The present invention relates to an oncolytic viral vector comprising a nucleic acid sequence encoding an anti-interleukin 8 neutralizing antibody.Further, the present invention relates to use of interleukin 8 as a prognostic and predictive biomarkerin oncolytic immunotherapy. In this respect, the present invention is directed to a method ofanalysing whether a subject suffering from a cancer is responsive or non-responsive to the treatment with an oncolytic viral vectorand to a method of monitoringefficacy of an oncolytic immunotherapy.