Phase I trial of oral talactoferrin alfa in refractory solid tumors

Lactoferrin is an iron-binding glycoprotein first identified in breast milk as a protein product of mammary epithelial cells. Its immunomodulatory functions include activation of NK and lymphokine-activated killer cells and enhancement of PMN and macrophage cytotoxicity. Studies in animal models have shown promising anti-cancer activity. The purpose of the present study was to evaluate the safety and tolerability of talactoferrin alfa (talactoferrin; TLF) in humans, as well as pharmacokinetics and pharmacodynamics.

Ten adult patients with progressive advanced solid tumors who had failed conventional chemotherapy were administered oral TLF at doses from 1.5 to 9 g/day, using a 2 weeks on, 2 weeks off schedule. Patients were evaluated for drug toxicity, tumor growth rate, talactoferrin pharmacokinetics and cytokine markers.

Talactoferrin was very well tolerated. No hematological, hepatic, or renal toxicities were reported. A single patient had Grade 2 diarrhea, and there were no Grade 3 or 4 toxicities. Following oral administration, significant levels of talactoferrin were undetectable in circulation, but a statistically significant increase in circulating IL-18, a pharmacodynamic indicator of talactoferrin activity, was observed. Of the eight patients who were radiologically evaluable, five (63%) had stable disease by RECIST criteria two months after start of therapy, including one patient with a minor response. Seven patients (88%) had a decrease in their tumor growth rate. The three patients with non-small cell lung cancer (NSCLC) all survived for at least one year following the start of talactoferrin monotherapy.

Talactoferrin is a promising, well-tolerated new agent that should be evaluated further in patients with refractory metastatic cancer.