Can masked biologics uncover new value by dialing down tox?

With promising clinical data reviving interest in masking technologies that conditionally activate biologics, the first drug classes poised to benefit are cancer therapies whose mechanisms have proven efficacious, but whose safety liabilities have limited use.

The goal of masking is to minimize side effects by curtailing a compound’s activity outside the tumor microenvironment. The strategy is particularly valuable for targets with expression on both tumor and healthy tissues, which creates liabilities for on-target, off-tumor toxicity...