Molecular predictors of immunophenotypic measurable residual disease clearance in acute myeloid leukemia.

Measurable residual disease (MRD) is a powerful prognostic factor in acute myeloid leukemia (AML). However, pre-treatment molecular predictors of immunophenotypic MRD clearance remain unclear. We analyzed a dataset of 211 patients with pre-treatment next-generation sequencing who received induction chemotherapy and had MRD assessed by serial immunophenotypic monitoring after induction, subsequent therapy, and allogeneic stem cell transplant (allo-SCT). Induction chemotherapy led to MRD- remission, MRD+ remission, and persistent disease in 35%, 27%, and 38% of patients, respectively. With subsequent therapy, 34% of patients with MRD+ and 26% of patients with persistent disease converted to MRD-. Mutations in CEBPA, NRAS, KRAS, and NPM1 predicted high rates of MRD- remission, while mutations in TP53, SF3B1, ASXL1, and RUNX1 and karyotypic abnormalities including inv (3), monosomy 5 or 7 predicted low rates of MRD- remission. Patients with fewer individual clones were more likely to achieve MRD- remission. Among 132 patients who underwent allo-SCT, outcomes were favorable whether patients achieved early MRD- after induction or later MRD- after subsequent therapy prior to allo-SCT. As MRD conversion with chemotherapy prior to allo-SCT is rarely achieved in patients with specific baseline mutational patterns and high clone numbers, upfront inclusion of these patients into clinical trials should be considered.

Atypical cutaneous histiocytic eruption in a patient with chronic myelomonocytic leukemia: A case report.

Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic stem cell malignancy with features of both a myeloproliferative neoplasm and a myelodysplastic syndrome. We present a case of 72-year-old man with CMML who presented with generalized hemorrhagic papules and plaques which on histopathology showed a peculiar infiltrate of atypical mature histiocytes. The immunohistochemical markers for Langerhans cells, indeterminate dendritic cells, and plasmacytoid dendritic cells were negative. Next generation sequencing performed on the paraffin block of the leg biopsy specimen revealed identical ASXL1, SRSF2, and KRAS mutations as seen in the CMML clone of the peripheral blood. Along with recent literature, this case illustrates the spectrum of histiocytic and dendritic cell proliferations in CMML, many of which may be clonally related to the hematopoietic malignancy.

Pre- and post-bone marrow harvest anaemia is associated with lower CD34+ stem cell collection, high harvest volume and female gender.

BACKGROUND: Donor safety is paramount when performing bone marrow stem cell harvest. The incidence of full blood count (FBC) abnormalities among donors and variables associated with anaemia after marrow harvest are not well established. AIMS: To describe the frequency of FBC abnormalities prior to bone marrow stem cell harvest and to identify variables associated with post harvest anaemia. METHODS: Outcomes of 80 consecutive adult marrow harvests performed at our centre were analysed retrospectively. RESULTS: FBC abnormalities were present in 28% of donors prior to marrow harvest with normocytic anaemia the most common abnormality in 13%. Reduced donor haemoglobin (Hb) was independently correlated with lower CD34+ cell count per kg of recipient body weight. Anaemia (Hb < 100 g/L) was seen in 20% of donors after harvest with median decrease in Hb of 19 g/L. Variables independently associated with anaemia after harvest included donor to recipient weight ratio (P = 0.011), high collection volume (P = 0.044) and female gender (P = 0.023). Total nucleated cell and CD34 concentration in the final collected product were associated with the inverse of harvested marrow volume (P < 0.001). CONCLUSIONS: Pre-harvest anaemia should be corrected where possible particularly in female donors. Marrow collection volume should be minimised to reduce post-harvest anaemia, optimise CD34+ cell number and improve nucleated and stem cell concentrations in the harvest product.

Prognostic impact of RAS-pathway mutations in patients with myelofibrosis.

RAS-pathway mutations are recurrent events in myeloid malignancies. However, there is limited data on the significance of RAS-pathway mutations in patients with myelofibrosis (MF). We analyzed next-generation sequencing data of 16 genes, including RAS-pathway genes, from 723 patients with primary and secondary MF across three international centers and evaluated their significance. N/KRAS variants were present in 6% of patients and were typically sub-clonal (median VAF = 20%) relative to other genes variants. RAS variants were associated with advanced MF features including leukocytosis (p = 0.02), high somatic mutation burden (p < 0.01) and the presence of established "molecular high-risk" (MHR) mutations. MF patients with N/KRAS mutations had shorter 3-year overall survival (OS) (34% vs 58%, p < 0.001) and higher incidence of acute myeloid leukemia at 3 years (18% vs 11%, p = 0.03). In a multivariate Cox model, RAS mutations were associated with decreased OS (HR 1.93, p < 0.001). We created a novel score to predict OS incorporating RAS mutations, and it predicted OS across training and validation cohorts. Patients with intermediate risk/high-risk DIPSS with RAS mutations who received ruxolitinib had a nonsignificant longer 2-year OS relative to those who did not receive ruxolitinib. These data demonstrate the importance of identifying RAS mutations in MF patients.

Loss of plasmacytoid dendritic cell differentiation is highly predictive for post-induction measurable residual disease and inferior outcomes in acute myeloid leukemia.

Measurable residual disease is associated with inferior outcomes in patients with acute myeloid leukemia (AML). Measurable residual disease monitoring enhances risk stratification and may guide therapeutic intervention. The European LeukemiaNet working party recently came to a consensus recommendation incorporating leukemia associated immunophenotype-based different from normal approach by multi-color flow cytometry for measurable residual disease evaluation. However, the analytical approach is highly expertise-dependent and difficult to standardize. Here we demonstrate that loss of plasmacytoid dendritic cell differentiation after 7+3 induction in AML is highly specific for measurable residual disease positivity (specificity 97.4%) in a uniformly treated patient cohort. Moreover, loss of plasmacytoid dendritic cell differentiation as determined by a blast-to-plasmacytoid dendritic cell ratio >10 was strongly associated with inferior overall and relapse-free survival (RFS) [Hazard ratio 2.79, 95% confidence interval (95%CI): 0.98-7.97; P=0.077) and 3.83 (95%CI: 1.51-9.74; P=0.007), respectively), which is similar in magnitude to measurable residual disease positivity. Importantly, measurable residual disease positive patients who reconstituted plasmacytoid dendritic cell differentiation (blast/ plasmacytoid dendritic cell ratio <10) showed a higher rate of measurable residual disease clearance at later pre-transplant time points compared to patients with loss of plasmacytoid dendritic cell differentiation (blast/ plasmacytoid dendritic cell ratio <10) (6 of 12, 50% vs 2 of 18, 11%; P=0.03). Furthermore pre-transplant plasmacytoid dendritic cell recovery was associated with superior outcome in measurable residual disease positive patients. Our study provides a novel, simple, broadly applicable, and quantitative multi-color flow cytometry approach to risk stratification in AML.

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.

Disease characteristics and clinical outcomes in patients aged less than 40 with chronic lymphocytic leukemia.

Outcomes in very young CLL patients (age ≤40) are not well characterized. We compared 71 consecutive patients aged ≤40 with 142 "older" matched patients >40 from our institution and used SEER database as an independent comparison group. Patients in the two age groups were diagnosed at similar Rai stage. At diagnosis, very young patients had a similar rate of adverse cytogenetics, IGHV mutation and ZAP70 expression and had lower beta-2-microglobulin and a lower incidence of second malignancies. There was no difference between the groups with respect to incidence of autoimmune manifestations, family history of lymphoma, time to initiation of CLL therapy, response to therapy, or Richter's transformation. Variables including un-mutated IGHV and elevated LDH were associated with shorter times to treatment initiation in both groups. A trend to longer 5-year survival for very young patients in our institution (93% v 82%, p = 0.082) was validated by SEER data.

Acute myeloid leukaemia relapsing after allogeneic haemopoietic stem cell transplantation: prognostic factors and impact of initial therapy of relapse.

BACKGROUND/AIMS: We sought to determine factors associated with the overall survival from relapse (OSR) of acute myeloid leukaemia (AML) after allogeneic haemopoietic stem cell transplantation (alloHSCT) and the effect of first salvage therapy and subsequent graft-versus-host disease (GVHD) on OSR. METHODS: Data on 386 patients from nine Australian centres with relapsed AML post-alloHSCT were collected retrospectively. OSR was calculated using the Kaplan-Meier method. Univariate and multivariate analyses were conducted using the log-rank test and proportional hazards modelling, respectively and a prognostic index for OSR was derived from multivariate modelling. RESULTS: On multivariate analysis, relapse within 6 months (hazard ratio (HR) 2.4, P < 0.001) and grade 3-4 acute GVHD preceding relapse (HR 2.0, P = 0.004), were associated with inferior OSR. Patients with 1-2 factors had inferior OSR compared to those with zero factors (all patients: HR 2.3, P < 0.001, patients given salvage: HR 1.8, P < 0.001). The first salvage therapy used post-relapse was donor cell therapy (DCT) (second alloHSCT or donor lymphocyte infusion) in 75, re-induction chemotherapy (CT) in 103, radiotherapy in 8 and interferon-α in 6. Although re-induction CT death rate was low (2%), survival after CT was inferior to DCT (HR 1.9, P < 0.001). No survival benefit was seen for patients who developed GVHD following salvage therapy (P = 0.405). CONCLUSION: Patients with AML who relapse beyond 6 months from alloHSCT without prior grade 3-4 acute GVHD have a better outcome from salvage therapy. Salvage treatments employing DCT as the initial treatment of AML relapse confer a survival advantage over CT.

Genomic analysis of hairy cell leukemia identifies novel recurrent genetic alterations.

Classical hairy cell leukemia (cHCL) is characterized by a near 100% frequency of the BRAFV600E mutation, whereas ∼30% of variant HCLs (vHCLs) have MAP2K1 mutations. However, recurrent genetic alterations cooperating with BRAFV600E or MAP2K1 mutations in HCL, as well as those in MAP2K1 wild-type vHCL, are not well defined. We therefore performed deep targeted mutational and copy number analysis of cHCL (n = 53) and vHCL (n = 8). The most common genetic alteration in cHCL apart from BRAFV600E was heterozygous loss of chromosome 7q, the minimally deleted region of which targeted wild-type BRAF, subdividing cHCL into those hemizygous versus heterozygous for the BRAFV600E mutation. In addition to CDKN1B mutations in cHCL, recurrent inactivating mutations in KMT2C (MLL3) were identified in 15% and 25% of cHCLs and vHCLs, respectively. Moreover, 13% of vHCLs harbored predicted activating mutations in CCND3 A change-of-function mutation in the splicing factor U2AF1 was also present in 13% of vHCLs. Genomic analysis of de novo vemurafenib-resistant cHCL identified a novel gain-of-function mutation in IRS1 and losses of NF1 and NF2, each of which contributed to resistance. These data provide further insight into the genetic bases of cHCL and vHCL and mechanisms of RAF inhibitor resistance encountered clinically.

Allogeneic Hematopoietic Stem Cell Transplantation with Myeloablative Conditioning Is Associated with Favorable Outcomes in Mixed Phenotype Acute Leukemia.

Mixed phenotype acute leukemia (MPAL) represents a poorly characterized group of acute leukemias that lack an accepted therapeutic approach and are typically associated with poor outcomes. We present our experience of genomic profiling, pretransplantation therapy, and transplantation outcomes for 36 well-characterized pediatric and adult patients with MPAL, defined according to the 2016 World Health Organization leukemia update. A predominance of acute lymphoid leukemia (ALL)-associated mutations and cytogenetic abnormalities was noted. Remission rates after induction appeared comparable among adults (20 of 23) and children (11 of 13) and among those who received ALL (10 of 11) or acute myeloid leukemia-type (21 of 25) induction. Adults underwent transplantation in first remission while children underwent transplantation in the setting of relapse or MLL rearrangement. The median follow-up among the 25 patients who underwent transplantation was 39.6 months and median overall survival was not reached. Relapse after transplantation was associated with MLL rearrangement (P = .022), reduced-intensity conditioning (P < .001), and higher WBC at diagnosis (P = .034). These data highlight differing therapeutic approaches between adult and pediatric MPAL and demonstrate favorable survival of adult MPAL patients consolidated with allogeneic hematopoietic cell transplantation.

Multicolor Flow Cytometry and Multigene Next-Generation Sequencing Are Complementary and Highly Predictive for Relapse in Acute Myeloid Leukemia after Allogeneic Transplantation.

Minimal residual disease (MRD) in acute myeloid leukemia (AML) is typically measured using multiparameter flow cytometry (MFC). Detection of leukemia mutations using multigene next-generation sequencing (NGS) can potentially be used to measure residual disease. We used a targeted 28-gene NGS panel to detect mutations and different-from-normal 10-color MFC to measure MRD in AML patients before allogeneic hematopoietic stem cell transplantation (HCT). Residual disease was defined when any abnormal blast population was detected using MFC and when any leukemia allele was detected with a variant allele frequency (VAF) ≥ 5% using NGS. We tracked the clearance of leukemia alleles between AML diagnosis and immediately before HCT and found that mutations in DNMT3A, TET2, and JAK2 were less likely to be cleared than NPM1, IDH 1/2, and FLT3-ITD. Despite varying sensitivities, the concordance rate of residual disease detection before HCT using the 2 assays was 44 of 62 (71%) evaluable cases. Discordance could be explained by residual mutations in DNMT3A and TET2 that were not detected by MFC and presence of residual leukemia mutations with VAF below the established thresholds for mutation calling. Presence of flow MRD and residual mutations immediately before HCT using the 2 assays was associated with relapse risk (MFC: hazard ratio, 4.62; 95% confidence interval [CI], 1.32 to 16.09; P = .016 and NGS: hazard ratio, 4.35; 95% CI, 1.63 to 11.6; P = .003) and survival (MFC: hazard ratio, 2.44; 95% CI, 1 to 5.97; P = .05 and NGS: hazard ratio, 2.1; 95% CI, .97 to 4.55; P = .059) after HCT. Residual disease detected concurrently by MFC and NGS conferred the highest relapse risk compared with patients who were either negative by both assays or had discordant status (overall, P = .008). Although MFC is universally applicable, a multigene NGS approach to measuring residual disease in AML provides additional information on differential clearance of disease alleles and can assess clonal architecture before transplantation.

Allogeneic Hematopoietic Stem Cell Transplantation Is Underutilized in Older Patients with Myelodysplastic Syndromes.

Allogeneic hematopoietic stem cell transplantation (HCT) is the only curative treatment for myelodysplastic syndrome (MDS). The proportion of MDS patients referred for transplantation evaluation, those undergoing transplantation, and the reasons for not undergoing transplantation are unknown. In this retrospective analysis, predefined HCT eligibility and indications criteria were applied to 362 unselected patients with newly diagnosed MDS seen by leukemia faculty between 2008 and 2015 at Memorial Sloan Kettering Cancer Center. Two hundred ninety-four patients (81%) were deemed eligible for transplantation and among these, transplantation was considered indicated in 244 (83%). Of these, 158 of 244 (65%) were referred for transplantation evaluation at a median of 3.9 months from diagnosis. Overall 120 of 362 (33%) underwent transplantation at a median of 7.7 months from diagnosis. Metastatic solid-organ malignancy was the major reason for transplantation ineligibility (54%), and death due to MDS, which occurred in 41% of candidates who did not undergo transplantation, was the major reason for not undergoing transplantation. Factors associated with a lower likelihood of referral for transplantation evaluation included age ≥65 (P < .001), ≥2 comorbidities (P = .008), intermediate-1/low risk MDS (P < .001), <5% blasts at diagnosis (overall P < .001), having Medicare/Medicaid health insurance (P < .001), not being married (P = .017), and diagnosis between 2008 and 2011 (P = .035). On multivariate analysis adjusting for all of the previous factors, diagnosis between 2008 and 2011 (P < .001), age ≥65 (P = .001), and <5% blasts at diagnosis (overall P = .031) were associated with a lower likelihood of referral for transplantation evaluation. Factors associated with a lower likelihood of undergoing transplantation included age ≥65 (P < .001), ≥2 comorbidities (P = .003), intermediate-1/low risk MDS (P < .001), <5% blasts (overall P < .001), very low/low/intermediate risk International Prognostic Scoring System-revised karyotype (P = .018), and having Medicare/Medicaid health insurance (P < .001). In multivariate analysis adjusting for all of the previous factors, age ≥65 (P = .021), presence of ≥2 comorbidities (P = .018), and <5% blasts (overall P = .011) were associated with a lower likelihood of undergoing transplantation. The results highlight that transplantation for MDS remains underutilized, particularly for candidates over the age of 65.

Treatment outcomes and secondary cancer incidence in young patients with hairy cell leukaemia.

Repeated therapy of hairy cell leukaemia (HCL) with treatments that have potential long-term toxicities has raised concerns regarding increased risk for younger patients. We compared clinical outcomes and disease complications in 63 patients with HCL aged ≤40 years at diagnosis with 268 patients >40 years treated at Memorial Sloan Kettering Cancer Center. The rate of complete remission following initial therapy was 87% and 83% (P = 0·71) and estimated 10-year overall survival was 100% and 82% (P = 0·25) in younger and older patients, respectively. Younger patients required therapy earlier and had a significantly shorter time between first and second therapy (median: 63 months vs. 145 months) (P = 0·008). Younger patients required significantly more lines of therapy during follow-up. The 10-year cumulative incidence of secondary malignancies in young and old patients was 0·205 and 0·287, respectively (P = 0·22). The incidence of secondary cancers in patients aged >40 years at diagnosis increased with the number of treatments for HCL (P = 0·018). These results highlight that young patients with HCL have shorter responses to treatment and require more lines of therapy to maintain disease control, while attaining similar long-term survival. This has implications in the design of future clinical trials given our findings that secondary malignancies increase with more chemotherapy exposure.

Hairy cell leukemia: Past, present and future.

This brief review highlights the sequence of therapeutic milestones and advances in our understanding of the biology of hairy cell leukemia (HCL) with a focus on recent molecular findings and how these may be applied to improve disease outcomes in the future. Targeted therapy is discussed in the context of the recently identified BRAF mutation and other genetic findings.