Robust human regulatory T cell expansion with fusion proteins HCW9302 and HCW9213 circumvents need for magnetic-bead or feeder cell approaches for adoptive cell therapy

Abstract

Abstract Regulatory T cells (CD4+CD25+FoxP3+) (Tregs) are a subset of CD4 T cells that suppress the activities of other immune cells and have applications in the treatment of autoimmune and inflammatory diseases. Their use as an adoptive cell therapy has been limited by the practicality of expanding and purifying clinically sufficient numbers of cells. HCW9213 and HCW9302 are fusion proteins based on HCW Biologics’ TOBI™ technology platform, consisting of anti-CD3/anti-CD28 antibody domains and IL-2 domains, respectively. When used in combination, these fusion proteins were capable of expanding human Treg cells in vitro without the use of anti-CD3/CD28 magnetic beads and/or feeder cells, improving the overall yield, process efficiency and overcoming regulatory hurdles in manufacturing. Tregs generated with these molecules displayed similar phenotypes and suppressive cytokine production as Tregs expanded with recombinant human IL-2. Using a proprietary anti-CD39 antibody to isolate CD39+ Tregs, we have also been able to generate a Treg population with twice the suppressive activity against CD4+ T responder cells as traditional CD4+CD25+CD127lo Tregs. Thus, using its novel fusion proteins, HCW Biologics has been able to develop a superior Treg cell product ideal for the use in adoptive cell transfer. Additionally, this Treg platform can potentially be further optimized with addition of disease-targeted chimeric antigen receptors (CAR).