A New Paradigm in Drug Development

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Cell and gene therapies are emerging as new therapeutic modalities. Unlike conventional biological therapies produced in cells, the cells themselves are developed as medicines. Full realization of their potential requires a new paradigm where technology development and manufacturing are conducted in parallel from the earliest stages of research to the clinic. New organizational and management approaches are required as well.

From chemistry to biology-based medicines 

Prior to the advent of biotechnology, drug discovery was focused primarily on chemistry first to mimic plant or microorganism derived molecules and progressively to synthesize a specific inhibitor or receptor ligand. Research and product manufacturing were absolutely dissociated, and each led its own life.

The pharmaceutical development process for small molecules dictates that of 5000–10,000 chemical compounds initially undergoing laboratory screening, approximately 2.5–5% will enter preclinical testing and 0.1% will enter clinical testing (1).

This overall process from discovery to marketing authorization of a chemical drug can take 10–15 years. In protein and monoclonal antibody development, the manufacturing process, which may involve bacteria, insect cells, or mammalian cells, is closely linked to the final product. Gene and cell-based therapies have definitively turned a page with multi-step processes based on mammalian producer cells and a resulting gene-expressing vector or cell product. Only one sequence of interest is considered as a candidate, and all the development is focused on gene and cell delivery and manufacturing to reach the optimal clinical product.

Robust methods required

Rapid growth in clinical study of gene and cell therapy is increasing the worldwide need for viral manufacturing technology. Much of this capacity in vector and cell manufacturing is likely to reside in contract manufacturing organizations (CMOs).

Developing cell-engineered products is challenging because of many aspects, including manufacturing, delivery, regulatory, and testing. The need for robust and well-characterized production methods has become increasingly important to ensure that the cell therapy will be successful not only in the initial clinical phases but also through to commercialization. In particular, viral vector manufacturing is a key step in the global cell manufacturing process. Historical challenges for gene-therapy manufacturing have included poor vector quality and a lack of scalable production systems for clinical and commercial manufacturing.

To address these needs, laboratories and companies have developed stable or transient technologies to manufacture and purify vectors for use in human gene therapy clinical trials and future marketed products. The objective is to deploy a manufacturing process template in which the downstream concentration and purification steps do not need to be customized based on the features of the genetic sequences in the product candidate. Once the crude supernatant exhibits a minimal titer and a threshold limit for protein and DNA content, the downstream purification process can be applied.

The aim is to develop a robust gene therapy development pipeline based on proof-of-concept data. The scalable and customizable design of a gene and cell manufacturing platform must have the capacity and flexibility to support clinical development and future commercialization of viral-based gene therapies across a broad range of programs.

Collaboration needed

A contradictory debate has emerged between scientists who want to translate their discoveries rapidly into first-in-man studies and manufacturers who aim to industrialize the global process to increase robustness and reproducibility. In reality, both views on the situation are required. The chimeric antigen receptor (CAR)-T cell story is expected to be a first step in the cell-based therapy field. New generations of CAR-T cells, engineered dendritic cells, are in development and should enter into clinical stages in the near future.

All these first-in-man studies must be facilitated and accelerated by manufacturing facilities able to support these gamechanging therapeutic approaches with standardized processes and expertise.

At the same time, a global process is needed to gain efficiency to drive down costs. Autologous but also allogeneic CAR-T cells’ manufacturing price is greatly impacted by the proliferation and viability of patient T cells during the manufacturing process. A sufficient number of engineered cells is required to reach a therapeutic benefit. The experience to date shows that the cell-based therapy field must encourage research institutes, hospitals, and manufacturers to work closely and build a continuum from research to market. For example, process development aims to result in large-scale production without losing the vector and cell’s basic properties, some of which have yet to be really defined. The industry has begun to understand the proliferation specifications of an engineered CAR-T cell but what about cell biomarkers of expression, phenotype, or cell culture duration on the expected clinical result? A step-by-step process needs to be implemented to encourage or force stakeholders to define these specifications.

Initial first-in-man study triggers rollout 

During the early years of cell- and genetherapy development, the choice of delivery tool was more related to laboratory knowhow than to the real need of the clinical protocol. Vector design and manufacturing were restricted to experts, and once preclinical studies have had been initiated, it was difficult to turn back. The cost in development time of not considering the downstream needs up front was significant.

One example is the case of a rare and devastating genetic disease called Junctional Epidermolysis Bullosa (JEB). The clinical protocol was known since the 2000s based on retroviral-engineered skin patches from biopsies. Questions about the vector (retroviral vs. lentiviral), the manufacturing mode (packaging cell line vs. transient transfection), or the vector pseudotype (Ampho vs. VSV-G) sharply slowed down the first-in-man studies. Other concerns such as cGMP facilities and funding were also time-consuming. The results of the first one-clinical study were reported at the European Society of Cell and Gene Therapy in 2017 by the stem-cell biologist and physician Michele De Luca of the University of Modena (2). It took more than 15 years to answer all the questions and to reach the first-in-man results.

Since then, companies and specialized institutes have initiated multiple clinical trials based on this first treatment showing that an initial first-in-man study is fundamental to trigger such an enterprise. But during these years, skin-cell manufacturing has significantly changed with the development of embryonic stem cells, and future clinical trials will have to consider these improvements.

CLICK TO ENLARGE. Table I. Viral vectors properties compared to RNA and DNA transfection.

Delivery tools shorten development steps Delivery technology remains crucial for gene therapies as well as for cell therapies considering immune tolerance strategies using human pluripotent stem cell-derived allografts. The delivery technology is designed depending on the target cell characteristics and the clinical protocol as described in Table I. 

For example, integrative lentiviral vectors (iLVs), which deliver DNA integrated into the host cell genome, are a leading ex-vivodelivery method for treating genetic diseases and CAR-T cancer immunotherapy. Furthermore, lentiviral vectors are really efficient for transducing primary and stem cells. In parallel, adenoassociated virus (AAV)-based vectors are used for direct in-vivoinjection especially into muscle, liver, or eyes. Both iLV and AAV technologies lead to stable and longterm gene expression and are good candidates to replace a defective gene with a functional copy, which is the very principle of gene therapy.

The emergence of new technologies, such as gene-editing that require the coexpression of several factors, brings RNA delivery technologies into center stage. Combining transient expression with safe and efficient RNA delivery remains a challenge, particularly with new therapeutic approaches based on gene-editing. Non-integrating viral technologies or non-viral approaches (electroporation or lipid nanoparticles) are emerging at the research level and are moving toward clinical research to demonstrate their potential in terms of gene transfer and cell preservation.

Cells as medicines

The next wave of these novel therapeutics for patients changes the regulatory and manufacturing environment. Cell manufacturing includes cell extraction from patients, cultivation, engineering, amplification, cryopreservation, and reengraftment into patients. The engineered living cell-based medicines must exhibit expected cell modification while maintaining all initial cell properties, including phenotype, viability, proliferation, and stability.

Engineered cell therapies imply manufacturing that requires the use of highly concentrated but also highly purified vector preparations to ensure cell preservation. For example, lentiviral vectors are large and complex macromolecular assemblies of proteins, lipids, and RNA and are secreted by producer cells in a cellular culture media containing proteins and DNA contaminants. All these characteristics greatly increase the difficulty in determining which sample components are associated with the vector and which are indeed contaminants in the supernatant. Protein impurities are the most abundant contaminants in vector supernatants. They mostly arise from serum and producer cells, and the proportion of stress proteins might increase while performing a serum free cell-culture process.

Integrating vector/cell-manufacturing processes

Production methods are designed to preserve the vector integrity and the production batch quality. Each parameter of the production process such as the presence/absence of serum, sodium butyrate induction, or vector harvest times may have an impact on the initial crude lentiviral vector supernatant composition. Concentration and purification methods based on ultracentrifugation, tangential flow ultrafiltration, or chromatography must remove cellular debris, membrane fragments, residual DNA, and proteins that are unsuitable for transducing delicate and specialized cells. It is crucial to define a lentiviral vector composition which, by virtue of the high titer and purity, minimizes the deleterious target cell phenotypic changes that occur following transduction of target cells. Regulatory agencies should ask for more stringent data about cell-based medicine characterization and specifications that can have a strong impact on the clinical results. Furthermore, new cell sources will be considered to provide the final engineered medicines. Embryonic stem cells have entered the clinic and have provided promising results as potential treatments for macular degeneration, spinal cord injury, and type 1 diabetes. Final product manufacturing will need to integrate complementary quality controls and in-process checks to obtain the best therapeutic added value in a reproducible and standardized manner. A continuum from research to clinical phases is required to result in improved design of robust processes and technologies. Process characterization must be initiated at the small-scale research level to define parameter ranges in which the product characteristics will be maintained within desired ranges and to design a process that is robust and reproducible.

Simultaneous technology and process development

The cell and gene therapy field can no longer rely on a unique cell- or gene-specific technology. A therapeutic approach based either on gene addition or gene editing needs to consider specific delivery technol ogy. Cell engineering and manufacturing must be adapted to the cell source, and engineered cell immune tolerance development should require additional steps and technologies. This means that cell-based therapy must simultaneously industrialize its processes to reach clinical standards and remain open to implement a global manufacturing process with new components and technologies. This approach implies a strong relationship between discovery and development teams.

Technology and manufacturing process development need to be conducted simultaneously from the earliest stages of research to the clinic and require new organizational and management approaches, as well. For example, each protocol implementation will need a new process qualification with a risk analysis on the change and its effect on the final product. 

How can one forecast the effects of the delivery tool or construct changes on the final cell product? More work will be needed to bring cell-based therapies to the bedside. The changing regulatory and manufacturing environment that will facilitate this new and powerful approach to drug development is one major challenge.

Technology and process integration

Combining technologies and processes requires know-how and clear rights access. Such situations encompass multiple technologies and know-how. Industrialization is a challenge as patents filed on these technologies increase exponentially, and it is more and more complex to ensure freedom to operate. Product commercialization frequently requires dynamic multiple agreements with third parties, such as universities and biotechnology companies, and constitutes a significant barrier to entry.

In view of the breakthrough potential of these technologies on one hand and the complex licensing landscape on the other hand, all stakeholders, including research organizations, companies, and economic players, have a long way to go to enable clear market access.

Gene and cell biology discoveries have generated a wave of hope within the health community. The drug development community must invent new strategies and modalities to make delivery of such therapies possible.

References

1. R.P. Evans, AAPS J.18(1) 281–285 (2016).
2. T. Hirsch et al., Nature551, 327–332 (2017).

About the Author

Pascale Bouillé, PHD, CEO of Flash Therapeutics, was initially involved in fundamental research in retrovirology and has worked in a number of government and biotechnology research laboratories before creating Vectalys in 2005. She has built up over 15 years' experience in R&D projects in the fields of drug discovery and virology. Bouillé has conducted gene therapy trials for the Genethon laboratories with Dr. Olivier Danos and implemented the transition of viral vector tools from a technology-based to a commercially oriented product with Vectalys.

Article Details

BioPharm International
Vol. 31, Number 8
August 2018
Pages: 26–29, 36

Citation

When referring to this article, please cite as P. Bouillé, “A New Paradigm in Drug Development,” BioPharm International 31 (8) 2018.