Phase II clinical study using tumor extract loaded IL-12 positive dendritic cells in patients with metastatic ovarian cancer. Free

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A GMP-conform dendritic cell (CD) production unit has been established and DC efficacy was tested in a clinical study. Blood monocyte derived DC were generated via leukopheresis followed by apheresis. Between 1,5-6 x 10⁹ (mean 2,1 x 10⁹) monocytes with a purity between 80 and 98% (mean=93%) were included. Monocytes are further enriched by adherence revealing >98% anti- CD14/16 reactive cells. DC were cultured for 7d in the presence of hrIL-4 and hrGM-CSF. Antigen pulsing was performed under serum free conditions without growth factors using tumor extract. Tumor extract was generated using corresponding areas of pure tumor according to the pathologist. Tumor tissue has been treated by a defined heat shock therapy before it was frozen for the first time. Extract derived proteins were labelled with KLH by co-incubation. Antigen pulsed DC were further maturated using the combination of LPS and hr-interferon-gamma according the protocol of Felzmann T et al.. The number of harvested dendritic cells ranged between 100 and 500 x 10⁶ DC. Cells were divided into 12 equal aliquots and were frozen until use for quality control or vaccination. The quality control of DC includes beside sterility tests, extensive phenotypic characterization, functional testing using autologous and allogeneic responder T-cells and IL-12 production. Culture conditions and lymphokine concentrations as well as the ideal time point of harvest were established according to the amount of IL-12 released into the supernatant. So far a total of 15 patients with metastatic ovarian cancer have been treated over a time period of 12 months (mean 8 months). Vaccination was performed 3-weekly, ultra sound guided into the loco-regional lymph node 9 times. Of the 15 patients included into the study one died immediately after start of therapy. One patient shows a partial remission and no signs of PD disease after 9 months. Of the remaining 13 patients 5 patients had SD and 6 patients revealed slowly PD with repeated longer periods of SD. 2 patients showed PD. No severe side effects were observed except flu-like symptoms. Interestingly, a significant improvement of the Kanovsky index could be demonstrated. None of the patients revealed a significant drop in tumor maker values but the curve of increase was impressively flattened. Due to the small number of patients no statistical evaluation was performed. Of the immunologic follow-up parameters analyzed none revealed a drastic change. Cellular composition, activation marker expression and TCR-Vβ usage was rather constant. Finally, IL-12 strongly positive DC can be generated by using adequate culture and maturation procedures.