Cancer immunotherapy by fusions of dendritic and tumour cells and rh-IL-12

Vaccination with fusion cells (FCs) comprising dendritic cells and tumour cells as well as administration of interleukin-12 (IL-12) showed a significant therapeutic effect against established tumours in mouse experimental models. We conducted immunotherapy against various malignant tumours using the FCs and rhIL-12, and investigated the safety and efficacy of the therapy.

Patients' DCs were mixed with autologous irradiated tumour cells and treated with 50% polyethylene glycol to generate FCs. The FCs were inoculated intradermally, and then 30 ng kg(-1) of rhIL-12 was injected at the same sites 2 and 6 days later. This process was carried out as one cycle, and three of these cycles were repeated at 1-week intervals to comprise one course. After completing the course, its safety and therapeutic effects were estimated.

The most frequently observed adverse event was fever, observed in 26% of patients in the first cycle. Decrease in white blood cell and an increase in serum ALT were observed in 28% and 25%, respectively. Three out of 12 patients with a malignant brain tumour (25%) achieved a partial response (PR), but other patients with a malignant tumour showed no regression of their tumours. Thirteen out of 16 patients with a brain tumour (81%) showed cutaneous delayed hypersensitivity responses. However, only one of 16 patients (6%) with a malignant tumour other than a brain tumour developed such responses.

Immunotherapy using a FC vaccine and rhIL-12 induced no serious adverse reactions, and provided good therapeutic responses in some of the patients with a brain tumour.