A ceramic system for delivering interleukin-2

Interleukin-2 (IL-2) is a potentially effective cytokine to be used for cancer treatment. Since keeping IL-2 doses at a low, continuous level is important to avoid side effects which accompany high IL-2 doses, a ceramic which release IL-2 could prove to be a beneficial method of drug delivery for cancer patients [1]. In vitro studies were performed to determine the optimal hydroxyapatite (HA) to IL-2 ratio for continuous release of IL-2 from HA using both a matrix and insert ceramic pellet. In the matrix pellet experiment, HA to IL-2 ratios of 25:1, 50:1 and 100:1 were tested by compressing a homogenous mixture of each variable in triplicate and placing each ceramic in 2.5 mL simulated body fluid (SBF) at 37 degrees C. The fluid was collected and replaced for each ceramic every two hours for 12 hours and at 24 hours. The collected fluid was then assayed for IL-2 content. Pellets consisting of 25:1 ceramic to drug ratio delivered almost the entire amount of IL-2 at the fastest rate. Composites of 100:1 IL-2 to HA delivered the least amount of IL-2 at the slowest rate. Release of IL-2 from the 50:1 ratio pellets was intermediate with respect to speed and amount of delivery. In the insert pellet experiment, similar laboratory procedures were used to show that 100:1 ratio insert pellets delivered IL-2 at a slower rate and in lesser amounts than 50:1 ratio insert pellets. Results of this study show that HA can deliver IL-2 at different rates by varying the ratio of HA to IL-2 in both matrix and insert ceramic pellets.