T-cell-engaging multispecific antibodies can redirect T cells toward tumors and have delivered substantial clinical benefit in blood cancers, but their use in solid tumors remains limited by a narrow therapeutic window: excessive CD3 activation can trigger cytokine release, off-tumor toxicity and rapid T-cell exhaustion. A research team at South China University of Technology, led by Jun Wang and Song Shen, has developed a modular nano-adaptor approach that provides an additional way to control this activation without changing the intrinsic affinity of the anti-CD3 antibody.
The study uses an Fc-binding nano-adaptor to assemble antibodies on a common particle scaffold. By varying the stoichiometric fraction of anti-CD3 while maintaining comparable total antibody loading and tumor-targeting capacity, the researchers could tune the effective level of anti-CD3 displayed on the particle surface. Lower presentation reduced nonspecific cytotoxicity and exhaustion-associated phenotypes while preserving tumor-directed killing in the tested co-culture systems.
The team then fixed the anti-CD3 fraction at an activation-optimized baseline of 1% and built a combinatorial library on a PD-L1/CD3 backbone. Fourteen immunoregulatory antibodies covering checkpoint blockade, costimulatory signaling and innate immune modulation were paired in all non-redundant two-antibody combinations, yielding 91 tetraspecific nanoantibody configurations.
Two representative lead designs, αPD-L1/CD3/PD1/KIR and αPD-L1/CD3/PD1/4-1BB, consistently ranked strongest in the screening assays. Further experiments indicated that a lead nanoantibody (αPD-L1/CD3/PD1/4-1BB) increased effector–target association and activation-related signals compared with selected lower-order or free-antibody controls.
In PBMC-humanized mouse tumor models, the screening-identified formulations inhibited tumor growth and increased markers associated with intratumoral cytotoxic immunity. In one humanized model, a lead candidate outperformed the clinically used anti-PD-1 antibody toripalimab, raising intratumoral human immune-cell infiltration from 1.67% in the free-antibody group to 7.28%. Body weight and the measured safety indicators remained favorable under the tested dosing conditions. The findings support anti-CD3 surface presentation as a complementary design parameter to antibody affinity.
The researchers note that the platform converts multispecific nanoantibody optimization into a quantitative and scalable assembly problem. Future studies will need to define context-dependent presentation ranges in patient-derived models and assess longer-term safety and therapeutic performance.
Science Bulletin
Experimental study