By Erin Harris, Editor-In-Chief, Cell & Gene
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Sam Wadsworth, Chief Scientific Officer at Ultragenyx Gene Therapy, shared with me details about the company’s HeLa gene therapy platform and how the company’s AAV-based therapies differ from others like it. He also shared his thoughts about the importance of partnerships for early-stage preclinical programs using the company’s HeLa platform.
1. Explain Ultragenyx Gene Therapy’s HeLa platform in detail.
Manufacturing scalability is becoming increasingly important for gene therapy. With higher dose requirements to address larger diseases and various types of diseases, we need to have a scalable platform that consistently produces high product yield and quality in a cost-effective way.
Our HeLa platform allows for scalable manufacturing of AAV vectors of high quality and reduced cost of goods compared with alternative platforms. We refer to this system as the HeLa Producer Cell Line, or PCL. Larger manufacturing scale is required for disorders where systemic administration to treat the liver is required such as Wilson Disease, where there is also a large, affected population, and for central nervous system disorders such as CDKL5 deficiency, where there is also a large affected population. Our HeLa platform is ideally suited for vector delivery to muscle, also by systemic administration, to treat Duchenne muscular dystrophy. For Duchenne, there is a large affected population and the dose per patient is extremely high. I’ll highlight a few key attributes that make the HeLa PCL manufacturing platform so ideal:
- First, a very basic point is that the HeLa PCL platform leverages the basic biology of AAV. In the engineered HeLa PCL, the AAV rep/cap genes and AAV vector genome are integrated into the cell at AAVS1 locus, the natural site for integration of AAV as a virus.
- Induction of AAV vector manufacturing is triggered by simple, efficient, and low-cost Ad5 infection, the natural mechanism for triggering AAV vector genome replication, which occurs very efficiently from the AAVS1 locus.
- The HeLa PCL platform is based on clonal selection, unique in the AAV manufacturing world, which enables selection of clones for manufacturing with consistent product yield and quality.
- A very important property of the HeLa PCL platform is the high proportion of full particles in the harvest. This feature can obviate the need to further enrich the product for full particles.
- A misconception about the HeLa PCL platform is that clone selection is a lengthy process. The innovation we have implemented to reduce the time for isolation of primary clone candidates as well as multiple backup clones led to what we refer to as HeLa 2.0. At ASGCT, we revealed additional details about further genetic engineering of the HeLa PCL platform leading to what we refer to as HeLa 3.0
- High vector yields of ≥1e11 GC/mL are readily achieved.
- Finally, I’ll point out that this process is highly scalable from discovery to GMP manufacturing. Product yield consistency is maintained across a scaling factor of more than 130,000, culminating in GMP manufacturing at the 2000 liter scale. The advantage of this feature is that numerous facets of bioreactor optimization can be readily explored early in development with the knowledge that there will be translation to the full GMP manufacturing scale.
2. Why are Ultragenyx AAV-based therapies different from others like it? How is the company ensuring such issues will not occur with its AAV-based therapies?
Ultagenyx’s gene therapy program has the ability to address multiple therapeutic areas that affect both large and small rare disease patient populations, but is uniquely focused on diseases with single gene mutations that do not have effective therapies. We are currently in clinical-stage development with three gene therapies for three severe genetic diseases: Glycogen Storage Disease type 1 a (GSDIa), Ornithine Transcarbamylase (OTC) deficiency, and Wilson disease.
Thinking beyond our current programs, we are constantly evolving and optimizing our HeLa PCL platform. We believe this platform provides us with significant opportunities, as it allows us to expand into larger disease areas as well as CNS and muscle diseases, all of which require much higher dose levels.
The industry has made tremendous progress since the early days of gene therapy, and we are constantly learning and evolving our programs to ultimately provide patients with the most effective and safest treatments possible. Some examples of this include the use of the AAV8 viral vector in our liver-directed programs. AAV8 is a variant that has been studied in multiple gene therapy programs and in hundreds of patients to date.
To date, in clinical trials with OTC and GSD1a patients, we have seen benefit without the use of extremely high vector doses. Careful use of corticosteroids has been able to control inflammatory reactions to the AAV vector at the doses given. We do not know yet what vector dose will be required for Wilson disease, but, for Duchenne, the field is employing much higher vector doses. In some cases, the effects of complement activation triggered by high vector doses of AAV9 are being treated with eculizimab. The total vector dose is a combination of vector capsids and vector genomes. We believe our HeLa PCL platform, which delivers a high proportion of full vector particles, gives us an advantage regarding safety.
3. With what companies are Ultragenyx partnering and why?
We are partnering with companies that have recognized how our expertise in rare genetic disease and unique AAV manufacturing technology offers the opportunity to accommodate larger-scale production of high-quality therapies for rare disease with scalability, high productivity and lower costs than ever before.
We are collaborating with Solid Biosciences to develop AAV-based gene therapies for Duchene muscular dystrophy. This partnership uniquely combines Solid’s differentiated microdystrophin construct with our HeLa PCL manufacturing platform and an AAV8 variant that has a favorable immunological profile that has been used successfully in the large-scale 2,000 liter production process.
We entered into a strategic partnership and non-exclusive license and technology access agreement with Daiichi Sankyo Company in 2020, which gives Daiichi access to use our proprietary AAV-based gene therapy manufacturing platform for its internal gene therapy programs.
Additionally, Bayer is using the HeLa PCL platform at 2,000 liter scale for its hemophilia A gene therapy program, which has advanced into the clinic.
4. What information did the company present at ASGCT that can be shared with Cell & Gene’s audience?
At ASGCT, we presented data from our two lead programs, showing durability of response, which is extremely important for gene therapies, as well as data highlighting further advancements for the HeLa 3.0 manufacturing platform.
On the HeLa PCL platform, the advancements we’ve made to the 3.0 version have significantly increased productivity:
These cell line engineering improvements result in up to a 5-fold yield improvement over the HeLa 2.0 platform, and a 50-fold yield improvement over HeLa 1.0. Additional improvements in yield are expected with future combinatorial knockdowns, with early studies suggesting a further 5-to-10-fold improvement.
These improvements in the HeLa PCL platform allow for increased productivity and reproducibility with higher full-to-empty AAV ratios while continuing to drive down AAV production costs – all important attributes in the manufacturing of gene therapies for diseases where high product yield is required.
On the data from the Glycogen Storage Disease Type Ia (GSDIa) and Ornithine Transcarbamylase (OTC) Deficiency Phase 1/2 studies:
These data demonstrated durability of response, with sustained responses lasting more than 2.5 years since treatment for GSDIa and durable metabolic control with sustained responses lasting more than 3 years since treatment for OTC.
GSDIa, the most common genetically inherited glycogen storage disease, results in the inability to regulate blood sugar (glucose). There are no approved pharmacologic therapies for GSDIa, which affects an estimated 6,000 patients in the developed world.
OTC deficiency, the most common urea cycle disorder, leads to increased levels of ammonia. Approximately 10,000 patients in the developed world have OTC deficiency, of which approximately 80% are classified as late onset, which is our target population. Approved therapies, which must be taken multiple times a day for the patient's entire life, do not eliminate the risk of future metabolic crises. Currently, the only curative approach is liver transplantation.