BioBuzz by Workforce Genetics

In Conversation with Gaspar Canepa, PhD, Principal Scientist at American Gene Technologies®

By Sarah Ellinwood
February 28, 2023

American Gene Technologies (AGT), located in Rockville, Maryland, is leading the charge in utilizing gene therapy to treat diseases that have largely been out of reach with traditional approaches. 

You likely know AGT best from their ongoing work to develop a potential HIV cure. Their lead candidate, AGT103-T, is currently in a Phase 1 trial and has shown encouraging data thus far both in patient safety and T cell responses. The company is currently planning for Phase 2.

Beyond HIV, AGT is also tackling additional diseases, including the rare metabolic disease phenylketonuria (PKU).

We caught up with one of AGT’s scientists, Dr. Gaspar Canepa, to learn more about PKU and how the team is working to create a potential cure* for this disease.

*DISCLAIMER: AGT’s PKU therapies are in the preclinical stages of development. They have not yet been tested in the clinic or administered to humans.

Tell us about PKU – what kind of disease is it, and what is the root cause?

PKU is an autosomal recessive genetic disease that is passed down to a child from their parents. Individuals have a mutation in the gene for phenylalanine hydroxylase (PAH), an enzyme that metabolizes the amino acid phenylalanine to tyrosine. In this disease PAH is nonfunctional, meaning that phenylalanine accumulates in the body. If left unchecked, phenylalanine levels become toxic and cause a variety of neurological symptoms, including intellectual disability.

PKU occurs in 1 in 10,000 to 15,000 newborns, and there isn’t currently a cure. These individuals can only manage the disease by following a strict diet and avoiding foods high in phenylalanine. This includes most meats in addition to a variety of beans/nuts, cereals, breads, snacks, and any drinks containing aspartame. You can imagine how challenging and frustrating this is.

How is AGT planning to correct the underlying cause of PKU? What makes this approach unique compared to other strategies out there?

AGT is creating a lentiviral-based gene therapy that selectively targets liver cells and replaces the dysfunctional gene with the correct copy, resulting in functional PAH enzymes and reconstituting the person’s ability to metabolize phenylalanine.

With this approach we also block the production of mutant PAH, which is crucial for the therapy to be fully effective. PAH is a four-unit tetramer, and just one mutant unit in the group would prohibit the enzyme from working.

Other companies are working on different approaches to treat PKU, such as injecting patients with a functional enzyme that can metabolize phenylalanine in place of native PAH. AGT’s approach is unique because we’re using a lentiviral vector that integrates with the patient’s DNA, permanently fixing the problem at its source. 

Using a lentiviral vector is also important in the context of PKU because our livers grow as we age. If you use a non-integrative, transient vector such as AAV, that therapy will become diluted as the individual grows up and will eventually fall below the level needed to contain the disease. You’d have to repeatedly dose the therapy throughout one’s life, while you wouldn’t have to do that for a lentiviral vector. Further, AAV has the potential to be highly immunogenic, meaning that it would not only be more costly due to multiple doses, but more risky.

Currently we have a vector that has shown encouraging activity in preclinical in vitro cell studies. We’re currently assessing reproducibility – I’m hopeful that by the end of this year we’ll have enough preclinical data to inform next steps, including clinical development.

Why do you think AGT will be successful?

I think AGT is well-equipped to tackle this mission for a few reasons. I think back to one of the first books my mother gave me as a kid – it was an encyclopedia attempting to answer life’s most fundamental questions in simple terms – how, why, where, and when. I think of that a lot in terms of why I think AGT will be successful.

How? We have a robust and safe lentiviral system that can deliver DNA or other forms of cargo to treat infectious and genetic diseases.

Why? Because we have the technology and the drive. We’ve seen how gene therapy has cured people of other genetic diseases such as sickle cell anemia, so we know how much potential this approach has. With that, it’s our duty to use our knowledge of biology and cutting-edge technologies to find cures for diseases once thought to be incurable.

Where? AGT is located in “DNA Valley”, the part of Maryland along the I-270 corridor that is not only home to innovative biotechs, but is also at the intersection of government, academia, and industry, providing an environment with millions of opportunities for collaboration and creativity.

And When? Given all the technological advancements that have happened in the gene therapy space over the past 20 years, I think now is really the time for us to unlock gene therapy’s true potential.

Let’s talk a bit about your background – how has your professional journey prepared you for this important endeavor? Was it difficult for you to transition from academia to a business environment?

I’ve always had an interest in understanding the molecular biology of diseases. I got my PhD in molecular biology from the University of Buenos Aires, where I studied neglected tropical diseases. After doing a postdoc at the Universidad Nacional de San Martín I came to the NIH in Bethesda to study potential malaria therapeutics for several years. I then spent two years at UPenn, where I was able to apply my molecular biology knowledge to human gene therapy. The program I worked in was also 50/50 between a research and business model, which helped provide me a bridge as I prepared for the next steps in my career. Keeping up with the literature, attending meetings, talking with people, and leading projects – those were all things I did along my academic journey, and things that I still do today. 

Throughout my career I always envisioned myself transitioning into industry because I wanted to have more of a role in developing therapies. The transition from academia to biotech was easy for me for a few reasons. First, I still feel like I’m learning something new every day. Second, I feel very supported by AGT’s work environment. Everyone at the company shares the same goals and ambitions, and I’m very happy where I am.

Do you have any guidance, perspective, or encouragement to impart to others working in the field of gene therapy?

Gene therapy is such a rapidly-growing field and is one of the most exciting areas of biotech – for good reason. We think it will have an impact on so many people who have diseases that were once considered impossible to cure.

It also sounds very simple when you break it down – you replace a dysfunctional gene with a working copy. It’s not like replacing a dead battery with a new one, though there are a lot of things you must consider. 

You have to figure out what vector you want to use and if it should only be expressed in specific areas of the body. For example, using a lentiviral vector to replace a broken copy of PAH may work for PKU, but for something like cancer where you need to kickstart an anti-tumor response, you might want to re-organize your use of the toolset and formulate a different approach. Understanding the biology of the disease you’re trying to treat is crucial. You also need to get the molecular machinery to work to create a viable product. Then you have to figure out how to introduce it into the body. This is all before you even start doing preclinical tests.

With all this said, because of how fast the field is moving, it’s tempting to want to get something into the clinic as quickly as possible. Resist the temptation to overlook details or make assumptions, do your due diligence and be meticulous in the beginning stages. Measure twice, cut once, as they say. Because the farther you go into drug development, the harder it is to backtrack if something isn’t quite right. At AGT we spend a lot of time evaluating vectors, designing our therapies, and assessing preclinical safety.