The administration of high dose continuous infusion Interleukin-2 is able to elicit cytolysis of cancer cells by lymphocytes, predominantly CD56 positive natural killer cells. These Lymphokine Activated Killer cells (LAK) are able to lyse natural killer cell-resistant tumor cells in vitro and renal cancer cells in vivo (Ellis et al. 1988; McMannis et al. 1988; Weil-Hillman et al. 1989; Horton et al. 1990; Dillman et al. 1993). Moderate to high-dose infusional Interleukin-2 (9–18 MIU/m2 /24 h × 72–120 h) yields tumor response rates of up to 26% (Foon et al. 1992; Dillman et al. 1993). Importantly, complete responses have been seen. Numerous trials have sought to increase the response rate for patients with kidney cancer. These have included devising regimens with other immunologic agents and/or cultured effector cells (Sosman et al. 1988; Kradin et al. 1989; Dillman et al. 1991; Figlin et al. 1999). None of these approaches appear to improve response rates compared to Interleukin-2 alone.
The antihistamine famotidine is an agent which may augment the antitumor abililty of lymphocytes. Tsunoda et al. (1992) described that in the presence of famotidine, lymphocytes displayed significantly enhanced uptake of radiolabelled Interleukin-2, resulting in higher tumor cell cytotoxicity by LAK and other tumor infiltrating lymphocytes. The dose of famotidine required for this effect corresponds to a clinically achievable dose. Other investigators have described greater infiltration of cancers in patients treated with famotidine preoperatively (Parshad et al. 2002). For these reasons, the combination of high-dose infusional Interleukin-2 with famotidine has been explored in patients with metastatic kidney cancer (Quan et al. 2004, 2006). With this regimen, we have seen activity in this disease including patients who are now disease-free.