Our previous studies have shown that a preoperative injection of high dose IL-2 is able to abrogate surgery-induced immunosuppression in colorectal cancer patients. Moreover, our previous clinical investigations have indicated the possibility of amplifying IL-2 activity by a concomitant administration of the pineal immunomodulating hormone melatonin (MLT). On this basis, a biological study was performed to investigate the immune effects of a preoperative biotherapy consisting of low-dose IL-2 plus MLT in patients with gastrointestinal tumors. The study included 20 consecutive patients with gastrointestinal tract tumors, who underwent radical or palliative surgery. Patients were randomized to receive no preoperative treatment or a presurgical neuroimmunotherapeutic regimen consisting of low dose of IL-2 and MLT. IL-2 was injected subcutaneously at 3 million IU twice/day for 5 days in combination with MLT at 40 mg/day in the evening. Patients underwent surgery within 36 h from the last IL-2 injection. The mean number of lymphocytes, T lymphocytes and NK cells significantly decreased during the postoperative period in control patients, whereas it increased in patients pre-treated by immunotherapy. CD25-positive mean cell number increased in both groups of patients; however, postoperative mean number of CD25 expressing cells was significantly higher in patients pretreated with IL-2 and MLT than in controls. No immunotherapy-related toxicity occurred. This preliminary study would suggest that a neuroimmunotherapeutic regimen with low-dose IL-2 and MLT given preoperatively is a well tolerated therapy, which is able to prevent surgery-induced lymphocytopenia in cancer patients. This perioperative manipulation of host anticancer defenses could have a prognostic role in the clinical course of the neoplastic disease.

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