Citations

Purpose This review provides an update on the current understanding of the clinical cardiac tolerability of trastuzumab, a humanized monoclonal antibody effective in the treatment of patients with advanced breast cancer overexpressing or amplifying HER2. Methods and Results We produced a summary of currently available information regarding the incidence and natural history of trastuzumab-associated cardiac dysfunction. Data from new, prospective clinical studies that incorporate close cardiac monitoring and standardized follow-up in patients with either advanced or earlier stages of breast cancer are also presented, and hypotheses regarding potential mechanisms of trastuzumab-related cardiotoxicity are discussed. Patients treated with trastuzumab in the pivotal trials were found to have increased risk for cardiac dysfunction, mostly when used concurrent with anthracyclines. Recent trials have required more stringent and consistent cardiac monitoring criteria and excluded patients with abnormal cardiac function, pre-existing heart disease, and/or high cumulative doses of anthracyclines. Decreases of ejection fraction and a few cases of congestive heart failure (CHF) requiring medical therapy have been detected. Improvements in ejection fraction and the symptoms of CHF have been subsequently noted in a significant number of these patients. Conclusion Trastuzumab is associated with an increased risk of asymptomatic decreases in ejection fraction, and, in a small number of patients, CHF that is almost always responsive to medical management. This risk is greatest in patients receiving concurrent anthracyclines. More data are needed to help elucidate the pathophysiology of this syndrome.

Purpose Few options are available for pain relief in patients with bone metastases who fail standard treatments. We sought to determine the benefit of radiofrequency ablation (RFA) in providing pain relief for patients with refractory pain secondary to metastases involving bone. Patients and Methods Thirty-one US and 12 European patients with painful osteolytic metastases involving bone were treated with image-guided RFA using a multitip needle. Treated patients had ≥ 4/10 pain and had either failed or were poor candidates for standard treatments such as radiation or opioid analgesics. Using the Brief Pain Inventory–Short Form, worst pain intensity was the primary end point, with a 2-unit drop considered clinically significant. Results Forty-three patients were treated (median follow-up, 16 weeks). Before RFA, the mean score for worst pain was 7.9 (range, 4/10 to 10/10). Four, 12, and 24 weeks following treatment, worst pain decreased to 4.5 (P < .0001), 3.0 (P < .0001), and 1.4 (P = .0005), respectively. Ninety-five percent (41 of 43 patients) experienced a decrease in pain that was considered clinically significant. Opioid usage significantly decreased at weeks 8 and 12. Adverse events were seen in 3 patients and included (1) a second-degree skin burn at the grounding pad site, (2) transient bowel and bladder incontinence following treatment of a metastasis involving the sacrum, and (3) a fracture of the acetabulum following RFA of an acetabular lesion. Conclusion RFA of painful osteolytic metastases provides significant pain relief for cancer patients who have failed standard treatments.

Ischemic damage to the subcortical white matter of the brain, referred to as leukoaraiosis, is a frequent complication of hypertension-related microvascular disease and contributes to the risk of stroke and vascular dementia. A large genetic contribution to this late-life form of target organ damage was suggested by a study of elderly male twins. As part of the Genetic Epidemiology Network of Arteriopathy (GENOA), 483 non-Hispanic white subjects were recruited to undergo MRI for determination of the brain volume of leukoaraiosis (291 women and 192 men from 210 sibships providing 434 sibling pairs; mean age±SD=65.2±7.3 years). The GENOA–Rochester sibships contain 2 or more siblings with essential hypertension diagnosed before age 60. The frequency distribution of the volume of leukoaraiosis was positively skewed, with a median value of 6.61 cm 3 (interquartile range: 4.77 to 9 0.83 cm 3 ). Variance component models were used to estimate the heritability (ie, the proportion of phenotypic variation caused by additive genetic factors). After logarithm transformation of the volume of leukoaraiosis, the estimated heritability (±SE) was 0.802±0.102 ( P <0.0001). Adjustments for sex, age, systolic blood pressure, and brain volume reduced the heritability estimate to 0.671±0.110 ( P <0.0001). This evidence of strong genetic influence on the susceptibility to leukoaraiosis justifies efforts to localize the responsible genes and characterize the predisposing genetic polymorphisms.

Hypertension increases oxidative stress, which can impair myocardial microvascular function and integrity. However, it is yet unclear whether long-term antioxidant intervention in early hypertension would preserve myocardial perfusion and vascular permeability responses to challenge. Pigs were studied after 12 weeks of renovascular hypertension without (n=8) or with daily supplementation of antioxidants (100 IU/kg vitamin E and 1 g vitamin C, n=6), and compared with normal controls (n=7). Myocardial perfusion and microvascular permeability were measured in vivo by electron beam computed tomography before and after 2 cardiac challenges (intravenous adenosine and dobutamine). Basal left ventricular muscle mass was also obtained. Mean arterial pressure was significantly increased in both groups of hypertensive animals (without and with antioxidants, 123±9 and 126±4 mm Hg, respectively, versus normal, 101±4 mm Hg; both P <0.05), but muscle mass was not different among the groups. The impaired myocardial perfusion response to adenosine observed in hypertensives (normal, +51±14%; P <0.05 versus baseline; hypertension, +14±15%; P =0.3 versus baseline) was preserved in hypertensive pigs that received antioxidants (+44±15%; P =0.01 compared with baseline). Long-term antioxidant intervention also preserved subendocardial microvascular permeability responses in hypertension. On the other hand, antioxidant intervention had little effect on the hypertension-induced myocardial vascular dysfunction observed in response to dobutamine. This study demonstrates that the impaired myocardial perfusion and permeability responses to increased cardiac demand in early hypertension are significantly improved by long-term antioxidant intervention. These results support the involvement of oxidative stress in myocardial vascular dysfunction in hypertension and suggest a role for antioxidant strategies to preserve the myocardial microvasculature.

Autosomal dominant polycystic kidney disease (ADPKD) is typified by the accumulation of fluid-filled cysts and abnormalities in renal epithelial cell function. The disease is principally caused by mutations in the gene encoding polycystin-1, a large basolateral plasma membrane protein expressed in kidney epithelial cells. Our studies reveal that, in normal kidney cells, polycystin-1 forms a complex with the adherens junction protein E-cadherin and its associated catenins, suggesting a role in cell adhesion or polarity. In primary cells from ADPKD patients, the polycystin-1/polycystin-2/E-cadherin/β-catenin complex was disrupted and both polycystin-1 and E-cadherin were depleted from the plasma membrane as a result of the increased phosphorylation of polycystin-1. The loss of E-cadherin was compensated by the transcriptional upregulation of the normally mesenchymal N-cadherin. Increased cell surface N-cadherin in the disease cells in turn stabilized the continued plasma membrane localization of β-catenin in the absence of E-cadherin. The results suggest that enhanced phosphorylation of polycystin-1 in ADPKD cells precipitates changes in its localization and its ability to form protein complexes that are critical for the stabilization of adherens junctions and the maintenance of a fully differentiated polarized renal epithelium.

Human cells can fuse with damaged or diseased somatic cells in vivo. Whether human cells fuse in vivo in the absence of disease and with cells of disparate species is unknown. Such a question is of current interest because blood exchanges between species through direct physical contact, via insect vectors or parasitism, are thought to underlie the transmission of zoonotic agents. In a model of human‐pig chimerism, we show that some human hematopoietic stem cells engrafted in pigs contain both human and porcine chromosomal DNA. These hybrid cells divide, express human and porcine proteins, and contribute to porcine nonhematopoietic tissues. In addition, the hybrid cells contain porcine endogenous retroviral DNA sequences and are able to transmit this virus to uninfected human cells in vitro. Thus, spontaneous fusion can occur in vivo between the cells of disparate species and in the absence of disease. The ability of these cell hybrids to acquire and transmit retroviral elements together with their ability to integrate into tissues could explain genetic recombination and generation of novel pathogens.