Alloy Therapeutics supports its clients with its mix of in vivo discovery platforms. Kent Bondensgaard, Senior Vice President at Alloy Therapeutics, introduced the ATX-GK platform as the main workhorse: a mouse with a fully humanised heavy chain and Kappa chain. The platform is available in several genetic backgrounds including BL6, BALB/C, and F1, and has proven successful across multiple discovery campaigns.
Bispecific antibodies can be deployed across multiple modalities and overcome several challenges in therapeutic contexts. Despite their popularity and success, their development presents various obstacles. Bondensgaard suggested that generating quality compatible antibody components is a good starting point for bispecifics as well as selecting stable manufacturable bispecific formats.
Alloy Therapeutics adopts a three-step approach. The first step uses common light chain discovery solutions to address the heavy chain light chain pairing. Secondly, this is followed by optimised format engineering. Finally, integrated high-throughput screening identifies functional leads.  Bondensgaard added that starting from a full diversity light chain transgenic mouse can lead to complications down the line when producing bispecific antibodies. Common light chain transgenic platforms provide insightful ways of overcoming these issues and facilitating the production of bispecific antibodies with high developability profiles.
Alloy engineered a suite of common light chain mice, including three Kappa mice and one Lambda mouse, validated for their ability to respond to antigenic stimulation and produce robust serum titres. They are all characterised by a full human heavy chain within the same diversity of the GK strains.
Regarding antibody discovery, the Alloy workflow relies on four different steps. The first one begins with the immunisation of transgenic platforms. The common light chain strains can be immunised with many methods, including recombinant protein, DNA, RNA, or cell lines.
Following immunisations, lymphoid tissues are collected, and B cell enrichment is performed using different methods like magnetic beads, FACS, or even yeast immune libraries, depending on the nature of the project. This generates thousands of reads that are fed into AI/ML programs that extract the best leads that are then expressed and characterised. Additionally, one can analyse the best leads again using AI/ML software to expand clonotypes or improve affinity maturation.
This method allowed the team to identify good clones with diverse sequence usage, robust cell binding, and good cross-reactivity. Various discovery projects demonstrated how they could use their technology to target tumour-associated receptors and Claudin 18.2 protein. Bondensgaard wrapped up his talk by emphasising the importance of functional validation of clones and Alloy Therapeutics' range of in vitro functional assays.
