Scientist Snapshot | Stephanie Johnson, Senior Development Scientist

At Sterling, our highly experienced team members and their passion for what they do are central to who we are. This month, we spoke with Stephanie Johnson, Senior Development Scientist at Sterling’s bioconjugation facility, to learn more about her role and Sterling’s work in antibody drug conjugate (ADC) discovery and development.

Can you briefly describe your background and current role at Sterling?

I have been a Sterling employee for about 6 months following the acquisition of ADC Biotechnology. It is the early days, but so far Sterling has been very supportive of our bioconjugation team, making investments in equipment, people and new labs.

After receiving my PhD from Bangor University, utilising enzymes in the synthesis of non-natural amino acids, I moved into industry and started working for ADC Biotechnology, a small company specialising in ADC process development

While I gained a basic understanding of ADCs during my PhD, it wasn’t until I worked in an ADC lab that I really understood their complexity and started to master the process and analytical skills required to make them for clients. Ten years on, and having made thousands of ADCs, I am still excited by this therapeutic modality.

Today, I am responsible for one of our key customers and manage a team who supports them in discovery, process and analytical development. We make many ADCs against their selected targets to enable them to progress the best into the clinic. Our thoughts on developability and manufacturability along with the client’s data on safety and efficacy are combined to inform lead candidate nomination.

As the customer has grown from a handful of people to a 400-strongcompany, I now work with teams spanning research, chemistry, analytical and CMC. Having to constantly switch disciplines is challenging but highly rewarding–as is knowing they rely on us for our expertise.

Why have ADCs gained momentum in recent years?

ADCs are desirable because of their ability to target cancerous cells directly, avoiding harm to healthy cells associated with treatments like chemotherapy. As I mentioned, commercially approved ADCs were relatively new when I began my career. Today, 11 are on the market, with many more in various stages of clinical trials. Their advantages are clear, and researchers have even begun exploring their viability for treating indications aside from cancer.

It took some time for ADCs to gain momentum because they are quite complex, requiring careful selection of several components. Developing an ADC that is both safe and effective requires specialised expertise, with extensive knowledge of different linkers, conjugation chemistries, and more.

How does Sterling support customers’ ADC projects?

We provide extensive services in ADC discovery and development to assist customers through the early phases of their ADC projects. Our goal is always to help customers develop a tailored ADC that meets their unique objectives.

This includes proof of concept materials, process and analytical development, and production of larger batches for preclinical safety studies.

We also support the technology transfer process as our customers look to produce their ADCs on a larger scale for clinical trials and beyond, including developing detailed process descriptions. Our team works very collaboratively to accomplish our customers’ goals, with everyone providing a unique contribution to each project.

Our work is supported by our ADC analytical team members, who are experienced in providing analytical services specifically for bioconjugation projects. Our facilities also provide the containment needed to work with a variety of potentially hazardous toxins that can be used in ADCs.

What have been some of Sterling’s greatest successes in ADC discovery and development?

One of our greatest successes has been working on an ADC that was ultimately approved for commercial sale in the US. We have worked with this customer on a variety of projects for many years, and we were thrilled to help see this one through to commercial approval.

Our team supported this project in a number of ways over the course of its lifecycle, and we worked closely with the customer’s team every step of the way. This included performing extensive research and development work in its early stages, developing a scalable process, aiding in technology transfer, performing full process characterisation as the product went through clinical trials, and providing support in writing certain sections of the Biologics License Application (BLA) as the customer sought approval. As this customer continues to push more molecules forward, we continue to work collaboratively with them in their projects’ early phases as well as late stage process characterisation to help maximise their long-term success.

Why should customers choose to work with Sterling for ADC projects?

I think that our team’s broad range of experience in the ADC space is what really sets us apart. We’ve worked with a variety of customers on an extremely diverse range of projects, which has given us invaluable experience utilising different linker chemistries, antibody formats, toxins and drugs. Because of this expertise, our customers recognise us for our commitment to getting things right the first time, and our ability to satisfy even the most complex of requirements.

Beyond that, the reasons customers choose to work with Sterling on any project hold true for ADCs as well. We are committed to serving as true partners to our customers, and we work closely with them to meet their specific needs, overcome challenges, maintain outstanding quality and adhere to deadlines. We value building lasting customer relationships that are rooted in transparency and collaboration.