More than 3 million people in Europe, including 200,000[1] in France, suffer from chronic inflammatory bowel diseases (IBDs). And their incidence is on the rise, notably among young people. "The most common forms are Crohn's disease and ulcerative colitis," notes Fabrice Navarro, head of the CEA-Leti laboratory. "These pathologies, characterized by an inflammation of the intestinal wall, can lead to significant disability." No curative treatment currently exists. Patients only have access to medications such as corticoids for reducing symptoms or preventing acute attacks. "The introduction of therapeutic antibodies around twenty years ago, which were the first generation of biological medications, was a revolution. However, they often only target a mediator of inflammation, and their efficacy decreases over time in many patients."
RNA Carried by a Lipidot
Recent discoveries, revealing the role of the enzymes JAK 1 and JAK 3 in these pathologies, led a group of researchers to develop a new therapeutic strategy five years ago. "As part of the European project New Deal,[2] we have developed a nanotherapy delivered by the oral route that directly targets JAK 1 or JAK 3, and in the right place, namely the intestine," explains Navarro, who also coordinates the project. These two enzymes are implicated in activating cells involved in the immune response, but in IBDs, they are over-expressed in the intestine, causing the observed inflammatory phenomena.
To deactivate them, the researchers decided to use interfering RNAs, small pieces of RNA that act specifically to block the process for synthesizing each protein. These RNAs, while very fragile, are quickly broken down in the organism. The challenge was thus to bring them intact to the right place using a high-performance vector—Lipidot®—inserted in a protective envelope. “This is an innovative delivery system for the therapeutic molecules CEA-Leti has developed, building on our nearly fifteen years of expertise,” adds Navarro. These particles are balls of oil nanometric in size (10-9 m). Very stable and well tolerated by the organism, they can easily penetrate cells due to affinity with the lipids making up the cell membrane (see Focus).
An Effective Therapeutic Strategy
These little strands of interfering RNA, prepared and selected by CEA-Irig, are attached at the surface of these Lipidots.® The Lipidot, together with the interfering RNAs, is then inserted in a polymer capsule developed by Seps Pharma, also one of the project partners. Its role? To enter the acid environment of the stomach unhindered, then dissolve in the intestine to deliver its “payload.”
After four years of R&D, the New Deal project is producing very promising results, which Navarro enthusiastically sums up this way: “Not only have we achieved the delivery of RNA in the right place; it also arrives intact and induces the expected result.” In vitro experiments have notably shown that with a system mimicking gastrointestinal digestion, the polymer shell remains stable while passing through various environments so that the RNA can be delivered to the intestine. Other experiments conducted in vivo in mice have confirmed the capacity of the nanoparticle to cross various biological barriers, enter the inflammatory cells of the intestine, and then deliver the interfering RNAs, whose efficacy in inhibiting the synthesis of the JAK protein has also been demonstrated.
Preparing the Future Clinical Trial
The team has even tested its treatment on a human organoid of the intestine developed by the clinical hospital in Barcelona. “We have worked on the protein JAK 1, achieving a significant decrease in its production and the associated inflammation. So the efficacy has been proven, along with the very high specificity of the strategy based on the interfering RNAs,” concludes the researcher.
With these proofs of concept, the first milestone of the long path leading to the development of a medication has thus been reached. The next step is finding an industrial partner to finance and initiate the next step, that of clinical trials, i.e., testing in humans. To have every chance of succeeding, the team has already validated toxicity tests in rodents and is preparing a first draft of the regulatory application so that clinical trials can be launched.
Glossary
Colitis: inflammation of the colon.
Interfering RNAs: Interfering RNAs regulate the protein synthesis process in cells. When a protein is synthesized, the gene corresponding to its "synthesis recipe" is read and copied in the form of a strand of messenger RNA (mRNA) which is then read for protein synthesis. The quantities of mRNA are regulated by interfering RNAs. These little strands attach to the mRNA, causing the cell to destroy it, thereby stopping the synthesis of the protein in question.
Organoid: 3D self-organized cell system that is representative of the architecture and function of an organ (see special feature in this issue).
Focus
Lipidots®: Fifteen Years of Expertise
Lipidots,® a CEA-Leti technology protected by some fifteen patents, are vectors for therapeutic molecules. Ideally, these molecules are encapsulated inside the Lipidot, but they may also be attached to their surface. One of the most recent developments aims to make an anti-Covid-19 vaccine in which messenger RNA is attached to a Lipidot, making it possible to synthesize one of the surface proteins of the SARS-Cov-2 virus (which causes the disease) on the Lipidot.
CEA-Leti is also working on ramping up the Lipidot production scale. In partnership with GTP-Nano, a contractor for the pharmaceutical industry, it is developing production processes for industrial environments. A first milestone has already been reached with batches of up to 500 ml. The following steps, which will enable reaching volumes of several liters, are now under preparation.
[1]Source: Inserm, 2015 figures.
[2]New Deal (2017–2021): 12 partners, 5 countries, 4 years and a €6 million budget.