In September, Avacta Life Sciences began shipping Affimers from its online catalog, following shipment of its custom line over the summer. Affimers are small proteins engineered as alternatives to antibodies. Priced comparably to antibodies, 40 are currently available through Avacta’s website.

Alastair Smith, PhD, chief executive of Avacta, told IBO, “Affimers are not restricted in their market segment or application, so in principle we can address a very wide range. We have decided to focus (mainly) on gaps in the antibody market.” He named cases in which generation of monoclonal antibodies is difficult or infeasible, such as against toxic targets or highly conserved proteins. “Clearly, those areas where antibodies struggle will be ripe for new science with Affimers,” he added. Dr. Smith commented that live-cell imaging and immunohistochemistry are two such applications. Affimers are based on protease inhibitors and thus can hold up in conditions, such as low pH and high temperature, than antibodies cannot. In addition, their small size allows them to permeate some membranes in cells.

According Dr. Smith, the most common reason cited for ordering custom Affimers has been the time required to produce them—seven weeks, as opposed to 7–12 months for monoclonal antibodies. Other reasons he provided, which also apply to those from the catalog, include high specificity, higher packing density compared to antibodies and robustness.

While the company is currently focusing on Affimers as research reagents, Dr. Smith indicated that Avacta will be working toward their use in therapeutic applications.