Curiously, rAAV clinical trials for cancer gene therapy applications to date have been relatively sparse when compared to the number of adenovirus-based cancer gene therapy trials (23 trials for rAAV vs. 436 trials for adenovirus) and are heavily focused on the use of rAAV to express the GM-CSF cytokine to induce an immune response against prostate cancer cells (Table 1) [23]. This evidence concerns the gene CSF2 and cancer.