6 research outputs found
Increased peptide contacts govern high affinity binding of a modified TCR whilst maintaining a native pMHC docking mode
NaturalT cell receptors (TCRs) generally bind to their cognate pMHC molecules with weak
affinity and fast kinetics, limiting their use as therapeutic agents. Using phage display, we
have engineered a high affinity version of the A6 wild-type TCR (A6wt), specific for the
human leukocyte antigen (HLA-A�0201) complexed with human T cell lymphotropic virus
type 111–19 peptide (A2-Tax). Mutations in just 4 residues in the CDR3b loop region of the
A6wt TCR were selected that improved binding to A2-Tax by nearly 1000-fold. Biophysical
measurements of this mutant TCR (A6c134) demonstrated that the enhanced binding
was derived through favorable enthalpy and a slower off-rate. The structure of the free
A6c134 TCR and the A6c134/A2-Tax complex revealed a native binding mode, similar to
the A6wt/A2-Tax complex. However, concordant with the more favorable binding enthalpy,
the A6c134TCR made increased contacts with theTax peptide compared with the A6wt/A2-
Tax complex, demonstrating a peptide-focused mechanism for the enhanced affinity that
directly involved the mutated residues in the A6c134TCR CDR3b loop.This peptide-focused
enhancedTCR binding may represent an important approach for developing antigen specific
high affinity TCR reagents for use in T cell based therapies
Myosin VIIA is specifically associated with calmodulin and microtubule-associated protein-2B (MAP-2B)
Myosin VIIA is specifically associated with calmodulin and microtubule-associated protein-2B (MAP-2B)
Monoclonal TCR-redirected tumor cell killing
T cell immunity can potentially eradicate malignant cells and lead to clinical remission in a minority of patients with cancer. In the majority of these individuals, however, there is a failure of the specific T cell receptor (TCR)–mediated immune recognition and activation process. Here we describe the engineering and characterization of new reagents termed immune-mobilizing monoclonal TCRs against cancer (ImmTACs). Four such ImmTACs, each comprising a distinct tumor-associated epitope-specific monoclonal TCR with picomolar affinity fused to a humanized cluster of differentiation 3 (CD3)-specific single-chain antibody fragment (scFv), effectively redirected T cells to kill cancer cells expressing extremely low surface epitope densities. Furthermore, these reagents potently suppressed tumor growth in vivo. Thus, ImmTACs overcome immune tolerance to cancer and represent a new approach to tumor immunotherapy