The future of advanced prostate cancer treatment may involve combining ADCs with bispecific T-cell engagers. This strategy could use ADCs for a short duration to deliver a potent hit, followed by immunotherapy to achieve durable remission, potentially reducing toxicity and enabling earlier use.

T-cell receptor (TCR) therapies offer a significant advantage over monoclonal antibodies by targeting intracellular proteins. They recognize peptides presented on the cell surface, effectively unlocking 90% of the proteome and requiring far fewer target molecules (5-10 copies vs. 1000+) to kill a cancer cell.

A therapeutic approach called "T-cell engagers" or "BiTEs" uses engineered antibodies with two different heads. One side binds to a cancer cell, while the other binds to a nearby T-cell. This effectively brings the killer cell and the target together, leveraging the body's existing immune cells without genetic modification.

Over 99% of cancer-specific targets are proteins located inside the cell, making them invisible to traditional antibody therapies. DEC-Bio's platform leverages the peptide MHC system, which naturally presents fragments of these internal proteins on the cell surface. This effectively unlocks a vast new library of highly cancer-specific targets.

While targeting intracellular peptide-MHC complexes opens the entire proteome as potential cancer targets, the approach is limited by HLA restriction. This means a drug might only be applicable to 30-40% of patients, a major commercial and clinical drawback that complicates development despite the potential for exquisite specificity.

Companies like VIR are making progress with masked T-cell engagers that limit systemic toxicity like cytokine release syndrome (CRS). This approach, which concentrates efficacy at the tumor site, could be the key to unlocking the broad potential of T-cell engagers beyond hematologic malignancies into the much larger solid tumor market.

Many promising solid tumor antigens (e.g., PSMA, HER2) are also on normal tissues, making them too toxic for T-cell engagers. By using masks that are cleaved only in the tumor microenvironment, these "dirty" targets become viable, dramatically expanding the therapeutic landscape for solid cancers.

Intracellular tumor-exclusive proteins present on the cell surface as peptide-MHC complexes at low copy numbers and with high heterogeneity. By identifying multiple distinct tumor proteins that process into identical or highly similar peptides on the same HLA complex, a single bispecific binder can recognize multiple targets simultaneously, increasing effective copy numbers and preventing single-antigen escape without adding manufacturing complexity.

While immunotherapy was a massive leap forward, Dr. Saav Solanki states the next innovation frontier is combining it with newer modalities. Antibody-drug conjugates (ADCs) and T-cell engagers are being used to recruit the immune system into the tumor microenvironment, helping patients who don't respond to current immunotherapies.