After stimulation, dendritic cells (DCs) mature and migrate to draining lymph nodes to induce immune responses1. As such, autologous DCs generated ex vivo have been pulsed with tumour antigens and injected back into patients as immunotherapy. While DC vaccines have shown limited promise in the treatment of patients with advanced cancers2,3,4 including glioblastoma5,6,7, the factors dictating DC vaccine efficacy remain poorly understood. Here we show that pre-conditioning the vaccine site with a potent recall antigen such as tetanus/diphtheria (Td) toxoid can significantly improve the lymph node homing and efficacy of tumour-antigen-specific DCs. To assess the effect of vaccine site pre-conditioning in humans, we randomized patients with glioblastoma to pre-conditioning with either mature DCs8 or Td unilaterally before bilateral vaccination with DCs pulsed with Cytomegalovirus phosphoprotein 65 (pp65) RNA. We and other laboratories have shown that pp65 is expressed in more than 90% of glioblastoma specimens but not in surrounding normal brain9,10,11,12, providing an unparalleled opportunity to subvert this viral protein as a tumour-specific target. Patients given Td had enhanced DC migration bilaterally and significantly improved survival. In mice, Td pre-conditioning also enhanced bilateral DC migration and suppressed tumour growth in a manner dependent on the chemokine CCL3. Our clinical studies and corroborating investigations in mice suggest that pre-conditioning with a potent recall antigen may represent a viable strategy to improve anti-tumour immunotherapy.
The authors thank the staff who supported this study, including R. Schmittling, P. Norberg, W. Xie, P. Healy, D. Lally-Goss, S. McGehee-Norman, B. Perry, S. Snipes and R. Edward Coleman. This work was supported by grants from the National Institutes of Health (NIH) National Institute of Neurological Disorders and Stroke Specialized Program of Research Excellence in brain cancer (P50-CA108786, D.D.B. and J.H.S.) and SRC on Primary and Metastatic Tumors of the CNS (P50-NS20023, D.D.B. and J.H.S.) as well as NIH RO1 (R01-CA177476-01, J.H.S.; R01-NS067037, R01-CA134844, D.A.M.) and P01 (P01-CA154291-01A1, D.D.B. and J.H.S.) funding sources. Additional support is from the National Brain Tumor Society (D.A.M. and J.H.S.), the American Brain Tumor Association (D.A.M. and J.H.S.), Accelerate Brain Cancer Cure Foundation Young Investigator’s Award (D.A.M.), The Kinetics Foundation, (J.H.S.) Ben and Catherine Ivy Foundation (J.H.S.), and in part by Duke University’s Clinical & Translational Science Awards grant 1UL2 RR024128-01 from the National Institutes of Health National Center for Research Resources.