Simona Soverini

Nilotinib for the frontline treatment of Ph(+) chronic myeloid leukemia.

Nilotinib has a higher binding affinity and selectivity for BCR-ABL with respect to imatinib and is an effective treatment of chronic myeloid leukemia (CML) after imatinib failure. In a phase 2 study, 73 early chronic-phase, untreated, Ph(+) CML patients, received nilotinib at a dose of 400 mg twice daily. The primary endpoint was the complete cytogenetic response (CCgR) rate at 1 year. With a median follow-up of 15 months, the CCgR rate at 1 year was 96%, and the major molecular response rate 85%. Responses were rapid, with 78% CCgR and 52% major molecular response at 3 months. During the first year, the treatment was interrupted at least once in 38 patients (52%). The mean daily dose ranged between 600 and 800 mg in 74% of patients, 400 and 599 mg in 18% of patients, and was less than 400 mg in 8% of patients. Dose interruptions were mainly due to nonhematologic and biochemical side effects. Myelosuppression was irrelevant. One patient progressed to blastic crisis after 6 months; one went off-treatment for lipase increase grade 4 (no pancreatitis). Nilotinib is safe and very active in early chronic-phase CML. These data support a role for nilotinib for the frontline treatment of CML. This study was registered at ClinicalTrials.gov as NCT00481052.

Expression of spliced oncogenic Ikaros isoforms in Philadelphia-positive acute lymphoblastic leukemia patients treated with tyrosine kinase inhibitors: implications for a new mechanism of resistance

Ikaros plays an important role in the control of differentiation and proliferation of all lymphoid lineages. The expression of short isoforms lacking DNA-binding motifs alters the differentiation capacities of hematopoietic progenitors, arresting lineage commitment. We sought to determine whether molecular abnormalities involving the IKZF1 gene were associated with resistance to tyrosine kinase inhibitors (TKIs) in Ph+ acute lymphoblastic leukemia (ALL) patients. Using reverse-transcribed polymerase chain reaction, cloning, and nucleotide sequencing, only the non-DNA-binding Ik6 isoform was detected in 49% of Ph+ ALL patients. Ik6 was predominantly localized to the cytoplasm versus DNA-binding Ik1 or Ik2 isoforms, which showed nuclear localization. There was a strong correlation between nonfunctional Ikaros isoforms and BCR-ABL transcript level. Furthermore, patient-derived leukemia cells expressed oncogenic Ikaros isoforms before TKI treatment, but not during response to TKIs, and predominantly at the time of relapse. In vitro overexpression of Ik6 strongly increased DNA synthesis and inhibited apoptosis in TKI-sensitive cells. Genomic sequence and computational analyses of exon splice junction regions of IKZF1 in Ph+ ALL patients predicted several mutations that may alter alternative splicing. These results establish a previously unknown link between specific molecular defects that involve alternative splicing of the IKZF1 gene and the resistance to TKIs in Ph+ ALL patients.

Response definitions and European Leukemianet Management recommendations

Imatinib is the standard front-line therapy of chronic myeloid leukaemia (CML). The evaluation of the response is based on blood counts and differential (haematologic response, HR), on the examination of marrow cell metaphases (cytogenetic response, CgR) and on a quantitative assessment of BCR-ABL transcripts level (molecular response, MolR). An optimal response to imatinib is defined by complete HR and at least minimal CgR (Ph + < 95%) at 3 months, at least partial CgR (Ph + < 35%) at 6 months, complete CgR at 12 months and major MolR (BCR-ABL: ABL < or = 0.1%) at 18 months. Failure is defined by incomplete HR at 3 months, no CgR (Ph + > 95%) at 6 months, less than partial CgR (Ph + > 35%) at 12 months, less than complete CgR at 18 months and loss of a complete HR or a complete CgR. In any other situation, the response is defined suboptimal. Treatment recommendations are to continue on imatinib in case of optimal response and to move to second-generation tyrosine kinase inhibitors (TKIs) and/or to allogeneic haematopoietic stem cell transplantation in case of failure. In case of suboptimal response, treatment may be continued with imatinib, at the same dose or a higher dose, but some patients may become eligible for second-generation TKIs. A provisional definition of the response to second-generation TKIs second line is provided.

Long-Term Outcome of Complete Cytogenetic Responders After Imatinib 400 mg in Late Chronic Phase, Philadelphia-Positive Chronic Myeloid Leukemia: The GIMEMA Working Party on CML

PURPOSEnImatinib mesylate (IM) has rapidly become the front-line treatment of Philadelphia-positive (Ph-pos) chronic myeloid leukemia, but the number of patients who were treated and are being treated with IM second-line is still substantial.nnnPATIENTS AND METHODSnWe have monitored and analyzed the cytogenetic and molecular response to IM 400 mg/d in a cohort of 277 late chronic phase (LCP) patients who were resistant or intolerant to interferon-alpha and were observed for 48 to 79 months (median, 72 months).nnnRESULTSnOne hundred fifty-three patients (55%) achieved a complete cytogenetic response (CCgR). Seventy-seven percent of them were still in CCgR after 5 years. The rate of response loss did not increase over time. The 6-year progression-free survival and overall survival of these 153 complete cytogenetic responders were 90% and 91%, respectively. Molecular response was less than major in 21%, major in 78%, and complete in one patient only.nnnCONCLUSIONnThese data confirm that, in LCP the CCgR rate to IM is 50% to 60%, and show that CCgR is stable and is associated with a prolonged survival, even if leukemia continues to be molecularly detectable.

Imatinib mesylate for the treatment of chronic myeloid leukemia.

Chronic myeloid leukemia (CML) is the first human malignancy for which the promise of targeted therapy has come true. CML is invariably associated with a specific genetic lesion – the t(9;22) chromosomal translocation. As a consequence of this translocation, a BCR-ABL fusion gene is formed on the 22q- derivative (traditionally known as the Philadelphia chromosome) and the deregulated tyrosine kinase activity of the protein encoded by this gene has been shown to be both necessary and sufficient for initiation and maintenance of the disease. Imatinib mesylate, an orally available tyrosine kinase inhibitor that targets Bcr-Abl, entered clinical evaluation in 1998. Its efficacy surpassed almost everyone’s predictions, and the observation of high response rates and favorable toxicity profile associated with imatinib therapy led to its approval as first-line treatment for all newly diagnosed CML patients over an exceptionally short period of time. The 6-year results of the Phase III trial have recently been reported and confirm durability of responses and declining incidence of adverse events over time, although, at present, occurrence of unexpected side effects in the long term cannot be excluded. Although imatinib does not ‘cure’ CML and has to be administered chronically to patients, it has revolutionized both outcome and quality of life of CML patients.

Identification of different Ikaros cDNA transcripts in Philadelphia-positive adult acute lymphoblastic leukemia by a high-throughput capillary electrophoresis sizing method

Ikaros is a member of the Kruppel family of zinc finger DNA-binding proteins. The findings of this study demonstrated that both aberrant splicing and genomic deletion leading to different non-DNA-binding transcripts are common features of Philadelphia chromosome-positive acute lymphoblastic leukemia. Background Ikaros is the prototypic member of a Kruppel-like zinc finger transcription factor subfamily that is required for normal hematopoietic cell differentiation and proliferation, particularly in the lymphoid lineages. Alternative splicing can generate multiple Ikaros isoforms that lack different numbers of exons and have different functions. Shorter isoforms, which lack the amino-terminal domain that mediates sequence-specific DNA binding, exert a dominant negative effect and inhibit the ability of longer heterodimer partners to bind DNA. Design and Methods In this study, we developed a high-throughput capillary electrophoresis sizing method to detect and quantify different Ikaros cDNA transcripts. Results We demonstrated that Philadelphia chromosome-positive acute lymphoblastic leukemia cells expressed high levels of the non-DNA-binding isoform Ik6 that was generated following IKZF1 genomic deletions (19/46 patients, 41%). Furthermore, a recurring 60 bp insertion immediately upstream of exon 5, at the exon 3/exon 5 junction, was frequently detected in the Ik2 and Ik4 isoforms. This insertion occurred either alone or together with an in-frame ten amino acid deletion that was due to a 30 bp loss at the end of exon 7. Both the alterations are due to the selection of alternative cryptic splice sites and have been suggested to cause impaired DNA-binding activity. Non-DNA-binding isoforms were localized in the cytoplasm whereas the DNA-binding isoforms were localized in the nucleus. Conclusions Our findings demonstrate that both aberrant splicing and genomic deletion leading to different non-DNA-binding Ikaros cDNA transcripts are common features of Philadelphia chromosome-positive acute lymphoblastic leukemia.

Treatment of Philadelphia-Positive Chronic Myeloid Leukemia with Imatinib: Importance of a Stable Molecular Response

Purpose: The achievement of a major molecular response (MMolR) at 12 months is a surrogate marker of progression-free survival in chronic myeloid leukemia patients treated with imatinib. Experimental Design: We evaluated the prognostic value of the long-term evolution of the molecular response based on a retrospective analysis of 130 late chronic phase chronic myeloid leukemia patients who achieved a complete cytogenetic response (CCgR) with 400 mg/d imatinib and have now a median follow-up of 72 months (range, 48-77). Results: In 71 (55%) patients, molecular response was consistently major (stable MMolR); in 19 (15%) patients, molecular response was occasionally less than major (unstable MMolR); in 40 (30%) patients, MMolR was never achieved (never MMolR) during all the course of CCgR. Patients with stable MMolR had a longer CCgR duration and a significantly better progression-free survival compared with patients with absent or unstable MMolR. The achievement of a MMolR, if maintained continuously, conferred a marked long-term stability to the CCgR: patients with a stable MMolR have a significantly lower risk of losing the CCgR than patients with unstable and never MMolR (4% versus 21%, P = 0.03, and 4% versus 33%, P < 0.0001, respectively). Finally, if a MMolR is not maintained consistently, the risk of losing the CCgR is higher but not significantly than if it is never achieved (33% versus 21%, P = 0.5). Conclusions: These data confirm that achieving a MMolR is prognostically important but point out that the prognostic value of achieving a MMolR is greater if the response is confirmed and stable.

New targets for Ph+ leukaemia therapy

The outcome for adults with Philadelphia chromosome (Ph+) leukaemias (chronic myeloid leukaemia (CML) and acute lymphoblastic leukaemia (ALL)) has been dramatically improved with the use of tyrosine kinase inhibitors (TKIs), but progression and/or relapse are still present in the majority of patients. We reviewed recent findings obtained from analysis of BCR-ABL point mutations, gene expression profiling (GEP) analysis single nucleotide polymorphism (SNP) arrays and characterised by the identification of multiple novel genetic alterations targeting key cellular pathways, including lymphoid differentiation, cell cycle, tumour suppression, apoptosis and drug responsiveness. By GEP analysis, several down/up-expressed genes have been identified. Furthermore, by SNP array analysis, deletions of genes such as IKAROS, PAX5 and CDKN2A-CDKN2B were frequently identified. New therapeutic approaches with novel TKIs are now available. Dasatinib, nilotinib and bosutinib are now in clinical development. Some emerging aurora kinase inhibitors, such as VX-680, PHA-739358, MK-0457 and AS703569, and Smo1 and Hedgehog (Hh) inhibitors promise clinical efficacy against the Bcr-Ab T315I mutant form and leukaemia stem cells, respectively. In this review, we highlight the most promising drugs for the treatment of adult BCR-ABL-positive leukaemias.

BCR-ABL1 -positive CML and BCR-ABL1 -negative chronic myeloproliferative disorders: some common and contrasting features

BCR-ABL1 -positive CML and BCR-ABL1 -negative chronic myeloproliferative disorders: some common and contrasting features

Nilotinib restores long-term full-donor chimerism in Ph-positive acute lymphoblastic leukemia relapsed after allogeneic transplantation

Nilotinib restores long-term full-donor chimerism in Ph-positive acute lymphoblastic leukemia relapsed after allogeneic transplantation