Advancing ADCs to the Next Level

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Following a long road to success with antibody-drug conjugates (ADCs), developers today are seeing regulatory approvals for ADCs as a more common occurrence. Better success in the current environment is largely due to technology improvements that have helped minimize risk and enhance therapeutic efficacy for these complicated drugs. However, the manufacturing of ADCs remains a complex process, involving requirements for both the large-molecule and small-molecule components. The linker technology joining the two pieces also has its own requirements. Because of their manufacturing complexity, ADC development and production increasingly requires outsourcing services.

Three major challenges for drug developers trying to bring ADCs to market include lack of capacity, lack of expertise in scaling up, and the complexity of the supply chain, notes Christian Morello, vice-president and head of the Bioconjugates Business Unit at Lonza.

In looking at the overall dynamic of innovation in the ADC space, the majority of innovation is coming from small biotech companies, and those companies are not necessarily well equipped with the internal capacity to produce the product, Morello points out. “There is also a lack of knowledge about the industrialization and the scale up of ADCs,” he says. “And [there is also] the complexity of the supply chain; Indeed [we] within the bioconjugate field, we are bringing different pieces, like a puzzle, to produce the drug substance. It implies [much] complexity [and requires] management of different sourcing in order to make it happen.”

These challenges are what ADC developers have to face and overcome to produce clinical supply or commercial supply, Morello emphasizes. “This is where CDMOs [contract development and manufacturing organizations] bring a lot of benefit, because we have [experience with] different modalities. [Especially at Lonza,] we’re totally integrated, so we offer fully integrated services to make it happen and to accelerate [the developer’s] path to commercialization,” Morello says.

Unique requirements

ADCs have unique manufacturing requirements, which is part of their complexity. “With ADC specificity, we are merging two worlds,” explains Morello. “We are merging the water and the solvent, the biologic and the chemistry. So, with this integration of two worlds, it requires specific skills.” Morello also cautions carefulness when dealing with the risks associated with the chemistry involved in ADC manufacture. “You need to take care about potential explosion or flammable risk associated [with] the chemistry, but you also need to take care about the potential contamination due to microbes if you’re not working with adequate procedure for clean environment. So, the operating model is very specific.”

The science of ADCs has evolved significantly over the past 20 years, Morello also points out. Many improvements can be seen in the carrier component (protein or peptide), the linker component, and the payload, all of which makes the conjugation technology more complex.

“There have been a lot of new developments in terms of congregation and linker technologies,” agrees Nicolas Camper, senior director, Bioconjugation, at Abzena. “There is a definitive move towards site-specific conjugation technologies and away from stochastic conjugation approaches that allows [us] to prepare better-defined antibiotic-[drug] conjugates,” he says.

Camper also points out another new development that he’s observed over the past few years, which is that linker technology is becoming more sophisticated. “Quite often, when you conjugate cytotoxic drugs, they are quite hydrophobic, and that can impact the performance of your ADC. So, there has been a lot of effort put into developing more hydrophilic linkers,” he explains.

Another noticeable advancement has been in the development of branch linkers. These branch linkers give some options for preparing the ADC and modulating the drug loading. “[T]hat is something relatively new and should have an impact on the performance of ADCs and ultimately result in better ADCs and more programs,” he says.

Unmet needs

Technological gaps are one area of unmet need in the ADC space. In Lonza’s case, the CDMO realized it needed a certain technology that would be valuable to its customers, which prompted it to acquire the Netherlands-based Synaffix in 2023 (1). Morello explains that the technology Synaffix brings offers a new way to do the conjugation “where we are connecting the linker at the glycan location on the mAb.”

“That is something that no one else has,” Morello emphasizes. This technology specifically addresses the challenge of how to manage the number of linkers and payload that can be connected to the carrier, the mAb. “So, it brings some solution to address the needs the customer has,” he says.

Morello also notes that Lonza is following the evolution of conjugation technology day-to-day to be able to capture new technologies and bring the best solutions to customers. “We have also created a toolbox [where we] identify very innovative companies/technology outside, bring them into the [Lonza] network, and identify where the customer may require this type of support, and then facilitating, connecting this technology at an early stage,” Morello states.

“When it is confirmed that [a] molecule is really interesting … then [we use] our ability to … master this very breakthrough technology [and bring it] into an industrial and GMP [good manufacturing practice] environment and to scale up this technology to support Phase I, Phase II, or Phase III [development], and then, later on, [scale up to] the commercialization of the drug,” Morello says.

Future path

ADC development has a robust future with much potential. Camper points out an important aspect currently driving ADC development: diversification. “I think that we’ve seen a lot of diversification. That’s a key word. The increased diversity can be noticed in the targeting moiety. Smaller targeting fragments, which allow for better penetration into the tumors, are being developed as targeting moieties; that can be nanobodies or fat fragments,” he explains.

“There is also diversity which is encompassed in the use of bispecific antibodies. They allow for targeting more selectively cancer cells,” Camper says. Camper also notes that there is a lot of diversity today in the payloads. “Traditionally, they were cytotoxic payloads, but, now, people are revisiting all potent small molecules, such as potent kinase inhibitors or payloads that have radically different mechanisms of action, such as molecular glues or PROTACs [proteolysis-targeting chimeras].”

Camper additionally observes how, in the past few years, there has been development of bioconjugates outside the area of oncology. “There are lots of antibody-drug conjugates being developed for the treatment of inflammation, for instance, or—something which is extremely hot at the moment—the development of antibody oligonucleotide conjugates for the treatment of genetic disorders,” he states. “Having access to more complex and linked payloads and conjugation technologies—more advanced conjugation technologies—that definitely results in better therapeutic profiles for antibody-drug congregates, and we’ll see more and more of those in the future.”

“The technology is now at the level of maturity that enable a lot of different things,” adds Morello. For instance, going back to Lonza’s Synaffix acquisition, Synaffix presents another type of linker technology in which the developer can define how many payloads it wants to have per mAb. “That is another possibility that will enable [the developer] to fine tune the benefits/risk ratio for the patient,” Morello states. “We can see [that] today for some cytotoxic compounds for oncology, for sure, but we also have radiolabeled compounds to facilitate diagnosis. [This is] also oncology treatment, but with a different approach.”

“We have nucleotide and mRNA [messenger RNA] that are more and more used for some applications. We have polysaccharides that are also used as a vaccine. So, the applications associated with bioconjugation is much broader than it was in the past,” Morello says.

In addition, Morello points out, when looking at the overall portfolio of clinical trials that are ongoing in the bioconjugates field, half of them is associated with oncology applications and the other half is associated with non-oncology products. The ability to tackle different type of disease is one clear direction where ADC development is heading. Another area is having the ability to improve the benefits/risk ratio to decrease side effects, particularly in oncology, while increasing efficiency. Being able to target a specific ratio of linker to payload to mAb is also an interesting area, he adds.

“Last but not least is the ability to simplify the process, again, through more integration,” Morello states. “We will need to accelerate the time to market and will accelerate, as well, the time to commercialization.”

Reference

1. Lonza. Lonza to Acquire Synaffix and Strengthen Antibody-Drug Conjugates Offering. Press Release. June 1, 2023.

About the author

Feliza Mirasol is science editor at Pharmaceutical Technology.

Article details

Pharmaceutical Technology®
Vol. 49, No. 1
January/February 2025
Pages: 29–30

Citation

When referring to this article, please cite it as Mirasol, F. Advancing ADCs to the Next Level. Pharmaceutical Technology 2025, 49 (1), 29–30.