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.

European LeukemiaNet 2020 recommendations for treating chronic myeloid leukemia.

The therapeutic landscape of chronic myeloid leukemia (CML) has profoundly changed over the past 7 years. Most patients with chronic phase (CP) now have a normal life expectancy. Another goal is achieving a stable deep molecular response (DMR) and discontinuing medication for treatment-free remission (TFR). The European LeukemiaNet convened an expert panel to critically evaluate and update the evidence to achieve these goals since its previous recommendations. First-line treatment is a tyrosine kinase inhibitor (TKI; imatinib brand or generic, dasatinib, nilotinib, and bosutinib are available first-line). Generic imatinib is the cost-effective initial treatment in CP. Various contraindications and side-effects of all TKIs should be considered. Patient risk status at diagnosis should be assessed with the new EUTOS long-term survival (ELTS)-score. Monitoring of response should be done by quantitative polymerase chain reaction whenever possible. A change of treatment is recommended when intolerance cannot be ameliorated or when molecular milestones are not reached. Greater than 10% BCR-ABL1 at 3 months indicates treatment failure when confirmed. Allogeneic transplantation continues to be a therapeutic option particularly for advanced phase CML. TKI treatment should be withheld during pregnancy. Treatment discontinuation may be considered in patients with durable DMR with the goal of achieving TFR.

A phase II, multicentre trial of decitabine in higher-risk chronic myelomonocytic leukemia.

Chronic myelomonocytic leukemia (CMML) is a complex clonal hematological disorder classified among myelodysplastic (MDS)/myeloproliferative neoplasms. Prognosis is poor and there is a lack of effective treatments. The hypomethylating agent decitabine has shown activity against MDS and elderly acute myeloid leukemia, but there is little data focusing specifically on its efficacy in CMML. In this prospective, phase 2 Italian study, CMML patients received intravenous decitabine 20 mg/m2 per day on Days 1-5 of a 28-day treatment cycle. Response was evaluated after four and six cycles; patients responding at the end of six cycles could continue treatment with decitabine. Forty-three patients were enrolled; >50% were high-risk according to four CMML-specific scoring systems. In the intent-to-treat population (n=42), the overall response rate after six cycles was 47.6%, with seven complete responses (16.6%), eight marrow responses (19%), one partial response (2.4%) and four hematological improvements (9.5%). After a median follow-up of 51.5 months (range: 44.4-57.2), median overall survival was 17 months, with responders having a significantly longer survival than non-responders (P=0.02). Grade 3/4 anemia, neutropenia and thrombocytopenia occurred in 28.6%, 50% and 38% of patients, respectively. Decitabine appears to be an effective and well-tolerated treatment for patients with high-risk CMML.

Altered Erythropoiesis in Mouse Models of Type 3 Hemochromatosis.

Type 3 haemochromatosis (HFE3) is a rare genetic iron overload disease which ultimately lead to compromised organs functioning. HFE3 is caused by mutations in transferrin receptor 2 (TFR2) gene that codes for two main isoforms (Tfr2α and Tfr2ß). Tfr2α is one of the hepatic regulators of iron inhibitor hepcidin. Tfr2ß is an intracellular isoform of the protein involved in the regulation of iron levels in reticuloendothelial cells. It has been recently demonstrated that Tfr2 is also involved in erythropoiesis. This study aims to further investigate Tfr2 erythropoietic role by evaluating the erythropoiesis of two Tfr2 murine models wherein either one or both of Tfr2 isoforms have been selectively silenced (Tfr2 KI and Tfr2 KO). The evaluations were performed in bone marrow and spleen, in 14 days' and 10 weeks' old mice, to assess erythropoiesis in young versus adult animals. The lack of Tfr2α leads to macrocytosis with low reticulocyte number and increased hemoglobin values, together with an anticipation of adult BM erythropoiesis and an increased splenic erythropoiesis. On the other hand, lack of Tfr2ß (Tfr2 KI mice) causes an increased and immature splenic erythropoiesis. Taken together, these data confirm the role of Tfr2α in modulation of erythropoiesis and of Tfr2ß in favoring iron availability for erythropoiesis.

Treatment-free remission following frontline nilotinib in patients with chronic myeloid leukemia in chronic phase: results from the ENESTfreedom study.

The single-arm, phase 2 ENESTfreedom trial assessed the potential for treatment-free remission (TFR; i.e., the ability to maintain a molecular response after stopping therapy) following frontline nilotinib treatment. Patients with Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase with MR4.5 (BCR-ABL1⩽0.0032% on the International Scale (BCR-ABL1IS)) and ⩾2 years of frontline nilotinib therapy were enrolled. Patients with sustained deep molecular response during the 1-year nilotinib consolidation phase were eligible to stop treatment and enter the TFR phase. Patients with loss of major molecular response (MMR; BCR-ABL1IS⩽0.1%) during the TFR phase reinitiated nilotinib. In total, 215 patients entered the consolidation phase, of whom 190 entered the TFR phase. The median duration of nilotinib before stopping treatment was 43.5 months. At 48 weeks after stopping nilotinib, 98 patients (51.6%; 95% confidence interval, 44.2-58.9%) remained in MMR or better (primary end point). Of the 86 patients who restarted nilotinib in the treatment reinitiation phase after loss of MMR, 98.8% and 88.4%, respectively, regained MMR and MR4.5 by the data cutoff date. Consistent with prior reports of imatinib-treated patients, musculoskeletal pain-related events were reported in 24.7% of patients in the TFR phase (consolidation phase, 16.3%).

Development and evaluation of a secondary reference panel for BCR-ABL1 quantification on the International Scale.

Molecular monitoring of chronic myeloid leukemia patients using robust BCR-ABL1 tests standardized to the International Scale (IS) is key to proper disease management, especially when treatment cessation is considered. Most laboratories currently use a time-consuming sample exchange process with reference laboratories for IS calibration. A World Health Organization (WHO) BCR-ABL1 reference panel was developed (MR(1)-MR(4)), but access to the material is limited. In this study, we describe the development of the first cell-based secondary reference panel that is traceable to and faithfully replicates the WHO panel, with an additional MR(4.5) level. The secondary panel was calibrated to IS using digital PCR with ABL1, BCR and GUSB as reference genes and evaluated by 44 laboratories worldwide. Interestingly, we found that >40% of BCR-ABL1 assays showed signs of inadequate optimization such as poor linearity and suboptimal PCR efficiency. Nonetheless, when optimized sample inputs were used, >60% demonstrated satisfactory IS accuracy, precision and/or MR(4.5) sensitivity, and 58% obtained IS conversion factors from the secondary reference concordant with their current values. Correlation analysis indicated no significant alterations in %BCR-ABL1 results caused by different assay configurations. More assays achieved good precision and/or sensitivity than IS accuracy, indicating the need for better IS calibration mechanisms.

Long-term benefits and risks of frontline nilotinib vs imatinib for chronic myeloid leukemia in chronic phase: 5-year update of the randomized ENESTnd trial.

In the phase 3 Evaluating Nilotinib Efficacy and Safety in Clinical Trials-Newly Diagnosed Patients (ENESTnd) study, nilotinib resulted in earlier and higher response rates and a lower risk of progression to accelerated phase/blast crisis (AP/BC) than imatinib in patients with newly diagnosed chronic myeloid leukemia in chronic phase (CML-CP). Here, patients' long-term outcomes in ENESTnd are evaluated after a minimum follow-up of 5 years. By 5 years, more than half of all patients in each nilotinib arm (300 mg twice daily, 54%; 400 mg twice daily, 52%) achieved a molecular response 4.5 (MR(4.5); BCR-ABL⩽0.0032% on the International Scale) compared with 31% of patients in the imatinib arm. A benefit of nilotinib was observed across all Sokal risk groups. Overall, safety results remained consistent with those from previous reports. Numerically more cardiovascular events (CVEs) occurred in patients receiving nilotinib vs imatinib, and elevations in blood cholesterol and glucose levels were also more frequent with nilotinib. In contrast to the high mortality rate associated with CML progression, few deaths in any arm were associated with CVEs, infections or pulmonary diseases. These long-term results support the positive benefit-risk profile of frontline nilotinib 300 mg twice daily in patients with CML-CP.

Frontline nilotinib in patients with chronic myeloid leukemia in chronic phase: results from the European ENEST1st study.

The Evaluating Nilotinib Efficacy and Safety in Clinical Trials as First-Line Treatment (ENEST1st) study included 1089 patients with newly diagnosed chronic myeloid leukemia in chronic phase. The rate of deep molecular response (MR(4) (BCR-ABL1⩽0.01% on the International Scale or undetectable BCR-ABL1 with ⩾10,000 ABL1 transcripts)) at 18 months was evaluated as the primary end point, with molecular responses monitored by the European Treatment and Outcome Study network of standardized laboratories. This analysis was conducted after all patients had completed 24 months of study treatment (80.9% of patients) or discontinued early. In patients with typical BCR-ABL1 transcripts and ⩽3 months of prior imatinib therapy, 38.4% (404/1052) achieved MR(4) at 18 months. Six patients (0.6%) developed accelerated or blastic phase, and 13 (1.2%) died. The safety profile of nilotinib was consistent with that of previous studies, although the frequencies of some nilotinib-associated adverse events were lower (for example, rash, 21.4%). Ischemic cardiovascular events occurred in 6.0% of patients. Routine monitoring of lipid and glucose levels was not mandated in the protocol. These results support the use of frontline nilotinib, particularly when achievement of a deep molecular response (a prerequisite for attempting treatment-free remission in clinical trials) is a treatment goal.

BCR-ABL1 mutation development during first-line treatment with dasatinib or imatinib for chronic myeloid leukemia in chronic phase.

BCR-ABL1 mutations are a common, well-characterized mechanism of resistance to imatinib as first-line treatment of chronic myeloid leukemia in chronic phase (CML-CP). Less is known about mutation development during first-line treatment with dasatinib and nilotinib, despite increased use because of higher response rates compared with imatinib. Retrospective analyses were conducted to characterize mutation development in patients with newly diagnosed CML-CP treated with dasatinib (n=259) or imatinib (n=260) in DASISION (Dasatinib versus Imatinib Study in Treatment-Naive CML-CP), with 3-year minimum follow-up. Mutation screening, including patients who discontinued treatment and patients who had a clinically relevant on-treatment event (no confirmed complete cytogenetic response (cCCyR) and no major molecular response (MMR) within 12 months; fivefold increase in BCR-ABL1 with loss of MMR; loss of CCyR), yielded a small number of patients with mutations (dasatinib, n=17; imatinib, n=18). Dasatinib patients had a narrower spectrum of mutations (4 vs 12 sites for dasatinib vs imatinib), fewer phosphate-binding loop mutations (1 vs 9 mutations), fewer multiple mutations (1 vs 6 patients) and greater occurrence of T315I (11 vs 0 patients). This trial was registered at www.clinicaltrials.gov as NCT00481247.

Long-term outcome of chronic myeloid leukemia patients treated frontline with imatinib.

For almost 10 years imatinib has been the therapeutic standard of chronic myeloid leukemia. The introduction of other tyrosine kinase inhibitors (TKIs) raised a debate on treatment optimization. The debate is still heated: some studies have protocol restrictions or limited follow-up; in other studies, some relevant data are missing. The aim of this report is to provide a comprehensive, long-term, intention-to-treat, analysis of 559 newly diagnosed, chronic-phase, patients treated frontline with imatinib. With a minimum follow-up of 66 months, 65% of patients were still on imatinib, 19% were on alternative treatment, 12% died and 4% were lost to follow-up. The prognostic value of BCR-ABL1 ratio at 3 months (⩽10% in 81% of patients) was confirmed. The prognostic value of complete cytogenetic response and major molecular response at 1 year was confirmed. The 6-year overall survival was 89%, but as 50% of deaths occurred in remission, the 6-year cumulative incidence of leukemia-related death was 5%. The long-term outcome of first-line imatinib was excellent, also because of second-line treatment with other TKIs, but all responses and outcomes were inferior in high-risk patients, suggesting that to optimize treatment results, a specific risk-adapted treatment is needed for such patients.

Laboratory recommendations for scoring deep molecular responses following treatment for chronic myeloid leukemia.

Treatment of chronic myeloid leukemia (CML) with tyrosine kinase inhibitors has advanced to a stage where many patients achieve very low or undetectable levels of disease. Remarkably, some of these patients remain in sustained remission when treatment is withdrawn, suggesting that they may be at least operationally cured of their disease. Accurate definition of deep molecular responses (MRs) is therefore increasingly important for optimal patient management and comparison of independent data sets. We previously published proposals for broad standardized definitions of MR at different levels of sensitivity. Here we present detailed laboratory recommendations, developed as part of the European Treatment and Outcome Study for CML (EUTOS), to enable testing laboratories to score MR in a reproducible manner for CML patients expressing the most common BCR-ABL1 variants.

Differences among young adults, adults and elderly chronic myeloid leukemia patients.

BACKGROUND: The incidence of chronic myeloid leukemia (CML) increases with age, but it is unclear how the characteristics of the disease vary with age. In children, where CML is very rare, it presents with more aggressive features, including huge splenomegaly, higher cell count and higher blast cell percentage. PATIENTS AND METHODS: To investigate if after childhood the disease maintains or loses these characteristics of aggressiveness, we analyzed 2784 adult patients, at least 18 years old, registered by GIMEMA CML WP over a 40-year period. RESULTS: Young adults (YAs: 18-29 years old) significantly differed from adults (30-59 years old) and elderly patients (at least 60 years old) particularly for the frequency of splenomegaly (71%, 63% and 55%, P < 0.001), and the greater spleen size (median value: 4.5, 3.0 and 1.0 cm, P < 0.001). According to the EUTOS score, that is age-independent, high-risk patients were more frequent among YAs, than among adult and elderly patients (18%, 9% and 6%, P < 0.001). In tyrosine kinase inhibitors-treated patients, the rates of complete cytogenetic and major molecular response were lower in YAs, and the probability of transformation was higher (16%, 5% and 7%, P = 0.011). CONCLUSIONS: The characteristics of CML or the host response to leukemia differ with age. The knowledge of these differences and of their causes may help to refine the treatment and to improve the outcome. CLINICAL TRIAL NUMBERS: NCT00510926, NCT00514488, NCT00769327, NCT00481052.

BCR-ABL disrupts PTEN nuclear-cytoplasmic shuttling through phosphorylation-dependent activation of HAUSP.

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by the t(9;22) translocation coding for the chimeric protein p210 BCR-ABL. The tumor suppressor phosphatase and tensin homolog (PTEN) has recently been shown to have a critical role in the pathogenesis of CML. Nuclear localization and proper nuclear-cytoplasmic shuttling are crucial for PTEN's tumor suppressive function. In this study, we show that BCR-ABL enhances HAUSP-induced de-ubiquitination of PTEN in turn favoring its nuclear exclusion. We further demonstrate that BCR-ABL physically interacts with and phosphorylates HAUSP on tyrosine residues to trigger its activity. Importantly, we also find that PTEN delocalization induced by BCR-ABL does not occur in the leukemic stem cell compartment due to high levels of PML, a potent inhibitor of HAUSP activity toward PTEN. We therefore identify a new proto-oncogenic mechanism whereby BCR-ABL antagonizes the nuclear function of the PTEN tumor suppressor, with important therapeutic implications for the eradication of CML minimal residual disease.

Rates of peripheral arterial occlusive disease in patients with chronic myeloid leukemia in the chronic phase treated with imatinib, nilotinib, or non-tyrosine kinase therapy: a retrospective cohort analysis.

Peripheral arterial occlusive disease (PAOD) occurs in patients with chronic phase chronic myeloid leukemia (CML-CP) treated with tyrosine kinase inhibitors (TKIs). The risk of developing PAOD on TKI therapy is unknown and causality has not been established. Patients with CML-CP from three randomized phase III studies (IRIS, TOPS and ENESTnd) were divided into three cohorts: no TKI (cohort 1; n=533), nilotinib (cohort 2; n=556) and imatinib (cohort 3; n=1301). Patients with atherosclerotic risk factors were not excluded. Data were queried for terms indicative of PAOD. Overall, 3, 7 and 2 patients in cohorts 1, 2 and 3, respectively, had PAOD; 11/12 patients had baseline PAOD risk factors. Compared with that of cohort 1, exposure-adjusted risks of PAOD for cohorts 2 and 3 were 0.9 (95% CI, 0.2-3.3) and 0.1 (95% CI, 0.0-0.5), respectively. Multivariate logistic regression revealed that nilotinib had no impact on PAOD rates compared with no TKI, whereas imatinib had decreased rates of PAOD compared with no TKI. Nilotinib was associated with higher rates of PAOD versus imatinib. Baseline assessments, preferably within clinical studies, of PAOD and associated risk factors should occur when initiating TKI therapy in CML; patients should receive monitoring and treatment according to the standard of care for these comorbidities.

Prediction of outcomes in patients with Ph+ chronic myeloid leukemia in chronic phase treated with nilotinib after imatinib resistance/intolerance.

The purpose was to assess predictive factors for outcome in patients with chronic myeloid leukemia (CML) in chronic phase (CML-CP) treated with nilotinib after imatinib failure. Imatinib-resistant and -intolerant patients with CML-CP (n=321) were treated with nilotinib 400 mg twice daily. Of 19 baseline patient and disease characteristics and two response end points analyzed, 10 independent prognostic factors were associated with progression-free survival (PFS). In the multivariate analysis, major cytogenetic response (MCyR) within 12 months, baseline hemoglobin ≥ 120 g/l, baseline basophils <4%, and absence of baseline mutations with low sensitivity to nilotinib were associated with PFS. A prognostic score was created to stratify patients into five groups (best group: 0 of 3 unfavorable risk factors and MCyR by 12 months; worst group: 3 of 3 unfavorable risk factors and no MCyR by 12 months). Estimated 24-month PFS rates were 90%, 79%, 67% and 37% for patients with prognostic scores of 0, 1, 2 and 3, respectively, (no patients with score of 4). Even in the presence of poor disease characteristics, nilotinib provided significant clinical benefit in patients with imatinib-resistant or -intolerant CML. This system may yield insight on the prognosis of patients.

Nilotinib in imatinib-resistant or imatinib-intolerant patients with chronic myeloid leukemia in chronic phase: 48-month follow-up results of a phase II study.

Nilotinib (Tasigna) is a BCR-ABL1 tyrosine kinase inhibitor approved for the treatment of patients with Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase (CML-CP) who are newly diagnosed or intolerant of or resistant to imatinib. The 48-month follow-up data for patients with CML-CP treated with nilotinib after imatinib resistance or intolerance on an international phase II study were analyzed. Overall, 59% of patients achieved major cytogenetic response; 45% achieved complete cytogenetic response while on study. The estimated rate of overall survival (OS) and progression-free survival (PFS) at 48 months was 78% and 57%, respectively. Deeper levels of molecular responses at 3 and 6 months were highly positively correlated with long-term outcomes, including PFS and OS at 48 months. Of the 321 patients initially enrolled in the study, 98 (31%) were treated for at least 48 months. Discontinuations were primarily due to disease progression (30%) or adverse events (21%). Nilotinib is safe and effective for long-term use in responding patients with CML-CP who are intolerant of or resistant to imatinib. Further significant improvements in therapy are required for patients who are resistant or intolerant to imatinib.

Nilotinib vs imatinib in patients with newly diagnosed Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase: ENESTnd 3-year follow-up.

Evaluating Nilotinib Efficacy and Safety in Clinical Trials Newly Diagnosed Patients compares nilotinib and imatinib in patients with newly diagnosed chronic myeloid leukemia in chronic phase (CML-CP). With a minimum follow-up of 3 years, major molecular response, molecular response of BCR-ABL≤ 0.01% expressed on the international scale (BCR-ABL(IS); MR(4)) and BCR-ABL(IS)≤ 0.0032% (MR(4.5)) rates were significantly higher with nilotinib compared with imatinib, and differences in the depth of molecular response between nilotinib and imatinib have increased over time. No new progressions occurred on treatment since the 2-year analysis. Nilotinib was associated with a significantly lower probability of progression to accelerated phase/blast crisis vs imatinib (two (0.7%) progressions on nilotinib 300 mg twice daily, three (1.1%) on nilotinib 400 mg twice daily and 12 (4.2%) on imatinib). When considering progressions occurring after study treatment discontinuation, the advantage of nilotinib over imatinib in preventing progression remained significant (nine (3.2%) progressions on nilotinib 300 mg twice daily, six (2.1%) on nilotinib 400 mg twice daily and 19 (6.7%) on imatinib). Both nilotinib and imatinib were well tolerated, with minimal changes in safety over time. Nilotinib continues to demonstrate superior efficacy in all key response and outcome parameters compared with imatinib for the treatment of patients with newly diagnosed CML-CP.

Standardized definitions of molecular response in chronic myeloid leukemia.

The International Randomized Study of Interferon and STI571 (IRIS) demonstrated long-term cytogenetic responses in patients with chronic-phase chronic myeloid leukemia (CML-CP) treated with the tyrosine kinase inhibitor (TKI) imatinib. However, deep molecular responses (MRs), as measured by reductions in BCR-ABL transcript levels below the threshold of major MR, were achieved only by a small proportion of patients. With the advent of the second-generation TKIs nilotinib and dasatinib for the treatment of patients with newly diagnosed CML-CP, the proportion of patients who achieve the deepest levels of MR is likely to increase significantly. With these changes, the potential for patient eligibility in TKI cessations studies is becoming a more widely discussed topic and area for research. These developments highlight the need for robust, standardized and workable definitions of deep MRs. Specifically, it is critical that the measurement of MR is standardized in a manner to withstand both intra- and inter-laboratory variability, as well as new methodological developments. This review summarizes the relevant clinical background and proposes a framework within which standardization of MR can be taken forward.

BCR/ABL1 fusion transcripts generated from alternative splicing: implications for future targeted therapies in Ph+ leukaemias.

Philadelphia (Ph+) positive leukaemias are an example of haematological malignant diseases where different chromosomal rearrangements involving both BCR and ABL1 genes generate a variety of chimeric proteins (BCR/ABL1 p210, p190 and p230) which are considered pathological "biomarkers". In addition to these three, there is a variety of fusion transcripts whose origin may depend either on diverse genetic rearrangement or on alternative/atypical splicing of the main mRNAs or on the occurrence of single-point mutations. Although the therapy of Ph+ leukaemias based on Imatinib represents a triumph of medicine, not all patients benefit from such drug and may show resistance and intolerance. Furthermore, interruption of Imatinib administration is often followed by clinical relapse, suggesting a failure in the eradication of residual leukaemic stem cells. Therefore, while the targeted therapy is searching for new and implemented pharmacological inhibitors covering all the possible mutations in the kinase domain, there is urge to identify alternative molecular targets to develop other specific and effective therapeutic approaches. In this review we discuss the importance of recent advances based on the discovery of novel BCR/ABL1 variants and their potential role as new targets/biomarkers of Ph+ leukaemias in the light of the current therapeutic trends. The limits of the pharmacological inhibitors used for treating the disease can be overcome by considering other targets than the kinase enzyme. Our evaluations highlight the potential of alternative perspectives in the therapy of Ph+ leukaemias.