MRK-560 is an orally active, brain barrier-penetrating γ-Secretase inhibitor, can potently reduce Aβ peptide in rat brain and cerebrospinal fluid. MRK-560 also decreases mutant NOTCH1 processing by selectively inhibiting PSEN1 . MRK-560 can be used in studies of Alzheimer's disease and T-cell acute lymphoblastic leukaemia (T-ALL) .