Concurrent dendritic cell vaccine and strontium-89 radiation therapy in the management of multiple bone metastases

In addition to its direct cytotoxic effects, radiation therapy renders tumor cells more susceptible to T cell-mediated cytotoxicity by modulating cell surface molecules involved in antigen presentation. The purpose of the present study was to determine the benefit of combined 89Sr radiation and dendritic cell (DC) vaccine therapy in bone metastasis patients.

Patients were treated with intravenous 89Sr at a dose of 40 μCi/kg of body weight on the first day after the peripheral blood mononuclear cell collection. Seven days later, patients received DCs once a week for 6 weeks. The first three vaccines were administered by intravenous infusion, and the last three vaccines were administered by 24-point intradermal injection. Clinical response was evaluated by the number of bone metastatic foci demonstrated on bone scintigraphy; cell-mediated cytotoxicity response was evaluated by delayed-type hypersensitivity (DTH) reaction. All treatment-related toxicities including vaccine-induced fever and 89Sr-associated hematological toxicity were carefully monitored.

Twenty-six patients with histologically diagnosed with primary cancers and multiple bone metastases demonstrated on bone scintigraphy were studied. The overall survival rate was 58.3%. The total positive DTH rate was 50%. The efficiency rate for pain relief was 60% (6/10), for quantity of life was 80%, and for clinic responses was 90%. Out of 10 cases, the Grade 1 or 2 of hematological depression in 4, erythema in 1, and fever in 7 were observed.

The study has important implications for that combined 89Sr radiation, and DC vaccine therapy can benefit cancer patients with bone metastasis.