Consensus statement on heart xenotransplantation in children: Toward clinical translation

Challenges in Paediatric Xenotransplantation: Ethical Components Requiring Distinct Attention in Children and Obligations to Patients and Society

The transplantation of non-human organs into humans, or xenotransplantation (XTx), has recently garnered new attention and is being developed to help address the problem of organ scarcity in transplantation. Ethical issues surrounding XTx have been studied since initial interest arose decades ago and have experienced renewed discussion in the literature. However, the distinct and relevant differences when applied to children has largely been overlooked with few groups attending to the concerns that XTx in children raises. In this paper, we explore ethical challenges to be expected in paediatric XTx, in particular exploring organ sizing concerns, infectious risks, psychological burdens, and issues of moral hazard. We review these domains with the aim of highlighting the implications of pursuing paediatric XTx and the cross-disciplinary approach needed to solve these issues. Children require a unique analysis from a bioethical perspective to best prepare for the issues XTx presents.

Pediatric Cardiac Xenotransplantation: Recommendations for the Ethical Design of Clinical Trials

For children with complex congenital heart problems, cardiac allotransplantation is sometimes the best therapeutic option. However, availability of hearts for pediatric patients is limited, resulting in a long and growing waitlist, and a high mortality rate while waiting. Cardiac xenotransplantation has been proposed as one therapeutic alternative for neonates and infants, either in lieu of allotransplantation or as a bridge until an allograft becomes available. Scientific and clinical developments in xenotransplantation appear likely to permit cardiac xenotransplantation clinical trials in adults in the coming years. The ethical issues around xenotransplantation of the heart and other organs and tissues have recently been examined, but to date, only limited literature is available on the ethical issues that are attendant with pediatric heart xenotransplantation. Here, we summarize the ethical issues, focusing on (1) whether cardiac xenotransplantation should proceed in adults or children first, (2) pediatric recipient selection for initial xenotransplantation trials, (3) special problems regarding informed consent in this context, and (4) related psychosocial and public perception considerations. We conclude with specific recommendations regarding ethically informed design of pediatric heart xenotransplantation trials.

Who shall go first? A multicriteria approach to patient selection for first clinical trials of cardiac xenotransplantation

After achieving sustained graft functioning in animal studies, the next step in the progression of xenotransplantation towards clinical application is the initiation of the first clinical trials. This raises the question according to which criteria patients shall be selected for these trials. While the discussion regarding medical criteria has already commenced, ethical considerations must also be taken into account. This is essential, first, to establish a procedure that is ethically reasonable and justified. Second, it is a prerequisite for a publicly acceptable and comprehensible implementation. This paper outlines a multicriteria approach for the selection of patients in first-in-human clinical trials of cardiac xenotransplantation with four ethical criteria: medical need, capacity to benefit, patient choice and compliance (as an exclusion criterion). Consequently, these criteria identify a primary target group of patients who exhibit a high medical need for cardiac xenotransplantation, face a high risk of morbidity and mortality without an organ replcaement therapy, have a substantial chance of benefiting from xenotransplantation, thereby also enhancing the scientific value of the trial, and qualify for an allotransplant to have a real choice between participating in a first-in-human xenotransplantation trial and waiting for a human organ. A secondary group would include patients for whom only the first two criteria are met, that is, who have a high medical need and a good capacity to benefit from xenotransplantation but who have a restricted choice because they do not qualify for an allotransplant.

Ethical considerations in xenotransplantation of thoracic organs - a call for a debate on value based decisions

Xenotransplant covers a broad ethical territory and there are several ethical questions that have arisen in parallel with the technological advances that have allowed the first porcine transplants to occur. This brief communication highlights ethical considerations regarding heart and lung xenotransplantation, with an emphasis on unresolved value-based concerns in the field. The aim of this text is therefore to encourage the readers to consider the vast potential of this emerging technique to do good, but also the risk of doing harm, and to participate in a discussion. The list of questions presented here is not exhaustive but hopefully represents some of the questions that appear to be most pressing as the field advances. The focus is on the value-based, or ethical questions, not the questions related to the practical medical procedures.

Pediatric heart transplantation: Looking forward after five decades of learning

Heart transplantation has become the standard of care for pediatric patients with end-stage heart disease throughout the world. Since the first transplant was performed in 1967, the number of transplants has grown dramatically with 13 449 pediatric heart transplants being reported to The International Society of Heart and Lung Transplant (ISHLT) between January 1992 and June 30, 2018. Outcomes have consistently improved over the last few decades, specifically short-term outcomes. Most recent survival data demonstrate that recipients who survive to 1-year post-transplant have excellent long-term survival with more than 60% of those who were transplanted as infants being alive 25 years later. Nonetheless, the rates of graft loss beyond the first year have remained relatively constant over time; driven primarily by our poor understanding and lack of treatments for chronic allograft vasculopathy (CAV). Acute rejection, CAV, graft failure, and infection continue to be the major causes of death within the first 5 years post-transplant. In addition, renal dysfunction, malignancy, and the need for re-transplantation remain as significant issues that require close follow-up. Looking forward, key challenges include improving donor utilization rates (including donation after cardiac death (DCD) and the use of ex vivo perfusion devices), the development of non-invasive biomarkers for rejection, efforts to mitigate the long-term effects of immunosuppression, and prevention of CAV. It is not possible to cover the entire evolution of pediatric heart transplantation over the last five decades, but in this review, we hope to touch on key observations, lessons learned, and practice changes that have advanced the field, as well as glance ahead to the next decade.

Paediatric heart transplantation: life-saving but not yet a cure

In the 1980s, heart transplantation was the first successful treatment for infants born with hypoplastic left heart syndrome. Infants who have required heart transplantation benefit from immunologic "advantages," including long-term survival free from cardiac allograft vasculopathy. Currently ∼ 90% of children undergoing a heart transplant are reaching their first-year anniversary and the clinical practices of paediatric heart transplantation have dramatically improved. These successes are largely attributed to research sponsored by the Pediatric Heart Transplant Study Group, the International Society of Heart and Lung Transplantation and, more recently, the Non-profits Enduring Hearts and Additional Ventures. Despite these successes, the field is challenged to increase progress to achieve long-term survival into adulthood. The wait-list mortality, especially among infants, is unacceptably high often leading to palliative measures that can increase post-transplant mortality. Cardiac allograft vasculopathy remains a major cause for progressive graft loss of function and sudden death. The relative tolerance seen in immature recipients has not been translated to modifying older recipients' post-transplant outcomes. The modifiable cause(s) for the increased risks of transplantation in children of different ethnicities and races require definition. Addressing these challenges faces the reality that for-profit research favours funding adult recipients, with ∼ 10-fold greater numbers, and their more modest longevity goals. Advocacy for funding "incentives" such as the Orphan Drug rules in the United States and upholding principles of equity and inclusion are critical to addressing the challenges of paediatric heart transplant recipients worldwide.

Ethically Advancing Pediatric Cardiac Xenotransplant

This Viewpoint examines how pediatrics should prepare for the prospect of cardiac xenotransplant, including its ethical implications.