“Twenty years ago, who knew that ADCs and next-generation bioconjugates were going to be so exciting, so successful?”
Campbell Bunce, Chief Scientific Officer at Abzena, reflects on the strategic positioning that has placed his company at the forefront of one of pharma’s fastest-growing segments.
Campbell leads a global team spanning discovery, development, and GMP manufacturing at Abzena, where he has spent nearly a decade building the company’s capabilities in complex modalities. His background as an immunologist, combined with 18 years in biotech before joining Abzena, gives him a unique perspective on translating scientific innovation into commercial manufacturing reality.
In this conversation on the PharmaSource podcast, Campbell discusses Abzena’s strategic focus on antibody-drug conjugates (ADCs) and bioconjugates, the company’s approach to proprietary platform development, and how the CDMO is responding to increased demand driven by geopolitical manufacturing shifts and clinical successes in the space.
Strategic Focus on Complex Modalities
While many CDMOs compete in the crowded monoclonal antibody space, Abzena carved out a distinct position by concentrating on technically challenging molecules that require specialized expertise.
“There are plenty of folks who can do vanilla antibodies well,” Campbell explains. “But, we came from a strong foundation in scientific and technical expertise, particularly in protein engineering, conjugation technologies, and ADC formats. With that level of expertise, it made sense for us to focus on next-generation biologics and bioconjugates.”
This strategic positioning has proven prescient. The ADC market has experienced significant growth in recent years, with major acquisitions validating the space. Campbell points to Novartis’s recent $12 billion acquisition of Avidity as evidence of the sector’s momentum.
“We’ve got a lot of experience with companies working in that space,” Campbell notes. “When it comes to ADCs and antibody-oligonucleotide conjugates (AOC) in particular, we are at the forefront of the science and technology required to design, develop, and manufacture those.”
The company’s portfolio extends beyond classical ADCs into emerging areas, such as bispecifics, multispecifics, fusion proteins, and AOC—modalities that Campbell believes will define the next decade of biologics development.
Proprietary Platforms as Business Tools
Abzena has invested significantly in developing proprietary technologies that address specific technical challenges in ADC development, including the company’s ThioBridge™ platform. This was developed to tackle persistent issues around stability and toxicity that have plagued earlier-generation ADCs.
“With ADCs, there’s a big issue of stability in vivo and off-target toxicity,” Campbell explains. “Using the expertise within the business, the team looked at how they could overcome that and developed ThioBridge™. We generate a highly stable, highly uniform drug-to-antibody ratio (DAR) form of the ADC. It’s scalable, and we’ve seen it perform better in vivo.”
The platform is now in clinical testing through a client program, with Campbell “eagerly anticipating” data that he expects will demonstrate improved safety profiles compared to competing conjugation technologies.
On the upstream side, Abzena developed AbZelectPRO™, a cell line development platform that Campbell describes as “agnostic to the type of molecule.” The platform uses a proprietary host cell line with a ProteoNic vector system, achieving productivity levels that Campbell says match or exceed competing technologies while offering superior stability.
“In our hands, we’ve seen it outperform transposons,” Campbell says. “It’s as quick in terms of timeline to get to a clone, but it outperforms in terms of stability and productivity.”
Critically, Abzena’s cell line development offering comes with transparent pricing, no royalties, and minimal one-off licensing fees, an unusual model in a space Campbell characterizes as often “smoke and mirrors.”
“It’s important to keep it as clean and transparent as possible, so that customers know what they’re paying and what they’re going to get,” Campbell explains. “We keep it so there’s no complexity, and it’s one and done. The customer can get on and deal with the bigger challenges of taking that molecule to the clinic.”
Tailored Collaboration Over Cookie-Cutter Solutions
Campbell emphasizes that Abzena’s differentiation extends beyond technical capabilities to how the company engages with clients across different stages of maturity, from virtual biotechs to large pharma.
“We don’t expect our customers to fit into how we work,” Campbell says. “We understand their pain points. We understand what they need to do to go through those value inflection points, and we tailor our services and expertise to fit into that.”
Responding to Manufacturing Demand and Geopolitical Pressure
Abzena operates manufacturing sites in San Diego (biologics) and Bristol, Pennsylvania (linker-payloads and ADC conjugation), positioning that Campbell describes as “right place, right time,” given the current push for on-shoring pharmaceutical manufacturing in the United States.
“From a geopolitical perspective, there’s a lot of activity around on-shoring manufacturing in the US for obvious reasons,” Campbell notes. “The demand there is super exciting, and we need to respond to that. There aren’t that many manufacturers of ADCs in the US.”
The company is responding to this demand on multiple fronts. Current clients are pushing Abzena to achieve Phase III and commercial-scale capabilities at both biologics and bioconjugate sites, with recent audits at the San Diego facility progressing favorably toward that goal.
Additionally, Abzena is leveraging existing space across its US footprint to create optionality for conjugation activities, particularly for non-toxic payloads in AOC applications.
“We’ve got a lot of flexibility within our business just now,” Campbell says. “We need to continue to look towards the future and what we need to do to keep up with the growth.”
Advice for the Next Generation
Reflecting on nearly three decades in the industry, Campbell offers straightforward guidance for those starting out. “Stay flexible, stay responsive. Look to get that balance right between a platform that can be modified slightly to suit some of the different challenges that come along.”
He also counsels resilience through industry cycles, pointing to the biotech investment downturn. “That can put a lot of people off. But if you’ve been around long enough, you know that it’s going to come back. Being open-minded, flexible, agile, and responsive—you’re going to be in the right place at the right time again.”
For Abzena, success ultimately comes down to seeing challenging scientific ideas reach patients.
“Our technical team gets to see first-on-planet drugs that they actually helped input in the design, manufacture, and success of,” Campbell says. “Success is seeing these sometimes incredibly challenging, crazy ideas come to fruition when they get to patients.”
