Delphine Rea

Discontinuation of imatinib in patients with chronic myeloid leukaemia who have maintained complete molecular remission for at least 2 years: the prospective, multicentre Stop Imatinib (STIM) trial

BACKGROUNDnImatinib treatment significantly improves survival in patients with chronic myeloid leukaemia (CML), but little is known about whether treatment can safely be discontinued in the long term. We aimed to assess whether imatinib can be discontinued without occurrence of molecular relapse in patients in complete molecular remission (CMR) while on imatinib.nnnMETHODSnIn our prospective, multicentre, non-randomised Stop Imatinib (STIM) study, imatinib treatment (of >2 years duration) was discontinued in patients with CML who were aged 18 years and older and in CMR (>5-log reduction in BCR-ABL and ABL levels and undetectable transcripts on quantitative RT-PCR). Patients who had undergone immunomodulatory treatment (apart from interferon α), treatment for other malignancies, or allogeneic haemopoietic stem-cell transplantation were not included. Patients were enrolled at 19 participating institutions in France. In this interim analysis, rate of relapse was assessed by use of RT-PCR for patients with at least 12 months of follow-up. Imatinib was reintroduced in patients who had molecular relapse. This study is registered with ClinicalTrials.gov, number NCT00478985.nnnFINDINGSn100 patients were enrolled between July 9, 2007, and Dec 17, 2009. Median follow-up was 17 months (range 1-30), and 69 patients had at least 12 months follow-up (median 24 months, range 13-30). 42 (61%) of these 69 patients relapsed (40 before 6 months, one patient at month 7, and one at month 19). At 12 months, the probability of persistent CMR for these 69 patients was 41% (95% CI 29-52). All patients who relapsed responded to reintroduction of imatinib: 16 of the 42 patients who relapsed showed decreases in their BCR-ABL levels, and 26 achieved CMR that was sustained after imatinib rechallenge.nnnINTERPRETATIONnImatinib can be safely discontinued in patients with a CMR of at least 2 years duration. Imatinib discontinuation in this setting yields promising results for molecular relapse-free survival, raising the possibility that, at least in some patients, CML might be cured with tyrosine kinase inhibitors.

A Phase 2 Trial of Ponatinib in Philadelphia Chromosome–Positive Leukemias

BACKGROUNDnPonatinib is a potent oral tyrosine kinase inhibitor of unmutated and mutated BCR-ABL, including BCR-ABL with the tyrosine kinase inhibitor-refractory threonine-to-isoleucine mutation at position 315 (T315I). We conducted a phase 2 trial of ponatinib in patients with chronic myeloid leukemia (CML) or Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph-positive ALL).nnnMETHODSnWe enrolled 449 heavily pretreated patients who had CML or Ph-positive ALL with resistance to or unacceptable side effects from dasatinib or nilotinib or who had the BCR-ABL T315I mutation. Ponatinib was administered at an initial dose of 45 mg once daily. The median follow-up was 15 months.nnnRESULTSnAmong 267 patients with chronic-phase CML, 56% had a major cytogenetic response (51% of patients with resistance to or unacceptable side effects from dasatinib or nilotinib and 70% of patients with the T315I mutation), 46% had a complete cytogenetic response (40% and 66% in the two subgroups, respectively), and 34% had a major molecular response (27% and 56% in the two subgroups, respectively). Responses were observed regardless of the baseline BCR-ABL kinase domain mutation status and were durable; the estimated rate of a sustained major cytogenetic response of at least 12 months was 91%. No single BCR-ABL mutation conferring resistance to ponatinib was detected. Among 83 patients with accelerated-phase CML, 55% had a major hematologic response and 39% had a major cytogenetic response. Among 62 patients with blast-phase CML, 31% had a major hematologic response and 23% had a major cytogenetic response. Among 32 patients with Ph-positive ALL, 41% had a major hematologic response and 47% had a major cytogenetic response. Common adverse events were thrombocytopenia (in 37% of patients), rash (in 34%), dry skin (in 32%), and abdominal pain (in 22%). Serious arterial thrombotic events were observed in 9% of patients; these events were considered to be treatment-related in 3%. A total of 12% of patients discontinued treatment because of an adverse event.nnnCONCLUSIONSnPonatinib had significant antileukemic activity across categories of disease stage and mutation status. (Funded by Ariad Pharmaceuticals and others; PACE ClinicalTrials.gov number, NCT01207440 .).

Intermittent Target Inhibition With Dasatinib 100 mg Once Daily Preserves Efficacy and Improves Tolerability in Imatinib-Resistant and -Intolerant Chronic-Phase Chronic Myeloid Leukemia

PURPOSEnDasatinib is a BCR-ABL inhibitor, 325-fold more potent than imatinib against unmutated BCR-ABL in vitro. Phase II studies have demonstrated efficacy and safety with dasatinib 70 mg twice daily in chronic-phase (CP) chronic myelogenous leukemia (CML) after imatinib treatment failure. In phase I, responses occurred with once-daily administration despite only intermittent BCR-ABL inhibition. Once-daily treatment resulted in less toxicity, suggesting that toxicity results from continuous inhibition of unintended targets. Here, a dose- and schedule-optimization study is reported.nnnPATIENTS AND METHODSnIn this open-label phase III trial, 670 patients with imatinib-resistant or -intolerant CP-CML were randomly assigned 1:1:1:1 between four dasatinib treatment groups: 100 mg once daily, 50 mg twice daily, 140 mg once daily, or 70 mg twice daily.nnnRESULTSnWith minimum follow-up of 6 months (median treatment duration, 8 months; range, < 1 to 15 months), marked and comparable hematologic (complete, 86% to 92%) and cytogenetic (major, 54% to 59%; complete, 41% to 45%) response rates were observed across the four groups. Time to and duration of cytogenetic response were similar, as was progression-free survival (8% to 11% of patients experienced disease progression or died). Compared with the approved 70-mg twice-daily regimen, dasatinib 100 mg once daily resulted in significantly lower rates of pleural effusion (all grades, 7% v 16%; P = .024) and grade 3 to 4 thrombocytopenia (22% v 37%; P = .004), and fewer patients required dose interruption (51% v 68%), reduction (30% v 55%), or discontinuation (16% v 23%).nnnCONCLUSIONnDasatinib 100 mg once daily retains the efficacy of 70 mg twice daily with less toxicity. Intermittent target inhibition with tyrosine kinase inhibitors may preserve efficacy and reduce adverse events.

Loss of Major Molecular Response As a Trigger for Restarting Tyrosine Kinase Inhibitor Therapy in Patients With Chronic-Phase Chronic Myelogenous Leukemia Who Have Stopped Imatinib After Durable Undetectable Disease

PURPOSEnMore than half of patients with chronic-phase chronic myelogenous leukemia (CP-CML) in complete molecular response (CMR) experience molecular relapse after imatinib discontinuation. We investigated loss of major molecular response (MMR) as a criterion for resuming therapy.nnnPATIENTS AND METHODSnA multicenter observational study (A-STIM [According to Stop Imatinib]) evaluating MMR persistence was conducted in 80 patients with CP-CML who had stopped imatinib after prolonged CMR.nnnRESULTSnMedian time from imatinib initiation to discontinuation was 79 months (range, 30 to 145 months);median duration of CMR before imatinib discontinuation was 41 months (range, 24 to 96 months); median follow-up after discontinuation was 31 months (range, 8 to 92 months). Twenty-nine patients (36%) lost MMR after a median of 4 months off therapy (range, 2 to 17 months). Cumulative incidence of MMR loss was estimated as 35% (95% CI, 25% to 46%) at 12 months and 36% (95% CI, 26% to 47%) at 24 months, whereas probability of losing CMR was higher. Fluctuation of BCR-ABL transcript levels below the MMR threshold (≥ two consecutive positive values) was observed in 31% of patients after imatinib discontinuation. Treatment-free remission was estimated as 64% (95% CI, 54% to 75%) at 12 and 24 months and 61% (95% CI, 51% to 73%) at 36 months. Median to time to second CMR was estimated as 7.3 months in re-treated patients.nnnCONCLUSIONnLoss of MMR is a practical and safe criterion for restarting therapy in patients with CML with prolonged CMR.

Vascular safety issues in CML patients treated with BCR/ABL1 kinase inhibitors.

Vascular safety is an emerging issue in patients with chronic myeloid leukemia (CML) treated with tyrosine kinase inhibitors (TKIs). Whereas imatinib exhibits a well-documented and favorable long-term safety profile without obvious accumulation of vascular events, several types of vascular adverse events (VAEs) have been described in patients receiving second- or third-generation BCR/ABL1 TKIs. Such VAEs include pulmonary hypertension in patients treated with dasatinib, peripheral arterial occlusive disease and other arterial disorders in patients receiving nilotinib, and venous and arterial vascular occlusive events during ponatinib. Although each TKI interacts with a unique profile of molecular targets and has been associated with a unique pattern of adverse events, the mechanisms of drug-induced vasculopathy are not well understood. Here, recent data and concepts around VAEs in TKI-treated patients with CML are discussed, with special reference to potential mechanisms, event management, and strategies aimed at avoiding occurrence of such events in long-term treated patients.

Peripheral artery occlusive disease in chronic phase chronic myeloid leukemia patients treated with nilotinib or imatinib

Several retrospective studies have described the clinical manifestation of peripheral artery occlusive disease (PAOD) in patients receiving nilotinib. We thus prospectively screened for PAOD in patients with chronic phase chronic myeloid leukemia (CP CML) being treated with tyrosine kinase inhibitors (TKI), including imatinib and nilotinib. One hundred and fifty-nine consecutive patients were evaluated for clinical and biochemical risk factors for cardiovascular disease. Non-invasive assessment for PAOD included determination of the ankle-brachial index (ABI) and duplex ultrasonography. A second cohort consisted of patients with clinically manifest PAOD recruited from additional collaborating centers. Pathological ABI were significantly more frequent in patients on first-line nilotinib (7 of 27; 26%) and in patients on second-line nilotinib (10 of 28; 35.7%) as compared with patients on first-line imatinib (3 of 48; 6.3%). Clinically manifest PAOD was identified in five patients, all with current or previous nilotinib exposure only. Relative risk for PAOD determined by a pathological ABI in first-line nilotinib-treated patients as compared with first-line imatinib-treated patients was 10.3. PAOD is more frequently observed in patients receiving nilotinib as compared with imatinib. Owing to the severe nature of clinically manifest PAOD, longitudinal non-invasive monitoring and careful assessment of risk factors is warranted.

BCR-ABL1 compound mutations combining key kinase domain positions confer clinical resistance to ponatinib in Ph chromosome-positive leukemia.

Ponatinib is the only currently approved tyrosine kinase inhibitor (TKI) that suppresses all BCR-ABL1 single mutants in Philadelphia chromosome-positive (Ph(+)) leukemia, including the recalcitrant BCR-ABL1(T315I) mutant. However, emergence of compound mutations in a BCR-ABL1 allele may confer ponatinib resistance. We found that clinically reported BCR-ABL1 compound mutants center on 12 key positions and confer varying resistance to imatinib, nilotinib, dasatinib, ponatinib, rebastinib, and bosutinib. T315I-inclusive compound mutants confer high-level resistance to TKIs, including ponatinib. Inxa0vitro resistance profiling was predictive of treatment outcomes in Ph(+) leukemia patients. Structural explanations for compound mutation-based resistance were obtained through molecular dynamics simulations. Our findings demonstrate that BCR-ABL1 compound mutants confer different levels of TKI resistance, necessitating rational treatment selection to optimize clinical outcome.

Combined Treatment With Arsenic Trioxide and All-Trans-Retinoic Acid in Patients With Relapsed Acute Promyelocytic Leukemia

PURPOSEnArsenic trioxide (ATO) is capable of inducing a high hematologic response rate in patients with relapsed acute promyelocytic leukemia (APL). Preclinical observations have indicated that all-trans-retinoic acid (ATRA) may strongly enhance the response to ATO.nnnPATIENTS AND METHODSnBetween 1998 and 2001, we conducted a randomized study of ATO alone versus ATO plus ATRA in 20 patients with relapsed APL, all previously treated with ATRA-containing chemotherapy. The primary objective was to demonstrate a significant reduction in the time necessary to obtain a complete remission (CR) in the ATO/ATRA group compared with the ATO group. Secondary objectives were safety and molecular response.nnnRESULTSnThe CR rate after one ATO with or without ATRA induction cycle was 80%. Clinical and pharmacokinetic observations indicated that the main mechanism of action of ATO in vivo was the induction of APL cell differentiation. Hematologic and molecular response, time necessary to reach CR, and outcome were comparable in both treatment groups. Of 16 CR patients, three patients who reached a molecular remission after one induction cycle had all received chemotherapy for a treatment-induced hyperleukocytosis. Three additional patients who received further additional ATO with or without ATRA cycles converted later to molecular negativity.nnnCONCLUSIONnATRA did not seem to significantly improve the response to ATO in patients relapsing from APL. Other potential combinations, including ATO plus chemotherapy, have to be tested.

BCR/ABL Oncogene Directly Controls MHC Class I Chain-Related Molecule A Expression in Chronic Myelogenous Leukemia

MHC class I chain-related molecules (MIC) participate in immune surveillance of cancer through engagement of the NKG2D-activating receptor on NK and T cells. Decreased NKG2D expression and function upon chronic exposure to NKG2D ligands and/or soluble forms of MIC (sMIC) may participate in immune escape. In chronic myeloid leukemia, a malignancy caused by the BCR/ABL fusion oncoprotein, we showed cell surface expression of MICA on leukemic, but not healthy, donor hemopoietic CD34+ cells. At diagnosis, chronic myeloid leukemia patients had abnormally high serum levels of sMICA and weak NKG2D expression on NK and CD8+ T cells, which were restored by imatinib mesylate (IM) therapy. In the BCR/ABL+ cell line K562, IM decreased both surface MICA/B expression and NKG2D-mediated lysis by NK cells. Silencing BCR/ABL gene expression directly evidenced its role in the control of MICA expression. IM did not affect MICA mRNA levels, but decreased MICA protein production and release. Sucrose density gradient fractionation of K562 cytoplasmic extracts treated with IM showed a shift in the distribution of MICA mRNA from the polysomal toward the monosomal fractions, consistent with decreased translation. Among the major pathways activated by BCR/ABL that regulate translation, PI3K and mammalian target of rapamycin were shown to control MICA expression. These data provide evidence for direct control of MICA expression by an oncogene in human malignancy and indicate that posttranscriptional mechanisms may participate in the regulation of MICA expression.

Severe peripheral arterial disease during nilotinib therapy

(36.4%) had a history of nicotine abuse, seven (63.6%) had arterial hypertension, three (27.3%) had diabetes mellitus, five (45.5%) had dyslipidemia, three (27.3%) were obese, six (54.5%) were male, and seven (63.6%) were older than 60 years (all cardiovascular risk factors). All 11 PAD patients had at least a cytogenetic remission while on nilotinib. One patient with hyper eosinophilic syndrome and one patient with CML received nilotinib as first-line treatment. Previous treatments for the remaining patients were hydroxyurea (nine patients), interferon alpha (seven patients), imatinib (nine patients), dasatinib (one patient), or another agent (four patients). In these 11 patients, the mean time from CML diagnosis to initiation of nilotinib was 347 weeks (range = 8–651 weeks) and the mean time from initiation of nilotinib to the first PAD event was 105.1 weeks (range = 16–212 weeks) (Table 1). In all cases, the lower limbs were affected; in nine patients, the femoral superficial artery was involved. These patients were treated with angioplasty (eight patients), stent implantation (eight patients), and/or amputation (four patients).