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First-generation bispecific T cell engagers (BTEs) have shown promise in preclinical models but often suffer from a short plasma half-life due to their small size and absence of an Fc domain. Additionally, limited tumor retention can lower local therapeutic concentrations and impede efficacy. Cancer cells can even adapt and evade immune targeting through antigen heterogeneity and loss, threatening sustained responses. The immunosuppressive tumor microenvironment further hinders T cell function and promotes therapeutic resistance. To develop an effective strategy, any cell engager must overcome these barriers to achieve robust, consistent targeting and immune activation.
Case study
A team led by David Weiner, PhD have examined how format-tuning bispecific T cell engagers (BTEs) boosts therapeutic efficacy against clear cell renal cell carcinoma (ccRCC). Using a novel persistent multivalent T cell engager (PMTE) to enhance cell avidity and tumor targeting, they tackle challenges like low plasma half-life, poor tumor retention, and antigen escape. Optimizing cell interactions through avidity-driven design offers a pathway to more effective, durable cancer therapies and renewed hope for advanced ccRCC patients.
Binding correlated with in vivo tumor cell-killing efficacy. Comparing the three BTE formats shows a significant delay in tumor volume increase between BTE, PBTE and PMTE. Data adapted from O’Connell et al. (CC-BY-NC)
Cell avidity curves represent the % of target cells bound with rising detachment force measured at 30 nM, 3 nM and 300 pM antibody concentration. Area-under-curve quantifications indicate the significant differences in cell avidity between PBTE and PMTE at relevant concentrations. Adapted from: O’Connell et al. (CC-BY-NC)
This study compared three BTE formats. Left: single-chain “BTE” with a tumor-targeting aCA9 linked to the T cell-targeting aCD3. Center: second-generation PBTE which reintroduces an Fc domain. Right: PMTE format which adds another tumor-targeting aCA9 part.