A Phase II trial of Denileukin Diftitox in patients with previously treated advanced non-small cell lung cancer

Denileukin diftitox, a chimeric protein, uses the cytocidal properties of diphtheria toxin to cells expressing interleukin-2 receptors. The aim of this study was to evaluate the efficacy and safety of denileukin diftitox in the treatment of advanced relapsed nonsmall cell lung cancer (NSCLC).

Multicenter phase II trial in patients with NSCLC with Eastern Cooperative Oncology Group PS 0-2, stage IIIB/IV at diagnosis, who had failed at least 1 previous chemotherapy regimen. Denileukin diftitox was infused at 18 microg/kg/d x 5 days, every 21 days for 6 cycles.

For the 41 patients enrolled, the median age was 56 years (range, 21-80), 25 were men, and the median number of previous chemotherapy regimens was 2 (range, 1-5). The median number of treatment cycles was 2 (range, 1-6). By RECIST criteria, 18 (44%) had stable disease, 10 (24%) progressive disease, and 13 (32%) were not evaluable for response as they received less than 2 treatment cycles. The median time to disease progression was 1.8 months [range, 0.3-11.3; 95% confidence interval (CI) 1.3-2.6]. Median survival was 5.8 months (range, 0.3-33.6; 95% CI 3.4-11.4). The median follow-up time was 16.1 month. One death from myocarditis verified at autopsy was attributed to treatment. One grade 4 toxicity (vascular leak syndrome) was encountered, and 18 grade 3 toxicities, primarily gastro-intestinal, vascular leak syndrome, and constitutional symptoms.

Denileukin diftitox at current dose schedule has limited activity in patients with previously treated NSCLC, manifested by disease control without impact on survival.