Treatment for chronic myeloid leukemia (CML) entails effective but mostly noncurative long-term use of tyrosine kinase inhibitors (TKIs) that require proactive, rational approaches to minimizing cardiovascular toxicities, according to a recent review.
Survival rates of patients with newly diagnosed CML are about 90%, and in those with a complete cytogenetic response, survival is comparable to that of age-matched controls. Although second-generation TKIs have increased efficacy, survival rates are similar to those of imatinib, possibly due in part to mortality from non-CML causes.
TKIs used in CML therapy target BCR-ABL1, but their potencies vary against other kinases, including receptors for vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and fibroblast growth factor (FGF). The relationship between off-target activities and adverse events (AEs) remains unclear, and AE management is largely empirical, said Dr. Javid Moslehi of Vanderbilt University Medical Center, Nashville, Tenn., and Dr. Michael Deininger, professor at the University of Utah Huntsman Cancer Institute, Salt Lake City.
“Reports of cardiovascular AEs with nilotinib, pulmonary arterial hypertension (PAH) on dasatinib, and frequent cardiovascular AEs with ponatinib have caused a reassessment of the situation,” they noted.
“Given the high population frequency of cardiovascular disease and the increased frequency of vascular events with nilotinib and ponatinib, cardiovascular risk assessment and, if necessary, treatment need to be integrated into the management of patients with CML on TKIs,” they wrote (J Clin Onc. 2015 Dec 10. doi: 10.1200/JCO.2015.62.4718).
Retrospective studies have indicated that imatinib may have favorable metabolic and vascular effects, but prospective controlled trials are lacking. Defining the cardiovascular baseline risk of the specific CML population under study will be crucial in future studies.
Dasatinib was approved for front-line CML treatment based on superior cytogenic response rates, compared with imatinib, but in 2011 the Food and Drug Administration warned against cardiopulmonary risks and recommended that patients be evaluated for signs and symptoms of cardiopulmonary disease before and during dasatinib treatment. Results of DASISION (Dasatinib Versus Imatinib Study in Treatment-Naive CML Patients) showed that, at 36 months of follow-up, PAH was reported in 3% of patients on dasatinib and 0% on imatinib.
Nilotinib has shown superior efficacy to imatinib and was FDA approved for first-line therapy, with recommendations for arrhythmia monitoring and avoidance of QT interval–prolonging medications. There have been no subsequent reports of ventricular arrhythmias with nilotinib, but 36% of patients on nilotinib experienced hyperglycemia in the ENESTnd (Evaluating Nilotinib Efficacy and Safety in Clinical Trials–Newly Diagnosed Patients) study, compared with 20% on imatinib. Nilotinib also has been associated with hyperlipidemia and increased body mass. Recent results point to vascular toxicity with nilotinib. At the 6-year follow-up of the ENESTnd study, 10% of patients on nilotinib 300 mg twice per day and 16% on nilotinib 400 mg twice per day had cardiovascular events, compared with 2.5% of patients taking imatinib 400 mg once per day. The dose-dependent increased risk implicates a drug-dependent process.
Ponatinib is the only clinical TKI active against the BCR-ABL1T315I mutation. It is a potent inhibitor of numerous other kinases as well, including VEGF receptors. In the PACE (Ponatinib Ph-positive Acute Lymphoblastic Leukemia and CML Evaluation) study, 26% of patients on ponatinib developed hypertension, and traditional atherosclerosis risk factors (age, hypertension, and diabetes) predisposed patients to serious vascular AEs. Cardiovascular toxicity was shown to be dose dependent, and older patients with history of diabetes or ischemic events are the least tolerant of high dose intensity. A subset of patients will benefit from ponatinib, particularly those with BCR-ABL1T315I, but leukemia-related and cardiovascular risks must both be assessed.
Dr. Moslehi reported financial ties with Novartis, ARIAD, Takeda/Millennium, Bristol-Myers Squibb, and Acceleron Pharma. Dr. Deininger reported ties to Novartis, Bristol-Myers Squibb, Incyte, ARIAD, Pfizer, and Cellgene.