Follow up of soluble IL-2 receptor level in metastatic malignant melanoma patients treated by chemoimmunotherapy

Immunological parameters following chemoimmunotherapy combination were studied in 31 patients with metastatic malignant melanoma. They received Cisplatin (100 mg/m2) on day 1 and 28, recombinant IL-2 (rIL-2; Eurocetus) in continuous infusion from day 3 to 6, 17 to 21, 31 to 34 and 45 to 49. Interferon-alpha (IFN-alpha; Roche) was given subcutaneously three times weekly. No significant change in CD4/CD8 ratio at onset or during treatment was observed between responder (n = 19) and non-responder (n = 12) patients. Regarding the IL-2 receptor (IL-2R) study, the percentage of cells expressing Tac (p55) receptor did not change either for healthy volunteers (n = 20) and patients before any therapy, or between responder and non-responder patients. Concerning serum soluble IL-2R shedding before therapy, we observed a significant increase (P = 0.001) in patients (79 +/- 40 pM) compared with healthy donors (30 +/- 15 pM), but no significant variation was seen between responder and non-responder patients. In contrast, during the treatment, the soluble IL-2R level increased in both groups but, interestingly, a significant difference was found between responder and non-responder patients from day 7 (P < 0.05) to day 21 (P < or = 0.01), suggesting that the cells from non-responder may be slower in becoming stimulated. This finding is the most striking point of our study and suggests that sIL-2R might be an early predictive factor of the clinical response as obtained by logistic regression (P = 0.0063). Therefore patients with a serum soluble IL-2R level greater than 250 pM at day 21 have a 12-fold more chance of undergoing a clinical response.