Abstract: The invention relates to a quinoline of the formula: ##STR1## wherein each of R.sup.1 and R.sup.2, which may be the same or different, is hydrogen, halogeno, hydroxy, cyano, carbamoyl, nitro or amino, alkyl, alkoxy, alkylthio, alkylamino, dialkylamino or alkanoylamino each of up to 4 carbon atoms, or substituted alkyl or alkoxy each of up to 3 carbon atoms, provided that both R.sup.1 and R.sup.2 are not hydrogen; the quinoline ring may bear further substituents; R.sup.3 is hydrogen or alkyl of up to 4 carbon atoms; R.sup.4 is hydrogen, alkyl, alkenyl or alkynyl each of up to 4 carbon atoms or substituted alkyl of up to 3 carbon atoms; Ar is phenylene, naphthylene or heterocyclene which is unsubstituted or which bears one or more substituents; R.sup.5 is such that R.sup.5 --NH.sub.2 is an amino acid; or a pharmaceutically-acceptable salt or ester thereof. The compounds possess anti-tumor activity.