Watertown Journal Club - Exploring the oRNA behind ORNA Therapeutics
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With the news last month that Eli Lily Purchased ORNA Therapeutics, We thought it would be interesting to take a look at the science that inspired a $2.4 billion deal. ORNA has kept their cards close to their chest and hasn’t yet publicly released most of their science, but they have released two posters from their early days that give insight into what the company is working on. Lets dive in.
Poster 1: Improved Immune Cell Expression with Circular RNA (oRNA™) in vivo
In this poster, originally presented at the American Society for Gene and Cell Therapy (ASGCT) Conference in 2022, ORNA scientists showcase their two main technologies: a circular RNA (oRNA) molecule and a proprietary lipid nanoparticles (LNPs) delivery system. In this work they evaluated their technology’s ability to induce gene expression in cells that make up the immune system.
To provide some background, ORNA’s technology is analogous to the mRNA vaccine technology used in Pfizer and Moderna’s COVID-19 vaccines. In both technologies, RNA molecules are delivered to cells via lipid nanoparticles to get the cell to express a gene of interest. The main difference between the technologies is the type of RNA: Moderna and Pfizer use linear mRNA, which is structurally similar to mRNA found in cells. ORNA on the other hand uses circular RNAs (which they call oRNAs, hence the name ORNA) which are linked on the end, and expresses the target gene using an IRES sequence. ORNA’s main hypothesis is that these oRNA molecules can express genes more effectively with less of an immune response compared to linear mRNA molecules.
Besides the different RNA structure, ORNA has also developed proprietary LNPs to deliver their oRNAs. Their lead program aims to express a Chimeric Antigen Receptor (CAR) in immune cells. CARs are engineered cell receptors designed to help the immune system recognize and remove specific cells in the body. CARs were initially designed to recognize tumor cells for cancer treatment, but ORNA is focusing on removing specific B-Cells that drive certain autoimmune diseases. Besides the difference in targets, ORNA is aiming to generate CAR expressing immune cells in the body through an injection, unlike current CAR-T therapies that take immune cells out of the patient, add the CAR ex vivo, and then put the cells back into the patient to then treat the cancer.
With this background in mind, the poster is exploring 4 questions: 1) how do the oRNA-LNP nanoparticles compare to mRNA-LNP nanoparticles, 2) Where do the different kinds of nanoparticles tend to accumulate in a mouse model 3) What is the relative expression of the delivered gene in immune cells between the two nanoparticles, and 4) can the oRNA-LNP nanoparticles transfect human immune cells in a petri dish?
The poster, through biophysical measurements, bioluminescence measurements, and flow cytometry, presents data suggesting that the oRNA nanoparticles can successfully form, are smaller than mRNA nanoparticles, preferentially accumulate in the spleen where the target immune cells reside, produce higher expression that mRNA nanoparticles in mouse immune cells, and can successfully transfect human immune cells, serving as a proof of concept for the technology.
Poster 2: Systemic Delivery of Circular RNA Encoding Partial Dystrophins and Expression in Skeletal Muscle
In this companion poster also presented at ASGCT in 2022, ORNA presented work as a proof of concept for a gene therapy for Duchenne Muscular Dystrophy (DMD) a lethal genetic disease where a genetic mutation causes cells to produce a non-functional version of the protein dystrophin, leading to progressive muscle weakness and death. In this work, ORNA attempted to use their oRNA platform to express the correct form of dystrophin, which would restore proper muscle function, which is also the basis of Sarepta Therapeutics’ gene therapy for DMD. In addition, the poster highlights the gene size capacity of their oRNA platform, since dystrophin is a large (12 kilobase) gene. In this work, oRNA presented western blot and microscopy data that suggests their oRNA platform can successfully package a large gene insert and deliver the gene into human muscle cells. They also provided data showing that a smaller dystrophin (5 kb) insert could be transfected into a mouse model and produce dystrophin in an animal disease model. While the data does show successful gene expression, the absence of a DMD therapy in ORNA’s pipeline suggests that this program was either de-prioritized or was meant more as a test of the oRNA platform capabilities than as major discovery program.
Taken together, these two posters provide some data on ORNA’s oRNA and LNP platform, or at least how the platform looked in 2022. Clearly the lead programs have advanced enough since then to catch the eye of Eli Lilly.
That’s all for this week. We’ll be back next week with more life science news!
