Realizing the Promise of RNA Therapies with Lipid Nanoparticle Delivery

Realizing the Promise of RNA Therapies with Lipid Nanoparticle Delivery

June 16, 2021PAO-06-21-CL-08

Pharma’s Almanac Scientific Editor-in-Chief David Alvaro had an opportunity to speak with Shiksha Mantri, Global Marketing Manager for RNA Solutions at MilliporeSigma, about RNA and DNA therapies and vaccines, the benefits of lipid nanoparticle formulations for these modalities, manufacturing challenges, the importance of finding the right CDMO partner, and where MilliporeSigma expects this field might be headed.

David Alvaro (DA): Shiksha, can you start us off with a bit of a primer on DNA and RNA therapies and vaccines in general and the scope of therapeutic strategies using nucleic acids? 

Shiksha Mantri (SM): DNA and RNA therapies present the potential to attack diseases at the genetic level. As a result, the potential for DNA and RNA therapies is far more broad-ranging and powerful than traditional small molecule and protein therapies.

With DNA therapies, typically, the gene of interest is delivered, causing the continued expression of a desired protein. With RNA, there are several different options available. Large messenger RNA (mRNA) strands mediate transient expression of the desired protein in a protein-replacement therapy. Once the mRNA is degraded, protein expression is halted, and that tight control of transient expression can be advantageous over DNA in some cases. Another advantage is that mRNA does not integrate into the genome.

Alternatively, smaller RNAs can be used for gene silencing or activation. For instance, if a disease leads to the production of a faulty protein, a strand of what is called small interfering RNA (siRNA) can be used to shut down expression of the mutant protein. Similarly, if a protein is not expressed in sufficient quantities, the expression of larger amounts of this protein can be enforced by the delivery of short activating RNA.

DA: What RNA therapies have received approval so far, and how would you characterize the current clinical landscape for these modalities?

SM: Two siRNA drugs comprising short strands of RNA that silence genes have been approved. As you know, two mRNA vaccines against COVID-19 received authorizations from the U.S. FDA and several other health agencies. There are many additional RNA and DNA vaccines and therapeutics in preclinical investigation and clinical trials.  In fact, since the emergence of the pandemic, there has not only been significant interest in RNA therapies and vaccines to address COVID-19, but also a massive increase in preclinical and clinical studies of mRNA therapies for other therapeutic targets. In essence, we have seen a profound shift in the clinical landscape in terms of mRNA-based approaches in the aftermath of the pandemic.

DA: Are mRNA therapies and vaccines particularly well-suited to COVID-19? Or was the timing just fortuitous because previous work with these modalities was beginning to bear real fruit?

SM: Well, mRNA is certainly not novel itself; mRNA was first discovered in 1961, and significant background research enabled the development of the COVID-19 vaccines. If companies like BioNTech and Moderna had not been working on these modalities already, we would not have realized the mRNA vaccines so rapidly.

In 2018, an siRNA drug was approved and served as a benchmark and confirmation that these therapeutics can work at the genetic level. Approval of any therapeutic or any therapeutic modality often causes a chain reaction. Now that the COVID-19 mRNA vaccines have been shown to be effective, companies have more confidence in exploring mRNA therapeutics, because the proof of concept has been shown.

In addition, because platform technologies can be used to synthetically produce mRNA, it is possible to generate new vaccines for variants — if needed — and therapeutics fairly quickly. This plug-and-play mechanism offers a lot of flexibility in what can be tackled with mRNA therapeutics and is driving the change in the landscape for mRNA therapeutics. 

DA: In the aftermath of the incredibly rapid success of the Pfizer/BioNTech and Moderna vaccines, there seem to be shifts in the expectations for program timelines, which may not be that realistic. But owing to the inherent plug-and-play platform aspect of mRNA vaccines, do you see these as a class of drug where more accelerated timelines might actually be achievable?

SM: Plug-and-play will definitely help with shorter development times, because you can change the mRNA sequence and get a different result, but it remains to be seen whether that will affect the approval timelines for these therapies. The pandemic created a unique situation in which the regulatory agencies were under pressure to provide authorization more rapidly than what they are used to. Whether that will translate to faster approvals in the future is uncertain. The development time from bench to clinic, though, will certainly be shortened.

DA: What are the unique molecular characteristics of RNA, and what are the consequent challenges to formulation and delivery?

SM: RNA is highly negatively charged and very fragile. Delivery systems, including lipids or lipid nanoparticles or even viral vectors, are often used to protect the RNA from degradation — not just in the human body, but also in the vial before it reaches the patient. In addition, for mRNA therapies, the mRNA must reach the right organ and cell type and then be released into the cytoplasm of the cell in its active form. As such, RNA presents unique challenges in formulation and delivery — the route of administration also plays an important role.

DA: What are the particular benefits of lipid delivery for RNA therapeutics and vaccines?

SM: Compared with other delivery systems, proof of concept has been demonstrated for lipid nanoparticles (LNPs). The LNPs protect the RNA and release it as an active molecule into the cytoplasm. Some lipids also have immunostimulant properties and can function as adjuvants, boosting efficacy. LNPs also fit into the plug-and-play mRNA manufacturing platform, and they present the potential for co-delivery of multiple RNAs or RNA with another API, such as an immunosuppressant. 

DA: Are there different approaches to formulation based on the therapeutic strategy, like for an mRNA vaccine versus an siRNA therapy?

SM: The composition of the LNP impacts the encapsulation efficiency of the RNA, its biodistribution, and how well it can release its payload into the cell. The selection of the right lipid mixture allows preferred delivery to certain tissues or cell types. A formulation that works well for mRNA vaccines would not necessarily work for protein-replacement therapy or gene silencing. As a result, the delivery vehicle formulation must be optimized for each type of RNA. However, if you are targeting the same cell type and the length of the mRNA is similar, one can use a similar formulation.

It is worth noting that, while LNPs are the prominent delivery vehicle for mRNA vaccines, there are a number of other options. For instance, there is a lot of work being done with viral vectors, especially for DNA delivery. Other nanoparticles are being investigated as well, including polymeric nanoparticles and cell-derived vesicles.

DA: What are some best practices or ways that a company can optimize their LNP synthesis or even their overall development and approval pathway for mRNA/LNP therapeutics and vaccines?

SM: The big picture should always be top of mind. The design of the formulation should be planned at the earliest possible stage, and the purity of the lipids, other excipients, and the RNA should be assured from the outset. Equally important is to establish processes that scale from the lab to GMP pilot to the commercial plant. That will enable consistent results throughout development and facilitate regulatory approval.

LNPs typically comprise four different lipids that must be of very high purity and consistent quality and have appropriate material handling characteristics. It is particularly important to control fatty acid impurities in lipids, because they can alter the characteristics of the formulation, including the stability and the RNA release profile. Every component that goes into the formulation — the RNA and the lipids — must be identified and fully characterized (physical, chemical, and biological attributes) for a complete characterization of the different components.

DA: Beyond the fundamental technical capabilities, what do you see as the critical criteria in selecting an effective CDMO partner for an RNA/LNP drug or vaccine program?

SM: It all comes down to track record. The CDMO should have demonstrated success and have an exemplary audit record with the larger health agencies and customers over multiple years. A good supplier management system and suppliers that can provide technical and regulatory support are also important. The facility should also have compliant quality systems to ensure GMP manufacturing. High technical knowledge and experience with controlling and scaling processes must be evident as well. It is also advisable to look for providers who can provide integrated services across the value chain, since limiting the total number of outsourcing partners and the number of interfaces can reduce risks of failure and increase speed. 

DA: Based on the trajectory you’ve seen over the last couple of years, where do you see this field going? How expansive do you think the potential market for RNA and DNA drugs is going to be, and what major shifts do you see on the horizon?

SM: That’s a great question. Before COVID-19, there were many different activities going on in the mRNA space: there was significant work being done on the use of mRNA for vaccines and therapies targeting cancer and infectious diseases. All this was proceeding at the normal pace of development. Then suddenly, COVID-19 hit, and the clinical results for mRNA were great. The technology was proven.

I think this was a real game-changer for the entire field, because the potential for mRNA vaccines is so much broader than just COVID-19. It can be used for many other infectious diseases as well. The efforts that were ongoing for cancer vaccines have now doubled because this technology has been shown to work, and the reality that we can make medicines that act at the genetic level will cause a paradigm shift in how diseases are addressed.

There are also applications in enzyme replacement therapy for metabolic diseases involving the replacement of faulty enzymes using mRNA technology. Potentially — maybe not in the next five years but over the longer term — mRNAs could be used for expression of therapeutic antibodies in the patient. That would eliminate the need for large production facilities and the logistics of storing, distributing, and administering these treatments. Instead, the patients’ bodies would be doing all of the work.

There are also exciting opportunities in the field of cell therapy. The knowledge we now have about the effectiveness of mRNA will have a direct impact on the development of future cell therapies. Last but not least is gene editing, which is also based on mRNA technology. There are already companies who are working on approaches using mRNA, for example with CRISPR gene editing. These efforts will take more shape now in light of the COVID-19 crisis.

So, all in all, we have a very exciting future ahead of us, because the way diseases are treated is completely going to change.

DA: What do you see as the real differentiators in the services that MilliporeSigma provides under its SAFC® portfolio brand?

SM: MilliporeSigma has over 24 years of experience in manufacturing GMP lipids. We have an established center of excellence and are a very trusted supplier for many parties. Our excellent track record includes the successful execution of a large number of projects for different clients. MilliporeSigma also has a dedicated contract manufacturing organization with the necessary competencies on site that is part of a global network of facilities for scale-up if needed and that can serve as secondary manufacturing sites. All of these facilities are frequently inspected by the FDA, EMA, other health agencies, and customers.

MilliporeSigma was working with mRNA companies before the pandemic, and we are very happy to see the progress being made in the field. The recent acquisition of AmpTec further expands our presence in the mRNA field. It also reflects our faith in the technology.

Our lipid team is also highly experienced, with over 85 years combined working in this field.  They have the deep know-how to develop solutions for even the most challenging customer projects. As an example, MilliporeSigma rose to the challenge of producing very large quantities of lipids for BioNTech’s vaccine for COVID-19.1

Our goal is to provide the best support possible to our customers — both our existing customers and other companies advancing the mRNA therapeutics and vaccines and the science behind them. Readers can learn more about MilliporeSigma’s insights regarding successful formulation development for lipid-based RNA delivery and vaccines in our recent white paper.


  1. Merck KGaA, Darmstadt, Germany, and BioNTech Extend Strategic Partnership Through Accelerated Supply of Urgently Needed Lipids. Merck KgaA. 5 Feb. 2021. 
  2. Mantri, Shiksha. “Strategies for Successful Formulation Development of Lipid-Based RNA Delivery and Vaccines.” MilliporeSigma.
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