Sequential dacarbazine chemotherapy followed by recombinant interleukin-2 in metastatic melanoma. A pilot multicentre phase I-II study.

Between April 1988 and August 1989, 30 melanoma patients were entered in a multicentre Phase II study of dacarbazine (DTIC) 850 mg/m2 i.v. bolus on day 1, and recombinant interleukin-2 (rIL-2) (Cetus) 18 x 10(6) IU/m2/day i.v. continuous infusion on days 4-9. Six treatment cycles were given: the first two at an interval of 13 days, and further cycles at intervals of 20 days. Twenty patients are currently evaluable for toxicity and 18 for response. Two of these patients presented with metastatic intraocular melanoma. Median age was 48 years (range 18-83), and median Karnofsky index was 100 (range 80-100). Four patients had received prior radiotherapy and one had received prior immunotherapy. Seventeen patients received two cycles of treatment and nine patients received three or more cycles. Four patients responded (22%): two complete remissions and two partial remissions. Stable disease was seen in six patients (33%). Responses occurred in the lung, skin, spleen and lymph nodes. Seventy-five percent of the patients received the full dose of rIL-2 during cycle 1, whilst only 2 out of 9 (22%) received the planned dose on the third cycle. Rebound lymphocytosis of 5.3 x 10(3)/L (range 1.2-18.1) occurred 24-48 h after rIL-2, but was not predictive for response. Currently, there is no evidence that pretreatment with DTIC impacts negatively on the rIL-2-stimulated lymphocyte proliferation. The toxicity profile of this treatment regimen did not differ significantly from that already described for similar regimens of rIL-2. However, in this interim analysis, there was a trend for a higher percentage of patients (25%) to experience severe weight gain (greater than 10%). This study shows that this treatment regimen is active in metastatic melanoma, with acceptable toxicity. Further research will focus on using other chemotherapeutic agents and/or other biological response modifiers (e.g. interferons, tumour necrosis factor) in combination with rIL-2.