Phase II trial of thymosin fraction 5 in advanced renal cancer.

Partially purified thymosin fraction 5 ( TF5 ) was administered to 21 patients with advanced renal cancer. Two different loading dose schedules and doses (60 and 120 mg/m2) of SQ TF5 were employed in 10 patients each. Of 20 evaluable patients, three exhibited partial responses and two exhibited stable disease. All five of these patients had had prior nephrectomies and lung metastases as the dominant site of disease. Toxicity was minimal but included one probable systemic allergic reaction. We could not identify any specific relationship between TF5 dose/schedule or pretreatment immune abnormalities and tumor responsiveness. Our results indicate that the administration of TF5 alone can induce regressions of renal cancer. Additional trials with larger numbers of patients appear to be justified.