"By intervening across different pathways at the same time, and through dysregulation of multiple mRNAs at the same time, you potentially make it much more difficult for the tumor cell to develop resistance."
Can you explain the promise microRNA therapeutics hold for treating multi gene diseases like cancer?
We see an opportunity for miRNAs as they can bind to several mRNAs at the same time to induce mRNA cleavage or inhibition of translation to functional proteins. What you see if you do transcriptomic analysis is that these small miRNAs bind to mRNAs across different signaling pathways. These mRNAs that are regulated by one miRNA are connected across pathways, so in that respect there is potential for higher efficacy, plus a decreased chance of developing resistance. What you see today with single target drugs is that tumor cells have the capability to get around it and activate alternative pathways, and thereby the tumor develops resistance to the drug. By intervening across different pathways at the same time, and through dysregulation of multiple mRNAs at the same time, you potentially make it much more difficult for the tumor cell to develop resistance.
What makes InteRNA’s approach to miRNA unique and what makes you believe in your discovery and functional validation platform?
We took a different R&D approach compared to other miRNA companies in the field. They started off with descriptive differential expression profiling using microarrays on which miRNA sequences were spotted. That still does not tell you anything about function. The different approach we took is that the company had already identified novel miRNAs at that time using deep sequencing and bioinformatics. We cloned the precursor molecules in a lentivector system to allow for high throughput functional genomics screening in cell-based assays. That is a non-biased genomics approach where you look to phenotypic readouts after you have transfected the tumor cell with a specific miRNA out of the library that we employ. Through these non-biased screens, we were able to pick up hits and we were able to confirm them with synthetic molecules. Therefore, once we make synthetic mimics of miRNA or synthetic antimiR's of miRNA, we were able to reproduce results in cell-based assays that we saw in the functional screens.
We then built a patent portfolio around them and took the validation further, expanding the cell line panel and extending the number of assays. After that we had to figure out the important step of transition from in vitro to in vivo. If you are using a double strand mimic of a miRNA, and you want to go for intravenous (IV) administration, you need to have a drug delivery technology to bring your cargo to the right place at the specific tumor cells in the body. To overcome this, we set up another platform using a mouse tumor model system to come up with a formulation that achieves this.
First, after IV administration, the liver is your first entry point, so you want to have your compound delivered beyond the liver to the tumor elsewhere in the body, and we succeeded in this. Next, after cellular uptake by tumor cells, you want to have the compound released into the cytoplasm and not getting stuck in the endosome. This is a common occurrence with many formulations. They do not deliver to the right cell type, or they get stuck in the endosome. In that way you do not get the API in the cytoplasm, so that the active strand of the miRNA can go into the RNA induced silencing complex (RISC) to bind to the mRNAs where it has its biological effect. It is a combination of two platforms that we used. First screening target identification and validation, plus a platform to come up with a formulation that allows for IV administration in people. With that, we were then able to generate preclinical proof of concepts in different mouse models, and we were able to build a preclinical product pipeline, with our first candidate recently entering the clinic. We have now made the transition from a platform company to a product company and from a preclinical company to a clinical company.
Are there any lessons you have taken from the progression of other companies in the field or in related fields such as Alnylam with siRNA?
We were not the first movers with miRNA, but we see ourselves as the smart followers. We have seen what the other parties have done, and we try to learn from their potential mistakes. Our focus has been on further validation of the compound before going into the clinic. It was also very helpful to have Alnylam's first approved product (ONPATTRO), which was the first siRNA in a lipid nanoparticle to receive approval. miRNA is similar in size, double stranded, different only in one base pair, so we were able to compare the lipid nanoparticle that we use in INT-1B3 with the one that Alnylam is using in their approved product. Once ONPATTRO got approved, we were able to analyze their preclinical data packages on the GLP tox. This allowed us to see that we were in similar dose ranges and that even with more frequent dosing, we were not impairing the safety profile that they had with less frequent dosing. For us, it was very comforting to have that information available as a benchmark.
How do you envision 2021 playing out for InteRNA?
Importantly for us, we are keeping our fingers crossed that COVID is not going to jeopardize our clinical trial. At the time our CTA application got approved, the clinical sites were closed. We did not go back too early to the clinic once they opened because we wanted to make sure that not only the sites are open and fully operational, but also the logistics behind it. If things go well, we will have our top line results readout by the end of the year. If those data look good, then we have a nice way forward, so we are preparing to start raising new capital again, and as soon as we have intermediate data from the trial, we will start that process. At the end of the day, the data of the trial will tell where we can go.