Serum cathepsin B (CB) levels are prognostic in chemotherapy-naive patients (pts) with advanced non-small cell lung cancer (NSCLC) and performance status (PS) of 2

18036 Background: CB is an estrogen-influenced lysosomal cysteine protease produced by tumor cells and tumor-associated macrophages; tumor tissue CB protein levels and proteolytic activity are prognostic in NSCLC (Anticancer Res. 2004; 24:4147–61). The prognostic value of serum CB has not previously been evaluated in NSCLC. Here we evaluate the impact of pretreatment CB levels on survival in pts from 2 phase III trials in advanced NSCLC, STELLAR 3 and 4. These trials compared paclitaxel poliglumex (PPX) against commonly used regimens. As the intratumoral metabolic pathway of PPX is characterized by the CB-mediated release of paclitaxel (P) from a polymeric backbone (Ca Chemother Pharm. 2006. Epub ahead of print), correlation of CB levels with PPX efficacy was assessed as well. Methods: Pretreatment serum samples from 450 chemo-naive pts with advanced NSCLC and PS 2 enrolled in STELLAR 3 (P + carboplatin (C) v. PPX + C) (N=315) and STELLAR 4 (vinorelbine or gemcitabine v. PPX) (N=135) were assayed for CB b...