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.

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.

Serial Transplantation of a Human Acute T Lymphoblastic Leukemia into Nude Mice

A human acute T lymphoblastic leukemia line (PF-382) was serially transplanted into nude mice. No takes were observed in untreated nude mice, whereas solid tumors were observed in splenectomized and total body, sublethally irradiated mice. The minimal tumor-inducing dose and the latency time remained unchanged after the third and fifth serial transplants. Moreover, leukemic cells recovered from the 8th in vivo passages displayed the same differentiation antigens and chromosomal markers as the in vitro PF-382 cell line used for the first transplant. This stable and well-characterized experimental system could be a new model for T-lymphocyte differentiation and immune-reactivity against human leukemias.

Normal T-Lymphocyte Function in Patients with Hodgkin's Disease in Long-Lasting Remission

In 18 patients with Hodgkin's disease (HD) in long-lasting remission (more than 5 years), the distribution of circulating T-lymphocytes was analyzed using a series of monoclonal antibodies (OKT3, T4, T8, Leu-7, Leu-11 and T10) and correlated with cell function (helper capacity in a pokeweed mitogen system and natural killer (NK) activity). A reduced proportion of OKT4 (helper/inducer)-positive cells associated with a normal absolute number was consistently accompanied by a significant increase (p < 0.005) in the proportion and absolute number of OKT8 (suppressor/cytotoxic)-positive cells. The OKT4-positive cells, despite their moderate percentage reduction, showed normal helper activity. A more extensive characterization of the lymphoid population in these patients documented a preserved cytotoxic function in a 51Cr release assay and increased proportion of cells expressing NK-associated antigens (Leu-7, Leu-11, OKT10) with a high number of cells coexpressing OKT8 and Leu-7. It is suggested that in patients with Hodgkin's disease in long-lasting remission no laboratory (or clinical) evidence of cellular immunodeficiency can be documented.

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.

Complete remission obtained with azacitidine in a patient with concomitant therapy related myeloid neoplasm and pulmonary mucormycosis

Mucormycosis is the third cause of invasive mycosis after candidiasis and aspergillosis in AML patients, representing a poor prognostic factor associated with a high rate of fatal outcome. We report a case of a patient with AML and a concomitant pulmonary mucormycosis at diagnosis, who obtained a complete remission both of her AML and of the fungal infection. The incidence of the infection at the onset of leukemia is extremely unusual, and, to our knowledge, the sporadic cases reported in the literature are included in heterogeneous series retrospectively examined. In our case, Liposomal Amphotericin B as single agent appeared incapable of controlling the infection, so anti-infective therapy was intensified with posaconazole and simultaneously antileukemic treatment with 5-azacitidine was started, with the understanding that the only antifungal treatment would not have been able to keep the infection under control for a long time if not associated with a reversal of neutropenia related to the disease. We observed a progressive improvement of the general conditions, a healing of pneumonia and a complete remission of the leukemic disease, suggesting that a careful utilization of the new compounds available today, in terms of both antifungal and antileukemic treatment, may offer a curative chance a patient who would have otherwise been considered unfit for a potentially curative therapeutic strategy.

The genome of chemorefractory chronic lymphocytic leukemia reveals frequent mutations of NOTCH1 and SF3B1

Next-generation whole-exome sequencing has revealed two novel genes, namely NOTCH1 and SF3B1, whose mutations predict poor outcome and preferentially associate with chemorefractory chronic lymphocytic leukemia (CLL). Analysis of 539 CLL cases documents that NOTCH1 mutations i) represent one of the most frequent cancer gene mutations involved at presentation; ii) cluster with cases harboring trisomy 12 and tend to be mutually exclusive with TP53 disruption among genetic subgroups; iii) identify high-risk patients showing poor survival similar to that associated with TP53 abnormalities; and iv) exert a prognostic role independent of widely accepted clinical and genetic risk factors. Mutations of SF3B1, a splicing factor that is a critical component of the spliceosome, recurrently associate with fludarabine-refractory CLL, occur at a low rate at CLL presentation and have a minor role in Richter transformation, corroborating the notion that CLL histological shift is molecularly distinct from chemorefractory progression without the Richter transformation.

"Zeus" a new oral anticoagulant therapy dosing algorithm: a cohort study

The demand for oral anticoagulant therapy (OAT) has constantly increased during the last ten years with an extended use of computer assistance. Many mathematical algorithms have been projected to suggest doses and time to next visit for patients on OAT. We designed a new algorithm: "Zeus". A "before-after" study was planned to compare the efficacy and safety of this algorithm dosing OAT with manual dosage decided by the same expert physicians according to the target of International Normalized Ratio (INR). The study analysed data of 1876 patients managed with each of the two modalities for eight months, with an interval of two years between them. The aim was to verify the increased quality of therapy by time spent in INR target and efficiency and safety of Zeus algorithm. Time in therapeutic range (TTR) was significantly (p < 0.0001) higher during the algorithm dosing period in comparison with the TTR during manual management period (62.3% vs 50.3%). The number of PT/INR tests above 5 was significantly (p < 0.001) reduced by algorithm suggested prescriptions in comparison with manual those (254 vs 537 times). The anticoagulant drug amount prescribed according to the algorithm suggestions was significantly (p < 0.0001) lower than that of the manual method. The number of clinical events observed in patients during the algorithm management time was significantly (p < 0.05) lower than that in those managed with the manual dosage. This study confirms the clinical utility of the computer-assisted OAT and shows the efficacy and safety of the Zeus algorithm.

IKZF1 (IKAROS) deletions as a prognostic marker in BCR-ABL1 positive acute lymphoblastic leukemia patients: A GIMEMA ALL WP Report

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Expression of BCR-ABL1 in hematopoietic stem cells can alone induce a chronic myeloid leukemia (CML) but cooperating oncogenic lesions are required for the generation of a blastic leukemia. To identify oncogenic sub-microscopic lesions that cooperate with BCR-ABL1 to induce ALL, by high resolution single nucleotide polymorphism (SNP) arrays (250K NspI and SNP 6.0, Affymetrix) we studied 106 patients (pts) with de novo adult BCR-ABL1-positive ALL. The most frequent somatic copy number alteration was deletion on 7p12 of IKZF1 (68/106, 64%), which encodes the transcription factor Ikaros required for the earliest stages of lymphoid lineage commitment. We characterized and mapped all breakpoints in IKZF1 gene to recognize that two major deletions occur: the first one characterized by loss of exons 4–7 (44%) and due to breakpoints in introns 3 and 7; the second one characterized by removal of exons 2–7 (19%) and due to a variable pattern of breakpoints in introns 1 and 7. In two pts we had both Δ2–7 and Δ4–7 deletions and in one we identified a deletion of all IKZF1 gene and part of GRB10. A variable number of nucleotides (patient-specific) were inserted at the conjunction and maintained with fidelity at the time of relapse. Gene expression profiling analysis of pts with IKZF1 deletion vs wild-type pts identified a unique signature characterized by a down-regulation of genes involved in pre-B-cell differentiation (e.g. VPREB1, VPREB3, IGLL3, BLK), demonstrating that genomic IKZF1 alterations have a strong impact on trascriptoma and contribute to an impaired B-cell differentiation. Univariate analysis showed that the IKZF1 deletion is a negative prognostic marker influencing the cumulative incidence of relapse (10.1 months for pts with deletion vs 56.1 months for wild-type pts, p=0.0103) and disease-free survival (DFS) (10.1 months vs 32.1 months, respectively, p=0.0229). The negative prognostic impact of the IKZF1 deletion on DFS was also confirmed by multivariate analysis (p=0.0445). In conclusion, deletion of IKZF1 is an important event in the development of BCR-ABL1 B-progenitor ALL which significantly influences clinical outcome. Supported by European LeukemiaNet, AIL, AIRC, FIRB 2006, Strategico di Ateneo, GIMEMA Onlus.

No significant financial relationships to disclose.

Expression of different isoforms of the B-cell mutator activation-induced cytidine deaminase (AID) in BCR-ABL1-positive acute lymphoblastic leukemia (ALL) patients

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Since the activation-induced cytidine deaminase (AID) enzyme can target non-immunoglobulin (Ig) genes and may even act as a genome-wide mutator, we investigated AID expression in BCR-ABL1-positive ALL and in chronic myeloid leukemia (CML) at the time of progression to blast crisis. On the 61 de novo adult BCR-ABL1-positive ALL patients (pts), AID mRNA and protein were detected in 36 (59%); their expression correlated with BCR-ABL1 transcript levels and disappeared after treatment with tyrosine kinase inhibitors at the time of remission. AID expression was also found in lymphoid blast crisis CML (50%), but not in myeloid lineage or in chronic phase CML. Different isoforms of AID were identified: 13/61 (21%) pts expressed the full-length isoform; 19/61 (31%) co-expressed the wild-type and different AID splice variants with deaminase activity (AIDΔE4a, with a 30 bp deletion of exon 4; AIDΔE4, with the exon 4 deletion; AIDins3, with the retention of intron 3–4); 4/61 (7%) expressed the AIDΔE3-E4 isoform without deaminase activity (deletion of exons 2 and 3). To investigate whether AID introduces DNA-single strand breaks, we performed a genome wide analysis by 250K NspI single nucleotide polymorphism (SNP) array. Patients who expressed wild-type AID had a higher number of alterations compared to AID-negative (median copy number alteration of 14 versus 4. respectively, p < 0.03). Recurring copy number abnormalities were identified in genes with an established role in leukemogenesis, such as IKZF1, CDKN2A, CDKN2B, PAX5, MELK, BTG1, and MDS1. Our findings show that BCR-ABL1-positive ALL cells aberrantly express different isoforms of AID that can act as mutator outside the Ig gene loci in promoting genetic instability in leukemia cells. Supported by: European LeukemiaNet, AIL, AIRC, FIRB 2006, Fondazione del Monte di Bologna e Ravenna, Strategico di Ateneo, GIMEMA Onlus.

No significant financial relationships to disclose.

PLZF-mediated control on c-kit expression in CD34(+) cells and early erythropoiesis

The promyelocytic leukemia zinc-finger protein (PLZF) is a transcription factor and c-kit is a receptor tyrosine kinase associated with human disease, particularly in hematopoietic cells. MicroRNAs (miRs) are post-transcriptional regulators of gene expression, and c-kit has been described as a target of miRs-221 and -222 in erythropoiesis. In the present study, we identified c-kit as a target of PLZF in normal and leukemic cells. Particularly, in erythropoietic (E) culture of CD34(+) progenitors, PLZF is downregulated, whereas c-kit expression at both the mRNA and protein levels inversely increases during the first days of E differentiation. In functional experiments, PLZF transfection induces c-kit downregulation, inhibits E proliferation and delays differentiation, whereas PLZF knockdown induces opposite effects, independently of miRs-221 and -222 expression. The inverse correlation between PLZF and c-kit expression was found in normal CD34(+)38(+/-) hematopoietic progenitor/stem cells and in acute myeloid leukemias of M0/M1 French-American-British subtypes, suggesting that the control of PLZF on c-kit expression may be crucial at the level of the stem cell/progenitor compartment. Altogether, our data indicate a new mechanism of regulation of c-kit expression that involves a transcriptional control by PLZF in CD34(+) cells and early erythropoiesis.

Relationship between immunological phenotype and hematological response to alpha-IFN treatment in 35 patients with hairy cell leukemia

During the past 6 years, clinical trials employing alpha-interferon (alpha-IFN) in hairy cell leukemia (HCL) have shown dramatic improvement in the management of this disease. Complete remissions (CR), however, are relatively rare (10-15%) and a minority of patients (10-25%) do not respond adequately to alpha-IFN. The possibility that the poor response to alpha-IFN treatment could be related to a peculiar immunological phenotype of the hairy cell (HC) was investigated in this study. The results demonstrated that, in the majority of patients who failed to respond to alpha-IFN, HC showed an immunological phenotype characterized by positivity with the CD5 monoclonal antibody which is usually absent on HC and characteristically expressed on B-chronic lymphocytic leukemia cells. In fact, among the 10 HCL patients who presented with this phenotype, only 5 partial remissions (PR) and 5 minor responses (MR) were achieved, as opposed to the 3 complete remissions (CR), 19 PR and 3 MR observed in the 25 CD5-negative patients. The possibility that a more extensive immunological analysis of HCL patients at diagnosis may be predictive of the response to IFN treatment is postulated.

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.

Idiopathic thrombocytopenic purpura (ITP) in the elderly: clinical course in 178 patients

Idiopathic thrombocytopenic purpura (ITP) is often diagnosed in the elderly (age >or=65 yr), where it generally presents as a chronic disease. The objective of the present study was to describe the natural history of ITP in the elderly and to evaluate the risk of bleeding and the possible occurrence of other pathologies. We retrospectively evaluated 178 ITP patients (82 men, 96 women; mean age: 72 yr) diagnosed between 1981 and 1998. Therapy was started at diagnosis or during follow-up, depending on the platelet count and/or bleeding events. Sixty-six out of one hundred and seventy-eight patients (37%) initiated therapy at diagnosis; whereas in 11 of the 112 untreated patients (9.8%) therapy was necessary during the follow-up. Low-dose of prednisone was the first-line treatment in all patients (mean daily dose of 0.43 mg/kg). Forty-nine (63.6%) of the seventy-seven treated patients showed a response, 14 of these (28.6%) suffered a relapse. Another pathology occurred in 19 of the 178 patients (10.7%). We conclude that low-dose prednisone is an appropriate initial treatment for elderly persons. We also stress that an adequate follow-up is advisable, given that isolated thrombocytopenia could in some cases be the first sign of another underlying pathology.

Secondary acute myeloid leukaemia: results of conventional treatments. Experience of GIMEMA trials

BACKGROUND

The aim of the study was to evaluate the outcome of acute myeloid leukaemia (AML) in patients with a previous malignancy (sAML) treated with chemo- and/or radiotherapy, enrolled in conventional trials.

PATIENTS AND METHODS

In a multicentre setting, a prospective non-concurrent analysis was performed on 2513 new AML patients, aged 12-78 years, consecutively enrolled in EORTC-GIMEMA trials between 1987 and 2001. Thirty-eight patients with sAML were identified and compared with a group of 114 de novo AML patients matched according to age, French-American-British criteria, white blood cell count at diagnosis, trial and time of diagnosis of AML. Induction treatment response, disease-free survival (DFS), duration and overall survival (OS) were evaluated in the two groups.

RESULTS

Comparing the complete remission (CR) rate between 38 sAML patients and 114 de novo AML patients, selected according to the previously reported criteria, we observed no difference in the CR rates [25/38 (66%) versus 66/114 (58%); Pearson chi(2) 0.7393, P=0.390] as well as no differences while comparing the DFS and the OS between the two groups.

CONCLUSION

The results of this study suggest that sAML patients are characterised by a good performance status permitting their recruitment in conventional trials without a previous myelodysplastic phase. Similar to de novo AML patients, sAML patients show good response to treatment and the possibility of cure.

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.

Evidence of biased immunoglobulin variable gene usage in highly stable B-cell chronic lymphocytic leukemia

Recognition of biased immunoglobulin variable (IgV) gene usage in B-cell chronic lymphocytic leukemia (B-CLL) may yield insight into leukemogenesis and may help to refine prognostic categories. We explored Ig variable heavy (VH) and light (VL) chain gene usage in highly stable and indolent B-CLL (n=25) who never required treatment over 10 or more years. We observed an unexpectedly high usage of mutated VH3-72 (6/25; 24.0%), a gene that was otherwise rare in B-CLL (7/805; 0.87%; P<0.01), including mutated cases (6/432; 1.39%; P<0.01) and was exceptional among indolent (1/230, 0.435%; P<0.01), and aggressive B-cell lymphomas (0/105; P<0.01). Three of six VH3-72 B-CLL cases utilized the same VL Vkappa4-1 gene. Two V(H)3-72 B-CLL cases had highly homologous VH complementarity determining regions 3 (CDR3s), encoding Cys-XXXX-Cys domains, and utilized Vkappa4-1 genes with homologous IgVL CDR3s. An identical threonine to isoleucine change at codon 84 of V(H)3-72 framework region 3 (FR3) recurred in four cases of highly stable VH3-72 B-CLL. This mutation is expected to cause a conformational change of FR3 proximal to CDR3 that might critically affect high-affinity antigen binding. B-cell receptors encoded by VH3-72 may identify a specific B-CLL group and be implicated in leukemogenesis through an antigen-driven expansion of B cells.

Retrospective comparison of qualitative and quantitative reverse transcriptase polymerase chain reaction in diagnosing and monitoring the ALL1-AF4 fusion transcript in patients with acute lymphoblastic leukaemia

We compared quantitative reverse transcriptase polymerase chain reaction (Q-RT-PCR) to qualitative RT-PCR in determining response to therapy and predicting clinical outcome in 18 retrospectively selected patients with ALL positive for the ALL1-AF4 fusion and with frozen RNA samples collected at diagnosis and during follow-up (96 samples analysed). The ALL1-AF4 junction was detected by qualitative RT-PCR in 18 patients and by Q-RT-PCR in 17 patients (one patient harboured the rare e10-e6 ALL1-AF4 junction, which falls outside of the primer and probe location designed for the Q-RT-PCR). In three of the 12 patients negative to qualitative RT-PCR after induction therapy, a small number of ALL1-AF4 copies was detected by Q-RT-PCR. Thus nine patients were negative and eight positive. Seven of the eight positive patients suffered a relapse, including two of the three patients positive to Q-RT-PCR yet negative to qualitative RT-PCR. Moreover, we found two (5%) discordant results among the 39 follow-up tests of the nine patients who converted to a negative qualitative-quantitative PCR status. The results suggest that qualitative RT-PCR is more appropriate for the routine diagnosis of this genetic alteration. However, Q-RT-PCR is more accurate in assessing the molecular response after induction treatment and could be more useful in clinical decision-making in ALL1-AF4-positive ALL patients.