Biomedical Engineering Reference
In-Depth Information
technologies like nanoparticles, both polymer and lipid based; electroporation-based
delivery, carrier mediated-delivery, biodegradable cationic polymer-based delivery,
and others, are being explored. A glance at the US patent scenario for a few major
companies involved in siRNA technology is presented in
Table 7.7
[261]
.
7.13 Future Directions
Antisense therapeutics, though being explored for a tremendous number of diseases
and disorders, is more biased toward anticancer therapeutics. Due to the differences
between normal and tumor vasculature, the highest concentration is achieved around
the tumor vasculature, and thus targeting genes within the endothelial and support-
ing cells has become an attractive antitumor strategy. Moreover, the applications for
liposome technology have also been explored more in the fields of cancer and vac-
cines. A coherent utilization of the liposomes for antisense agents has thus become
a hot area for many leading companies involved in RNAi therapeutics. In fact, lipo-
somes, polyconjugates, and other biodegradable polymeric carriers have emerged as
the leading platform for the systemic delivery of RNAi therapeutics and offer consid-
erable promise for diseases of the liver, solid cancers, as well as potentially enhanced
vaccines, infectious diseases, and immune cell-related disorders. Because the drugs
based on liposomal and biodegradable polymeric carriers systems are already on the
market, a big leap forward should occur toward the development of polymer- and
liposome-based RNAi formulations to make a swift and safer dosage form; from
a regulatory perspective. An attention toward the development of an attractive and
feasible field of RNAi-based vaccines is also the need of the hour. Many flu vac-
cines, like that for severe acute respiratory syndrome (SARS), swine flu, and its fur-
ther mutating varieties, can be developed and put into one pool to cover the closer
probable mutations of the existing mutant variety in a single formulation. Because
these antisense formulations can have potential side effects and can lose their viabil-
ity in the biological milieu, extensive but satisfactory pharmacological and toxico-
logical studies should be performed at the initial development and preclinical stages
so as to avoid failures at the later clinical phases. Many experiments and evaluations
have already been performed on the eldest antisense technology of oligonucleotides.
Thus, all the shortcomings and profits from such studies should be taken into account
while developing newer antisense-based formulations. Highly specific agents like
siRNA can boom as agents for individualized therapies. Principal companies that are
actively involved in RNAi-based therapeutics should focus on investing in developing
these as personalized therapeutic agents for patients suffering from either major dis-
orders or rare ones that have occurred because of an individual-specific gene defect
or mutation. As a potent agent effective at very low doses, siRNA is a strikingly suit-
able agent to be delivered via inhalation route. Also many studies done on inhalation
of various genes can support the development of stable and effective aerosolizable or
nebulizable siRNA formulations. Simplicity of siRNA design, its specificity, potency,
availability of human genome information, feasibility of fabrication into required
sequence, and applications for an endless number of disease-related expressions
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