Keytruda obstructs the PD-1 pathway to help keep Malignant growth cells from stowing away. Pembrolizumab Keytruda is a sort of Immunotherapy that works by Hindering. the PD-1 pathway and to help keep Malignant growth cells from covering up. Keytruda cost enables the Invulnerable Framework to do what it was intend to do. Distinguish and battle malignant growth cells.