Phototherapy and topical treatments for cutaneous graft vs. host disease in haematopoietic stem cell transplantation patients: a scoping review.

Skin is usually the first and most affected organ involved in graft-versus-host disease (GvHD), and treatment is still a clinical challenge. Although the need for skin-directed treatments such as physical treatments and topical medications are generally agreed on, what the gold standard treatment strategy should be remains open to debate. The aim of this scoping review was to synthesize the current knowledge on the topical and physical treatments of cutaneous GvHD in haematopoietic stem cell transplantation patients and to highlight the best evidence available so as to reduce the gap between 'what is known' and 'what is done' in the clinical practice. Twenty-eight studies were included in this qualitative synthesis. Photo-biomodulation with psoralen was not included in this review. Phototherapy (ultraviolet A or B or narrowband B) was the physical treatment most described in the literature in both acute GvHD and chronic GvHD. Topical calcineurin inhibitors such as tacrolimus ointment and pimecrolimus cream as well as corticosteroid creams such as clobetasol and triamcinolone are mainly used in case of chronic GvHD. In all of the studies included in the review, topical treatments were always associated with systemic therapy. None of the topical interventions identified in our review provided strong evidence supporting its use, and the topical approaches seemed to have an adjuvant role in the treatment of cutaneous GvHD.

Genetic landscape of ultra-stable chronic lymphocytic leukemia patients.

Background: Chronic lymphocytic leukemia (CLL) has a heterogeneous clinical course. Beside patients requiring immediate treatment, others show an initial indolent phase followed by progression and others do not progress for decades. The latter two subgroups usually display mutated IGHV genes and a favorable FISH profile. Patients and methods: Patients with absence of disease progression for over 10 years (10-34) from diagnosis were defined as ultra-stable CLL (US-CLL). Forty US-CLL underwent extensive characterization including whole exome sequencing (WES), ultra-deep sequencing and copy number aberration (CNA) analysis to define their unexplored genetic landscape. Microarray analysis, comparing US-CLL with non-US-CLL with similar immunogenetic features (mutated IGHV/favorable FISH), was also carried out to recognize US-CLL at diagnosis. Results: WES was carried out in 20 US-CLL and 84 non-silent somatic mutations in 78 genes were found. When re-tested in a validation cohort of 20 further US-CLL, no recurrent lesion was identified. No clonal mutations of NOTCH1, BIRC3, SF3B1 and TP53 were found, including ATM and other potential progression driving mutations. CNA analysis identified 31 lesions, none with known poor prognostic impact. No novel recurrent lesion was identified: most cases showed no lesions (38%) or an isolated del(13q) (31%). The expression of 6 genes, selected from a gene expression profile analysis by microarray and quantified by droplet digital PCR on a cohort of 79 CLL (58 US-CLL and 21 non-US-CLL), allowed to build a decision-tree capable of recognizing at diagnosis US-CLL patients. Conclusions: The genetic landscape of US-CLL is characterized by the absence of known unfavorable driver mutations/CNA and of novel recurrent genetic lesions. Among CLL patients with favorable immunogenetics, a decision-tree based on the expression of 6 genes may identify at diagnosis patients who are likely to maintain an indolent disease for decades.

Bleeding phenotype and correlation with factor XI (FXI) activity in congenital FXI deficiency: results of a retrospective study from a single centre.

Bleeding phenotype in factor XI (FXI)-deficient patients is variable, and not related to baseline FXI:Act. Aims of our study were to describe the characteristics and the management of surgery and deliveries in FXI-deficient patients, and to investigate the relationship between the haemorrhagic phenotype and the baseline FXI:Act. Ninety-five patients were diagnosed and followed in our centre for a median follow-up of 0.9 years (0.1-36.2); median FXI:Act of all patients: 38% (0.5-69%). Fifty-six patients (59%) experienced bleeding episodes not surgery-related. Prior to diagnosis, 64 patients underwent 132 surgeries, and after diagnosis, 23 patients underwent 36 surgeries. Globally 26 of 168 surgeries were prophylactically treated, whereas 142 of 168 were not. As regard as surgeries performed without prophylaxis, 30 bleeding events (21%) occurred in 21 patients. At diagnosis, the median FXI:Act of bleeding and non-bleeding patients was 28% and 37%, respectively, without statistically significant difference between the two groups (P = 0.26). As regard as surgeries performed under prophylactic treatment just 1 bleeding event occurred. Prior to diagnosis, 31 spontaneous deliveries (SD) and eight caesarian sections (CS) were performed without prophylaxis: 4 postpartum haemorrhages (10.5%) occurred (patients FXI:Act: 2%, 6%, 27%, 52.3% respectively). After diagnosis, four SD and five CS were performed with prophylaxis: no postpartum haemorrhages occurred. We confirm the wide bleeding phenotype variability in FXI-deficient patients, not related to the baseline FXI:Act levels. We highlight the importance of performing a correct diagnosis and follow-up, because a good management of prophylactic treatment, dramatically reduces the bleeding rate in case of surgery or deliveries.

Strongyloides stercoralis infection in allogeneic stem cell transplant: a case report and review of the literature.

Strongyloides stercoralis infections may be documented in low-endemicity areas, particularly in immigrants from endemic areas. The case of a patient from Bangladesh, an immigrant to Italy who developed a S. stercoralis infection after allogeneic stem cell transplant, is described, and 7 further cases are reviewed. Because of the atypical clinical presentation, the low predictive role of the eosinophil count, and the low sensitivity of the microbiological tests, diagnosis of strongyloidiasis is a challenging problem. When a case of S. stercoralis infection is suspected, previous exposure may be the only clue to guide the diagnostic approach.

Treatment discontinuation following low-dose TKIs in 248 chronic myeloid leukemia patients: Updated results from a campus CML real-life study.

TKIs long-term treatment in CML may lead to persistent adverse events (AEs) that can promote relevant morbidity and mortality. Consequently, TKIs dose reduction is often used to prevent AEs. However, data on its impact on successful treatment-free remission (TFR) are quite scarce. We conducted a retrospective study on the outcome of CML subjects who discontinued low-dose TKIs from 54 Italian hematology centers participating in the Campus CML network. Overall, 1.785 of 5.108 (35.0%) regularly followed CML patients were treated with low-dose TKIs, more frequently due to relevant comorbidities or AEs (1.288, 72.2%). TFR was attempted in 248 (13.9%) subjects, all but three while in deep molecular response (DMR). After a median follow-up of 24.9 months, 172 (69.4%) patients were still in TFR. TFR outcome was not influenced by gender, Sokal/ELTS risk scores, prior interferon, number and last type of TKI used prior to treatment cessation, DMR degree, reason for dose reduction or median TKIs duration. Conversely, TFR probability was significantly better in the absence of resistance to any prior TKI. In addition, patients with a longer DMR duration before TKI discontinuation (i.e., >6.8 years) and those with an e14a2 BCR::ABL1 transcript type showed a trend towards prolonged TFR. It should also be emphasized that only 30.6% of our cases suffered from molecular relapse, less than reported during full-dose TKI treatment. The use of low-dose TKIs does not appear to affect the likelihood of achieving a DMR and thus trying a treatment withdrawal, but might even promote the TFR rate.

Managing hematological cancer patients during the COVID-19 pandemic: an ESMO-EHA Interdisciplinary Expert Consensus.

BACKGROUND: The COVID-19 pandemic has created enormous challenges for the clinical management of patients with hematological malignancies (HMs), raising questions about the optimal care of this patient group. METHODS: This consensus manuscript aims at discussing clinical evidence and providing expert advice on statements related to the management of HMs in the COVID-19 pandemic. For this purpose, an international consortium was established including a steering committee, which prepared six working packages addressing significant clinical questions from the COVID-19 diagnosis, treatment, and mitigation strategies to specific HMs management in the pandemic. During a virtual consensus meeting, including global experts and lead by the European Society for Medical Oncology and the European Hematology Association, statements were discussed and voted upon. When a consensus could not be reached, the panel revised statements to develop consensual clinical guidance. RESULTS AND CONCLUSION: The expert panel agreed on 33 statements, reflecting a consensus, which will guide clinical decision making for patients with hematological neoplasms during the COVID-19 pandemic.

Rearrangements of immunoglobulin and T cell receptor beta and gamma genes are associated with terminal deoxynucleotidyl transferase expression in acute myeloid leukemia.

The cell origin of the rare terminal deoxynucleotidyl transferase (TdT)-positive acute myeloid leukemias (AML) was investigated at the molecular level, by examining the configuration of the Ig H (Igh) and L (Ig kappa, Ig lambda) chain gene regions, and of the T cell receptor (TCR) beta and T cell rearranging (TRG) gamma loci. In 8 of the 10 TdT+ AML analyzed (classified as myeloid according to morphological and cytochemical criteria, and to the reactivity with one or more antimyeloid mAbs), a rearrangement of the Igh chain gene was found. In TdT- AML, evidence of an Igh gene reorganization was instead observed only in 2 of the 42 patients studied. Furthermore, evidence of TCR-beta and/or TRG-gamma gene rearrangement was observed in four AML, all of which belonged to the Igh-rearranged TdT+ group. In three cases (one TdT+ and two TdT-), the Ig kappa L chain gene was also in a rearranged position. These findings demonstrate a highly significant correlation between TdT expression and DNA rearrangements at the Igh and TCR chain gene regions and support the view that this enzyme plays an important role in the V-(D)-J recombination machinery. Overall, the genomic configuration, i.e., JH gene rearrangement sometimes coupled to a kappa L chain and TCR gene reorganization, similar to that found in non-T-ALL, suggests that in most cases of TdT+ AML, the neoplastic clone, despite the expression of myeloid-related features, is characterized by cells molecularly committed along the B cell lineage.

Results of a phase I/II study of ocrelizumab, a fully humanized anti-CD20 mAb, in patients with relapsed/refractory follicular lymphoma.

BACKGROUND: Ocrelizumab is a humanized anti-CD20 antibody with increased antibody-dependent cellular cytotoxicity compared with rituximab. This phase I/II study evaluated its safety and efficacy in patients with relapsed/refractory follicular lymphoma (FL) after prior rituximab therapy. DESIGN AND METHODS: Forty-seven patients were treated in three dose cohorts and received eight infusions every 3 weeks: cohort A, 200 mg/m(2) (n = 15); cohort B, 375 mg/m(2) (n = 16); cohort C, first dose 375 mg/m(2), seven subsequent doses of 750 mg/m(2) (n = 16). Patients were assessed for safety, efficacy, pharmacodynamics and pharmacokinetics. RESULTS: The median patient age was 58 years, the majority had Ann Arbor stage III/IV disease and had received a median of 2 (range 1-6) prior regimens. Ocrelizumab was well tolerated with grade 3/4 toxicity occurring in 9% of patients. The most common toxicity was infusion-related reactions (74% patients), all grade 1/2 except one grade 3 event. The objective response rate was 38% and was similar in patients with low-affinity and high-affinity variants of the Fcgamma receptor IIIa (FcgammaRIIIa). With follow-up of approximately 28 months, the median progression-free survival was 11.4 months. CONCLUSION: Ocrelizumab demonstrated activity in patients with relapsed/refractory FL following prior rituximab treatment, with safety similar to rituximab although adverse events appeared milder.

A Rare Case of Coexisting Breast Cancer and Refractory Acute Myeloid Leukemia.

The occurrence of acute myeloid leukemia (AML) within six months from a diagnosis of breast cancer (BC) is rarely reported in the literature, and it is associated with a poor prognosis. We report herein the case of a 40-year-old woman referred to our centre affected by BC and simultaneous AML. The patient proved refractory to first line therapy and achieved complete remission (CR) with a clofarabine-based regimen followed by allogeneic stem cell transplantation (ASCT). Both during salvage chemotherapy and after ASCT, the patient presented severe infectious complications ( acute cholecistytis and Nocardia pneumonia, respectively) treated with surgery, and currently she is alive in CR for both diseases after 29 months of follow-up. The case highlights the importance of a diagnostic assessment of any unexplained cytopenia in association with solid neoplasia under treatment, underlining the feasibility and priority of a timely treatment of the haematological neoplasm in order to achieve long-term survival.

EBMT prospective observational study on allogeneic hematopoietic stem cell transplantation in T-prolymphocytic leukemia (T-PLL).

Preliminary data suggest that allogeneic stem cell transplantation (allo-SCT) may be effective in T-prolymphocytic leukemia (T-PLL). The purpose of the present observational study was to assess the outcome of allo-SCT in patients aged 65 years or younger with a centrally confirmed diagnosis of T-PLL. Patients were consecutively registered with the EBMT at the time of transplantation and followed by routine EBMT monitoring but with an extended dataset. Between 2007 and 2012, 37 evaluable patients (median age 56 years) were accrued. Pre-treatment contained alemtuzumab in 95% of patients. Sixty-two percent were in complete remission (CR) at the time of allo-SCT. Conditioning contained total body irradiation with 6 Gy or more (TBI6) in 30% of patients. With a median follow-up of 50 months, the 4-year non-relapse mortality, relapse incidence, progression-free (PFS) and overall survival were 32, 38, 30 and 42%, respectively. By univariate analysis, TBI6 in the conditioning was the only significant predictor for a low relapse risk, and an interval between diagnosis and allo-SCT of more than 12 months was associated with a lower NRM. This study confirms for the first time prospectively that allo-SCT can provide long-term disease control in a sizable albeit limited proportion of patients with T-PLL.

PLZF-mediated control on VLA-4 expression in normal and leukemic myeloid cells.

The promyelocytic leukemia zinc-finger protein (PLZF) is a transcriptional repressor. To investigate the role of PLZF in the regulation of cytoadhesion molecules involved in the mobilization of hemopoietic cells, we have analysed PLZF and very late antigen 4 (VLA-4) expression in normal and leukemic cells. In hematopoiesis, we found a negative correlation between PLZF and VLA-4 expression, except for the megakaryocytic lineage. In contrast, we observed a positive correlation between PLZF and VLA-4 expression in a panel of acute myeloid leukemia (AML) samples. In K562 cells expressing PLZF (K562-PLZF), we found that the expression of VLA-4 and c-kit was downmodulated. We have investigated the possibility for VLA-4 or the c-kit receptor to be direct target genes of PLZF in K562-PLZF cells and identified a PLZF DNA-binding site within the VLA-4 promoter. Furthermore, decrease in VLA-4 expression was associated with loss of adhesion on fibronectin-coated plates, which promotes drug-induced apoptosis of K562-PLZF cells. Our findings indicate that VLA-4 is a potential target gene of PLZF. However, in primary AMLs the control of PLZF on VLA-4 expression is lost. Altogether, we suggest that VLA-4 modulation by PLZF may represent an important step in the control of normal and leukemic cell mobilization.

Different stages of B cell differentiation in non-T acute lymphoblastic leukemia.

Immunoglobulin heavy chain gene rearrangement was evaluated in 19 cases of acute lymphoblastic leukemia (ALL) and correlated with the immunological phenotypic expression on primary or phorbol diester (12-O-tetradecanoylphorbol-13-acetate [TPA])-induced cells. One case of common ALL (cALL), one case of T-ALL, and one undifferentiated acute leukemia that responded to anti-myeloid drugs after unsuccessful anti-lymphoid induction therapy, had germ line heavy chain genes. Rearranged immunoglobulin genes were instead found in 15 of the 16 cALL cases studied and in a case of non-T, non-B, non-common ("null") ALL, which suggested the B cell origin of the neoplastic cells. All cases bearing a heavy chain gene rearrangement were HLA-DR positive. However, the unique cALL case with a germ line configuration was also HLA-DR positive, which confirmed that both the cALL antigen and HLA-DR antigen were not per se expression of B cell commitment. On the other hand, a complete search for B cell-related markers (BA-1 and B1 monoclonal antibodies, as well as cytoplasmic immunoglobulins [CyIg]) in the cALL cases showed that at least one B cell marker could be detected either on primary or on TPA-induced cells in all cases in which a gene rearrangement had occurred. Incubation with TPA allowed the detection of one B cell marker in a case in which the primary cells were negative, and increased the expression of B cell markers in all but one of the cALLs tested. The only cALL case that was not rearranged expressed no B cell markers either on primary or on TPA-induced cells. The non-T, non-B, non-common ("null") case that was rearranged also showed no phenotypic evidence of B cell markers on primary and induced cells. These findings indicate that: (a) practically all cases of cALL appear to be of B cell origin as shown by gene rearrangement analysis; (b) DNA studies are relevant for a more precise characterization of individual cases of undifferentiated acute leukemia; (c) a complete survey for B cell markers may establish the B cell origin of the cALL blasts, as long as the analysis on primary cells is complemented by differentiation induction assessment; and (d) most cases of non-T ALL appear to be characterized by the expansion of neoplastic cells "frozen" at different levels along the B cell differentiation pathway, the first detectable marker being heavy chain gene rearrangement, followed by BA-1, B1, and CyIg expression.

Impact of killer-immunoglobulin-like receptor and human leukocyte antigen genotypes on the efficacy of immunotherapy in acute myeloid leukemia.

Interactions between killer-immunoglobulin-like receptors (KIRs) and their HLA class I ligands are instrumental in natural killer (NK) cell regulation and protect normal tissue from NK cell attack. Human KIR haplotypes comprise genes encoding mainly inhibitory receptors (KIR A) or activating and inhibitory receptors (KIR B). A substantial fraction of humans lack ligands for inhibitory KIRs (iKIRs), that is, a 'missing ligand' genotype. KIR B/x and missing ligand genotypes may thus give rise to potentially autoreactive, unlicensed NK cells. Little is known regarding the impact of such genotypes in untransplanted acute myeloid leukemia (AML). For this study, NK cell phenotypes and KIR/HLA genotypes were determined in 81 AML patients who received immunotherapy with histamine dihydrochloride and low-dose IL-2 for relapse prevention (NCT01347996). We observed that presence of unlicensed NK cells impacted favorably on clinical outcome, in particular among patients harboring functional NK cells reflected by high expression of the natural cytotoxicity receptor (NCR) NKp46. Genotype analyses suggested that the clinical benefit of high NCR expression was restricted to patients with a missing ligand genotype and/or a KIR B/x genotype. These data imply that functional NK cells are significant anti-leukemic effector cells in patients with KIR/HLA genotypes that favor NK cell autoreactivity.

Significant reduction of the hybrid BCR/ABL transcripts after induction and consolidation therapy is a powerful predictor of treatment response in adult Philadelphia-positive acute lymphoblastic leukemia.

Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) has a dismal prognosis. We prospectively evaluated minimal residual disease (MRD) by measuring BCR/ ABL levels with a quantitative real-time PCR procedure after induction and after consolidation in 45 adults with Ph+ ALL who obtained complete hematological remission after a high-dose daunorubicin induction schedule. At diagnosis, the mean BCR-ABL/GUS ratio was 1.55 +/- 1.78. A total of 42 patients evaluable for outcome analysis were operationally divided into two MRD groups: good molecular responders (GMRs; n = 28) with > 2 log reduction of residual disease after induction and > 3 log reduction after consolidation therapy, and poor molecular responders (PMRs; n = 14) who, despite complete hematological remission, had a higher MRD at both time points. In GMR, the actuarial probability of relapse-free, disease-free and overall survival at two years was 38, 27 and 48%, respectively, as compared to 0, 0 and 0% in PMR (P = 0.0035, 0.0076 and 0.0026, respectively). Salvage therapy induced a second sustained complete hematological remission in three GMR patients, but in no PMR patient. Our data indicate that, as already shown in children, adult Ph+ ALL patients have a heterogeneous sensitivity to treatment, and that early quantification of residual disease is a prognostic parameter in this disease.

A novel leukemia T-cell line (PF-382) with phenotypic and functional features of suppressor lymphocytes.

A human leukemia T-cell line (PF-382) spontaneously derived from the pleural effusion of a child with T-cell acute lymphoblastic leukemia is described. The cell line, which has been maintained in culture for over 10 months, has a modal number of 46 chromosomes and is characterized by a chromosomal abnormality, present in most of the cells, consisting of a translocation between chromosome X and chromosome 15 (46X,Xq-,15p+). The cells are not recognized by the OKT3 and OKT11 monoclonal antibodies (MoAb), nor do they form rosettes with sheep erythrocytes. By contrast, they react with the OKT6, Leu-1, and Leu-9 MoAb, which detect early T-lymphocytes, and express the more mature OKT8 antigen. The presence of the OKT8 marker is associated with suppressor activity on the pokeweed mitogen-induced proliferation and differentiation of normal B-cells, both by the PF-382 cells and by their supernatant. However, no cytotoxic activity against natural killer (NK)-sensitive target cells (K562) was found, indicating that the proliferating cells do not correspond to the subset of NK cells expressing the OKT8 antigen. Furthermore, the cells are incapable of both spontaneous and mitogen-induced interleukin-2 and interferon production. The ability of the PF-382 cell line to release a soluble factor(s) capable of modulating the differentiation of the B-cell compartment suggests that this new cell line represents a valuable model for the investigation of the interrelationships between T-cell subsets and other hematopoietic cell lineages.

Transduction of the IL2 gene into human acute leukemia cells: induction of tumor rejection without modifying cell proliferation and IL2 receptor expression.

BACKGROUND: Previous studies have suggested that some of the limitations associated with the administration of high-dose exogenous interleukin 2 (IL2) may be overcome, at least partly, by cytokine gene transfer modalities. These findings have prompted investigations into whether human tumor cells may be transduced with the IL2 gene and whether tumor cell lines could be engineered to release IL2. PURPOSE: The purpose of this study was to evaluate the possibility of inducing a productive transfer of the IL2 gene into human acute leukemia cells and to assess the phenotypic and proliferative changes generated in the engineered cells, as well as their tumorigenic potential in nude mice. METHODS: Three retroviral vectors (DC/TK/IL2, DC/AD/R/IL2, and N2/CMV/IL2) carrying the IL2 gene were used to transduce three human leukemic cell lines: K562 and U937 (myeloid) and ST4 (lymphoid). Messenger RNA expression of the IL2 gene was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) and productive IL2 release using a human IL2 assay and an enzyme-linked immunosorbent assay kit. The expression of the p55 (alpha) and p75 (beta) chains of the IL2 receptor were determined by RT-PCR and indirect immunofluorescence. The kinetics of in vitro growth and proliferation of parental and engineered cells were also measured. Parental and IL2 gene-transduced ST4 lymphoblasts were injected into immunosuppressed nude mice that had their tumors measured twice weekly. RESULTS: The productive insertion of the IL2 gene was achieved in all three cell lines studied. The amounts of IL2 constitutively released by the engineered neoplastic cells ranged between 1 and 11 U/mL of IL2 produced from 10(6) cells in 72 hours. A fivefold increase in IL2 production was obtained in ST4 cells by further limiting dilution cloning of the bulk-infected cells. The stable integration of the IL2 gene did not modify the phenotype of the leukemic cells, the expression of the IL2 receptor alpha and beta chains and of several cytokine genes, or the kinetics of in vitro growth and proliferation. In nude mice injected with various IL2-producing ST4 clones, tumor growth associated inversely with the amounts of IL2 secreted by the leukemic cells. CONCLUSIONS: The results of this study demonstrate that the IL2 gene can be productively transduced into human myeloid and lymphoid leukemic cells without modifying their phenotypic and proliferative properties and that this transduction leads to a reduced or abrogated in vivo tumorigenic potential.

Rearrangement of the c-myc oncogene with heavy-chain immunoglobulin enhancer in tumor DNA from an acute lymphoblastic leukemia patient.

The DNA obtained from the leukemia cells of an acute lymphoblastic leukemia (ALL, L3 type) with a pre-B-phenotype and a typical t(8;14) chromosomal translocation showed a rearrangement juxtaposing the c-myc gene and the immunoglobulin (Ig) heavy-chain gene enhancer. This abnormality was only present in the leukemia cells of the patient and correlated with the clinical course of the disease. The breakpoint on chromosome 8 occurred within c-myc intron 1, between 790 and 638 base pairs upstream of c-myc exon 2. This breakpoint position was the nearest to the c-myc exon 2 so far described in Burkitt's type lymphoma-leukemias, and it mapped very near to the location of a major cryptic promoter used by truncated c-myc genes. In spite of what was detected in a human lymphoma cell line (Manca) carrying a similar rearrangement, in this case the amount of c-myc transcript was not increased compared to an Epstein-Barr virus-transformed normal lymphoblastoid cell line obtained from the same patient. This may in part be due to the breakpoint position and to the fact that the efficiency of the major cryptic promoter present within the first intron could have been affected by the translocation event. Finally, as previously suggested by others, the phenotype expressed by the leukemia cells supported the notion that this particular type of rearrangement (linking together the c-myc gene and the Ig heavy-chain gene enhancer element) may be associated with a subgroup of B-ALLs showing an immunologic phenotype relatively more immature than that of classical B-ALL.