Disclosed herein are methods for treating solid mass tumors with direct delivery of an anti-tumor immunotherapeutic agent to the tumor site. In one aspect, this invention encompasses methods of treating solid mass tumors by direct microinjection via a microcatheter of an anti-tumor immunotherapeutic agent into the microvasculature leading into tumor thereby providing high levels of contact with the tumor while minimizing the degree of systemic buildup of the immunotherapeutic agent.
