Meir Wetzler, MD

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111978/1/cncr29391.pd

Differential effects of dosing regimen on the safety and efficacy of dasatinib: retrospective exposure-response analysis of a Phase III study.

PurposeDasatinib is a prototypic short half-life BCR-ABL1 tyrosine kinase inhibitor. The recommended dose of dasatinib for chronic myeloid leukemia in chronic phase was changed from 70 mg twice daily to 100 mg once daily following a Phase III dose-optimization study. To better understand the superior benefit-risk profile of dasatinib 100 mg once daily, exposure-response was characterized for efficacy (major cytogenetic response) and safety (pleural effusion).Patients and methodsDasatinib exposure in patients with chronic myeloid leukemia in chronic phase was determined by population pharmacokinetic analysis of data from seven dasatinib clinical studies (N = 981), including the Phase III dose-optimization study (n = 567). Data from the Phase III study were then used to characterize exposure-response relationships for the four dasatinib treatment regimens investigated (100 mg once daily, 50 mg twice daily, 140 mg once daily, and 70 mg twice daily).ResultsMajor cytogenetic response was significantly (P < 0.01) associated with weighted average steady-state dasatinib plasma concentrations, and pleural effusion was significantly associated with trough concentration. Major cytogenetic response was also significantly associated with maintenance of uninterrupted dosing. The 100 mg once daily arm had the lowest steady-state trough concentration of the four dose arms investigated in the Phase III study, and although this arm also had the lowest weighted average steady-state dasatinib plasma concentration, it had the highest dose maintenance.ConclusionDasatinib dose optimization to 100 mg once daily from 70 mg twice daily significantly minimizes adverse events while maintaining efficacy by exploiting differences in the measures of exposure associated with efficacy and safety

Targeting DNA methylation

Abstract Two nucleoside inhibitors of DNA methylation, azacitidine and decitabine, are now standard of care for the treatment of the myelodysplastic syndrome, a deadly form of leukemia. These old drugs, developed as cytotoxic agents and nearly abandoned decades ago were resurrected by the renewed interest in DNA methylation. They have now provided proof of principle for epigenetic therapy, the final chapter in the long saga to provide legitimacy to the field of epigenetics in cancer. But challenges remain; we don't understand precisely how or why the drugs work or stop working after an initial response. Extending these promising findings to solid tumors faces substantial hurdles from drug uptake to clinical trial design.We do not know yet how to select patients for this therapy and how to move it from life extension to cure. The epigenetic potential of DNA methylation inhibitors may be limited by other epigenetic mechanisms that are also worth exploring as therapeutic targets. But the idea of stably changing gene expression in vivo has transformative potential in cancer therapy and beyond

The organic arsenic derivative GMZ27 induces PML-RARα-independent apoptosis in myeloid leukemia cells

Arsenic trioxide (ATO) is an inorganic arsenic derivative that is very effective against acute promyelocytic leukemia. However, organic arsenic derivatives (OAD) have a more favorable toxicity profile than ATO. We herein characterized dipropil-S-glycerol arsenic (GMZ27), a novel OAD. GMZ27 had potent antiproliferative activity against human acute myeloid leukemia (AML) cell lines that was higher than that of ATO. In contrast to ATO, GMZ27 only marginally induced maturation of leukemia cells and had no effect on the cell cycle. The anti-leukemia activity of GMZ27 against AML cells was independent of the presence of the PML-RARα fusion protein. GMZ27 dissipates mitochondrial transmembrane potential, and induces cleavage of caspase 9 and activation of caspase 3 without altering the expression levels of (BCL-2), BAX and BCL-xl. GMZ27 induces the formation of intracellular superoxide, a reactive oxygen species (ROS) which plays a major role in the antileukemia activity of this OAD. In addition to ROS generation, GMZ27 concomitantly reduces intracellular glutathione which markedly weakens the cellular antioxidant capacity, thus enhancing the detrimental intracellular effects of ROS production. These results indicate that GMZ27 induces apoptosis in AML cells in a PML-RARα-independent fashion, through the induction of ROS production. This activity provides the rationale for the testing of GMZ27 in patients with AML

Pulmonary Hypertension Is a Frequent Event in Patients with Chronic Myeloid Leukemia Treated with Tyrosine Kinase Inhibitors

Poster presented at American Society of Clinical Oncology in Chicago Illinois. Background: Tyrosine kinase inhibitors (TKI) are the current standard therapy for patients with chronic myeloid leukemia (CML). Fluid retention and pleural effusions have been reported in patients treated with TKIs, particularly with dasatinib. Although TKIs have been shown to reverse pulmonary hypertension (PH) in animal models, there have been some reports of development of reversible PH with dasatinib. Methods: We conducted a retrospective analysis on 401 patients diagnosed with CML in chronic phase (CP) who were treated with TKIs (imatinib, dasatinib, or nilotinib) as initial therapy for CML and had a transthoracic echocardiogram (TTE) done at some point during the course of therapy. PH was diagnosed if the patient had an estimated right ventricular systolic pressure (RVSP) of 35 mm Hg or greater. Secondary causes of PH (systolic or diastolic dysfunction on TTE, chronic obstructive pulmonary diseases [COPD], obstructive sleep apnea [OSA] and pulmonary embolism) were investigated during chart review. Results: Twenty (23%) out of 87 patients had evidence of PH by TTE; median age 57 years, with 46% being males. Six pts (30%) received nilotinib 400mg twice daily, 4 (20%) patients had imatinib (400mg; n=1, 600mg; n=1 and 800mg daily; n=2), and 10 (50%) patients received dasatinib (dose varied 40-140mg daily). Five (25%) patients had coronary artery disease, 9 (45%) had systemic hypertension, 2 (10%) had COPD and 3 (15%) had OSA. Thirteen pts had serial TTE to compare the progression of PH including 6 (7%) who had a TTE prior to starting TKI. Among these 13 pts with serial TTE, 7 had rising RVSP with one patient having mild global hypokinesia, another with diastolic dysfunction and another with OSA. Four of those 7 patients had normal RVSP on their TTE prior to starting therapy. Six other pts had improvement in the RVSP on serial TTE, 4 of them with systemic hypertension. Two of those 6 patients had elevated RVSP on their TTE prior to starting therapy; one pt had no change. Eleven patients had pleural effusions (7 dasatinib, 3 imatinib, 1 nilotinib) associated with PH. Conclusions: TKI therapy is occasionally associated with development of PH, but RVSP may improve spontaneously in some patients. A prospective study is needed to further investigate the relationship between TKIs and the development of PH

Final 5-Year Study Results of DASISION: The Dasatinib Versus Imatinib Study in Treatment-Naïve Chronic Myeloid Leukemia Patients Trial

Purpose: We report the 5-year analysis from the phase III Dasatinib Versus Imatinib Study in Treatment-Naive Chronic Myeloid Leukemia Patients (DASISION) trial, evaluating long-term efficacy and safety outcomes of patients with chronic myeloid leukemia (CML) in chronic phase (CP) treated with dasatinib or imatinib. Patients and Methods: Patients with newly diagnosed CML-CP were randomly assigned to receive dasatinib 100 mg once daily (n = 259) or imatinib 400 mg once daily (n = 260). Results: At the time of study closure, 61% and 63% of dasatinib- and imatinib-treated patients remained on initial therapy, respectively. Cumulative rates of major molecular response and molecular responses with a 4.0- or 4.5-log reduction in BCR-ABL1 transcripts from baseline by 5 years remained statistically significantly higher for dasatinib compared with imatinib. Rates for progression-free and overall survival at 5 years remained high and similar across treatment arms. In patients who achieved BCR-ABL1 <= 10% at 3 months (dasatinib, 84%; imatinib, 64%), improvements in progression-free and overall survival and lower rates of transformation to accelerated/blast phase were reported compared with patients with BCR-ABL1 greater than 10% at 3 months. Transformation to accelerated/blast phase occurred in 5% and 7% of patients in the dasatinib and imatinib arms, respectively. Fifteen dasatinib-treated and 19 imatinib-treated patients had BCR-ABL1 mutations identified at discontinuation. There were no new or unexpected adverse events identified in either treatment arm, and pleural effusion was the only drug-related, nonhematologic adverse event reported more frequently with dasatinib (28% v 0.8% with imatinib). First occurrences of pleural effusion were reported with dasatinib, with the highest incidence in year 1. Arterial ischemic events were uncommon in both treatment arms. Conclusion: These final results from the DASISION trial continue to support dasatinib 100 mg once daily as a safe and effective first-line therapy for the long-term treatment of CML-CP

Effects of Bosutinib Treatment on Renal Function in Patients With Philadelphia Chromosome-Positive Leukemias

Abstract Background The purpose of the study was to assess renal function in patients with Philadelphia chromosome-positive leukemias receiving bosutinib or imatinib. Patients and Methods Patients received first-line bosutinib (n = 248) or imatinib (n = 251; phase III trial), or second-line or later bosutinib (phase I/II trial; n = 570). Adverse events (AEs) and changes from baseline in estimated glomerular filtration rate (eGFR) and serum creatinine were assessed. Results Time from the last patient's first dose to data cutoff was ≥ 48 months. Renal AEs were reported in 73/570 patients (13%) receiving second-line or later bosutinib, and in 22/248 (9%) and 16/251 (6%) receiving first-line bosutinib and imatinib, respectively. eGFR in patients receiving bosutinib declined over time with more patients developing Grade ≥ 3b eGFR ( 2 according to the Modification of Diet in Renal Disease method) with second-line or later bosutinib (139/570, 24%) compared with first-line bosutinib (26/248, 10%) and imatinib (25/251, 10%); time to Grade ≥ 3b eGFR was shortest with second-line or later bosutinib. Similar proportions of patients receiving second-line or later bosutinib (74/139, 53%), first-line bosutinib (15/26, 58%), and first-line imatinib (15/25, 60%) improved to ≥ 45 mL/min/1.73 m 2 eGFR as of the last follow-up. In a regression analysis, first-line treatment with bosutinib versus imatinib was not a significant predictor of Grade ≥ 3b eGFR. Conclusion Long-term bosutinib treatment is associated with an apparently reversible decline in renal function with frequency and characteristics similar to renal decline observed with long-term imatinib treatment. Patients with risk factors for Grade ≥ 3b eGFR should be monitored closely

Ponatinib in patients with refractory acute myeloid leukaemia: findings from a phase 1 study

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99099/1/bjh12382.pd