Protein-based therapeutics, such
as monoclonal antibodies
and cytokines,
are important therapies for various pathophysiological conditions
such as oncology, autoimmune disorders, and viral infections. However,
the wide application of such protein therapeutics is often hindered
by dose-limiting toxicities and adverse effects, namely, cytokine
storm syndrome, organ failure, and others. Therefore, spatiotemporal
control of the activities of these proteins is crucial to further
expand their application. Here, we report the design and application
of small-molecule-controlled switchable protein therapeutics by taking
advantage of a previously engineered OFF-switch system. We used the
Rosetta modeling suite to computationally optimize the affinity between
B-cell lymphoma 2 (Bcl-2) protein and a previously developed computationally
designed protein partner (LD3) to obtain a fast and efficient heterodimer
disruption upon the addition of a competing drug (Venetoclax). The
incorporation of the engineered OFF-switch system into anti-CTLA4,
anti-HER2 antibodies, or an Fc-fused IL-15 cytokine demonstrated an
efficient disruption in vitro, as well as fast clearance in vivo upon
the addition of the competing drug Venetoclax. These results provide
a proof-of-concept for the rational design of controllable biologics
by introducing a drug-induced OFF-switch into existing protein-based
therapeutics.