Asociaciones de pacientes y autorización de nuevos fármacos en Estados Unidos. El caso del eteplirseno para la distrofia muscular de Duchenne / Patients organizations and new drug approval in the US. Eteplirsen and Duchenne muscular dystrophy case

Introducción. En 2016, la Agencia de Medicamentos y Alimentos (FDA) estadounidense autorizó la comercialización del eteplirseno para el tratamiento de la distrofia muscular de Duchenne. Este hecho ha sido muy controvertido, por cuanto la autorización se produjo tras una evaluación negativa por parte del comité asesor de la FDA y de sus propios técnicos. Fue la directora del Centro de Investigación y Evaluación de Fármacos quien autorizó el medicamento, decisión que no revocó el director de la FDA. Objetivo. Informar sobre los acontecimientos más relevantes que han conducido a la autorización del eteplirseno por la FDA. Desarrollo. En el artículo se exponen pormenorizadamente los hechos relevantes que acontecieron durante el desarrollo clínico y la evaluación reguladora del eteplirseno siguiendo la vía de la ‘autorización acelerada’. Se comentan las razones por las que los técnicos de la FDA entienden que este medicamento no ha mostrado producir beneficio clínico, la actitud de las asociaciones de pacientes y las exigencias postautorización que la FDA ha impuesto a la compañía propietaria del medicamento. Por último, se reflexiona sobre la situación en que quedan los pacientes españoles una vez que el eteplirseno está comercializado en Estados Unidos. Conclusiones. Este caso, único en la historia de autorización de medicamentos en el mundo occidental, pone de manifiesto las dificultades que las regulaciones actuales de autorización acelerada de nuevos medicamentos pueden tener en la interpretación de datos del desarrollo clínico, cuando éstos son escasos y de poca calidad, y cuando se trata de enfermedades raras sin terapias disponibles (AU)

Introduction. In 2016 the US Food and Drug Administration (FDA) granted the marketing authorization for eteplirsen for Duchenne muscular dystrophy. This has been a very controversial decision since it happened after a negative assessment from both the Advisory Committee and the technical FDA evaluation team. The FDA’s Center for Drug Evaluation and Research (CDER) director was who ultimately approved the product, while the FDA Commissioner did not overrule that decision. Aim. To report about the most relevant events regarding the approval of eteplirsen by the US FDA. Development. All relevant facts that occurred during the clinical development and evaluation phase following "accelerated approval" procedure of eteplirsen are discussed in detail. The technical FDA evaluation team reasons supporting that the drug has not proven clinical benefit, the attitude of patient advocacy groups and the post-approval FDA requirements to the marketing authorization holder are discussed. Finally, we reflect on what is the situation Spanish patients face once eteplirsen is on the US market. Conclusions. This is a unique case in the history of drug authorizations in western countries, that shows the difficulties thatcurrent regulations on accelerated approval of new medicines could have when interpreting scarce and low quality clinical development data, when dealing with rare diseases with no available therapies (AU)

Identification of novel, therapy-responsive protein biomarkers in a mouse model of Duchenne muscular dystrophy by aptamer-based serum proteomics.

There is currently an urgent need for biomarkers that can be used to monitor the efficacy of experimental therapies for Duchenne Muscular Dystrophy (DMD) in clinical trials. Identification of novel protein biomarkers has been limited due to the massive complexity of the serum proteome and the presence of a small number of very highly abundant proteins. Here we have utilised an aptamer-based proteomics approach to profile 1,129 proteins in the serum of wild-type and mdx (dystrophin deficient) mice. The serum levels of 96 proteins were found to be significantly altered (P < 0.001, q < 0.01) in mdx mice. Additionally, systemic treatment with a peptide-antisense oligonucleotide conjugate designed to induce Dmd exon skipping and recover dystrophin protein expression caused many of the differentially abundant serum proteins to be restored towards wild-type levels. Results for five leading candidate protein biomarkers (Pgam1, Tnni3, Camk2b, Cycs and Adamts5) were validated by ELISA in the mouse samples. Furthermore, ADAMTS5 was found to be significantly elevated in human DMD patient serum. This study has identified multiple novel, therapy-responsive protein biomarkers in the serum of the mdx mouse with potential utility in DMD patients.

Dose-dependent pharmacokinetic profiles of 2'-O-methyl phosphorothioate antisense oligonucleotidesin mdx mice.

Antisense-mediated exon skipping is a promising therapeutic approach for Duchenne muscular dystrophy. It aims to restore the dystrophin open reading frame by skipping exons with antisense oligonucleotides (AONs) to allow production of partly functional proteins. The approach is currently tested in phase 3 clinical trials, but dosing and maintenance regimens have not yet been well studied. This study compared pharmacokinetic and pharmacodynamic effects of different 2'-O-methyl phosphorothioate RNA AON dosing and maintenance regimens in the preclinical mdx mouse model. When comparing different dosing regimens over a period of 8 weeks, higher levels of AON, exon skipping, and protein were observed in muscle after low daily doses compared with large weekly doses. Secondly, after receiving a high loading dose (1,250 mg/kg) in the first week, mice treated with maintenance injections twice weekly for 8 weeks showed higher preservation of therapeutic effects than mice receiving less or no maintenance injections. In both cases, the regimen resulting in the highest AON and exon skipping levels in muscle also resulted in high AON levels in liver and kidneys. These studies underline the importance of balancing optimal AON efficacy and tolerable levels in non-target organs, which may be fine-tuned by further optimization of AON treatment regimens.