OptiMAL® R&D Update

Fusion Antibodies plc (AIM: FAB), specialists in pre-clinical antibody discovery, engineering and supply for both therapeutic drug and diagnostic applications, provides an update to the OptiMAL® project being performed under the collaboration agreement (the "Agreement") with the National Cancer Institute ("NCI"), details of which were originally announced on 28 November 2023.

Having already demonstrated superior single digit nM affinities for antibodies against protein targets, as detailed in the announcement on 17 September 2025, the Company can report that OptiMAL® has been now shown to be similarly successful with smaller peptide targets.

Peptides are often used as antigens as they can be designed to represent specific epitopes (regions of the protein) for the antibodies generated. They are also easier and more cost effective to synthesize. However, they are less immunogenic which can result in poorer antibodies. This is not the case with OptiMAL® as no immune response is required.

This evidence will better enable Fusion to propose the use of OptiMAL® for a wider range of targets, thereby broadening the accessible market and increasing revenue potential. The next steps are to test the antibodies in cell-based assays at the NCI, to evaluate their potential to become therapeutic drug candidates.

This latest finding provides further validation of OptiMAL® as a platform for the isolation of specific antibodies against proteins and peptides and places the Company on track for the commercial launch of OptiMAL® at the Antibody Engineering and Therapeutics conference in December 2025. Work continues within Fusion to further optimise and expand the OptiMAL® platform.

NCI, part of the US National Institutes of Health, is the US federal government's principal agency for cancer research and training. Pursuant to the Agreement, Fusion has provided NCI with access to OptiMAL® for use in the discovery of novel antibodies against targets selected by NCI. This Agreement is due to continue until November 2025, however, the NCI has asked to extend its use of the OptiMAL® platform for use against further targets in the coming years. Negotiations are underway to establish mutually agreeable terms for an extended agreement.

• Adrian Kinkaid, CEO of Fusion Antibodies plc, commented: "We are again delighted with the performance of the OptiMAL® platform providing very high affinity antibodies against peptides, a prevalent but challenging target class. The latest developments provide us with a more solid foundation with which to address a wider market and positions OptiMAL® as the potential front line discovery platform of choice for human therapeutic antibody discovery."