Immunological and side effects of low sc recombinant interleukin-2 dose in addition to conventional treatment in relapsed breast and colorectal cancer patients

Thirteen relapsed cancer patients, four of them operated for colorectal and the nine remaining for breast cancer, were cyclically given low subcutaneous (sc) recombinant interleukin-2 (rIL-2) doses in addition to chemo- or hormone therapy. Cycle intervals were 2 or 6 weeks in length, and the number of cycles ranged from one to 14 and from one to six respectively. Tolerance assessed by clinical and laboratory data, eosinophils, lymphocytes (total number), T subpopulations, B lymphocytes and NK cells were the evaluated parameters. One (7.6%) of the 13 studied patients interrupted the first low dose sc rIL-2 cycle due to a hypersensitive reaction. This case showed relapse from breast cancer. During further cycles, three patients (25%), one operated on for colorectal and two others for breast cancer of the 12 remaining cases who completed all rIL-2 cycles showed an increase in glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), gamma-gt, and creatininemia without any clinical symptoms. A slight influenza-like syndrome and 10-20 mmHg decrease in blood pressure sporadically occurred in all patients under rIL-2 therapy. In both cancer types, a significant (P < 0.05 - P < 0.001) increase in lymphocytes, eosinophils. T4 and T3 subpopulations but not in T8 subpopulations and NK cells occurred at the end of the rIL-2 cycles. In 11 of the 13 patients responsive to conventional therapy, a highly significant increase (P < 0.001) in all parameters apart from B lymphocytes and T4/T8 ratio was observed, while in three cases which were no longer responsive and in another case which had never been responsive to conventional therapy, a slightly significant increase in eosinophils only occurred (P < 0.05). Three colorectal cancer patients showed a partial response and the last a complete response to conventional therapy. In these four patients, time to progression during rIL-2 cycles ranged from 2.5-5 months and the duration of response ranged from 8-19 months. In seven of the eight breast cancer patients who completed all rIL-2 cycles, the response ranged from 3-51+ months and in the last case, which was not responsive to conventional therapy, the disease progressed in spite of the addition of rIL-2. These data suggest that: a) rIL-2 is likely to constitute a well-tolerated and suitable home therapy even when cyclically given for a prolonged period; b) following rIL-2 administration, eosinophils and lymphocytes increase in addition to the T subpopulations.