RNA interference (RNAi) has increased the possibility
of restoring
RNA drug targets for cancer treatment. Small interfering RNA (siRNA)
is a promising therapeutic RNAi tool that targets the defective gene
by inhibiting its mRNA expression and stopping its translation. However,
siRNAs have flaws like poor intracellular trafficking, RNase degradation,
rapid kidney filtration, off-targeting, and toxicity, which limit
their therapeutic efficiency. Nanocarriers (NCs) have been designed
to overcome such flaws and increase antitumor activity. Combining
siRNA and anticancer drugs can give synergistic effects in cancer
cells, making them a significant gene-modification tool in cancer
therapy. Our discussion of NCs-mediated siRNA delivery in this review
includes their mechanism, limitations, and advantages in comparison
with naked siRNA delivery. We will also discuss organic NCs (polymers
and lipids) and inorganic NCs (quantum dots, carbon nanotubes, and
gold) that have been reported for extensive delivery of therapeutic
siRNA to tumor sites. Finally, we will conclude by discussing the
studies based on organic and inorganic NCs-mediated siRNA drug delivery
systems conducted in the years 2020 and 2021.
Local therapy modalities such as radiation therapy, photodynamic therapy, photothermal therapy, and cryoablation have been used to treat localized tumors for decades. The discovery of the abscopal effect causes a paradigm shift where local therapy also causes systemic effects and leads to the remission of nonirradiated tumors. The abscopal effect of radiation therapy, alone or in combination with other treatments, has been extensively studied over the last six decades. However, the results are unsatisfactory in producing robust, reproducible, and long‐lasting systemic effects. Although immunotherapy and radiation therapy are promising in producing the abscopal effect, the abscopal effect's mechanism is still unclear, owing to various factors such as irradiation type and dose and cancer type. This article reviews the research progress, clinical and preclinical evidence of the abscopal effect by various local therapies alone and in combination with chemotherapy and immunotherapy, case reports, and the current challenges in producing the abscopal effect by various local therapies, focusing on radiotherapy, photodynamic therapy, cryoablation, and the prospects for obtaining a robust, reproducible, and long‐lasting abscopal effect.
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