Phase 2 trial of talactoferrin in previously treated patients with metastatic renal cell carcinoma

BACKGROUND. Talactoferrin (TLF), a recombinant form of human lactoferrin (hLF), is an immunomodulatory iron-binding glycoprotein first identified in breast milk. Its immunomodulatory functions include activation of natural killer (NK) and lymphokine-activated killer cells and enhancement of polymorphonuclear cells and macrophage cytotoxicity. Studies in animal models have shown promising anticancer activity, and clinical antitumor activity has been observed in nonsmall cell lung cancer and other tumor types. The purpose of the current study was to evaluate the activity and safety of TLF in patients with refractory metastatic renal cell carcinoma (RCC). METHODS. Forty-four adult patients with progressive advanced or metastatic RCC who had failed prior systemic therapy received oral talactoferrin at a dose of 1.5 g twice daily on a 12-week-on 2-week-off schedule. Patients were evaluated for progression-free survival at 14 weeks, overall response rate, and progression-free and overall survival. RESULTS. TLF was well tolerated. No significant hematologic, hepatic, or renal toxicities were reported. The study met its predefined target with a 14-week progression-free survival rate of 59%. The response rate was 4.5%. The mMedian progression-free survival was 6.4 months and the median overall survival was 21.1 months. CONCLUSIONS. TLF is a well-tolerated new agent that has demonstrated preliminary signs of clinical activity. Given the lack of toxicity, the lack of rapid disease progression in this cohort, and the preclinical data on immune activation, a randomized study assessing its effects on disease progression in patients with metastatic RCC is rational.