Oxytocin exerts harmful cardiac repolarization prolonging effects in drug-induced LQTS.

Background Oxytocin is used therapeutically in psychiatric patients. Many of these also receive anti-depressant or anti-psychotic drugs causing acquired long-QT-syndrome (LQTS) by blocking HERG/IKr. We previously identified an oxytocin-induced QT-prolongation in LQT2 rabbits, indicating potential harmful effects of combined therapy. We thus aimed to analyze the effects of dual therapy with oxytocin and fluoxetine/risperidone on cardiac repolarization. Methods Effects of risperidone, fluoxetine and oxytocin on QT/QTc, short-term variability (STV) of QT, and APD were assessed in rabbits using in vivo ECG and ex vivo monophasic AP recordings in Langendorff-perfused hearts. Underlying mechanisms were assessed using patch clamp in isolated cardiomyocytes. Results Oxytocin, fluoxetine and risperidone prolonged QTc and APD in whole hearts. The combination of fluoxetine + oxytocin resulted in further QTc- and APD-prolongation, risperidone + oxytocin tended to increase QTc and APD compared to monotherapy. Temporal QT instability, STVQTc was increased by oxytocin, fluoxetine / fluoxetine + oxytocin and risperidone / risperidone + oxytocin. Similar APD-prolonging effects were confirmed in isolated cardiomyocytes due to differential effects of the compounds on repolarizing ion currents: Oxytocin reduced IKs, fluoxetine and risperidone reduced IKr, resulting in additive effects on IKtotal-tail. In addition, oxytocin reduced IK1, further reducing the repolarization reserve. Conclusion Oxytocin, risperidone and fluoxetine prolong QTc / APD. Combined treatment further prolongs QTc/APD due to differential effects on IKs and IK1 (block by oxytocin) and IKr (block by risperidone and fluoxetine), leading to pronounced impairment of repolarization reserve. Oxytocin should be used with caution in patients in the context of acquired LQTS

Transgenic LQT2, LQT5, and LQT2-5 rabbit models with decreased repolarisation reserve for prediction of drug-induced ventricular arrhythmias

Background and Purpose Reliable prediction of pro‐arrhythmic side effects of novel drug candidates is still a major challenge. Although drug‐induced pro‐arrhythmia occurs primarily in patients with pre‐existing repolarisation disturbances, healthy animals are employed for pro‐arrhythmia testing. To improve current safety screening, transgenic long QT (LQTS) rabbit models with impaired repolarisation reserve were generated by overexpressing loss‐of‐function mutations of human HERG (HERG‐G628S , loss of IKr; LQT2), KCNE1 (KCNE1‐G52R , decreased IKs; LQT5), or both transgenes (LQT2‐5) in the heart. Experimental Approach Effects of K+ channel blockers on cardiac repolarisation and arrhythmia susceptibility were assessed in healthy wild‐type (WT) and LQTS rabbits using in vivo ECG and ex vivo monophasic action potential and ECG recordings in Langendorff‐perfused hearts. Key Results LQTS models reflect patients with clinically “silent” (LQT5) or “manifest” (LQT2 and LQT2‐5) impairment in cardiac repolarisation reserve: they were more sensitive in detecting IKr‐blocking (LQT5) or IK1/IKs‐blocking (LQT2 and LQT2‐5) properties of drugs compared to healthy WT animals. Impaired QT‐shortening capacity at fast heart rates was observed due to disturbed IKs function in LQT5 and LQT2‐5. Importantly, LQTS models exhibited higher incidence, longer duration, and more malignant types of ex vivo arrhythmias than WT. Conclusion and Implications LQTS models represent patients with reduced repolarisation reserve due to different pathomechanisms. As they demonstrate increased sensitivity to different specific ion channel blockers (IKr blockade in LQT5 and IK1 and IKs blockade in LQT2 and LQT2‐5), their combined use could provide more reliable and more thorough prediction of (multichannel‐based) pro‐arrhythmic potential of novel drug candidates

The 'Survivorship Passport' for childhood cancer survivors

Background: Currently, there are between 300,000 and 500,000 childhood cancer survivors (CCSs) in Europe. A significant proportion is at high risk, and at least 60% of them develop adverse health-related outcomes that can appear several years after treatment completion. Many survivors are unaware of their personal risk, and there seems to be a general lack of information among healthcare providers about pathophysiology and natural history of treatment-related complications. This can generate incorrect or delayed diagnosis and treatments. Method: The Survivorship Passport (SurPass) consists of electronic documents, which summarise the clinical history of the childhood or adolescent cancer survivor. It was developed by paediatric oncologists of the PanCare and SIOPE networks and IT experts of Cineca, together with parents, patients, and survivors' organisations within the European Union–funded European Network for Cancer research in Children and Adolescents. It consists of a template of a web-based, simply written document, translatable in all European languages, to be given to each CCS. The SurPass provides a summary of each survivor's clinical history, with detailed information about the original cancer and of treatments received, together with personalised follow-up and screening recommendations based on guidelines published by the International Guidelines Harmonization Group and PanCareSurFup. Results: The SurPass data schema contains a maximum of 168 variables and uses internationally approved nomenclature, except for radiotherapy fields, where a new classification was defined by radiotherapy experts. The survivor-specific screening recommendations are mainly based on treatment received and are automatically suggested, thanks to built-in algorithms. These may be adapted and further individualised by the treating physician in case of special disease and survivor circumstances. The SurPass was tested at the Istituto Giannina Gaslini, Italy, and received positive feedback. It is now being integrated at the institutional, regional and national level. Conclusions: The SurPass is potentially an essential tool for improved and more harmonised follow-up of CCS. It also has the potential to be a useful tool for empowering CCSs to be responsible for their own well-being and preventing adverse events whenever possible. With sufficient commitment on the European level, this solution should increase the capacity to respond more effectively to the needs of European CCS

Transgenic LQT2, LQT5, and LQT2-5 rabbit models with decreased repolarisation reserve for prediction of drug-induced ventricular arrhythmias.

BACKGROUND AND PURPOSE Reliable prediction of pro-arrhythmic side effects of novel drug candidates is still a major challenge. Although drug-induced pro-arrhythmia occurs primarily in patients with pre-existing repolarisation disturbances, healthy animals are employed for pro-arrhythmia testing. To improve current safety screening, transgenic long QT (LQTS) rabbit models with impaired repolarisation reserve were generated by overexpressing loss-of-function mutations of human HERG (HERG-G628S, loss of IKr ; LQT2), KCNE1 (KCNE1-G52R, decreased IKs ; LQT5), or both transgenes (LQT2-5) in the heart. EXPERIMENTAL APPROACH Effects of K+ channel blockers on cardiac repolarisation and arrhythmia susceptibility were assessed in healthy wild-type (WT) and LQTS rabbits using in vivo ECG and ex vivo monophasic action potential and ECG recordings in Langendorff-perfused hearts. KEY RESULTS LQTS models reflect patients with clinically "silent" (LQT5) or "manifest" (LQT2 and LQT2-5) impairment in cardiac repolarisation reserve: they were more sensitive in detecting IKr -blocking (LQT5) or IK1 /IKs -blocking (LQT2 and LQT2-5) properties of drugs compared to healthy WT animals. Impaired QT-shortening capacity at fast heart rates was observed due to disturbed IKs function in LQT5 and LQT2-5. Importantly, LQTS models exhibited higher incidence, longer duration, and more malignant types of ex vivo arrhythmias than WT. CONCLUSION AND IMPLICATIONS LQTS models represent patients with reduced repolarisation reserve due to different pathomechanisms. As they demonstrate increased sensitivity to different specific ion channel blockers (IKr blockade in LQT5 and IK1 and IKs blockade in LQT2 and LQT2-5), their combined use could provide more reliable and more thorough prediction of (multichannel-based) pro-arrhythmic potential of novel drug candidates

Pronounced effects of HERG-blockers E-4031 and erythromycin on APD, spatial APD dispersion and triangulation in transgenic long-QT type 1 rabbits.

Prolongation of action potential duration (APD), increased spatial APD dispersion, and triangulation are major factors promoting drug-induced ventricular arrhythmia. Preclinical identification of HERG/IKr-blocking drugs and their pro-arrhythmic potential, however, remains a challenge. We hypothesize that transgenic long-QT type 1 (LQT1) rabbits lacking repolarizing IKs current may help to sensitively detect HERG/IKr-blocking properties of drugs.Hearts of adult female transgenic LQT1 and wild type littermate control (LMC) rabbits were Langendorff-perfused with increasing concentrations of HERG/IKr-blockers E-4031 (0.001-0.1 µM, n=9/7) or erythromycin (1-300 µM, n=9/7) and APD, APD dispersion, and triangulation were analyzed.At baseline, APD was longer in LQT1 than in LMC rabbits in LV apex and RV mid. Erythromycin and E-4031 prolonged APD in LQT1 and LMC rabbits in all positions. However, erythromycin-induced percentaged APD prolongation related to baseline (%APD) was more pronounced in LQT1 at LV base-lateral and RV mid positions (100 µM, LQT1, +40.6 ± 9.7% vs. LMC, +24.1 ± 10.0%, p<0.05) and E-4031-induced %APD prolongation was more pronounced in LQT1 at LV base-lateral (0.01 µM, LQT1, +29.6 ± 10.6% vs. LMC, +19.1 ± 3.8%, p<0.05) and LV base-septal positions. Moreover, erythromycin significantly increased spatial APD dispersion only in LQT1 and increased triangulation only in LQT1 in LV base-septal and RV mid positions. Similarly, E-4031 increased triangulation only in LQT1 in LV apex and base-septal positions.E-4031 and erythromycin prolonged APD and increased triangulation more pronouncedly in LQT1 than in LMC rabbits. Moreover, erythromycin increased APD dispersion only in LQT1, indicating that transgenic LQT1 rabbits could serve as sensitive model to detect HERG/IKr-blocking properties of drugs

Creating a unique, multi-stakeholder paediatric oncology platform to improve drug development for children and adolescents with cancer

Seven years after the launch of the European Paediatric Medicine Regulation, limited progress in paediatric oncology drug development remains a major concern amongst stakeholders – academics, industry, regulatory authorities, parents, patients and caregivers. Restricted increases in early phase paediatric oncology trials, legal requirements and regulatory pressure to propose early Paediatric Investigation Plans (PIPs), missed opportunities to explore new drugs potentially relevant for paediatric malignancies, lack of innovative trial designs and no new incentives to develop drugs against specific paediatric targets are some unmet needs. Better access to new anti-cancer drugs for paediatric clinical studies and improved collaboration between stakeholders are essential. The Cancer Drug Development Forum (CDDF), previously Biotherapy Development Association (BDA), with Innovative Therapy for Children with Cancer Consortium (ITCC), European Society for Paediatric Oncology (SIOPE) and European Network for Cancer Research in Children and Adolescents (ENCCA) has created a unique Paediatric Oncology Platform, involving multiple stakeholders and the European Union (EU) Commission, with an urgent remit to improve paediatric oncology drug development. The Paediatric Oncology Platform proposes to recommend immediate changes in the implementation of the Regulation and set the framework for its 2017 revision; initiatives to incentivise drug development against specific paediatric oncology targets, and repositioning of drugs not developed in adults. Underpinning these changes is a strategy for mechanism of action and biology driven selection and prioritisation of potential paediatric indications rather than the current process based on adult cancer indications. Pre-competitive research and drug prioritisation, early portfolio evaluation, cross-industry cooperation and multi-compound/sponsor trials are being explored, from which guidance for innovative trial designs will be provided

Spatial Correlation of Action Potential Duration and Diastolic Dysfunction in Transgenic and Drug-induced LQT2 Rabbits

Focus Issue: Sudden Cardiac DeathInternational audienceEnhanced dispersion of action potential duration (APD) is a major contributor to long-QT-(LQTS)-related arrhythmias.We aimed at investigating spatial correlations of regional heterogeneities in cardiac repolarization and mechanical function in LQTS.Female transgenic LQT2 (n=11) and wildtype (LMC) rabbits (n=9/10 without/with E4031) were subjected to phase contrast MRI to assess regional myocardial velocities. In the same rabbits' hearts, monophasic APDs were assessed in corresponding segments.In LQT2 and E4031 rabbits, APD was longer in all LV segments (p<0.01) and APD dispersion was greater than in LMC (p<0.01). In diastole, peak radial velocities (Vr) were reduced in LQT2 and E4031 compared to LMC in base and mid (cm/s, LQT2, -3.36±0.4, p<0.01, E4031, -3.24±0.6, p<0.0001, LMC, -4.42±0.5) - indicating an impaired diastolic function. Regionally heterogeneous diastolic Vr correlated with APD (LQT2, CC 0.3