PIKTOR's Phase 2 endometrial readout will determine whether a 71% Phase 1b response rate in PI3K-mutant tumors translates to registrational-quality evidence

Faeth Therapeutics is a clinical-stage company developing an oral combination drug for PI3K-mutant endometrial cancer, which is not yet approved.

PIKTOR, an oral serabelisib/sapanisertib combination targeting the PI3K/AKT/mTOR pathway, is in Phase 2 for second-line PI3K-mutant advanced endometrial cancer and Phase 1b/2 for HR+/HER2- advanced breast cancer. The thesis resolves on whether Phase 2 topline endometrial data confirm the 71% Phase 1b response rate at a level sufficient to support regulatory advancement. The primary risks are competition from Iovance's lifileucel in the same platinum/PD-1-failed endometrial population and resistance emergence across dual mTOR/PI3K blockade, a known liability of this pathway class.