The invention provides manipulated adenovirus, i.e. a viral particle based on a manipulated adenovirus, for use as a medicament, especially for use in the treatment of tumours. The viral particle of the invention has the advantage of having a preference or specificity for tumour cells, yielding a preferred infection of tumour cells. The viral particle is based on adenovirus, especially type C, preferably serotype 2 (Ad2), more preferably serotype 5 (Ad5), in which the native entire fiber protein, and its coding sequence, respectively, is deleted and replaced by a fusion protein providing specificity for cell surface bound polysialic acid.
