Generation of immature autologous clinical grade dendritic cells for vaccination of cancer patients

Abstract

Dendritic cell (DC)-based vaccine is a promising approach for cancer therapy. Pioneer trials have been conducted using DC generated in research conditions. There is now a need for generating DC in clinical grade conditions, including the use of closed systems, avoidance ofFCS and respect of good manufacturing practices (GMP). DC were generated from 84 leukapheresis products of 27 cancer patients enrolled in two Phase I/II trials of vaccination of either MAGEþtumors (n = 24) or prostate cancer (n = 3). Monocytes were seeded in culture bags in a serum-free medium supplemented with IL-4 and GM-CSF. After a 7 day culture, DC were collected and most were pulsed with various MAGE-derivedpeptides. After a short leukapheresis (mean time: 66 min; mean processed blood: 5L), a mean of 6 × 10⁹ WBC were collected, from which 2.25 × 10⁹ were seeded. The culture procedure yielded a number of DC (mean: 62 × 10⁶ DC) harboring the expected phenotype of immature DC (CD1a⁺ CD14⁻ HLA-DR⁺ CD80⁺ CD86⁺ CD83⁻). This phenotype was not altered by peptide loading. These DC, either fresh or thawed, were functionally effective in vitro. Their s.c. and i.v. injections were devoid of any short-term side effect and associated with the induction of immune responses in the patients. Large numbers of functional immature clinical grade DC can be generated in a closed system from leukapheresis products in cancer patients. These results provide the basis for large-scale studies of cancer immunotherapy under improved safety conditions.