Aissatou Touré

Randomised controlled trials for Ebola: practical and ethical issues

2 months ago, when the numbers known to have died from Ebola in west Africa could still be counted in hundreds, WHO made an important statement about investigational drugs and vaccines. This crisis is so acute, WHO declared, that it is ethical to offer interventions with potential benefits but unknown efficacy and side-effects, though every effort should be made to evaluate benefits and risks and share all data generated. The need for drugs and vaccines was urgent then. With cases now rising exponentially and health systems overwhelmed, it is even greater today. Vaccine safety trials are underway in the USA and the UK, and poised to roll out to Africa soon. But treatments for those with infection are required too. Besides playing a direct part in containing the epidemic, interventions that could improve outcomes for the sick would help to rebuild the confidence of affected communities in health services, a critical step if Ebola is to be overcome. A fast-track initiative for evaluating investigational drugs was launched in September, 2014.1 But although the question of whether unproven treatments should be offered at all is now settled, the question of how they should be deployed and tested is not. Still at issue is whether such treatments should be made available only in the context of randomised controlled trials (RCTs) in which patients receive either a new intervention and conventional care, or conventional care alone or with a placebo. Advocates of this RCT approach2 state that as this experimental design will create the most robust evidence for the future, and is what regulators are used to, it is the only approach that should be considered. We disagree. While we concur that RCTs provide robust evidence, and support their use where this is ethical and practical, we do not believe that either consideration is likely to be satisfied in the context of this epidemic. The priority must be to generate data about effectiveness and safety as swiftly as possible, so that the most useful new treatments can be identified for rapid deployment. Alternative trial designs have the potential to do this more quickly, and with greatest social and ethical acceptability. The first objection to RCTs in which investigational drugs plus conventional care are compared purely with conventional care is ethical. Such randomisation is ethical when there is equipoise—when there is genuine uncertainty about whether an untested treatment has benefits or risks that exceed those of conventional care. Equipoise is a useful principle, but it can break down when conventional care offers little benefit and mortality is extremely high. This is precisely the problem with Ebola: current conventional care does not much affect clinical outcomes and mortality is as high as 70%. When conventional care means such a high probability of death, it is problematic to insist on randomising patients to it when the intervention arm holds out at least the possibility of benefit. Ethical arguments are not the same for all levels of risk. No-one insisted that western medical workers offered zMapp and other investigational products were randomised to receive the drug or conventional care plus a placebo. None of us would consent to be randomised in such circumstances. In cancers with a poor prognosis for which there are no good treatments, evidence from studies without a control group can be accepted as sufficient for deployment, and even for licensing by regulators, with fuller analysis following later. There is no need for rules to be bent or corners to be cut: the necessary procedures already exist, and are used. The second objection is practical. Even if randomisation were ethically acceptable, it might not be deliverable in the context of health-care systems, and indeed wider social order, that are breaking down as in Liberia, Guinea, and Sierra Leone. Populations who are terrified by the progress of the epidemic, and who lack trust in health-care and aid workers, and in public authorities in the aftermath of civil wars, cannot be expected to offer informed consent to such randomised trials. It is also unclear that any capacity exists to impose controlled conditions during a raging epidemic. Insisting on RCTs could even worsen the epidemic, by undermining trust in the Ebola treatment centres that are central to containing it. Randomisation is not, moreover, the only way to gather reliable information about the safety and effectiveness of potential Ebola therapies. Indeed, other methods might be more appropriate for achieving the key objective, which is to identify drug regimens that improve outcomes over existing methods of care, quickly, so that WHO can recommend their use and lives can be saved. One viable approach would be to try different treatments in parallel and at different sites, following observational studies that document mortality under standard care. This approach could effectively triage treatments into those with great benefits that should be rolled out immediately, those with no effect that should be discarded quickly, and those with promise needing follow-up in randomised trials. These trials can be designed adaptively, meaning that patient enrolment can be altered as efficacy data emerge, minimising the numbers of individuals who get ineffective treatments and increasing the numbers getting those that show benefits. This is not different from phase 2 studies as currently conducted and accepted by regulatory authorities for other diseases. It will also enable quick follow-up trials of combinations of antivirals and new treatments that have already shown evidence of activity. A different type of RCT might also become an option once more than one drug has shown efficacy—even efficacy in animal models. Then, patients could ethically be randomised to one investigational drug or another. No-one would get only standard care. We accept that RCTs can generate strong evidence in ordinary circumstances; not, however, in the midst of the worst Ebola epidemic in history. The urgent need is to establish whether new investigational drugs offer survival benefits, and thus which, if any, should be recommended by WHO to save lives. We have innovative but proven trial designs for doing exactly that. We should be using them, rather than doggedly insisting on gold standards that were developed for different settings and purposes.

Use of HRP-2-based rapid diagnostic test for Plasmodium falciparum malaria: assessing accuracy and cost-effectiveness in the villages of Dielmo and Ndiop, Senegal.

BackgroundIn 2006, the Senegalese National Malaria Control Programme (NMCP) has recommended artemisinin-based combination therapy (ACT) as the first-line treatment for uncomplicated malaria and, in 2007, mandated testing for all suspected cases of malaria with a Plasmodium falciparum HRP-2-based rapid diagnostic test for malaria (RDT(Paracheck®). Given the higher cost of ACT compared to earlier anti-malarials, the objectives of the present study were i) to study the accuracy of Paracheck® compared to the thick blood smear (TBS) in two areas with different levels of malaria endemicity and ii) analyse the cost-effectiveness of the strategy of the parasitological confirmation of clinically suspected malaria cases management recommended by the NMCP.MethodsA cross-sectional study was undertaken in the villages of Dielmo and Ndiop (Senegal) nested in a cohort study of about 800 inhabitants. For all the individuals consulting between October 2008 and January 2009 with a clinical diagnosis of malaria, a questionnaire was filled and finger-prick blood samples were taken both for microscopic examination and RDT. The estimated costs and cost-effectiveness analysis were made considering five scenarios, the recommendations of the NMCP being the reference scenario. In addition, a sensitivity analysis was performed assuming that all the RDT-positive patients and 50% of RDT-negative patients were treated with ACT.ResultsA total of 189 consultations for clinically suspected malaria occurred during the study period. The sensitivity, specificity, positive and negative predictive values were respectively 100%, 98.3%, 80.0% and 100%. The estimated cost of the reference scenario was close to 700€ per 1000 episodes of illness, approximately twice as expensive as most of the other scenarios. Nevertheless, it appeared to us cost-effective while ensuring the diagnosis and the treatment of 100% of malaria attacks and an adequate management of 98.4% of episodes of illness. The present study also demonstrated that full compliance of health care providers with RDT results was required in order to avoid severe incremental costs.ConclusionsA rational use of ACT requires laboratory testing of all patients presenting with presumed malaria. Use of RDTs inevitably has incremental costs, but the strategy associating RDT use for all clinically suspected malaria and prescribing ACT only to patients tested positive is cost-effective in areas where microscopy is unavailable.

Comparative analysis of IgG responses to Plasmodium falciparum MSP1p19 and PF13-DBL1α1 using ELISA and a magnetic bead-based duplex assay (MAGPIX®-Luminex) in a Senegalese meso-endemic community

BackgroundNumerous Plasmodium falciparum antigens elicit humoral responses in humans living in endemic areas. Use of multiplex assays is a convenient approach to monitor the antibody response against multiple antigens, but to integrate multiplex assay-derived data with datasets, generated previously using ELISA, comparative studies are needed. This work compares antibody responses to two P. falciparum antigens monitored using both technologies.MethodsThe IgG response against the merozoite surface protein-1 PfMSP1p19 and the PF13-DBL1α1 domain of the P. falciparum Erythrocyte Membrane Protein1, expressed by the rosette-forming parasite 3D7/PF13 (PF13), was investigated using ELISA and a MAGPIX®-Luminex duplex assay. Archived plasma samples collected before the rainy season from 217 villagers living in Ndiop, a Senegalese meso-endemic setting, were studied. ROC analysis was used to define the optimal antibody measure readout. Association of antibody levels with protection against clinical malaria was analysed using Poisson regression in a retrospective study from active case detection records performed during the 5.5-month transmission season that followed blood sampling.ResultsThere was a strong positive correlation (P <10-3) between ELISA and MAGPIX®-Luminex-MFI (median fluorescence intensity) values for antibody to PfMSP1p19 (rho = 0.78) and PF13-DBL1α1 (rho = 0.89), with a similar degree of concordance in all age groups. Antibody levels to both antigens were high but displayed a different age-associated pattern. Independent age-adjusted Poisson regression analysis showed a significant association with protection only for IgG responses to MSP1p19 (P <0.01 RR = 0.71 [0.53-0.93]) measured by ELISA.ConclusionThe individual ELISA and duplex-MAGPIX assays provide a concordant evaluation of age-associated antibody responses to MSP1p19 and PF13-DBL1α1, irrespective of the formulation of antibody levels (values, ratios or ROC-adjusted figures) but do diverge with regard to the association of antibody levels with clinical protection in age-adjusted models. This may reflect incomplete overlap of the epitopes presented in the two formats. Further development for multiplex assessment of antibody responses to a larger panel of antigens with the robust and cost effective MAGPIX®-Luminex technology is warranted.

Serological signatures of declining exposure following intensification of integrated malaria control in two rural Senegalese communities

Recent control scale-up has reduced malaria in many areas but new tools are needed to monitor further progress, including indicators of decreasing exposure to parasite infection. Although serology is considered a promising approach in this regard, the serological impact of control interventions has been so far studied using indirect quantification of exposure. Cohort surveys concomitantly recording entomological and malariometric indices have been conducted in two Senegalese settings where supervised control intensification implemented in 2006 shifted malaria from historically holoendemic in Dielmo and mesoendemic in Ndiop to hypoendemic in both settings by 2013. We analyse here serological signatures of declining transmission using archived blood samples. Responses against ten pre-erythrocytic and erythrocytic antigens from Plasmodium falciparum and P. malariae alongside an Anopheles gambiae salivary gland antigen were analysed. Cross-sectional surveys conducted before (2002) and after (2013) control intensification showed a major impact of control intensification in both settings. The age-associated prevalence, magnitude and breadth of the IgG responses to all antigens were village-specific in 2002. In 2013, remarkably similar patterns were observed in both villages, with marginal responses against all parasite antigens in the 0-5y children and reduced responses in all previously seropositive age groups. Waning of humoral responses of individuals who were immune at the time of control intensification was studied from 2006 to 2013 using yearly samplings. Longitudinal data were analysed using the Cochran-Armittage trend test and an age-related reversible catalytic conversion model. This showed that the antigen-specific antibody declines were more rapid in older children than adults. There was a strong association of antibody decline with the declining entomological inoculation rate. We thus identified serological markers of declining exposure to malaria parasites that should help future monitoring of progress towards malaria elimination.

Longitudinal analysis of antibody responses in symptomatic malaria cases do not mirror parasite transmission in peri-urban area of Cote d’Ivoire between 2010 and 2013

Background In the agenda towards malaria eradication, assessment of both malaria exposure and efficacy of anti-vectorial and therapeutic strategies is a key component of management and the follow-up of field interventions. The simultaneous use of several antigens (Ags) as serological markers has the potential for accurate evaluation of malaria exposure. Here we aimed to measure the longitudinal evolution of the background levels of immunity in an urban setting in confirmed clinical cases of malaria. Methods A retrospective serological cross-sectional study on was carried out using 234 samples taken from 2010 to 2013 in peri-urban sentinel facility of Cote d’Ivoire. Antibody responses to recombinant proteins or BSA-peptides, 8 Plasmodium falciparum (PfAMA1, PfMSP4, PfMSP1, PfEMP1-DBL1α1-PF13, PfLSA1-41, PfLSA3-NR2, PfGLURP and PfCSP), one P. malariae (PmCSP) and one Anopheles gambiae salivary (gSG6-P1) antigens were measured using magnetic bead-based multiplex immunoassay (MBA). Total anti- P. falciparum IgG responses against schizont lysate from african 07/03 strain (adapted to culture) and 3D7 strain was measured by ELISA. Results High prevalence (7–93%) and levels of antibody responses to most of the antigens were evidenced. However, analysis showed only marginal decreasing trend of Ab responses from 2010 to 2013 that did not parallel the reduction of clinical malaria prevalence following the implementation of intervention in this area. There was a significant inverse correlation between Ab responses and parasitaemia (P<10−3, rho = 0.3). The particular recruitment of asymptomatic individuals in 2011 underlined a high background level of immunity almost equivalent to symptomatic patients, possibly obscuring observable yearly variations. Conclusion The use of cross-sectional clinical malaria surveys and MBA can help to identify endemic sites where control measures have unequal impact providing relevant information about population immunity and possible decrease of transmission. However, when immunity is substantially boosted despite observable clinical decline, a larger cohort including asymptomatic recruitment is needed to monitor the impact of control measures on level of immunity.

Association of antibodies to Plasmodium falciparum merozoite surface protein-4 with protection against clinical malaria

Identification of parasite antigens targeted by immune effector mechanisms that confer protection against malaria is important for the design of a multi-component malaria vaccine. Here, the association of antibodies reacting with the Plasmodium falciparum merozoite surface protein-4 (MSP4) with protection against clinical malaria was investigated in a Senegalese community living in an area of moderate, seasonal malaria transmission. Blood samples were collected at the end of an 8-month long dry season without any recorded parasite transmission from 206 residents enrolled in a prospective follow-up study. Active daily clinical monitoring was implemented during the subsequent five months. Entomologic monitoring documented parasite transmission during the first three months of follow-up. Serum IgG levels were determined by ELISA against three MSP4 baculovirus-encoded recombinant protein constructs, namely the full-length MSP4p40, MSP4p30 devoid of a highly polymorphic sequence stretch and the conserved C-terminal EGF-containing MSP4p20, as well as against a merozoite crude extract. Community seroprevalence against all three constructs was quite high, the lowest being against MSP4p30. Seroprevalence and antibody levels against the three MSP4 constructs were age-dependent. IgG1 dominated the anti-MSP4p20 responses, while both IgG1 and IgG3 were observed against MSP4p40. Anti-MSP4 antibodies were associated with the antibody-dependent respiratory burst (ADRB) activity in a functional assay of merozoite phagocytosis by polymorphonuclear cells. Importantly, high antibody levels against each of the three MSP4 constructs at the end of the dry season were associated with reduced morbidity during the subsequent transmission season in an age-adjusted Poisson regression model (IRR = 0.65 [0.50-0.83], P<0.001 for responses over the median values). These data are consistent with a protective role for the naturally acquired anti-MSP4 antibodies and support further development of MSP4 as a candidate component of malaria vaccine.

Bioethics Development in Africa: The Contributions of the UNESCO International Bioethics Committee

The International Bioethics Committee (IBC) of UNESCO was created in 1993 to provide leadership and influence the culture of bioethics in science and medicine and to ensure that human dignity, human rights and fundamental freedoms are respected. In the last two decades, the IBC has contributed immensely to the development of Bioethics in Africa by supporting the establishment of National Bioethics Committees, strengthening the capacity of these committees, training teachers in bioethics and providing ongoing direction in addressing bioethical issues in the life sciences. Africa is also represented on the membership of UNESCO-IBC and contributes to the global IBC agenda. Africa has a rich diversity of cultures and the growth of bioethics in Africa is varied as there are few trained bioethicists and few institutions of higher learning that teach bioethics. Inadequate resource mobilization to fulfill the bioethical agenda, slow progress in terms of bioethics education in Africa and the lack of a vibrant culture of bioethical discourse are among the challenges. In Africa, it is important to also engage the public in bioethical debates.