Abstract: The invention relates to quinazoline derivatives or pharceutically-acceptable salts thereof, which possess anti-tumor activity; to processes for their manufacture; and to pharmaceutical compositions containing them.The invention provides a quinazoline of the formula: ##STR1## wherein R.sup.1 is (1-4C)alkyl; the quinazoline ring may optionally bear one or two further substituents selected from halogeno, (1-4C)alkyl and (1-4C)alkoxy;R.sup.2 is hydrogen or (1-4C)alkyl;R.sup.3 includes hydrogen and (1-4C)alkyl; andAr is optionally substituted phenylene or heterocyclene;or a pharmaceutically-acceptable salt or ester thereof.