition using valspodar (PSC-833) does not improve outcomes for patients younger than age 60 years with newly diagnosed acute myeloid leukemia: Cancer and Leukemia Group B study 19808.

Cancer and Leukemia Group B 19808 (CALGB 19808) is the only randomized trial of a second-generation P-glycoprotein (Pgp) modulator in untreated patients with acute myeloid leukemia (AML) younger than age 60 years. We randomly assigned 302 patients to receive induction chemotherapy regimens consisting of cytosine arabinoside (Ara-C; A), daunorubicin (D), and etoposide (E), without (ADE) or with (ADEP) PSC-833 (P). The incidence of complete remission was 75% with both regimens. Reversible grade 3 and 4 liver and mucosal toxicities were significantly more common with ADEP. Therapy-related mortality was 7% and did not differ by induction arm. Excess cardiotoxicity was not seen with high doses of D in ADE. The median disease-free survival was 1.34 years in the ADE arm and 1.09 years in the ADEP arm (P = .74, log-rank test); the median overall survival was 1.86 years in the ADE arm and 1.69 years in the ADEP arm (P = .82). There was no evidence of a treatment difference within any identifiable patient subgroup. Inhibition of Pgp-mediated drug efflux by PSC-833 did not improve clinical outcomes in younger patients with untreated AML. This trial was registered at www.clinicaltrials.gov as #NCT00006363.

The 2008 revision of the World Health Organization (WHO) classification of myeloid neoplasms and acute leukemia: rationale and important changes.

Recently the World Health Organization (WHO), in collaboration with the European Association for Haematopathology and the Society for Hematopathology, published a revised and updated edition of the WHO Classification of Tumors of the Hematopoietic and Lymphoid Tissues. The 4th edition of the WHO classification incorporates new information that has emerged from scientific and clinical studies in the interval since the publication of the 3rd edition in 2001, and includes new criteria for the recognition of some previously described neoplasms as well as clarification and refinement of the defining criteria for others. It also adds entities-some defined principally by genetic features-that have only recently been characterized. In this paper, the classification of myeloid neoplasms and acute leukemia is highlighted with the aim of familiarizing hematologists, clinical scientists, and hematopathologists not only with the major changes in the classification but also with the rationale for those changes.

Myelodysplastic/myeloproliferative neoplasms.

The myelodysplastic/myeloproliferative neoplasms (MDS/MPN) include clonal myeloid neoplasms that overlap the MDS and MPN categories and at the time of initial diagnosis exhibit some clinical, laboratory, or morphologic features supporting the diagnosis of myelodysplastic syndrome (MDS) and at the same time show proliferative features in keeping with the diagnosis of a myeloproliferative neoplasm (MPN). Although the clinical, morphologic, and laboratory findings vary along a continuum from MDS to MPN, distinctive features are usually present that allow assignment of most of the cases to 1 of 3 distinct subtypes recognized by the 2008 World Health Organization (WHO) classification: chronic myelomonocytic leukemia (CMML), atypical chronic myeloid leukemia, BCR-ABL(-)(aCML, BCR-ABL1(-)), and juvenile myelomonocytic leukemia (JMML). The WHO classification also recognizes a provisional category of the MDS/MPN, unclassifiable (MDS/MPN, U), including the provisional entity of refractory anemia with ring sideroblasts and thrombocytosis (RARS-T). In the past 2 to 3 years since the publication of the WHO classification in 2008, dynamic progress in array technologies and next-generation amplicon deep sequencing has provided new insights into the molecular pathogenesis of MDS/MPN, especially CMML and JMML. In this review we will give an overview of these neoplasms and focus on adult MDS/MPN, especially CMML. We will give only brief updates for aCML and RARS-T; JMML will be discussed in a separate article.

What determines the outcomes for adolescents and young adults with acute lymphoblastic leukemia treated on cooperative group protocols? A comparison of Children's Cancer Group and Cancer and Leukemia Group B studies.

We performed a retrospective comparison of presenting features, planned treatment, complete remission (CR) rate, and outcome of 321 adolescents and young adults (AYAs) ages 16 to 20 years with newly diagnosed acute lymphoblastic leukemia (ALL) who were treated on consecutive trials in either the Children's Cancer Group (CCG) or the Cancer and Leukemia Group B (CALGB) from 1988 to 2001. CR rates were identical, 90% for both CALGB and CCG AYAs. CCG AYAs had a 63% event-free survival (EFS) and 67% overall survival (OS) at 7 years in contrast to the CALGB AYAs, in which 7-year EFS was only 34% (P < .001; relative hazard rate [RHR] = 2.2) and OS was 46% (P < .001; RHR = 1.9). While CALGB AYAs aged 16 to 17 years achieved similar outcomes to all CCG AYAs with a 7-year EFS of 55%, the EFS for 18- to 20-year-old CALGB patients was only 29%. Comparison of the regimens showed that CCG AYAs received earlier and more intensive central nervous system prophylaxis and higher cumulative doses of nonmyelosuppressive agents. There were no differences in outcomes of those who reached maintenance therapy on time compared with those who were delayed. Based on these observations, a prospective study for AYAs with ALL using the more successful approach of the CCG has been initiated.

Megakaryocytic blast crisis as a presenting manifestation of chronic myeloid leukemia.

Acute megakaryocytic leukemia is a rare form of acute myelogenous leukemia and may occur either de novo or by transformation of a preexisting myelodysplastic or myeloproliferative process including blast crisis of chronic myeloid leukemia (CML). Megakaryocytic blast crisis as the presenting manifestation of CML is extremely rare. We describe such a patient with no prior hematologic disease who presented with acute megakaryoblastic leukemia and extramedullary involvement, in whom the leukemic cells carried the BCR-ABL1 translocation as part of a complex karyotype. Using targeted sequential fluorescence in situ hybridization (T-FISH) technique, we detected two copies of BCR-ABL1 fusion gene in the leukemic blasts while the neutrophils carried a single copy of BCR-ABL1 fusion gene, thereby proving the origin of the megakaryoblastic leukemia from a previously undiagnosed CML clone. Blast crisis as a presenting manifestation of CML is rare and detecting clonal evolution of acute leukemia by specialized cytogenetic techniques may have important diagnostic and therapeutic implications.

Author Correction: RNA cytosine methylation and methyltransferases mediate chromatin organization and 5-azacytidine response and resistance in leukaemia.

In the originally published version of this Article, the GAPDH loading control blot in Fig. 1a was inadvertently replaced with a duplicate of the DNMT2 blot in the same panel during assembly of the figure. This has now been corrected in both the PDF and HTML versions of the Article.

RNA cytosine methylation and methyltransferases mediate chromatin organization and 5-azacytidine response and resistance in leukaemia.

The roles of RNA 5-methylcytosine (RNA:m5C) and RNA:m5C methyltransferases (RCMTs) in lineage-associated chromatin organization and drug response/resistance are unclear. Here we demonstrate that the RCMTs, namely NSUN3 and DNMT2, directly bind hnRNPK, a conserved RNA-binding protein. hnRNPK interacts with the lineage-determining transcription factors (TFs), GATA1 and SPI1/PU.1, and with CDK9/P-TEFb to recruit RNA-polymerase-II at nascent RNA, leading to formation of 5-Azacitidine (5-AZA)-sensitive chromatin structure. In contrast, NSUN1 binds BRD4 and RNA-polymerase-II to form an active chromatin structure that is insensitive to 5-AZA, but hypersensitive to the BRD4 inhibitor JQ1 and to the downregulation of NSUN1 by siRNAs. Both 5-AZA-resistant leukaemia cell lines and clinically 5-AZA-resistant myelodysplastic syndrome and acute myeloid leukaemia specimens have a significant increase in RNA:m5C and NSUN1-/BRD4-associated active chromatin. This study reveals novel RNA:m5C/RCMT-mediated chromatin structures that modulate 5-AZA response/resistance in leukaemia cells, and hence provides a new insight into treatment of leukaemia.

Primary myelofibrosis (PMF), post polycythemia vera myelofibrosis (post-PV MF), post essential thrombocythemia myelofibrosis (post-ET MF), blast phase PMF (PMF-BP): Consensus on terminology by the international working group for myelofibrosis research and treatment (IWG-MRT).

The International Working Group for Myelofibrosis Research and Treatment (IWG-MRT) is comprised of hematologists, hematopathologists, and laboratory scientists and its main goal is to provide a forum for scientific exchange and collaboration. During its first general meeting in April 2006, the IWG-MRT established uniform treatment response criteria for chronic idiopathic myelofibrosis (CIMF); also known as agnogenic myeloid metaplasia (AMM), myelofibrosis with myeloid metaplasia (MMM), and many other names in the hematologic literature. This document summarizes the proceedings from the second meeting of the IWG-MRT, in November 2006, where the group discussed and agreed to standardize the nomenclature referring to CIMF: (i) the term primary myelofibrosis (PMF) was chosen over several other designations including CIMF, AMM, and MMM, (ii) myelofibrosis that develops in the setting of either polycythemia vera (PV) or essential thrombocythemia (ET) will be referred to as post-PV MF and post-ET MF, respectively, and (iii) "leukemic" transformation will be recognized as blast phase disease (PMF-BP, post-PV/ET MF in blast phase).

Therapy-related myelodysplastic syndrome: morphologic subclassification may not be clinically relevant.

In practice, cases of therapy-related myelodysplastic syndrome (t-MDS) are often classified according to morphologic schemes used for de novo MDS. However, there are few data addressing the appropriateness of such classification. We studied 155 patients with therapy-related acute myeloid leukemia (t-AML)/t-MDS to determine whether subclassification by the World Health Organization (WHO) criteria for de novo MDS provides prognostic information in t-MDS. In addition, we assessed whether cytogenetic stratification by the International Prognostic Scoring System (IPSS) guidelines or karyotypic complexity was prognostically important. We found no differences in median survival times among patients classified into the different WHO subgroup of MDS or according to their bone marrow blast percentage; our results indicate a uniformly poor outcome in t-MDS regardless of morphologic classification. However, significant survival differences correlated with cytogenetic stratification according to IPSS guidelines and/or karyotypic complexity. We found only a borderline difference in median survival of patients with an initial t-MDS diagnosis compared with patients with an initial t-AML diagnosis.

Initial Diagnostic Workup of Acute Leukemia: Guideline From the College of American Pathologists and the American Society of Hematology.

CONTEXT: - A complete diagnosis of acute leukemia requires knowledge of clinical information combined with morphologic evaluation, immunophenotyping and karyotype analysis, and often, molecular genetic testing. Although many aspects of the workup for acute leukemia are well accepted, few guidelines have addressed the different aspects of the diagnostic evaluation of samples from patients suspected to have acute leukemia. OBJECTIVE: - To develop a guideline for treating physicians and pathologists involved in the diagnostic and prognostic evaluation of new acute leukemia samples, including acute lymphoblastic leukemia, acute myeloid leukemia, and acute leukemias of ambiguous lineage. DESIGN: - The College of American Pathologists and the American Society of Hematology convened a panel of experts in hematology and hematopathology to develop recommendations. A systematic evidence review was conducted to address 6 key questions. Recommendations were derived from strength of evidence, feedback received during the public comment period, and expert panel consensus. RESULTS: - Twenty-seven guideline statements were established, which ranged from recommendations on what clinical and laboratory information should be available as part of the diagnostic and prognostic evaluation of acute leukemia samples to what types of testing should be performed routinely, with recommendations on where such testing should be performed and how the results should be reported. CONCLUSIONS: - The guideline provides a framework for the multiple steps, including laboratory testing, in the evaluation of acute leukemia samples. Some aspects of the guideline, especially molecular genetic testing in acute leukemia, are rapidly changing with new supportive literature, which will require on-going updates for the guideline to remain relevant.

Prognostic factors and outcome of core binding factor acute myeloid leukemia patients with t(8;21) differ from those of patients with inv(16): a Cancer and Leukemia Group B study.

PURPOSE: Because both t(8;21) and inv(16) disrupt core binding factor (CBF) in acute myeloid leukemia (AML) and confer relatively favorable prognoses, these cytogenetic groups are often treated similarly. Recent studies, however, have shown different gene profiling for the two groups, underscoring potential biologic differences. Therefore, we sought to determine whether these two cytogenetic groups should also be considered separate entities from a clinical standpoint. PATIENTS AND METHODS: We analyzed 144 consecutive adults with t(8;21) and 168 with inv(16) treated on Cancer and Leukemia Group B front-line studies. We compared pretreatment features, probability of achieving complete remission (CR), overall survival (OS) and cumulative incidence of relapse (CIR) between the two groups. RESULTS: With a median follow-up of 6.4 years, for CBF AML as a whole, the CR rate was 88%, 5-year OS was 50% and CIR was 53%. After adjusting for covariates, patients with t(8;21) had shorter OS (hazard ratio [HR] = 1.5; P = .045) and survival after first relapse (HR = 1.7; P = .009) than patients with inv(16). Unexpectedly, race was an important predictor for t(8;21) AML, in that nonwhites failed induction more often (odds ratio = 5.7; P = .006) and had shorter OS than whites when certain secondary cytogenetic abnormalities were present. In patients with t(8;21) younger than 60 years, type of induction also correlated with relapse risk. For inv(16) AML, secondary cytogenetic abnormalities (especially +22) and male sex predicted better outcome. CONCLUSION: When the prognostic impact of race, secondary cytogenetic abnormalities, sex, and response to salvage treatment is considered, t(8;21) and inv(16) AMLs seem to be distinct clinical entities and should be stratified and reported separately.

Outcome of induction and postremission therapy in younger adults with acute myeloid leukemia with normal karyotype: a cancer and leukemia group B study.

PURPOSE: Evaluate the outcome of induction and postremission therapy in adults younger than 60 years with normal cytogenetics acute myeloid leukemia (AML). PATIENTS AND METHODS: In 490 patients, induction included cytarabine and daunorubicin (AD) or cytarabine and escalated doses of daunorubicin and etoposide +/- PSC-833 (ADE/ADEP). Intensification included one cycle of high-dose cytarabine (HDAC) followed by etoposide/cyclophosphamide and mitoxantrone/diaziquone (group I), three HDAC cycles (group II), four intermediate-dose cytarabine (IDAC) or HDAC cycles (group III), or one HDAC/etoposide cycle and autologous stem-cell transplantation (ASCT; group IV). RESULTS: Of 350 patients receiving AD, 73% achieved complete remission (CR), compared with 82% of 140 receiving ADE/ADEP (P = .04). Splenomegaly was associated with a lower CR rate (P < .001), and ADE/ADEP, with a higher CR rate in younger patients (P = .005). The 5-year disease-free survival (DFS) rate was 28% each for intensification groups I and II, compared with 41% and 45% for groups III and IV, respectively (P = .02). The 5-year cumulative incidence of relapse (CIR) was 62% and 67% for groups I and II, respectively, compared with 54% and 44% for groups III and IV, respectively (P = .049). The type of postremission intensification remained significant for DFS and CIR in multivariable analysis. CONCLUSION: In younger adults with normal cytogenetics AML, splenomegaly predicts a lower CR rate, and the postremission strategies of either four cycles of I/HDAC or one cycle of HDAC/etoposide followed by ASCT are associated with improved DFS and reduced relapse compared with therapies that include fewer cycles of cytarabine or no transplantation.

Overexpression of the ETS-related gene, ERG, predicts a worse outcome in acute myeloid leukemia with normal karyotype: a Cancer and Leukemia Group B study.

PURPOSE: To test the prognostic significance of ETS-related gene (ERG) expression in cytogenetically normal primary acute myeloid leukemia (AML). PATIENTS AND METHODS: Pretreatment blood samples from 84 cytogenetically normal AML patients aged less than 60 years, who were characterized for BAALC expression, FLT3 internal tandem duplication (ITD), and MLL partial tandem duplication (PTD) and uniformly treated on Cancer and Leukemia Group B 9621 protocol, were analyzed for ERG expression by real-time reverse transcriptase polymerase chain reaction. Patients were divided into quartiles according to ERG levels and were compared for clinical outcome. High-density oligonucleotide arrays were used to identify genes differentially expressed between high and low ERG expressers. RESULTS: With a median follow-up of 5.7 years, patients with the upper 25% of ERG expression values had a worse cumulative incidence of relapse (CIR; P < .001) and overall survival (OS; P = .011) than the remaining patients. In a multivariable analysis, high ERG expression (P < .001) and the presence of MLL PTD (P = .027) predicted worse CIR. With regard to OS, an interaction was observed between expression of ERG and BAALC (P = .013), with ERG overexpression predicting shorter survival only in low BAALC expressers (P = .002). ERG overexpression was an independent prognostic factor even when the unfavorable group of FLT3 ITD patients lacking an FLT3 wild-type allele was included. High ERG expression was associated with upregulation of 112 expressed-sequenced tags and named genes, many of which are involved in cell proliferation, differentiation, and apoptosis. CONCLUSION: ERG overexpression in AML patients with normal cytogenetics predicts an adverse clinical outcome and seems to be associated with a specific molecular signature.