Dr Richard Buick, Chief Scientific Officer
Biotherapeutic medicines are proving crucial in our fight against a wide variety of chronic and life-threatening diseases. For biotherapeutics based on monoclonal antibodies (mAbs), humanization is a critical step in creating a therapy that is less immunogenic, more tolerated in vivo and, therefore, more effective in patients.
During humanization, the sequence of a mAb is modified to mimic an antibody that is naturally produced in humans – but this is a highly complex task, requiring deep expertise and significant resources. As a result, and with pharmaceutical pipeline pressures growing, organizations are increasingly looking to outsource their antibody humanization efforts. Outsourcing can cut costs, shorten timelines, and provide valuable flexibility and external expertise throughout the drug development process, without the need to relinquish value or control (as in licensing). However, a key question remains: how do you identify and select the best, and most effective, outsourcing partner for you? There are multiple factors to consider when choosing such a partner that go beyond cost or resource efficiency – factors that will go on to have a real impact on the success of your project. With this in mind, here’s a quick rundown of four key criteria to consider when selecting an outsourcing partner.
- A proven track record of successful humanization
- An expert team
- An affinity guarantee
- An expertly curated human antibody database
Look for an outsourcing partner that…
Your choice of service provider is a critical element in whether your antibody innovation succeeds or fails. To see success, it’s crucial to work with a provider that…
…has a proven track record of successful humanization
When evaluating a potential outsourcing partner, make sure you ascertain how many humanization projects they have successfully completed – and how relevant these projects are for you and your objectives.
Prior experience is hugely valuable, as illustrated by the example of rabbit humanization. Rabbit antibodies have unique differences in structure that make them especially difficult to humanize, with the rabbit immune system also diversifying its antibodies by rearranging specific genes (via ‘gene conversion’) such that multiple rabbit germlines are needed to derive an antibody. As a result, humanization approaches that use germlines can be limited by their quality and availability. In such a complex case, an ideal CRO would have proven experience and proof of success in humanizing rabbit antibodies to minimize your risk of project failure.
Overall, a CRO with proven success and capabilities over multiple species – mouse, rabbit, llama, chicken – and clinical phases – Phase I, II, scale-up – is ideal. Such a breadth of experience demonstrates knowledge of the relevant cGMP and regulatory landscapes, and gives you peace of mind and confidence in the partnering process.
…has an expert team
One of the most significant reasons to outsource is to gain access to external expertise that you can draw from and rely upon throughout the complex humanization process. Such expertise enables the best possible humanized candidates to progress to clinic – and, further down the line, to reach patients in need – in a timely, cost-effective way.
However, successful collaboration depends not only on the ability, availability, expertise and experience of your partner’s team, but on how this team integrates with your own. It’s vital to ensure that your partner views your working relationship in a collaborative way, rather than one involving two disparate entities. Is your chosen CRO transaction-based and offering minimal levels of ongoing support, or do they treat your project and molecule as if it were their own?
A humanization team should go beyond simply deimmunizing a molecule; they should act as an extension of your in-house capabilities, and offer additional value by producing variants with guaranteed comparable affinities and improved developability profiles. In other words, they should be invested in your success and help further your innovation activities, rather than simply providing products or services on request.
…offers an affinity guarantee
An important aspect of antibody humanization is affinity, or the speed and strength with which an antibody binds to an antigen. The higher an antibody’s affinity, the more reliable and sensitive its bonding ability under difficult conditions and the less of that antibody is required for treatment, making it a highly attractive therapeutic candidate.
Different CROs offer different affinity guarantees for the humanized antibody variants they produce. For the best success and confidence in both your working partnership and a given project, look for a CRO that offers a two-fold guarantee: a promise to produce a humanized variant within two-fold affinity of the chimeric control (i.e. a variant that will bind as well to its target as the original antibody), and a commitment to keep going until they achieve this.
Many CROs halt development and issue refunds if an antibody doesn’t initially successfully humanize, resulting in costly delays, lost potential, and requiring you to invest additional time and effort into sourcing another partner. However, some CROs instead promise to keep working on a molecule until it succeeds – a hugely valuable guarantee given the ever-increasing pressures facing pharmaceutical organizations, and the swiftly accelerating pace of industry innovation.
…has an expertly curated human antibody database
For successful humanization, CROs that offer mature human antibody sequences over germline-based approaches bring additional value. Some organizations rely upon a couple of germlines or ‘back mutations’ to generate effective variants, but it can be more effective to opt for a provider that can realize the potential of human antibody frameworks as increasing diversity of frameworks can lead to a higher chance of a successful humanization.
Additionally, diverse libraries can cope better with difficult antibody types, result in excellent developability profiles, and bring better affinity and activity without the need for multiple back mutations (a process in which some of an antibody’s pre-humanization residues are retained and used to replace human residues at corresponding positions, in order to restore some of the original sequence and regain any affinity lost during the modification process).
Large, diverse, well-managed databases also create opportunities for further innovation – such as homology-based grafting of complementarity-determining regions (CDRs) – and enable CROs to comprehensively consider the impact of their sequence modifications in terms of immunogenicity, stability, aggregation, affinity and more.
It’s time to outsource antibody humanization
Outsourcing undeniably holds great value for pharmaceutical organizations. While sourcing the right partner for you is important, it needn’t be stressful. You can maximize your chances of outsourcing success by opting for a partner with proven success, a diverse antibody database, a highly experienced team of antibody experts, and a true commitment to you and your objectives.