John Lewis, PhD, is CEO of Entos Pharmaceuticals.

John Lewis

The 2023 Nobel Prize in Physiology or Medicine was awarded to Katalin Karikó and Drew Weissman (1) for their research on what allowed RNA molecules made in cells to be more stable and less immunogenic than RNA produced in cell-free systems. Their discoveries about nucleoside base modifications in mammalian systems enabled the development of messenger RNA (mRNA) payloads for genetic therapies and vaccines such as the COVID-19 vaccines.

Awarding the Nobel Prize to RNA molecular biologists highlights the value that RNA-based genetic medicines can bring to protecting and improving human health. In addition to recognizing the critical contributions that the recipients have made to the field of RNA-based vaccines, this award also underscores how far the field of genetic medicine has advanced since the first National Institutes of Health (NIH)-approved gene therapy procedure was performed on a child with severe combined immunodeficiency in 1990.

This first effort at what would come to be called gene therapy utilized a viral vector to deliver a functional copy of the adenosine deaminase gene to the patient’s hematopoietic stem cells in-culture and then readministered the cells to the patient. Nearly 30 years later, this same approach was used for the first two FDA-approved chimeric antigen receptor-T (CAR-T) cell therapies for the treatment of cancer. However, over the same time period, a variety of alternative approaches to introducing therapeutically beneficial nucleic acids have been developed, leading to several additional FDA approvals and a rapidly growing pipeline of investigational therapies designed to deliver mRNA molecules in addition to DNA sequences encoding proteins to supply the missing or aberrantly functioning proteins causing the disease.

The methods for delivering these nucleic acids have also expanded to include multiple viral vectors and non-viral formulations (such as lipid nanoparticles [LNPs] and proteolipid vehicles [PLVs]). The advances in vector technology enabled in vivo gene delivery, with the first such therapy receiving FDA approval in 2017 (2), expanding the use of genetic medicine to treat cells that are not readily collected and grown in culture, such as retinal, neuronal, and muscle cells.

Today, the term “genetic medicine” is used to describe the broad and exciting array of approved and investigational therapies that use nucleic acids to modulate gene expression. In addition to traditional gene replacement approaches, these new therapeutic classes include inhibitory RNAs or oligonucleotides designed to reduce the expression of harmful proteins, oligonucleotides that catalyze base editing of DNA or RNA and, as in CAR-T therapies, DNA sequences encoding engineered proteins that provide therapeutic benefit. Despite the potential variations in payload, delivery system, and method or route of administration, all genetic medicines must achieve the same critical goals: the safe and effective delivery of the nucleic acid payload to disease-relevant cells and the function of the payload over a period of time sufficient to achieve the desired therapeutic benefit. The delivery platforms need to be well tolerated, non-immunogenic, and scalable.

To successfully translate genetic medicines to the clinic, researchers must carefully consider the payload characteristics; nucleic acid type (DNA, RNA, editing tools), payload size, single or multiplexed payloads, along with the desired vector features; safe, non-toxic, effective dosing, targeting the right tissue with durability, and re-dosability. The biopharma industry also needs to determine the best route of administration to achieve these goals in the context of disease biology, unmet medical needs, and patient preferences. Manufacturing considerations also need to be part of this calculus, with respect to the design and formulation of the payload of the vehicle.

Viral vectors are validated delivery systems for ex vivo and in vivo gene therapy and have been used in FDA-approved treatments for cancer, inherited retinal disease, spinal muscular atrophy, Duchenne muscular dystrophy, beta thalassemia, and cerebral adrenoleukodystrophy. While these therapies have transformed care and outcomes for patients living with these diseases, viral vectors still have a number of limitations. Viral vectors are inherently immunogenic, which can pose safety concerns during initial dosing and, with current technology, do not allow for re-dosing. Additionally, viral vector manufacturing is highly complex and expensive, which may create barriers to using virally delivered genetic medicines for diseases with large patient populations. Additionally, manufacturing processes that use helper viruses to package genetic payloads into replication-deficient vectors must include purification steps to remove any residual helper virus and also require additional quality control and quality assurance assays to ensure that these steps have achieved their intended goals.

Non-viral delivery systems such as LNPs offer a variety of safety, efficacy, and manufacturing benefits compared with viral vectors. The success of the mRNA COVID-19 vaccines, which used LNP formulations, has validated the clinical utility and feasibility of these non-viral systems. LNPs rely on the host cells’ endosomal pathway to enter the cells and are formulated with positively charged lipids to facilitate delivery of the nucleic acid payload inside the cell. However, these lipids can cause inflammation. LNPs also preferentially accumulate in the liver, which may be beneficial if liver cell activity contributes to the disease the therapy is intended to treat but may reduce efficacy if the genetic medicine needs to be delivered elsewhere, such as to muscle or neuronal cells. The combined toxicity and accumulation in liver cells can result in dose-limiting liver toxicity following systemic delivery.

PLVs are another nucleic acid delivery platform that offers the best features of viral vectors and LNPs while avoiding their limitations. PLVs are formulated with well-tolerated lipids and are able to deliver genetic material directly into the cytoplasm by direct fusion with the plasma membrane. This is achieved through the incorporation of fusion-associated small transmembrane (FAST) proteins from Orthoreoviruses, which are the smallest known viral fusogens. These FAST proteins enable direct intracellular delivery of membrane-impermeable payloads, bypassing the endocytosis pathway, and increasing the biological activity of the payload. PLVs mediate effective intracellular delivery of mRNA and plasmid DNA payloads while maintaining excellent tolerability, low immunogenicity, and favorable biodistribution in mammalian models.

Regardless of the formulation selected, companies developing non-viral gene medicines face similar manufacturing challenges. As with the manufacture of other pharmaceutical products, companies have a variety of options with respect to investing in internal process development and manufacturing infrastructure and resources, identifying a contract development and manufacturing organization partner, or pursuing a hybrid model that utilizes both internal and external resources.

The challenges and opportunities associated with these different options include the financial risks of internal investment, the industry-wide shortage of contract manufacturing suites, the challenges of transferring innovative and proprietary manufacturing processes to an external vendor, and how best to gain and retain access to essential personnel expertise. Another manufacturing challenge specific to the development of RNA-based genetic medicines is the inherent instability of RNA, which makes it difficult to store and transport.

While, in theory, the manufacture of these delivery systems can be outsourced, the formulations need to be adapted and manufactured based on the specific payload of a particular therapeutic candidate. Thus, there is no “off-the-shelf” solution that would enable manufacturing to be commoditized, and manufacturing performed by external vendors will still require significant input from and collaboration with the drug developer.

The growing pipeline of non-viral delivery technologies has created another challenge for everyone in the field, which is the shortage of personnel with relevant expertise in non-viral delivery system formulation, manufacturing process development, and scale-up. To mitigate these challenges, companies need to proactively attract and retain highly skilled personnel. It has also become necessary for the industry to establish training programs in GMP manufacturing in order to grow and sustain a relevant talent pool.

Challenges also arise in the large-scale production and purification of mRNA used in some genetic medicines. For instance, in Entos’ case, the company generally obtains mRNA from strategic partners or vendors and considers the maintenance of mRNA stability during incorporation into a PLV delivery system a key aspect of the process development strategy for these types of molecules. The company also carries that consideration through to the subsequent manufacturing and purification steps. These are important aspects that mRNA developers need to consider as well.

Another challenge is that there is a shortage of personnel with relevant expertise in overcoming these challenges. Expanding the talent pool of project managers and process development specialists highly qualified in the use of mRNA as a therapeutic molecule is essential for avoiding delays in performing or completing mRNA production activities.

While every company pursuing development of genetic medicines must determine its own manufacturing strategy based on its financial and personnel resources, production capacity needs, and project development timelines, other constituencies have critical roles to play in ensuring the full realization of the potential of these novel therapies.

Academic organizations need to expand their offerings in the chemistry and biology of non-viral delivery systems at all educational levels. A variety of two-year degree programs have helped to expand the biotechnology talent pool, and additional programs focused on genetic medicine manufacturing would help to meet current and future demand while providing excellent career opportunities to additional students.

Government agencies that fund scientific advances, including the NIH, the National Science Foundation, and the Biomedical Advanced Research and Development Authority should also consider providing additional training funds. Public-private partnerships designed to increase manufacturing capacity for non-viral delivery systems could address unmet industry needs while creating new jobs that provide local economic benefit.

While there are risks in these types of investments—for biopharmaceutical companies, government agencies, and private investors—the greater risk is not investing. Genetic medicines have the potential to address unmet medical needs that exact tremendous human, societal, and financial costs. Ensuring the availability of resources needed to innovate the delivery systems that make genetic medicines possible is essential for delivering on their promise to protect and improve human health.

1. The Nobel Prize. The Nobel Assembly at the Karolinska Institutet has Today Decided to Award the 2023 Nobel Prize in Physiology or Medicine Jointly to Katalin Karikó and Drew Weissman. Press Release, Oct. 2, 2023.
2. FDA. FDA Approval Brings First Gene Therapy to the United States. Press Release, Aug. 30, 2017.


Volume 47, No.12
December 2023
Pages: 21–23

When referring to this article, please cite it as Lewis, J. Risks and Rewards of Investing in RNA-based Genetic Medicine Manufacturing. 

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