July 30, 2012
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Welcome to your Monday Biotech Deal Review for Monday July 30, 2012. Highlights from the previous weeks include the closing of the $13 million public offering by Trimel Pharmaceuticals and $7.5 million loan, as well as the M&A activity involving Functional Technologies Inc. and Medifocus Inc. Read on to learn more. Read more of this post
July 20, 2012
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TDP-43 and its C. elegans ortholog, TDP-1 are DNA and RNA binding proteins that have multiple functions in repressing transcription, splicing pre-mRNA and regulating translation. TDP-43 is found to be a constituent of stress granules, cytosolic RNA/protein aggregates that form in response to cellular stress, be it from heat, oxidative or osmotic.
TDP-43 has also been found to be mutated and accumulated in multiple neurodegenerative disorders, including ALS (Lou Gehrig’s disease), frontotemporal dementia (a form of pre-senile dementia second in prevalence only to Alzheimer’s disease) and chronic traumatic encephalopathy (including dementia pugilistica).
Given TDP-1/TDP-43’s role in cellular stress response the Parker lab at the Université de Montréal asked whether TDP-1 participated in C. elegans’s cellular stress response and longevity pathways and whether it was through participation in the Insulin/IGF-signaling (IIS) pathway, a major axis of stress-response signaling and longevity in worms.
They found that the tdp-1 gene is responsive to stress and participates in the Insulin/IGF signaling pathway to regulate lifespan, as well as to respond to oxidative stress. While worms that lack tdp-1 were more sensitive to external stresses, over-expression of tdp-1 was itself toxic. Furthermore, tdp-1 expression was induced by the introduction of mutant TDP-43 due to increased oxidative stress and that this led to increase neuronal degradation and reduced lifespan. This leads to the model that tdp-1 was intended to protect from unfavourable conditions, but is now becoming aberrantly activated and is contributing to proteotoxicity and oxidative stress in the cell. If this malfunction is present in humans it may explain why TDP-43 is found to be associated with an increasing number of neurodegenerative conditions and would support the exploration of TDP-43 as a therapeutic target.
July 13, 2012
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Oncolytic viruses are a promising therapeutic approach that may finally be approaching the market; Amgen’s recently acquired OncoVEX GM-CSF is in phase III for melanoma with results expected in 2013 and Canada’s own Oncolytics has recently completed the first stage of its phase III trial for the treatment of platinum-refractory head and neck cancers.
For tumour types that are permissive to these viruses much of the promise arises from the specific replication in cancer cells and subsequent lysis. However, another activity that can help improve complete responses and prevent recurrence even when the virus has been cleared from the patient is the induction of antitumor immunity. This immunity is greatly stimulated by the viral replication and lysis process. Aiming to harness this effect, the recent paper in Molecular Therapy by researchers at the University of Ottawa describes an approach to generate a broad anti-tumour immunity against a multitude of tumour antigens through the use of an infected cell vaccine (ICV) platform, which is even applicable for tumours that are not permissive to oncolytic viruses.
The oncolytic VSV-Δ51 virus is able to induce a strong anti-tumour immunity in tumour cell lines, but only when viral replication occurs in the tumour cells. To overcome this, the researchers chose an ex vivo approach, whereby infection of isolated tumour cells with their oncolytic virus construct (the VSV-Δ51 virus, but expressing GM-CSF similar to the BioVEX approach) could be ensured in vitro by a high multiplicity of infection. A vaccine could then be prepared from this population of infected cells. With this approach mice were protected from subsequent tumour challenge and the induced innate and adaptive immune response was robust enough to control the growth of established tumours.
This approach offers a personalized vaccine comprising the full range of a patient’s tumour-specific antigens improving the hope for complete response and effective control of recurrence, albeit with a significant commercialization challenge arising from the inherently unscalable manufacturing, operational complexity and high production costs that is currently being faced by Dendreon’s Provenge.
July 9, 2012
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Welcome to your Monday Biotech Deal Review for July 9, 2012. Highlights from the previous two weeks include the announcement of a $13.25 million prospectus offering by Trimel Pharmaceuticals, and the announcement of a $200 million exchange offer by Angiotech on its Senior Floating Rate Notes due 2013. Read on to learn more. Read more of this post
July 6, 2012
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While there are a surprisingly low number of genes in the human genome, 95% of the multi-exonic genes are subject to alternative splicing and therefore the role of alternative splicing in permitting increased cellular and functional complexity should be more widely appreciated.
In different cell types and in response to different conditions, coordinated splicing regulation leads to the specific use of alternative exons and these regulated exon networks can be assumed to play important roles in specific processes and pathways – why else would it occur and be conserved. However, while this regulated behaviour is well known, there is a current lack of understanding of the functional effects imparted by the tissue-regulated alternative exons. A desire to fill in some of this gap motivated the research by a collaborative trio of labs at the University of Toronto. In their Molecular Cell paper, they show that proteins containing regulated exon networks tend to have more interactions in protein-protein interaction networks and that these regulated exons, together with their flanking constitutive exons, are enriched in sequences predicted to be highly disordered.
In a specific example of an alternative exon network regulated by nSR100/SRRM4 (neural-specific Ser/Arg-repeat related protein of 100 kDa), which is responsible for the inclusion of ~11% of brain specific exons, they show that the inclusion of the regulated exons could result in more or fewer protein-protein interactions, depending on the specific gene. Therefore, introduction of a regulated exon and the corresponding additional protein segment does not merely have an additive effect on the range of interactions in which an alternatively spliced protein can engage. Continuing on to a deeper level of detail, the authors show that the inclusion of one of these regulated exons in Bin1 promotes the interaction with the GTPase Dnm2 and that this interaction was needed for efficient endocytosis in neural cells, linking the splicing regulation all the way to cellular function.
Changes in exon splicing are known to be both causes and consequences of multiple human diseases, including tauopathies, spinal muscular atrophy and familial dysautonomia; adding to the functional understanding of alternative splicing will surely allow the identification of more, and the increased chance for the development of a treatment.