TISSUE POLYPEPTIDE-SPECIFIC - ANTIGEN IN RENAL-CELL CARCINOMA

Objectives: The usefulness of serum tissue polypeptide-specific antige n (TPS), a cytokeratin 18-associated marker, in renal eel carcinoma (R CC) was assessed in vitro and in vivo. Methods: Indirect immunoperoxid ase staining for TPS expression was performed on frozen sections of no rmal renal tissue and RCC specimens. By using a monoclonal TPS immunor adiometric assay, serum TPS concentrations were analyzed in 82 healthy controls, in 20 patients with locoregional RCC before and after surge ry and in 18 patients with advanced disease following surgery receivin g immunotherapy with interferon-gamma. Results: Using immunohistochemi stry, TPS was found to be expressed by both normal and concerous renal epithelial cells. The mean TPS concentrations in 82 healthy controls was 56 +/- 49 U/l with a 95% percentile of 78.5 U/l. Out of 20 patient s with locoregional RCC, 8 presented with elevated values (mean 168 +/ - 82 U/l) above the cut-off level (78.5 U/l, sensitivity 40%) which dr opped to normal within 2 weeks after surgery. During a follow-up perio d of 1 year, none of the patients presented with tumor recurrence and TPS concentrations remained low (mean 52 +/- 36 U/l). In Is patients r eceiving interferon-gamma therapy, serum TPS concentrations were monit ored over a period of 12 months. In 5/18 patients, baseline levels wer e within the normal range (mean 37 +/- 21 U/l); interestingly, these a t the same time were the only responders to immunotherapy (n = 2) or a t least showed stable disease (n = 3). Response to therapy was reflect ed by low serum TPS levels (mean 28 +/- 23 U/l) over the entire observ ation period. Thirteen patients suffered progressive disease during th erapy, all of them exhibiting significantly elevated (p < 0.005) preth erapeutic TPS concentrations (mean 186 +/- 124 U/l) that remained equa lly elevated throughout therapy (mean 192 +/- 102 U/l), reflecting tum or progression. Conclusions: TPS might have some clinical value as pro gnostic marker in RCC, possibly by reflecting the proliferative tenden cy of the tumor.