Drug development for children: how adequate is the current European ethical guidance?

Transcription

1 Chapter 7 Drug development for children: how adequate is the current European ethical guidance?

2 ABSTRACT It is unacceptable that many drugs prescribed to children have not been proven safe and effective for them. Yet some of the necessary drug studies do not provide the participating children direct benefit. From an ethical point of view, involving children in such studies is complex: because there are no direct advantages, the possible disadvantages must be strictly limited. A European ethical framework that provides guidance regarding these limits and that can and will be consistently applied by all European countries is essential for facilitating a harmonized approach to pediatric clinical trials across Europe. Limits for pediatric research without direct benefit are defined in two European documents. According to the Council of Europe s European Convention on Human Rights and Biomedicine such research may be approved only if it entails minimal risk and minimal burden. In contrast, in a more recent document aimed to provide guidance on the application of the Clinical Trials Directive with regard to trials with minors, the European Union recommends allowing a minor increase over minimal risk in case of benefit for the group of children with the same disease. On the basis of an example, this paper shows that the inconsistency between these two documents may either prohibit important research or expose participants to unjustified risks of harm. We recommend that the two documents use the same terminology and that the European Union recommendations emphasize that exposing children to higher levels of risk and burden that cannot be compensated for by direct benefits must always be regarded as a last resort. a. e. westra 1, d. p. engberts 2, r. n. sukhai 1, J. m. wit 1, i. d. de beaufort 3 1. Department of Pediatrics, Leiden University Medical Center; 2. Department of Health Care Ethics and Health Law, Leiden University Medical Center; 3. Department of Medical Ethics and Philosophy of Medicine, Erasmus Medical Center Rotterdam Archives of Disease in Childhood 2010;95(1): CHAPTER 7

3 INTRODUCTION The European Union (EU) Regulation on medicinal products for pediatric use (Pediatric Regulation) (2007) is based on the growing insight that it is unacceptable that drugs prescribed to children often have not been proven safe and effective for them. 49 Yet some of the studies necessary for drug development do not directly benefit the participating children. Many pharmacokinetic (PK) studies, for instance, fail to provide direct benefit, as they provide very few doses and/or are conducted in children who are already benefiting from existing therapy. Ethically speaking, involving children in such studies is complex: in view of the absence of direct advantages, strict limits are required regarding the possible disadvantages. A European ethical framework that provides guidance regarding these limits and that can and will be consistently applied by all countries is essential for facilitating a harmonized approach to pediatric clinical trials across Europe. This means that such a framework should clearly define such limits and should also be unambiguous: otherwise it cannot be consistently applied. Furthermore, it must result in an optimal balance between the ethical demands to protect individual children from harm and to facilitate important research: otherwise it will not be consistently applied. Currently, limits are defined in two European documents (See boxed text ). According to the Council of Europe s European Convention on Human Rights and Biomedicine (European Convention) such research may be approved only if it entails minimal risk and minimal burden. 32 In a more recent document, Ethical considerations for clinical trials on medicinal products conducted with the pediatric population, intended to provide guidance on the application of the Clinical Trials Directive with regard to trials with minors (EU Recommendations), on the other hand, the EU recommends allowing a minor increase over minimal risk in case of benefit for the group. 34 Using the Etravirine PK study as an example (See Appendix 1, example study 1), this paper critically evaluates the adequacy of the guidance provided by these two European documents. 1 We will show that the inconsistency between the two may either prohibit important research or expose participants to unjustified risks of harm. We do not discuss the justification of pediatric research without direct benefit in general, or the concept of direct benefit itself, even though they are relevant to our reasoning: these complicated issues deserve more attention than we can offer within the scope of this paper. THE EUROPEAN ETHICAL FRAMEWORk 85

4 EUROPEAN CONVENTION Minimal risk The European Convention states that a pediatric study without direct benefit may be approved only if the risk and burden for the participating children are minimal. In this paragraph we evaluate whether the Etravirine study can comply with the first requirement: minimal risk. The main risks for the children involved in this study were related to the venipunctures and the intravenous cannula (IV cannula), the possible development of drug resistance, and the potential adverse effects of this new drug. 1 As the participants were above six years old and did not need to stop their current medication, other possible risks of PK studies, such as the risks of anemia and of being undertreated, were basically absent in this study. According to the Additional Protocol to the European Convention, a research study entails minimal risk if it will result, at the most, in a very slight and temporary negative impact on the health of the person concerned. 33 Risks are commonly expressed as the magnitude of some harm multiplied by the likelihood of its occurrence. This means that, strictly speaking, this definition implies that the likelihood of harms resulting in a more than very slight and/or permanent negative impact on the health of any participating child should be close to zero. This holds for venipunctures and the IV cannula, as its more severe complications, such as phlebitis, infiltration and bacteraemia, are extremely unlikely when the duration of the intravenous access is relatively short. Local reactions are more common but may be considered to result in a very slight and temporary negative impact on the health of the child. 119;120 The risk that these patients will develop drug resistance can also be considered extremely unlikely, given their very low viral load. Minimal risk does not apply, however, to the possible adverse effects. Previous adult studies had shown that rash, diarrhea, headache, fatigue, and nausea are common (each in >10% of participants). 121;122 Serious or permanent adverse events were exceptional in patients with no other risk factors. Although this safety profile seems reasonable in relation to the efficacy of the drug as shown so far, it was not certain that the negative impact on the health of the participating children would be very slight at most: if a child got both diarrhea and nausea, for instance, this could result in dehydration. Moreover, it was uncertain whether the safety profile of the drug in children is similar to that in adults at all: that was one of the reasons for carrying out the study. Minimal burden Both the research risk and the research burden should be minimal, according to the European Convention. This concept relates to the drawbacks that will occur in all cases. Regardless of the risks, all children involved in the Etravirine trial had to swallow several additional tablets a day for seven days, had to spend quite a 86 CHAPTER 7

5 lot of time in hospital and were bothered by venipunctures and the insertion of an IV cannula. 1 According to the Additional Protocol to the European Convention, minimal burden applies if it is to be expected that the discomfort will be, at the most, temporary and very slight for the person concerned. 33 Assessing whether the discomfort is very slight for the person concerned is difficult, given the lack of systematic empirical data on children s anticipatory anxiety and actual distress caused by the various procedures, in relation to individual characteristics. However, very slight can also be considered in relation to more objective and pre-trial identifiable characteristics of a study, such as the disturbance of daily life and the invasiveness. We realize that there exists a gap between this qualitative (very slight) and these quantitative concepts (for instance a certain time in hospital or a certain number of venipunctures). During the translation, a subjective component cannot be avoided: for instance, whereas some people consider the discomfort caused by a one-day hospital admission very slight, others may disagree. We believe that a broad consensus exists, though, that the discomfort caused by the invasiveness of multiple venipunctures and an IV cannula exceeds very slight, even if it concerns older and/or experienced children. This implies that, as with the research risk, the research burden of the Etravirine and comparable PK studies cannot be considered minimal. EU RECOMMENDATIONS The EU Recommendations allow for pediatric research without direct benefit for the participants, in case of benefit for the group, a minor increase over minimal risk. 34 With regard to the acceptability of the Etravirine study, the main questions then are: 1) Whether this particular study provided benefit for the group, 2) Whether the burden of this study may be considered acceptable and 3) Whether the risk may be considered to be a minor increase over minimal. We will show that all three questions can be answered yes. The children participating in the Etravirine study would not need the drug to be tested (at least not before long). They were, however, affected by HIV themselves. As the group is defined as children affected by the same disease, or disease which shares similar features and for which the medicinal product could be of benefit, the study could indeed provide the required benefit for the group. 34 The burden of the study consisted of, among others, multiple venipunctures and the insertion of an IV cannula. How this burden should be evaluated according to the EU Recommendations is not immediately clear: although a special paragraph of this document is devoted to pain, distress, and fear minimization, limits regarding pediatric research without direct benefit are only provided for the research risks. Probably minimal risk is used as some sort of umbrella concept, referring both to the risk and burden of a study. This is at least suggested by THE EUROPEAN ETHICAL FRAMEWORk 87

6 the fact that the following definition of minimal risk is used: the probability and magnitude of harm or discomfort anticipated in the research are not greater in and of themselves than those ordinarily encountered in daily life or during the performance of routine physical or psychological examinations or tests (italics ours). 34 In that case, the burden needs not be evaluated separately. For each of the three risk categories (minimal risk, a minor increase over minimal risk, and more than a minor increase over minimal risk) then, the document provides a list of examples. Venipunctures and subcutaneous injections, for instance, are considered minimal risk; IV cannula s and umbilical catheters, a minor increase over minimal risk. It is emphasized that the proposed categorization only applies to single of very infrequent use of the procedure. Further guidance for combinations or frequently repeated procedures is not provided. One could argue, though, that repeating a procedure which is categorized as minimal (venipuncture) is not a problem, even if combined with (only) one procedure involving a minor increase over minimal risk (IV cannula). The risk of adverse effects after administration of a (unlicensed) drug is not included in one of the lists. On the one hand, this is not surprising, as this risk differs according to the product, but on the other hand, it is: in the Etravirine and many other drug trials, the possible harm caused by these adverse effects poses the most important risk. This evaluation consequently depends on one s own interpretation. Different interpretations by reasonable people may be possible, but if willing to approve the study, one could probably convincingly argue that it is unlikely that the risk on adverse effects will be more than a minor increase over minimal. DISCUSSION The EU Pediatric Regulation is based on the growing insight that it is unacceptable that drugs prescribed to children have not been proven safe and effective to them. Yet some of the necessary studies do not provide direct benefit, which means that strict limits are required regarding the level of possible harm. In order to facilitate a harmonized approach to clinical trials across the EU, European guidance regarding these limits must be unambiguous and must strike the right balance between the ethical demand to protect individual children from harm and the demand to facilitate important research. We have shown, though, that the two European documents in which such limits are defined are not consistent: the European Convention would require rejection of PK studies such as the Etravirine study, whereas the EU Recommendations seem to allow approval. More importantly, neither of the two documents seems to strike the right balance between the ethical demands to protect individual children from harm and to facilitate important research. The absolute limit of minimal risk and minimal burden stipulated by the European Convention may prohibit important 88 CHAPTER 7

7 and appropriate research. Drug studies often expose their participants to higher levels of risk and burden than we used to consider acceptable for children, and the growing insight in the necessity of these studies means that we have to adjust to that. The requirement of minimal risk and minimal burden is a good basis, but exceptions must be possible: otherwise researchers and research ethics committee members may feel that they have to ignore the ethical framework or have to resort to flexible interpretations of these concepts or the concept of direct benefit, thereby undermining the ethical basis on which the whole idea of strict limitations for research without direct benefit relies. The EU Recommendations allow for such exceptions, but allowing a minor increase over minimal risk in case of benefit for the group also seems problematic. On the one hand, this strategy may still prohibit important research that involves more than a minor increase over minimal risk. On the other hand, it may expose participants to unjustified risks of harm: first, because of the lack of guidance regarding the research burden; and second, because the EU Recommendations in their current form fail to emphasize that exposing children to higher levels of risk and burden that cannot be compensated for by direct benefits must always be regarded as a last resort. Benefit for the group does not automatically justify exposing children to a higher level of risk. Increasing the acceptable level of risk for all studies with benefit for the group would decrease the pressure on the questions as to whether the desired results are truly important and whether they cannot be obtained with direct benefit or with lower levels of risk and burden. If we want more adequate European guidance regarding the limits of pediatric research without direct benefit, the EU Recommendations should complement the European Convention better, by using the same terminology (e.g., risk and burden) and definitions (the proposed definition of minimal risk is not necessarily a more favorable option, considering all objections against this risks of daily life or of routine examinations standard) ;86;91;123;124 Clearly specified criteria should then be provided for studies that may be approved despite involving higher levels of risk and/or burden. According to the US Federal Regulations, the higher level of risk applies to all types of study, as long as the expected results are vitally important for the group and the experimental procedures commensurate with those inherent in the participants situations. 18 Europe must consider whether it wants to adopt these criteria or wants to develop its own. Finally, reflection is needed on which levels of risk and burden we consider acceptable for those exceptional cases. Do we need an absolute limit again, or one that is relative to the importance of the expected benefits? Empirical studies may provide insight in the types of studies that cannot comply with the requirement of minimal risk and minimal burden but are still needed to improve health care for sick children. THE EUROPEAN ETHICAL FRAMEWORk 89

8 European Convention Exceptionally and under the protective conditions described by law, where the research has not the potential to produce results of direct benefit to the health of the person concerned, such research may be authorized subject to the conditions laid down in paragraph 1, sub-paragraph I, iii, iv and v above, and to the following additional conditions: 1) The research has the aim of contributing, through significant improvement in the scientific understanding of the individual s condition, disease or disorder, to the ultimate attainment of results capable of conferring benefit to the person concerned or to other persons in the same age category or afflicted with the same disease or disorder or having the same condition. 2) The research entails only minimal risk and minimal burden for the individual concerned. EU Recommendations In the following examples, levels of risk are considered to be in balance with the benefit for a trial with the pediatric population:» Minimal risk with benefit for the individual of benefit for the group (i.e. children affected by the same disease, or a disease which shares similar features and for which the medicinal product could be of benefit).» Minor increase over minimal risk, with benefit for the individual of benefit for the group, and with the benefit to risk ratio being at least a favorable as that of available alternative approaches. 90 CHAPTER 7