Tadalafil augmented immune response , increasing ex vivo T-cell expansion to a mean 2.4-fold increase compared with 1.1-fold in control patients ( P = 0.01 ) , reducing peripheral MDSC numbers to mean 0.81-fold change compared with a 1.26-fold change in control patients ( P = 0.001 ) , and increasing general immunity as measured by delayed type hypersensitivity response ( P = 0.002 ) .