miRNA Replacement Therapy
Another increasingly important research focus is on the regulatory role of miRNAs in gene expression and cell growth, differentiation, and death—all of which frequently go awry in cancer. “It might be an advantage that miRNAs affect many cellular pathways, because cancer involves several mutations. You have to look at cancer as a pathway disease,” states Andreas Bader, Ph.D., senior scientist at miRNA Therapeutics. He adds that one of the parameters of how they choose lead candidates is to show how the miRNA affects multioncogenic pathways and shuts them down. “Hopefully, this is why they may be more efficacious than standard targeted therapies.”
This, says Matt Winkler, Ph.D., CEO, is a key point. “We’re looking at tumors that have lost or express low levels of a particular miRNA, and we’re replacing that missing and naturally occurring miRNA—triggering apoptosis, tumor regression, etc. So, we like to call it miRNA replacement therapy.” He adds that it’s “akin to providing insulin to a diabetic.”
The company has chosen to focus on three cancers: non-small-cell lung cancer, metastatic prostate cancer, and acute myelogenous leukemia. Six recently discovered miRNAs show the ability to induce a response in lung and prostate cancers in animal models—meaning interference with the oncogenic property of tumor cells, i.e., inhibition of tumor growth or regression of tumor growth by inducing cell death.
Another advantage to the miRNA therapeutic approach is that it’s similar to gene therapy, but doesn’t have to be delivered into the cell nucleus to be active—only the cytoplasm. Also, since what’s being replaced is a natural molecule this avoids problems associated with antisense and siRNA approaches, such as unwanted side effects and nonspecificity.