Compounds of formula (1) are described wherein R represents a --CONHOH, carboxyl, carboxyl ester, or --P(O)(X.sup.1 R.sup.8)X.sup.2 R.sup.9, where X.sup.1 and X.sup.2 are the same or different and each is oxygen or sulphur, R.sup.8 and R.sup.9 are the same or different and each represents hydrogen or an optionally substituted alkyl, aryl or aralkylthioalkyl group; R.sup.2 represents an optionally substituted alkyl, alkenyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, aralkoxy, or aralkylthio group, or an amino, substituted amino, carboxyl, or carboxyl ester group; R.sup.3 represents hydrogen or alkyl; R.sup.4 represents hydrogen or alkyl; R.sup.5 represents an optionally substituted alkyl or alkenyl group optionally interrupted by one or more --O-- or --S-- atoms or --N(R.sup.7)-- groups, where R.sup.7 is a hydrogen atom or a C.sub.1-6 alkyl group, or --(Alk).sub.n R.sup.6 where Alk is an alkyl or alkenyl group optionally interrupted by one or more --O-- or --S-- atoms or --N(R.sup.7)-- groups, n is zero or 1, and R.sup.6 is an optionally substituted cycloalkyl or cycloalkenyl group; X represents --NR.sup.10 R.sup.11 where R.sup.10 is hydrogen or an optionally substituted alkyl, alkanoyl, aryl, aroyl, aralkyl or aralkanoyl group, and R.sup.11 is a straight or branched alkylaminosulphonylamino group wherein the alkyl portion is optionally interrupted by one or more --O-- or --S-- atoms of --N(R.sup.7)-- or aminocarbonyloxy groups; or the salts, solvates and hydrates thereof. The compounds are metalloproteinase inhibitors and in particular have a selective inhibitory action against gelatinase and are useful in the treatment of cancer to control tumor metastasis.