It has been demonstrated that cytokine activities are under neuroendocrine control, recently mainly exerted by the pineal gland through the circadian secretion of its main hormone melatonin (MLT). It is mainly released during the night, but at present it is still unclear which relation exists between MLT and the circadian secretion of cytokines. This study was performed to evaluate the circadian secretion of IL-2, IL-6, IL-10 and IL-12 in relation to that of MLT. The study included 10 healthy volunteers whose venous blood samples were collected at 8 a.m., noon, 4 p.m., 8 p.m., 1 a.m. and 4 a.m. The mean levels of MLT were significantly higher during the night than during the light phase of the day. Similarly, IL-2 mean levels significantly increased during the night. IL-6 mean values were higher during the light period of the day without, however, any significant differences with respect to the nocturnal mean levels. Finally, no substantial circadian variation was seen in IL-10 and IL-12 mean concentrations. These results show that IL-2 secretion increases during the night, concomitantly to that of the pineal hormone MLT, whereas there is no evidence of a circadian secretion for the other cytokines. Since the pineal gland has been proven to stimulate IL-2 endogenous production, the nocturnal increase in IL-2 blood concentrations could depend at least in part on the promoting action of MLT, whose release increases during the dark period of the day.

Summary Our previous experimental studies have shown that the best approach to increase the biological anti-tumour activity of interleukin 2 (IL-2) is not co-administration of another cytokine, but the association with immunomodulating neurohormones, in an attempt to reproduce the physiological links between psychoendocrine and immune systems, which play a fundamental role in the regulation of the immune responses. In particular, the association with the pineal neurohormone melatonin (MLT) has been shown to cause tumour regressions in neoplasms that are generally non-responsive to IL-2 alone. To confirm these preliminary results, a clinical trial was performed in locally advanced or metastatic patients with solid tumours other than renal cell cancer and melanoma. The study included 80 consecutive patients, who were randomised to be treated with IL-2 alone subcutaneously (3 million IU day-' at 8.00 p.m. 6 days a week for 4 weeks) or IL-2 plus MLT (40 mg day-' orally at 8.00 p.m. every day starting 7 days before IL-2). A complete response was obtained in 3/41 patients treated with IL-2 plus MLT and in none of the patients receiving IL-2 alone. A partial response was achieved in 8/41 patients treated with IL-2 plus MLT and in only 1/39 patients treated with IL-2 alone. Tumour objective regression rate was significantly higher in patients treated with IL-2 and MLT than in those receiving IL-2 alone (11/41 vs 1/39, P<0.001). The survival at 1 year was significantly higher in patients treated with IL-2 and MLT than in the IL-2 group (19/41 vs 6/39, P<0.05). Finally, the mean increase in lymphocyte and eosinophil number was significantly higher in the IL-2 plus MLT group than in patients treated with IL-2 alone; on the contrary, the mean increase in the specific marker of macrophage activation neopterin was significantly higher in patients treated with IL-2 alone. The treatment was well tolerated in both groups of patients. This study shows that the concomitant administration of the pineal hormone MLT may increase the efficacy of low-dose IL-2 subcutaneous therapy.

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The mechanisms responsible for the immunostimulatory role of the pineal hormone melatonin (MLT) are still obscure. To investigate the influence of MLT on interleukin-2 (IL-2)-induced immune effects in cancer, we compared the results obtained in 14 cancer patients treated with IL-2 (6 x 10⁶ IU/day s.c. for 5 days/week for 4 weeks) plus MLT (10 mg/day orally) with those seen in 14 patients treated with IL-2 alone and with those obtained from 14 other patients treated with MLT only. All patients were affected by metastatic solid neoplasms. The increase in the mean number of lymphocytes, T lymphocytes, natural killer cells, CD25-positive cells and eosinophils was significantly higher in patients treated with IL-2 plus MLT than in those receiving IL-2 alone. On the contrary, the increase in mean serum levels of the macrophage marker neo-pterin was significantly higher in patients treated with IL-2 alone than in those treated with IL-2 plus MLT. Finally, MLT alone has no significant effect on immune cell mean number and on neopterin secretion. These results would suggest that the immunostimulatory action of M LT requires the concomitant presence of IL-2 and that two of the main target cells for MLT activity in humans are represented by T helper lymphocytes of type 2, which are involved in IL-2-induced eosinophilia by the release of IL-5, and macrophages, which may inhibit IL-2-dependent immune functions.

The possibility of natural cancer therapy has been recently suggested by advances in the knowledge of tumor immunobiology. Either cytokines such as IL-2, or neurohormones, such as the pineal indole melatonin (MLT), may activate anticancer immunity. In addition, immunomodulating substances have also been isolated from plants, particularly from Aloe vera. Preliminary clinical studies had already shown that MLT may induce some benefits in untreatable metastatic solid tumor patients, whereas, for the time being, no clinical trial has been performed with aloe products. We have carried out a clinical study to evaluate whether the concomitant administration of aloe may enhance the therapeutic results of MLT in patients with advanced solid tumors for whom no effective standard anticancer therapies are available. The study included 50 patients suffering from lung cancer, gastrointestinal tract tumors, breast cancer or brain glioblastoma, who were treated with MLT alone (20 mg/day orally in the dark period) or MLT plus A. vera tincture (1 ml twice/day). A partial response (PR) was achieved in 2/24 patients treated with MLT plus aloe and in none of the patients treated with MLT alone. Stable disease (SD) was achieved in 12/24 and in 7/26 patients treated with MLT plus aloe or MLT alone, respectively. Therefore, the percentage of nonprogressing patients (PR + SD) was significantly higher in the group treated with MLT plus aloe than in the MLT gorup (14/24 vs. 7/26, p < 0.05). The percent 1-year survival was significantly higher in patients treated with MLT plus aloe (9/24 vs. 4/26, p < 0.05). Both treatments were well tolerated. This preliminary study would suggest that natural cancer therapy with MLT plus A. vera extracts may produce some therapeutic benefits, at least in terms of stabilization of disease and survival, in patients with advanced solid tumors, for whom no other standard effective therapy is available.

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SummaryThe

Abnormally high blood levels of vascular endothelial growth factor (VEGF) appear to be associated with a poor prognosis in advanced cancer, probably as a consequence of its angiogenic and immunosuppressive effects. The prognostic significance of changes in VEGF secretion during cancer chemotherapy is still unknown. This study aimed to investigate the relation between VEGF variations and therapeutic results during chemotherapy in advanced malignancies. The study included 90 metastatic cancer patients, 59 with non-small cell lung cancer and 31 with colorectal carcinoma. Chemotherapy consisted of cisplatin plus etoposide for NSCLC and camptothecin for colorectal cancer. Abnormally high (> 2 SD with respect to values in healthy controls) pretreatment VEGF levels were found in 38/90 (42%) patients. The percentage of non-progressive disease in response to chemotherapy was significantly higher in patients with normal levels of VEGF prior to therapy than in those with elevated pretreatment values of VEGF (10/32 vs 4/27; p < 0.05). Moreover, the percentage of VEGF level normalization during chemotherapy was significantly higher in patients with objective tumor response or stable disease than in progressing patients (10/18 vs 0/20; p < 0.001). Finally, among patients with tumor response or disease stabilization, the one-year survival rate was significantly higher in patients with chemotherapy-induced normalization of VEGF than in those with persistently high VEGF blood levels (9/10 vs 3/8; p < 0.05). These results suggest that changes in VEGF levels during chemotherapy may represent a useful biomarker to predict the effect of chemotherapy in terms of tumor response and survival in patients with metastatic solid neoplasms.