This study investigates the combination of tumor lysate-pulsed autologous dendritic cells (DCs) vaccination to maximal safe resection with radiotherapy on patients diagnosed with Glioblastoma to improve patients survival. The findings suggest that the combination of f tumor lysate-pulsed autologous DCs vaccination to tumor resection and combined radio-chemotherapy is safe and feasible.
Thirty-two newly diagnosed patients GBM with a median age of 61 years (range 42–70) who were candidates to complete or near complete resection received autologous dendritic cells (DCs) vaccination. Eligible patients should have not received previous treatment with chemotherapy nor radiotherapy, and resection surgery with less than 1 cm3 residual tumor.
Fresh tumor was sent from the operating room to the Cell Therapy Laboratory. Tumor single-cell suspensions were obtained by mechanical disaggregation and then frozen and stored. Tumor lysate was obtained through four cycles of thawing and freezing and then irradiated and stored at −20 °C.
Seven days after dexamethasone termination, peripheral blood mononuclear cells were collected by leukapheresis. CD14+ cells were selected by immunomagnetic separation using a CliniMacsTM , following manufacturer’s instruction. These cells were cultured at 2 × 106 cells/ ml in AIM-V supplemented with antibiotics, 1000 UI/ml of IL-4 and 1000 UI/ml GM-CSF in culture bags at 37 °C in a humidified incubator. IL-4 (500 UI/ ml) and GM-CSF (500 UI/ml) were further added to the medium on the 4th day and cultured cells were harvested on the 7th day.
These immature DC were adjusted at 107 cells/ml and pulsed with autologous tumor lysate during 2h at 37°C and 5% CO2. At that time, to induce DC maturation, 50 ng/ml of TNF-α, 1000 UI/ml of IFN-α and 20 ng/ml Poli I:C were added to the medium and cells were placed in culture bags at 2 × 106 cells/ml. Mature DC were harvested on the 8th day and frozen in aliquots following standard procedures until use.
Briefly, the cells were resuspended in RPMI-1640 complete medium + 50 ml of 10% FCS + 5 ml of L-Glutamine 200 mM + 5 ml Pen/Strep solution at twice the desired cryopreservation concentration. The cryopreservation solution was prepared containing 40% complete RPMI- 1640, 40% FCS and 20% DMSO. The cryopreservation vials were placed in the cryopreservation box and 500 microliters of the cell suspension were added to each vial; then 500 μl of the cryopreservation solution were added and the final suspension was carefully mixed. The cryopreservation box was brought to a −80 °C freezer and after 24 h the cell vials were stored in a liquid nitrogen tank. Ten million cells were considered the optimal dose for each administration. The viability of cells was determined before and after freezing.
All patients were scheduled to receive postoperative intensity modulated radiotherapy with concomitant temozolomide (TMZ) (75 mg/m2/day), followed by up to 12 cycles of adjuvant TMZ (200 mg/m2/day for 5 consecutive days every 28 days) or until disease progression. The first intradermal DCs administrations were scheduled prior to radiotherapy, and the second 3 weeks after radiotherapy. This was followed by two monthly, four bi-monthly, and subsequent quarterly administrations until the end of all available doses. During adjuvant TMZ treatment, DC were administered on day 21 of the corresponding cycle. Vaccines were administered intradermally, with patients receiving, on average, 8 vaccines.
Median PFS was 12.7 months and median OS was 23.4 months. Increase in post-vaccination tumour specific immune response after vaccines (proliferation or cytokine production) was detected in 11/27 evaluated patients (27 patients screened for the clinical trial and 5 treated as compassionate use before the clinical trial). No severe adverse effects related to immunotherapy were registered.
The addition of tumor lysate-pulsed autologous DCs vaccination to tumor resection and combined radio-chemotherapy is feasible and safe. A multicenter randomized clinical trial is warranted to evaluate the potential survival benefit of this therapeutic approach.