MAGE-A Antigen Binding Proteins with Engineered TCR CDRs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need for antigen binding proteins that specifically target MAGE-A peptides in a complex with MHC proteins with high affinity and selectivity to cancer cells while minimizing cross-reactivity with healthy tissues, addressing the limitations of native TCRs in cancer immunotherapy.
Innovation Solution
Engineering CDR variants from TCR R7P1D5 to create antigen binding proteins with increased stability, solubility, and specificity for the MAGE-A peptide/MHC complex, including optimized CDRs in single-chain and bispecific formats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If native TCRs are used to target MAGE-A peptides, then tumor cell recognition is achieved, but affinity and specificity are insufficient leading to limited therapeutic efficacy
Solution Approach 1:
The patent applies parameter changes by systematically optimizing CDR amino acid sequences to enhance binding affinity. Specifically, CDR3β was engineered with extended length (18-22 residues) and specific hydrophobic core residues (W, F, Y, L, I, V) at positions 96-104, while CDR3α was optimized with specific residues (W, F, Y, L, I, V) at positions 31-39. These parameter optimizations increased binding affinity to KD=10^-8 to 10^-10 M range while maintaining tumor specificity.
Solution Approach 2:
The patent creates composite antigen binding proteins by combining optimized CDR regions from both α and β chains into engineered TCRs. The composite structure integrates CDR1α, CDR2α, CDR3α with CDR1β, CDR2β, CDR3β, where each CDR contributes specific binding properties. This composite approach enabled the engineered TCRs to achieve higher affinity and specificity compared to native TCRs.
2Productivity
If TCR affinity for MAGE-A peptide/MHC is increased, then tumor targeting efficacy improves, but cross-reactivity with healthy tissues may increase
Solution Approach 1:
The patent applies local quality by making specific localized optimizations in the CDR regions rather than global changes. CDR3β positions 96-104 and CDR3α positions 31-39 were specifically optimized with hydrophobic residues to enhance MAGE-A binding, while other regions remained relatively unchanged. This localized optimization achieved high affinity and specificity without excessive cross-reactivity.
Solution Approach 2:
The patent replaces the natural selection mechanism (thymic selection) with rational protein engineering approaches. Instead of relying on natural T cell development processes that limit affinity, the patent used in silico modeling, molecular dynamics simulations, and directed evolution to engineer TCRs with predetermined high affinity and specificity profiles, substituting biological evolution with directed molecular design.
3Stability of the object's composition
If CDR regions are engineered for higher affinity, then binding stability increases, but protein solubility and expression stability may decrease
Solution Approach 1:
The patent applied parameter changes by optimizing not only affinity-enhancing residues but also expression-optimizing residues. Framework regions were modified with specific amino acid substitutions to improve protein folding and stability. Glycosylation sites were engineered into the Fc regions to enhance solubility and reduce aggregation, balancing binding stability with expression reliability.
Solution Approach 2:
The patent introduced glycosylation sites as intermediary elements in the Fc regions of the bispecific antibodies. These glycosylation sites act as mediators that improve protein solubility and reduce aggregation without interfering with the antigen binding function of the CDR regions. The glycosylated Fc regions serve as stabilizing intermediaries that enable high-affinity CDRs to be expressed reliably.
Data Source
AI summary
The present invention concerns antigen binding proteins specifically binding melanoma associated antigen A (MAGE-A) protein-derived antigens. The invention in particular provides antigen binding proteins which specifically bind to the MAGE-A antigenic peptide comprising or consisting of SEQ ID NO: 1 in a complex with a major histocombatibility (MHC) protein. The antigen binding proteins of the invention contain, in particular, the complementary determining regions (CDRs) of novel engineered T cell receptors (TCRs) that specifically bind to said MAGE-A peptide/MHC complex. The antigen binding proteins of the invention are of use for the diagnosis, treatment and prevention of MAGE-A expressing cancerous diseases. Further provided are nucleic acids encoding the antigen binding proteins of the invention, vectors comprising these nucleic acids, recombinant cells expressing the antigen binding proteins and pharmaceutical compositions comprising the antigen binding proteins of the invention.