Search

Background. Doxorubicin (DOX) produces a well-known cardiomyopathy through multiple mechanisms, which include, among many, Ca2+ overload due to reduced SERCA2a activity and inappropriate opening of the RyR2, and impaired myocardial energetics. DOX generate Reactive Oxygen and Nitrogen Species (ROS and RNS), posing the heart at increased demand for oxygen, setting the stage for metabolic ischemia that also activates late I Na , target of ranolazine (RAN). Here, we aim at assessing whether RAN, diminishing intracellular Ca2+ through inhibition of late I Na , and enhancing myocardial glucose utilization (and/or reverting impairment of glucose utilization caused by chemotherapy) blunts DOX cardiotoxicity. Methods. We measured left ventricular (LV) end-diastolic and end-systolic diameters (LVEDD and LVESD), and evaluated LV function with fractional shortening (FS) by echocardiography in C57BL6 mice, 2-4 mo old, pretreated with RAN (370mg/kg/day, a dose comparable to the one used in humans) per os for 3 days. RAN was then administered for additional 7 days, alone and together with DOX (2.17mg/kg/day ip), according to our well established protocol. Hearts were then excised, mRNA expression was analyzed by RT PCR. Results . After 7 days with DOX, hearts were dilated with depressed function: LVEDD and LVESD increased from 2.8±.03 and 1.1±.03mm to 3.04±.06 and to 1.55±.08mm, respectively (both p Conclusions . RAN blunts DOX cardiotoxic effects in mice, improving remodeling and function. We plan to test RAN as a cardioprotective agent with other antineoplastic cardiotoxic drugs in mice, and to better characterize the cardioprotective mechanisms of RAN in all these settings.

Background: ErbB2, tyrosine kinase receptor of the EGFR family, overexpressed in about 25% of breast cancers, modulates development and function in the myocardium. Lapatinib (LAP) is a small molecule that inhibits ErbB2-tyrosine kinase domain. The few existing trials report it to be associated with a low risk of LV dysfunction (2%), while the prototypical antibody Trastuzumab (TRAS) increases the frequency of asymptomatic ejection fraction decrease by 3-18%, and the risk of heart failure by 2-4%. Here, we characterize our LAP murine cardiotoxicity model in vivo by echocardiography, comparing it to TRAS and doxorubicin (DOX) cardiotoxicities. Methods: LV end-diastolic and end-systolic diameters (LVEDD and LVESD) were assessed. LV function was measured with fractional shortening (FS) by M-mode echo, and with radial myocardial strain (%) with speckle tracking (ST) in sedated C57BL6 mice (2-4 mo. old) at day 0, and after 2 and 7 days of daily administration of LAP (100mg/kg/day orally), and in control mice. For comparison we used our well-established models with TRAS (2.25 mg/kg/day, ip), and DOX (2.17 mg/kg/day ip) as positive control. Results: FS was already reduced with DOX at 2 days: 52±.2%, p Conclusions: Differently from DOX, ErbB2 inhibition in mice does not produce LV dilation, but only decreases LV function. In particular, specifically targeting ErbB2-tyrosine kinase domain with LAP confers less cardiotoxicity than TRAS. Myocardial strain identifies LV systolic dysfunction earlier than conventional echo and can be a useful tool to predict ErbB2 inhibitors cardiotoxicity.

Background: Cardiotoxicity is a major drawback and social problem linked to many anticancer treatments. Early identification of signs of this adversity would certainly benefit the management of oncologic patients. The mTOR-inhibitor temsirolimus is currently being evaluated for anticancer efficacy in hundreds of clinical trials and is approved for treatment of advanced renal cell carcinoma. However, the PI3K/Akt pathway converges on mTOR, which is a central regulator of cell growth, including cardiomyocyte growth. Here, we aim at evaluating the cardiac effects of the anticancer mTOR-inhibitor temsirolimus in a mouse model in vivo. Methods: Left Ventricular (LV) fractional shortening (FS) was assessed by M-mode echocardiography in sedated C57BL/6 mice (2–4 mo. old) at day 0, and after 2, 7, 14, 21 days from a single i.p. injection of temsirolimus (0.1mg/kg, a dose comparable to the one used to treat cancer in humans) or vehicle. Doxorubicin (Doxo, 2.17 mg/kg/day for 7 days) was used as a positive control. With Speckle Tracking echocardiography (ST) we also evaluated radial myocardial strain (%), a very sensitive parameter which can detect subtle changes in cardiac function. Results: After 2 days, there was no change in FS with temsirolimus, but FS was already reduced with Doxo: 52±0.2%, p=.0000001 vs sham (60±0.4%). With temsirolimus, FS was reduced only after 21 days: 50±3%, p=.009 vs sham. Interestingly, with Speckle Tracking echocardiography we found that in the temsirolimus group radial strain was already decreased at 7 days: 42±5%, p=.01 vs sham (59±1%). Conclusions: The antineoplastic mTOR-inhibitor temsirolimus induces LV dysfunction in mice. Such dysfunction occurs later than the one observed with Doxo, but speckle tracking echocardiography is more sensitive than conventional echocardiography and can detect early signs of myocardial alteration that may prelude to overt LV dysfunction. The clear mechanisms of temsirolimus cardiotoxicity are to be elucidated in further experimental studies. We also plan to apply speckle tracking echocardiography to clinical studies, in order to evaluate the impact of early identification of temsirolimus cardiotoxicity in the treatment of renal cell carcinoma.

Skin, lymph node (popliteal), and bone marrow samples were collected from 50 red foxes (Vulpes vulpes) from May 2004 to May 2005 in southern Italy. Samples were tested for Leishmania infantum by polymerase chain reaction (PCR). The parasite was detected by PCR from 20 of 50 (40%) fox carcasses. All 20 positive cases were PCR-positive from lymph node and bone marrow samples, whereas 17 of 20 positive cases were PCR-positive from skin samples. Infection status was not related to age or sex. This is the first report of leishmaniasis in red foxes in Italy based on PCR results, and these results reinforce the assumption that this wild canid can serve as a reservoir for Leishmania.

e11052 Background: Lapatinib (L) inhibits ErbB2-tyrosine kinase domain and has been reported (in the few existing trials) to be associated with a low risk of cardiac dysfunction (2%), while the prototypical Trastuzumab (T) increases the frequency of asymptomatic ejection fraction decrease by 3-18%, and the risk of heart failure by 2-4%. Here, we characterize our L murine cardiotoxicity model. Methods: Cardiac function was measured with fractional shortening (FS) by M-mode echocardiography, and with radial myocardial strain (%) with speckle tracking (ST) in sedated C57BL6 mice (2-4 mo. old) at day 0, and after 2 and 7 days of daily administration of L (100mg/kg/day orally), and in control mice. For comparison we used our well-established models with T (2.25 mg/kg/day, ip), and Doxorubicin (D, 2.17 mg/kg/day ip) as positive control. On excised hearts, we evaluated TNFα and CD68 by immunohistochemistry. Results: FS was reduced with D at 2 days: 52±0.2%, p2 (72±6) compared to L (2±.2% and 27±4, respectively, both p

e13539 Background: Anthracyclines produce a well-known cardiomyopathy through multiple mechanisms, which also include, among many, Ca2+ overload due to reduced SERCA2a activity and inappropriate opening of the RyR2, and impaired myocardial energetics. Anthracyclines generate Reactive Oxigen and Nitrogen Species (ROS and RNS), posing the heart at increased demand for oxygen, thus setting the stage for a metabolic ischemia that also activates late INa, the target of ranolazine (RAN). Here, we aim at assessing whether RAN, diminishing intracellular Ca2+ through its inhibition of late INa, and enhancing myocardial glucose utilization (and/or reverting impairment of glucose utilization caused by chemotherapy) blunts anthracyclines cardiotoxicity. Methods: To assess for toxicity in vitro, rat H9C2 cardiomyoblasts were pretreated with RAN (0.1-1mM) for 72 hours and then treated with doxorubicin (DOX, 0.1 mM) for additional 24 hours. Cells counts were assessed by Trypan exclusion test. To evaluate cardiac function in vivo, fractional shortening (FS) and ejection fraction (EF) were measured by echocardiography in C57BL6 mice, 2-4 mo old, pretreated with RAN (370mg/kg/day, a dose comparable to the one used in humans) per os for 3 days. RAN was then administered for additional 7 days, together with DOX (2.17mg/kg/day ip), according to our well established protocol. Results: After DOX, only 68% of the cells were viable. RAN alone did not affect cell survival, but blunted DOX toxicity, rescuing % cell survival to 87% (p=.01 vs DOX alone). In our in vivo studies, after 7 days with DOX, FS decreased to 50±2%, p=.002 vs 60±1% (sham), and EF to 81±2%, p=0.0001 vs 91±1% (sham). RAN alone did not change FS (59±2%) nor EF (89±1%). Interestingly, in mice treated with RAN and DOX, the reduction in cardiac function was milder: FS was 57±1%, EF was 89±1%, p=0.01 and 0.0009 respectively, vs DOX alone. Conclusions: RAN blunts DOX cardiotoxic effects in 2 different models, in vitro and in vivo. We plan to test RAN as a cardioprotective agent with other antineoplastic cardiotoxic drugs in our experimental models, and to better characterize the cardioprotective mechanisms of RAN in all these settings.

e11040 Background: Anti-ErbB2 therapies are associated with increased risk of left ventricular (LV) dysfunction. Trastuzumab increases the frequency of asymptomatic decrease in LV ejection fraction (LVEF) by 3-18%, and the risk of heart failure (HF) by 2-4%. The newer ErbB2 antibody rhuMAb 2C4 (pertuzumab) seems to affect ligand induced ErbB signaling in a more direct fashion, affecting EGFR/ErbB2 dimerization; yet, its cardiac side effects are only beginning to emerge. Here, we test whether the murine 2C4 induces cardiac dysfunction in normal mice. Methods: In vivo cardiac function was measured with LV fractional shortening (FS) by M-mode echocardiography in sedated C57BL/6 mice (2-4 mo. old) at day 0, and after 2 and 6 days of daily i.p. administration of 2C4 (2.25 μg/g/day) or doxorubicin (Doxo, 2.17 μg/g/day) as a positive control, and in sham animals. With Speckle Tracking echocardiography (ST) we also evaluated radial myocardial strain (%), a very sensitive parameter which can predict LV dysfunction...

e13612 Background: The mTOR inhibitor temsirolimus is being evaluated for anticancer efficacy in hundreds of clinical trials and is approved for treatment of advanced renal cell carcinoma. The PI3K...

Introduction: The CXCR4 inhibitor AMD3100 is FDA-approved to provide stem cell mobilization for autologous transplantation in NHL and Multiple Myeloma patients. Newly designed CXCR4 inhibitory molecules, named Hys-7 inv, Phe-7 inv and Hys-OH, were recently discovered and validated in in vitro and in vivo studies (patent MI2010A-000093). Aim of the study was to evaluate the role of new CXCR4 inhibitors in hematopoietic stem cell and neutrophil mobilization. Experimental procedures: 60 DBA/2 female were injected subcutaneously with 5 or 30 mg/kg of CXCR4 antagonist in comparison with AMD3100 (3 or 20 mg/kg). Blood was collected at 1, 2, 6 and 24 hours from the treatment. Neutrophilis were evaluated trough flow cytometry (Ly-6G+ cells) and colony forming unit assay (CFU) of the mobilized stem cell were performed. Bone marrow was also evaluated through flow cytometry and cytological analysis. Results: Hys-7 inv, Phe-7 inv and Hys-OH, cyclic peptides CXCR4 antagonists, induced potent stem cell and neutrophils mobilization compared with AMD3100. Treatment resulted in a rapid and dose related increment in neutrophils count as well as hematopoietic stem and progenitor cells increase in peripheral blood (2 to 5 fold increase). Although Hys-7inv and Hys-OH induced neutrophils increment similar to AMD3100 the kinetic was different. AMD3100 (20 mg/kg) mobilized Ly-6G cells within 1 hour but transiently (no increase at 24 hours); instead Hys-7inv and Hys-OH mobilized Ly-6G within 2 hours lasting up to 24 hours. Interestingly, Phe-7 inv increased neutrophils mobilization within 1 hour lasting up to 24 hours. AMD3100 treated bone marrow showed an increase in progenitor cells myelo-committed (from 1.5 to 3 fold increase) and polimorphonuclear cells (PMN) (1.5 to 2.5 fold increase) and a reduction in mature-lymphocyte (0.4 to 0.28 fold increase); CXCR4 inhibitor peptides increased the immature myelo-committed progenitor cells (from 2 to 3 fold increase VS control) compared with AMD3100 (1.5 fold increase VS control) reducing PMN (1.5 to 1.65 fold increase) compared to AMD3100 (2.5 fold increase). CFU showed increased colonies in peripheral blood from mice treated with cyclic-peptides (from 2.5 to 4 fold increase) compared to AMD3100 (3.5 fold increase); the highest number of CFU was reached earlier in mice treated with Hys-7inv, Phe-7 inv and Hys-OH rapidly (within 1h) versus AMD3100 (6 hours). Conclusions: In vivo studies demonstrated that three newly synthesized CXCR4 inhibitors increased neutrophil and hematopoietic stem cells release from the bone marrow with different kinetic and duration compared to the FDA approved stem cell mobilizer AMD3100. Ongoing experiments are evaluating advantages in mobilizing precursors cells with CXCR4 cyclic-peptides antagonists compared to AMD3100. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 394. doi:10.1158/1538-7445.AM2011-394