Could gene therapy be the key to a fast coronavirus vaccine?
It generally takes a decade to bring a new drug candidate from the initial research phase to final market approval. This is a painstakingly long process, and especially during fast moving pandemics as we currently witness with the novel coronavirus, one might wonder how this timeline could be shortened.
Multiple strategies are currently being explored. Probably the most obvious one is to figure out if there are existing drugs that could be used. Unfortunately, since the virus that is causing COVID-19 is a novel coronavirus strain, there are no existing vaccines available. It is useful however, to figure out if there are more efficient treatments for COVID-19 symptoms until a vaccine is developed. Sanofi and Roche for example are setting up trials to test their existing rheumatoid arthritis drugs (Kevzara and Actemra respectively) to treat the respiratory distress syndrome caused by SARS-CoV-2.
The second strategy is to start the development of a new vaccine. Based on previous knowledge of other coronavirus outbreaks like SARS and MERS, there are multiple initiatives to pursue the development of a classic vaccine. This traditional strategy aims for immunisation via low dose exposure to weakened forms of the virus, for example by producing inactivated forms of the virus or virus particles. Even with our existing understanding from the other corona-type viruses, the fact that the virus itself is used as a basis of the treatment makes things quite complex regarding manufacturing and safety testing. Most virologists therefore believe that (even with fast track clinical testing) these vaccines will only be available within 12 to 18 months at the earliest.
There is a novel approach that could be more promising against fast spreading diseases like COVID-19; mRNA vaccines. mRNA-based gene therapies make use of in-vitro produced messenger RNA strands that are delivered to the patient via lipid nanoparticles. These particles carry the mRNA inside the patient’s own cells, where the existing biologic machinery (i.e. the ribosomes) translate the mRNA into protein with the wanted therapeutic action.
This technology is currently used to develop novel cancer therapies, but the same concept could revolutionise the vaccinology field by producing mRNA which activates our own immune system and providing it with precise instructions to produce coronavirus fighting protein. Since the sequence of the genetic material of the virus is easily determined and we’re able to produce mRNA cheap and efficiently (at least at small scales), these mRNA-based therapies can be manufactured and tested significantly faster compared to classical vaccines that depend on cell-based cultures of the virus followed by multiple de-activation and purification steps. Indicative of the huge potential of mRNA-based vaccines and their record speed development, it’s therefore no surprise that the first clinical trial for a vaccine against the novel coronavirus will be mRNA-based.
Moderna, Inc., located in Cambridge, Massachusetts (in collaboration with the U.S. National Institutes of Health), received the genetic sequence of novel coronavirus on January 11, 2020. Only 2 days later they finalised the sequence of their mRNA-based vaccine. On February 7, 2020 the first clinical batch was produced and only 63 days after the first sequencing of the genetic info from the virus, on March 16, 2020 the first 4 (healthy) patients were dosed in a Phase 1 clinical trial [1]. Not far behind in the race towards a vaccine are 2 other mRNA companies; BioNTech and CureVac. These 2 German companies (at least for now [2]), aim to start clinical trials in April and summer respectively.
It is important to note however that these types of vaccines are untested and it is still possible that unwanted side effects occur. Even with the current sense of urgency that allows for slightly more flexible regulatory trajectories (e.g. according to the Chief Medical Officer of Moderna, their mRNA-based Covid-19 vaccine has not been tested for safety in an animal model which would be the current standard procedure [3]), the start of the first clinical trials is only the very beginning to prove the safety and efficacy of the technology. Additionally, given the worldwide nature of a pandemic, producing the required volume to provide an effective dose for millions of people is still a challenge. Thorough streamlining of production processes and improvements in data management methods for distributed manufacturing sites to automate reporting and facilitate regulatory compliance will be needed for a widespread use of these vaccines.
In conclusion, a classical vaccine or an mRNA-based vaccine will unfortunately not be ready for this COVID-19 outbreak (so make sure to wash your hands frequently and apply social distancing for now!), but for a possible next SARS-CoV-2 season, or even for the next currently unknown pandemic, we’ll be better prepared than ever.