Cytokine and immuno-gene therapy for solid tumors.

Despite recent progress in our understanding of cancer biology and in many areas of cancer treatment, the success rate for cancer therapy remains dismal. Immunotherapy for cancer has long been an exciting field for many cancer researchers due to the possibility to mobilize the body's own immune system to eradicate cancer not only locally but also systemically. Since its initial discovery, cytokine-based immunotherapy has been vigorously and extensively investigated for cancer treatment due to the perception of it as a relatively easily purifiable, injectable form of cancer treatment agent. However, so far most cytokine-based therapy trials have fallen short of expectations. One of main obstacles is the difficulty to achieve therapeutically relevant dosage in patients without generating excessive normal tissue toxicity. The emergence of novel gene therapy approach to deliver therapeutic cytokine to tumors locally generated great excitement since it has the potential of generating sustained high local concentration of immunostimulatory cytokine without raising the systemic levels of the cytokines, which is responsible for most of the observed toxicity. In this review, we will attempt to provide an overview of the field and discuss some of the problems associated with cytokine-based immuno-gene therapy and potential solutions.