Positioning TGN-S15 as Synergistic With Keytruda in HPV-Induced Cancers

In the final part of her conversation with Pharmaceutical Executive, Sandra Coufal, MD, CEO of Toragen, explains why her company is not positioning TGN-S15 against Keytruda, but in combination with it.

The logic begins with mechanism. Keytruda and other checkpoint inhibitors work by stimulating immune cells to be more active. TGN-S15 works upstream: by inhibiting the HPV E5 protein, it restores the infected cell’s ability to display viral protein fragments on its surface, effectively uncloaking the infection to the immune system. When paired with Keytruda, the two drugs address complementary steps in the same immune response: Toragen’s drug reveals the target, Keytruda activates the attack.

This synergistic rationale drove the two-part structure of Toragen’s Phase 1 trial, with monotherapy in Part 1 and combination therapy in Part 2. Because TGN-S15 is a small molecule and Keytruda is a biologic, there is no chemical interaction between them, enabling co-administration without formulation complexity.

With Keytruda’s patent expiring in 2028 and its current overall response rate in HPV cancers sitting at just 15%, Coufal sees a clear and achievable bar: double it. The goal is not to replace the standard of care, but to make it dramatically more effective.