A phase I clinical trial was conducted to evaluate the toxicology and biological activity of a new liposome-incorporated lipophilic disaccharide tripeptide, ImmTher. Twelve patients with advanced nonhematological malignant disease received 13 courses of therapy at dose levels of 200-1,200 micrograms/m2. A course of therapy consisted of once-weekly administration of the drug for 2-12 weeks. The major clinical toxicities observed were chills and hypotension. No renal, hepatic, cardiac, or hematological toxicity was observed. A small decrease in pulmonary diffusion capacity was observed. Biological activity was demonstrated by changes in plasma cytokine levels, changes in in vitro monocyte cytotoxicity, and by a decrease in tumor size. Improvement was observed in three of three patients with metastatic disease to the liver. Response in these three patients correlated with an increase in their tumor necrosis factor and neopterin levels compared with nonresponders. These preliminary indications of biological and clinical activity of a liposome-incorporated lipophilic disaccharide tripeptide in patients with advanced metastatic hepatic disease suggest a potential new therapeutic approach to this common problem.