Therapeutic efficacy of IL-2-loaded hydrogels in a mouse tumor model

Interleukin-2 (IL-2) is a highly effective anticancer drug if it is applied locally for 5 consecutive days. In most cases this requires 5 invasive treatments, which is not usually acceptable for either the patient or the clinician. For this reason we have developed dextran-based hydrogels from which the required amount of encapsulated IL-2 (1-4 x 10(6) IU of IL-2) is gradually released during 5-10 days. Initially IL-2-containing macroscopic cylinder-shaped gels (implants), and later IL-2-containing injectable microspheres, were developed. These preparations were characterized in vitro, and the therapeutic activity was tested in DBA/2 mice with SL2 lymphosarcoma. The therapy was given to mice with a large and extensively metastasized tumor load (at least 5% of the body weight). If 1-4 x 10(6) IU of IL-2 was slowly released from the hydrogels over a period of 5-10 days, the therapeutic effects were very good and comparable to the effects of free IL-2 injections for 5 consecutive days. In conclusion, dextran-based hydrogels are promising systems for the controlled release of IL-2.