Affimer Therapeutic Platform Development Milestone Achieved

Important multi-Affimer formats can be manufactured easily and with high yields


Avacta Group plc (AIM: AVCT), the developer of Affimer® biotherapeutics and research reagents, announces that a range of multimeric Affimer constructs central to its immuno-oncology programme have been successfully generated and manufactured with excellent production yields in simple production systems.

The ability to produce a biotherapeutic efficiently during early development and for clinical trials is an essential attribute that can make the difference between success and failure. Low manufacturing yields are a common problem with biotherapeutic platforms and can lead to significant delays in development because of lack of availability of material. In extreme cases, the inability to manufacture the therapeutic product can end a development programme or limit its availability for patients once approved.

As set out by the Company during 2015, a critical milestone in the development of Affimer molecules as a therapeutic platform is the ease of production of clinically and commercially relevant therapeutic structures. These include monomers, dimers, trimers and larger multimers, fusions with other proteins and modification of the Affimer for PEGylation or drug conjugation. These larger therapeutic structures are central, for instance, to the high value immuno-oncology applications such as T-cell recruitment or multi-specific agonist/antagonist combination therapies on which the Company is focusing.

The Company has been carrying out a planned programme of work to generate a range of therapeutic Affimer structures and lab scale production tests to establish the production yields of these various product formats. The outcome of the tests has been excellent. Affimer dimers, trimers and even tetramers have been produced using simple production methods with no significant reduction in yield compared with the monomeric Affimer molecule which has yields that are five to ten times greater than the Company was targeting as being competitive with other protein scaffold therapeutic platforms.

Other important drug structures have also been demonstrated. Affimers have been formatted as so called fusion proteins, including “Fc fusions” which is a potentially important class of therapeutic molecule combining Affimers with part of an antibody. Surface modifications to the Affimer for half life extension and to allow drug conjugates to be formed have also been produced. Excellent production yields have been achieved for all of these different constructs.

Alastair Smith, Chief Executive Officer, commented:

“There are several key attributes that are needed to produce a good therapeutic protein platform. Of particular importance is the ability to generate multimeric product formats such as the bispecific oncology therapies recently reported by Ablynx and Molecular Partners. Critically, it is essential to be able to manufacture these products with high yield which is what we have demonstrated. The ease with which we have been able to produce a wide range of important multi-Affimer structures and fusion proteins is a strong validation of the Affimer platform and was an important pre-clinical milestone to be achieved. The data are very encouraging and bode well for our ongoing programme to develop best-in-class cancer immuno-therapies.”

Dr Amrik Basan, Chief Scientific Officer, added:

“In my extensive experience of developing therapeutic proteins, the production yields that we have achieved with Affimers, without the need to employ any complicated and expensive processes, are very good indeed making it possible to consider generating a wide range of powerful therapeutic molecules with the knowledge that they will be commercially viable. We have even been able to make tetrameric formats containing four Affimers which makes the Affimer technology highly competitive or superior to comparable therapeutic protein scaffold platforms that are currently in development.”