Impaired Interleukin-12 Production is Associated with a Defective Anti- Tumor Response in Colorectal Cancer Richard J. O'Hara, F.R.C.S.(Edinb.),* John Greenman, Ph.D.,* Philip J. Drew, F.R.C.S.(Edinb.),* Alistair W. McDonald, M.R.C.Path.,t Graeme S. Duthie, M.D.,* Peter W. R. Lee, M.D.,'* John R. T. Monson, M.D.'* From the University of Hull, *Academic Surgical Unit and the tDepartment of Histopathology, Castle Hill Hospital, Hull, East Yorkshire, United Kingdom INTRODUCTION: Despite development of many chemo- therapeutic regimens, colorectal cancer continues to have a high mortality. One of the major new potential therapies is interleukin-12, a heterodimcric cytokine produced by anti- gen presenting ceils. In vitro and in vivo studies have demonstrated the role of interleukin-12 in stimulating a cell-mediated anti-tumor response against a number of co- lon adenocarcinoma tumor models. However, it is un- known whether patients with colorectal cancer have im- paired interleukin-12 production. A study was performed to investigate production of interleukha-12 preoperatively and the relationship between these levels and disease stage at surgery. METHODS: Preoperative peripheral blood mono- nuclear cells from colorectal cancer patients and age- matched controls were stimulated by Staphylococcus au- reus Cowan's Strain 1 (0.0075 percent wt/vol) in vitro for 24 hours. Expression of interleukin-12 was then assessed by enzyme-linked immtmosorbent assay. A single pathologist assessed the tumors for stage according to TNM and Dukes classifications. RESULTS: Twenty-eight patients with colo- rectal cancer and 14 controls were recruited for the study. Interleukin-12 production was significantly impaired in pa- tients with colorectal cancer compared with controls (P = 0.014), especially those with advanced disease: Dukes C, P = 0.001 and T4, P < 0.05. CONCLUSION: Interleukin-12 production is impaired in patients with colorectal cancer, especially those with advanced disease, suggesting a defec- tive Thl-mediated anti-tumor response. These patients may well benefit from exogenous interleukin-12 treatment. [Key words: Interleuldn-12; Impaired; Colorectal cancer; Ad- vanced] O'Hara RJ, Greenman J, Drew PJ, McDonald AW, Duthie GC, Lee PW, Monson JR. Impaired intefleukin-12 produc- tion is associated with a defective anti-tumor response in colorectal cancer. Dis Colon Rectum 1998;41:460-463. C olorectal cancer is the second most common cause of cancer death in the United Kingdom, with 19,000 deaths per year. During recent years, there has been a minimum improvement in mortality, Read at the meeting of The American Society of Colon and Rectal Surgeons, Philadelphia, Pennsylvania, June 22 to 26, 1997. Winner of The Piedmont Society Award. Address reprint requests to Dr. Monson: The University of Hull, Academic Surgical Unit, Castle Hill Hospital, Hull, East Yorkshire, United Kingdom HU16 5JQ. with an overall five-year survival rate of less than 40 percent. ~ This poor survival may well be improved by adju- vant therapy, and one area of huge interest is the use of cytokines, glycoproteins that play an important role in immunoregulation. Several cytokines have been demonstrated to exhibit a significant anti-tumor activ- ity in humans, including interleukin (IL)-2 in renal cell carcinoma and melanoma 2 and interferon-~ in colo- rectal cancer. 3 However, efficacy has been disap- pointing with marked levels of toxicity, including the capillary leak syndrome following IL-2 administra- tion. 4 Interleukin-12 is a 70-kDa heterodimeric cytokine, produced by antigen-presenting ceils, primarily those of the monocyte/macrophage system. 5 In vitro and in vivo studies have demonstrated that IL-12 skews the immune response in favor of a Thl cytokine profile, 6-8 preferentially inducing cell-mediated immunity. An anti-tumoral and anti-metastatic role has been dem- onstrated in vitro and in vivo in a number of colon adenocarcinoma tumor models. 9-12 Because IL-12 has been shown to have a funda- mental role in initiating a cell-mediated immune re- sponse, the following study was performed to inves- tigate whether patients with colorectal cancer have impaired production of IL-12 preoperatively and whether these levels are related to disease stage at surgery. PATIENTS AND METHODS Patients M1 patients undergoing elective surgery with colo- rectal cancer were recruited to the study. Age- matched patients undergoing elective hernia repair were used as controls. Any patients who had under- 460