CD40L-transfected myeloma cells transfer prolonged immunity in vivo.

Background: In a large number of patients with multiple myeloma, chemotherapy is the only therapeutic option. During recent years, major effort has been put into immunotherapeutic approaches for this malignancy. Materials and Methods: In this study, wild-type (wt) myeloma cells (5x10(5)) were injected subcutaneously into Balb/c mice. CD40L-transfected myeloma cells (5x10(5)) were subsequently injected intratumorally into the established (>100 mm(3)) wt tumor nodules. Overall survival and tumor growth were measured. Results: Out of eight animals receiving wt tumor cells, one died prior to the formation of a solid tumor nodule. Following the CD40L-transfected myeloma cell injection, stable complete remission at day 60 with all the animals surviving resulted. On day 60, a re-challenge was performed with wt myeloma cells. No tumor growth was observed after 120 days out of seven remaining animals, one died. Conclusion: Intratumoral injection of CD40L-transfected myeloma cells induces complete tumor remission and long lasting immunity against tumor recurrence.