Safe and Reproducible Preparation of Functional Dendritic Cells for Immunotherapy in Glioblastoma Patients

Cell therapy based on dendritic cells (DCs) pulsed with tumor lysate is a promising approach in addition to conventional therapy for the treatment of patients with glioblastoma (GB). The success of this approach strongly depends on the ability to generate high-quality, functionally mature DCs (mDCs), with a high level of standardization and in compliance with Good Manufacturing Practices. In the cell factory of the Carlo Besta Foundation, two phase I clinical trials on immunotherapy with tumor lysate-loaded DCs as treatment for GB are ongoing. From 2010 to 2014, 54 patients were enrolled in the studies and 54 batches of DCs were prepared. We retrospectively analyzed the results of the quality control tests carried out on each produced batch, evaluating yield of mDCs and their quality in terms of microbiological safety and immunological efficacy. The number of mDCs obtained allowed the treatment of all the enrolled patients. All 54 batches were sterile, conformed to acceptable endotoxin levels, and were free of Mycoplasma species and adventitious viruses. During culture, cells maintained a high percentage of viability (87%–98%), and all batches showed high viability after thawing (mean ± SD: 94.6% ± 2.9%). Phenotype evaluation of mDCs showed an evident upregulation of markers typical of DC maturation; mixed lymphocyte reaction tests for the functional evaluation of DCs demonstrated that all batches were able to induce lymphocyte responses. These results demonstrated that our protocol for DC preparation is highly reproducible and permits generation of large numbers of safe and functional DCs for in vivo use in immunotherapy approaches. Significance Cell therapy based on antigen-pulsed dendritic cells (DCs) is a promising approach for the treatment of glioblastoma patients. The success of this approach strongly depends on the ability to generate high-quality, functional DCs with a high level of standardization, ensuring reproducibility, efficacy, and safety of the final product. This article summarizes the results of the quality controls on 54 batches, to demonstrate the feasibility of producing a therapeutic cell-based vaccine via a well-controlled Good Manufacturing Practices (GMP)-compliant production process. The findings may be of scientific interest to those working in the field of preparation of GMP-compliant products for cell-therapy applications.