Gene therapy comes of age Dunbar, Cynthia E; High, Katherine A; Joung, J Keith ...
Science (American Association for the Advancement of Science),
01/2018, Volume:
359, Issue:
6372
Journal Article
Peer reviewed
After almost 30 years of promise tempered by setbacks, gene therapies are rapidly becoming a critical component of the therapeutic armamentarium for a variety of inherited and acquired human ...diseases. Gene therapies for inherited immune disorders, hemophilia, eye and neurodegenerative disorders, and lymphoid cancers recently progressed to approved drug status in the United States and Europe, or are anticipated to receive approval in the near future. In this Review, we discuss milestones in the development of gene therapies, focusing on direct in vivo administration of viral vectors and adoptive transfer of genetically engineered T cells or hematopoietic stem cells. We also discuss emerging genome editing technologies that should further advance the scope and efficacy of gene therapy approaches.
Here we investigated the transduction characteristics of adeno-associated viral vector (AAV) serotypes 1, 2, 5, 8 and 9 in the marmoset cerebral cortex. Using three constructs that each has hrGFP ...under ubiquitous (CMV), or neuron-specific (CaMKII and Synapsin I (SynI)) promoters, we investigated (1) the extent of viral spread, (2) cell type tropism, and (3) neuronal transduction efficiency of each serotype. AAV2 was clearly distinct from other serotypes in small spreading and neuronal tropism. We did not observe significant differences in viral spread among other serotypes. Regarding the cell tropism, AAV1, 5, 8 and 9 exhibited mostly glial expression for CMV construct. However, when the CaMKII construct was tested, cortical neurons were efficiently transduced (>∼70% in layer 3) by all serotypes, suggesting that glial expression obscured neuronal expression for CMV construct. For both SynI and CaMKII constructs, we observed generally high-level expression in large pyramidal cells especially in layer 5, as well as in parvalbumin-positive interneurons. The expression from the CaMKII construct was more uniformly observed in excitatory cells compared with SynI construct. Injection of the same viral preparations in mouse and macaque cortex resulted in essentially the same result with some species-specific differences.
The lateral habenula (LHb) regulates the activity of monoaminergic neurons in the brainstem. This area has recently attracted a surge of interest in psychiatry because studies have reported the ...pathological activation of the habenula in patients with major depression and in animal models. The LHb plays a significant role in the pathophysiology of depression; however, how habenular neurons are activated to cause various depression symptoms, such as reduced motivation and sleep disturbance, remain unclear. We hypothesized that dysfunctional astrocytes may cause LHb hyperactivity due to the defective uptake activity of extracellular glutamate, which induces depressive-like behaviors. We examined the activity of neurons in habenular pathways and performed behavioral and sleep analyses in mice with pharmacological and genetic inhibition of the activity of the glial glutamate transporter GLT-1 in the LHb. The habenula-specific inhibition of GLT-1 increased the neuronal firing rate and the level of c-Fos expression in the LHb. Mice with reduced GLT-1 activity in the habenula exhibited a depressive-like phenotype in the tail suspension and novelty-suppressed feeding tests. These animals also displayed increased susceptibility to chronic stress, displaying more frequent avoidant behavior without affecting locomotor activity in the open-field test. Intriguingly, the mice showed disinhibition of rapid eye movement sleep, which is a characteristic sleep pattern in patients with depression. These results provide evidence that disrupting glutamate clearance in habenular astrocytes increases neuronal excitability and depressive-like phenotypes in behaviors and sleep.
Haemophilia B, a congenital haemorrhagic disease caused by mutations in coagulation factor IX gene (F9), is considered an appropriate target for genome editing technology. Here, we describe treatment ...strategies for haemophilia B mice using the clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 system. Administration of adeno-associated virus (AAV) 8 vector harbouring Staphylococcus aureus Cas9 (SaCas9) and single guide RNA (sgRNA) to wild-type adult mice induced a double-strand break (DSB) at the target site of F9 in hepatocytes, sufficiently developing haemophilia B. Mutation-specific gene editing by simultaneous induction of homology-directed repair (HDR) sufficiently increased FIX levels to correct the disease phenotype. Insertion of F9 cDNA into the intron more efficiently restored haemostasis via both processes of non-homologous end-joining (NHEJ) and HDR following DSB. Notably, these therapies also cured neonate mice with haemophilia, which cannot be achieved with conventional gene therapy with AAV vector. Ongoing haemophilia therapy targeting the antithrombin gene with antisense oligonucleotide could be replaced by SaCas9/sgRNA-expressing AAV8 vector. Our results suggest that CRISPR/Cas9-mediated genome editing using an AAV8 vector provides a flexible approach to induce DSB at target genes in hepatocytes and could be a good strategy for haemophilia gene therapy.
Cellular and gene therapies represent promising treatment strategies at the frontier of medicine. Hematopoietic stem cells, lymphocytes, and mesenchymal stem cells (MSCs) can all serve as sources of ...cells for use in such therapies. Strategies for gene therapy are often based on those of cell therapy, and it is anticipated that some examples will be put to practical use in the near future. Given their ability to support hematopoiesis, MSCs may be useful for the enhancement of stem cell engraftment, and the acceleration of hematopoietic reconstitution. Furthermore, MSCs may advance the treatment of severe graft-versus-host disease, based on their immunosuppressive ability. This application is also based on the homing behavior of MSCs to sites of injury and inflammation. Interestingly, MSCs possess tumor-homing ability, opening up the possibility of applications in the targeted delivery of anti-cancer genes to tumors. Many reports have indicated that MSCs can be utilized to target tumors and to deliver anti-cancer molecules locally, as tumors are recognized as non-healing wounds with inflammatory tissue. Here, we review both the potential of MSCs as cellular vehicles for targeted cancer therapy and the molecular mechanisms underlying MSC accumulation at tumor sites.
Although corticospinal neurons are known to be distributed in both the primary motor and somatosensory cortices (S1), details of the projection pattern of their fibers to the lumbar cord gray matter ...remain largely uncharacterized, especially in rodents. We previously investigated the cortical area projecting to the gray matter of the fourth lumbar cord segment (L4) (L4 Cx) in mice. In the present study, we injected an anterograde tracer into multiple sites to cover the entire L4 Cx. We found that (1) the rostromedial part of the L4 Cx projects to the intermediate and ventral zones of the lumbar cord gray matter, (2) the lateral part projects to the medial dorsal horn, and (3) the caudal part projects to the lateral dorsal horn. We also found that the border between the rostromedial and caudolateral parts corresponds to the border between the agranular and granular cortex. Analysis of the somatotopic patterns formed by the cortical projection cells and the primary sensory neurons innervating the skin of the hindlimb and its related area suggests that the lateral part corresponds to the S1 hindlimb area and the caudal part to the S1 trunk area. Examination of thalamic innervation by the L4 Cx revealed that the caudolateral L4 Cx focally projects to the ventrobasal complex (VB) and the posterior complex (PO), while the medial L4 Cx widely projects to the PO but little to the VB. These findings suggest that the L4 Cx is parceled into subregions defined by the cytoarchitecture and subcortical projection.
We investigated fiber distribution patterns of corticospinal neurons within the cortical area projecting to the lumbar cord gray matter of mice. The lumbar‐cord‐projecting area fundamentally innervates the gray matter in the same way as the cervical‐cord‐projecting area does.
The Pharmaceuticals and Medical Devices Agency and the Ministry of Health, Labour and Welfare in Japan and the US Food and Drug Administration are responsible for reviewing applications and approving ...drugs, medical devices, and regenerative medicines. In the EU, the European Medicines Agency is responsible for the centralized authorization procedure of medicines including oncologic drugs. In this review, we discuss general pathways for the marketing authorization of oncologic drugs and other drugs in Japan, the EU, and the US. There are still unmet medical needs in oncology, whereas scientific innovation and clinical development in oncology are rapid and active, suggesting a reasonable scope for new regulatory schemes for expedited review. Because regulatory schemes are also evolving rapidly, clinicians and academic researchers may have difficulty following the updated regulations in other regions as well as those in their own countries. However, keeping current with new regulations is important for the conduct of translational research and clinical development of new therapeutic products efficiently. This review is intended to help an international audience better understand the essence of the regulatory frameworks for the marketing authorization of oncologic drugs in Japan, the EU, and the US.
Summary
Background
As relapsed disease is frequently the first target of newly developed therapies, it is vital to address the difficulty in demonstrating the efficacy of new drugs for relapsed ...malignancy in randomized phase 3 trials.
Methods
We analyzed the approved indications, target populations, and development status of post-marketing confirmatory trials of all oncology-related drugs that were granted accelerated approval for both hematological and solid malignancies. Furthermore, we searched for randomized phase 3 trials for adult patients with relapsed lymphoid malignancy, other than chronic lymphocytic leukemia (CLL) and multiple myeloma (MM).
Results
Thirty-one (81.6%) of the 38 hematological indications and 23 (53.5%) of the 43 solid malignancy indications were in the relapsed settings. The target population of post-marketing studies was different from the approved indication in 18 (47.4%) of 38 hematological indications and 11 (25.6%) of 43 solid malignancy indications; all 18 hematological indications involved relapsed settings. Improved time-to-event outcome for relapsed patients was the primary endpoint in 6 (19.3%) of the 31 relapsed hematological indications. In 4 published studies of relapsed lymphoid malignancy, the medication significantly improved outcomes. From 33 trials listed at
Clinicaltrials.gov
, 2 were positive and 13 were negative. Five out of the 13 negative trials were terminated due to poor accrual.
Conclusion
Our analysis indicates that drug approval based on phase 3 trials is more challenging for relapsed hematological malignancies than for solid malignancies. Therefore, determining proper evaluation methods for the efficacy and safety of drugs for relapsed malignancy, without randomized trials, is important.
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