A randomized trial to evaluate the immunorestorative properties of synthetic thymosin-alpha 1 in patients with lung cancer.

A randomized trial was performed in 42 postradiotherapy patients with non-small cell lung cancer to determine whether the administration of synthetic thymosin-alpha 1 by either a loading dose or a twice-weekly schedule could accelerate the reconstitution of thymic dependent immunity. The radiotherapy-induced immunosuppression was characterized by an absolute T cell lymphopenia and by impaired T cell function in lymphoproliferative assays. Placebo-treated patients did not show any improvement in T cell numbers or function over 15 weeks of serial immune monitoring, and exhibited gradual depressions of helper T lymphocyte percentages. Patients treated with thymosin by the loading dose regimen exhibited a normalization of T cell function (p = 0.04), whereas patients treated with the twice-weekly schedule maintained normal helper T cell percentages (p = 0.04). Thymosin treatment was associated with significant improvements in relapse-free and overall survival, which was most pronounced for patients with nonbulky tumors. Thymosin-alpha 1 exhibits schedule-dependent immune restorative and homeostatic properties. Large scale Phase III trials are indicated to definitively establish the impact of thymosin therapy in lung cancer patients treated with radiotherapy.