PDCD1 and neoplasm: Furthermore, AAV vector-mediated IL-27 expression effectively inhibited tumor growth and extended mice survival when combined with GM-CSF vaccination and IL-27 transfer was also able to break anti-PD-1 resistance in tumor models that were not responding to anti-PD-1 monotherapy, but led to highly reduced tumor growth and even complete rejection when combined with anti-PD-1 treatment.