Anti-tumour compounds

The invention relates to quinazoline derivatives, or pharmaceutically-acceptable salts thereof, which possess anti-tumour activity; to processes for their manufacture; and to pharmaceutical compositions containing them. The invention provides a quinazoline of the formula:- wherein R 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 is hydrogen or (1-4C)alkyl; R includes hydrogen and (1-4C)alkyl; and Ar is optionally substituted phenylene or heterocyclene; or a pharmaceutically-acceptable salt or ester thereof.