News | April 06, 2015 | Chronic Myeloid Leukemia, Hematologic Malignancies, Leukemia & Lymphoma
By Ian Ingram

A small retrospective study of heavily pretreated patients with chronic myeloid leukemia (CML) found bosutinib to be a good option in the fourth-line setting.

A Burchert1, S Saussele2, E Eigendorff3, M C Müller2, K Sohlbach1, S Inselmann1, C Schütz1, S K Metzelder1, J Ziermann3, P Kostrewa1, J Hoffmann1, R Hehlmann2, A Neubauer1 and A Hochhaus3

Abstract
A minority of chronic myeloid leukemia (CML) patients is capable of successfully discontinuing imatinib. Treatment modalities to increase this proportion are currently unknown. Here, we assessed the role of interferon alpha 2a (IFN) on therapy discontinuation in a previously reported cohort of 20 chronic phase CML patients who were treated upfront with IFN alpha plus imatinib followed by IFN monotherapy to maintain cytogenetic or molecular remission (MR) after imatinib discontinuation. After a median follow-up of 7.9 years (range, 5.2–12.2), relapse-free survival was 73% (8/11 patients) and 84% (5/6 patients) for patients who discontinued imatinib in major MR (MMR) and MR4/MR4.5, respectively. Ten patients discontinued IFN after a median of 4.5 years (range, 0.24–9.3). After a median of 2.8 years (range, 0.7–5.1), nine of them remain in ongoing treatment-free remission with MR5 (n=6) and MR4.5 (n=3). The four patients who still administer IFN are in stable MR5, MR4.5, MR4, and MMR, respectively. In conclusion, an IFN/imatinib induction treatment followed by a temporary IFN maintenance therapy may enable a high rate of treatment discontinuation in CML patients in at least MMR when stopping imatinib.

C M Lucas1, R J Harris1, A K Holcroft1, L J Scott1, N Carmell1, E McDonald1, F Polydoros2 and R E Clark1

1Section of Haematology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, Liverpool, UK
2CR-UK Liverpool Cancer Trials Unit, University of Liverpool

High CIP2A protein levels at diagnosis of chronic myeloid leukaemia (CML) are predictive of disease progression in imatinib treated patients. It is not known whether this is true in patients treated with second generation tyrosine kinase inhibitors (2G TKI) from diagnosis, and whether 2G TKIs modulate the CIP2A pathway. Here, we show that patients with high diagnostic CIP2A levels who receive a 2G TKI do not progress, unlike those treated with imatinib (P=<0.0001). 2G TKIs induce more potent suppression of CIP2A and c-Myc than imatinib. The transcription factor E2F1 is elevated in high CIP2A patients and following 1 month of in vivo treatment 2G TKIs suppress E2F1 and reduce CIP2A; these effects are not seen with imatinib. Silencing of CIP2A, c-Myc or E2F1 in K562 cells or CML CD34+ cells reactivates PP2A leading to BCR-ABL suppression. CIP2A increases proliferation and this is only reduced by 2G TKIs. Patients with high CIP2A levels should be offered 2G TKI treatment in preference to imatinib. 2G TKIs disrupt the CIP2A/c-Myc/E2F1 positive-feedback loop, leading to lower disease progression risk. The data supports the view that CIP2A inhibits PP2Ac, stabilising E2F1, creating a CIP2A/c-Myc/E2F1 positive-feedback loop which imatinib cannot overcome.

News | March 17, 2015 | Chronic Myeloid Leukemia, Hematologic Malignancies, Leukemia & Lymphoma
By Cancer Network Staff

A single-arm, open-label trial in Australia found that selective early switching from imatinib to nilotinib is feasible and effective in patients with chronic myeloid leukemia (CML).

Simona Soverini1, Andreas Hochhaus2, Franck E. Nicolini3, Franz Gruber4, Thoralf Lange5, Giuseppe Saglio6, Fabrizio Pane7,8, Martin C. Müller9, Thomas Ernst2, Gianantonio Rosti1, Kimmo Porkka10, Michele Baccarani1, Nicholas C. P. Cross11,12, and Giovanni Martinelli1

There has been substantial interest in intermittent or other alternative scheduling of tyrosine kinase inhibitors in treatment for CML. The success of the drugs has been remarkable, but because of that success and the relative young age of many CML patients, many are forced to take the drugs for many years and even decades. This carries high financial burden, as well as increasing chances of non-compliance. Affirming the safety of intermittent scheduling could ease some of those concerns in CML patients.

January 13, 2015 | Chronic Myeloid Leukemia, ASH 2014, Hematologic Malignancies, Leukemia & Lymphoma
By Dave Levitan

Despite the early termination of a phase III trial due to safety concerns, an analysis suggests that ponatinib offers improved efficacy over imatinib in patients with newly diagnosed chronic-phase chronic myeloid leukemia (CP-CML). That improvement comes at the expense of higher rates of adverse events, according to the EPIC trial.

The tyrosine kinase inhibitor (TKI) imatinib has revolutionized the management of chronic myeloid leukaemia (CML). However, around 25% of patients fail to sustain an adequate response. We sought to identify gene-expression biomarkers that could be used to predict imatinib response. The expression of 29 genes, previously implicated in CML pathogenesis, were measured by TaqMan Low Density Array in 73 CML patient samples. Patients were divided into low and high expression for each gene and imatinib failure (IF), probability of achieving CCyR, progression free survival and CML related OS were compared by Kaplan-Meier and log-rank. Results were validated in a second cohort of 56 patients, with a further technical validation using custom gene-expression assays in a conventional RT-qPCR in a sub-cohort of 37 patients. Patients with low PTCH1 expression showed a worse clinical response for all variables in all cohorts. PTCH1 was the most significant predictor in the multivariate analysis compared with Sokal, age and EUTOS. PTCH1 expression assay showed the adequate sensitivity, specificity and predictive values to predict for IF. Given the different treatments available for CML, measuring PTCH1 expression at diagnosis may help establish who will benefit best from imatinib and who is better selected for second generation TKI.

L Schafranek E Nievergall, J A Powell D K Hiwase T Leclercq T P Hughes and D L White

Kinase inhibitors block proliferative signals in BCR-ABL1+ leukemic cells, but their capacity to induce apoptosis is poorly understood. Initial studies suggested that very brief exposure to kinase inhibitors was sufficient to induce apoptosis in chronic myeloid leukemia (CML) cells. However, flaws in this experimental model have subsequently been identified, leading to the conclusion that apoptosis only occurs with sustained low-level kinase inhibition. Thus, the minimum duration of complete kinase inhibition required to commit CML cells to death is unknown. Here we confirm that <1 h is insufficient to induce significant commitment to death in BCR-ABL1+ cell lines and in primary CD34+ progenitor cells, and establish that commitment to cell death only occurs if kinase inhibition is maintained for 4 h or more. Remarkably, signal transducer and activator of transcription 5 (STAT5) inhibition in combination with transient (<1 h) tyrosine kinase inhibitor (TKI) exposure proved lethal for CML progenitors, despite the reactivation of Bcr-Abl after 1 h. JAK kinase inhibition did not induce cell death in combination with transient TKI exposure. Thus, STAT5 appears to be a critical determinant of the time-dependent sensitivity of CML progenitor cells to TKI treatment in a Bcr-Abl-dependent, but JAK-independent, manner. We conclude that combining kinase inhibition with STAT5 inhibition represents a promising therapeutic approach in BCR-ABL1+ leukemias.

November 28, 2014

Hematologists from Goethe University Frankfurt, working with a Russian pharmaceutical company, have developed a new active substance that effectively combats the most aggressive forms of Philadelphia chromosome-positive leukemia.