Compounds of formula (I) ##STR00001## wherein R1 to R4, X and A are as defined in the claims and pharmaceutically acceptable salts and esters thereof, are disclosed. The compounds of formula (I) possess utility as tissue-selective androgen receptor modulators (SARM) and are useful in hormonal therapy, e.g., in the treatment or prevention of male hypogonadism and age-related conditions such as andropause.