Nucleic acid therapeutics最新文献

Antisense oligonucleotides (ASOs), a novel paradigm in modern therapeutics, modulate cellular gene expression by binding to complementary messenger RNA (mRNA) sequences. While advances in ASO medicinal chemistry have greatly improved the efficiency of cellular uptake, selective uptake by specific cell types has been difficult to achieve. For more efficient and selective uptake, ASOs are often conjugated with molecules with high binding affinity for transmembrane receptors. Triantennary N-acetyl-galactosamine conjugated phosphorothioate ASOs (GalNAc-PS-ASOs) were developed to enhance targeted ASO delivery into liver through the hepatocyte-specific asialoglycoprotein receptor (ASGR). We assessed the kinetics of uptake and subsequent intracellular distribution of AlexaFluor 488 (AF488)-labeled PS-ASOs and GalNAc-PS-ASOs in J774A.1 mouse macrophages and primary mouse or rat hepatocytes using simultaneous coherent anti-Stokes Raman scattering (CARS) and two-photon fluorescence (2PF) imaging. The CARS modality captured the dynamic lipid distributions and overall morphology of the cells; two-photon fluorescence (2PF) measured the time- and dose-dependent localization of ASOs delivered by a modified treatment of suspension cells. Our results show that in macrophages, the uptake rate of PS-ASOs did not significantly differ from that of GalNAc-PS-ASOs. However, in hepatocytes, GalNAc-PS-ASOs exhibited a peripheral uptake distribution compared to a polar uptake distribution observed in macrophages. The peripheral distribution correlated with a significantly larger amount of internalized GalNAc-PS-ASOs compared to the PS-ASOs. This work demonstrates the relevance of multimodal imaging for elucidating the uptake mechanism, accumulation, and fate of different ASOs in liver cells that can be used further in complex in vitro models and liver tissues to evaluate ASO distribution and activity.

Antisense oligonucleotides are a relatively new therapeutic modality and safety evaluation is still a developing area of research. We have observed that some oligonucleotides can produce acute, nonhybridization dependent, neurobehavioral side effects after intracerebroventricular (ICV) dosing in mice. In this study, we use a combination of in vitro, in vivo, and bioinformatics approaches to identify a sequence design algorithm, which can reduce the number of acutely toxic molecules synthesized and tested in mice. We find a cellular assay measuring spontaneous calcium oscillations in neuronal cells can predict the behavioral side effects after ICV dosing, and may provide a mechanistic explanation for these observations. We identify sequence features that are overrepresented or underrepresented among oligonucleotides causing these reductions in calcium oscillations. A weighted linear combination of the five most informative sequence features predicts the outcome of ICV dosing with >80% accuracy. From this, we develop a bioinformatics tool that allows oligonucleotide designs with acceptable acute neurotoxic potential to be identified, thereby reducing the number of toxic molecules entering drug discovery pipelines. The informative sequence features we identified also suggest areas in which to focus future medicinal chemistry efforts.

Dysregulation of RNA splicing causes many diseases and disorders. Several therapeutic approaches have been developed to correct aberrant alternative splicing events for the treatment of cancers and hereditary diseases, including gene therapy and redirecting splicing, using small molecules or splice switching oligonucleotides (SSO). Significant advances in the chemistry and pharmacology of nucleic acid have led to the development of clinically approved SSO drugs for the treatment of spinal muscular dystrophy and Duchenne muscular dystrophy (DMD). In this review, we discuss the mechanisms of SSO action with emphasis on "less common" approaches to modulate alternative splicing, including bipartite and bifunctional SSO, oligonucleotide decoys for splice factors and SSO-mediated mRNA degradation via AS-NMD and NGD pathways. We briefly discuss the current progress and future perspectives of SSO therapy for rare and ultrarare diseases.

The drug development process is a long and arduous one, especially for rare diseases. Patient and patient representatives can and should be involved in this process from an early stage, since they have the perspective of living with a disease on a daily basis and can best identify which symptoms are the largest burden and which benefits would be more important to them. In this perspective, we outline how patients can be involved optimally in drug development. We outline success factors such as finding the right partners, bilateral education, having realistic expectations, and an open and honest dialog with all stakeholders.

With the development of antisense oligonucleotides over more than 30 years and the increasing number of identified unique severely debilitating or life-threatening diseases affecting only 1 person in the world-now referred to as N-of-1 diseases-it is more and more appealing to use antisense technology to treat N-of-1 diseases when they are caused by well-identified mutations in single genes. N-of-1 patients present unique challenges to the health care system because the patient may be, and often is, the single patient in the world with the specific mutation in question, thus requiring an approach particular to that patient. Yet, we now know that there are millions of such patients, requiring scalable solutions. This article offers suggestions on how a specific and very regulated area of the new drug development process, chemistry, manufacturing, and control, could be addressed for N-of-1 oligonucleotides from a regulatory standpoint.

The first individualized therapy was administered in the United States just 2 years ago, when milasen, a therapeutic adapted from a Food and Drug Administration (FDA)-approved antisense oligonucleotide technology, was developed for a young girl with an extremely rare genetic mutation associated with Batten disease. Since then there has been an explosion of enthusiasm in developing customized treatments for extremely rare genetic conditions. These interventions raise some of the ethics concerns characteristic of novel therapeutics while simultaneously challenging existing legal, regulatory, and ethical understandings. Their individualized aspect blurs to the point of erasing the historically distinct line separating research from treatment, leading regulators and ethics oversight bodies to reevaluate existing policies. As experimental therapeutics, they raise the potential for both compromised informed consent and conflicts of interest, and their considerable expense provokes serious justice concerns. This article examines these challenges, urges multidisciplinary stakeholder engagement to address them in a transparent and practicable manner, and recommends initial policy responses.