Angiogenesis in non-small cell lung cancer (NSCLC): Gender differences in tumor and circulating angiogenic factors

A24 Background: Gender-specific differences in benefit from anti-angiogenic agents in NSCLC have been reported. A greater benefit in overall survival was observed in males (M) with the addition of bevacizumab to 1st-line carboplatin and paclitaxel (CP) for stage IIIB/IV non-squamous NSCLC (Brahmer, ASCO 2006 abst #7036). In 2 randomized phase II trials of vandetanib (V; dual EGFR/VEGFR-2 inhibitor) for stage IIIB/IV NSCLC, a greater benefit in progression free survival was observed in females (F) with the addition of V to 2nd-line docetaxel and to 1st-line CP (Heymach, ASCO 2006 abst #7016, ASCO 2007 abst #7544). We evaluated differences in expression of cytokines and angiogenic factors (CAF) in plasma and tumor from M and F NSCLC patients to determine if there are gender differences in the regulation of NSCLC angiogenesis. Methods: We used multiplexed bead suspension arrays and ELISA to measure concentrations of 35 CAFs (including VEGF, sVEGFR-2, bFGF, EGF, E-selectin, ICAM-1, multiple chemokines and interleukins) in plasma samples collected pre-treatment from patients with stage IIIB/IV NSCLC participating in the above trial of CP +/- V. Tissue microarrays (TMA) were constructed from archived, formalin-fixed, paraffin-embedded NSCLC tumor specimens from the institutional tissue bank. TMAs were subjected to immunohistochemistry to assess the expression of 22 CAFs, including AF receptors and related signaling pathways. The associations between gender and CAFs were assessed using linear regression model for normally-distributed factors and logistic regression model for binary measured factors. Results: Pre-treatment plasma samples were available from 123 patients: 86 M and 37 F. Significant gender differences in baseline plasma concentrations of a number of CAFs were seen, and all were higher in Fs: IL-5 (mean 27 vs. 5 pg/mL; P = .04), IL-15 (mean 1193 vs. 291 pg/mL; P = .01), IL-1RA (mean 2375 vs. 872 pg/mL; P = .015), sIL-2R (mean 1413 vs. 577 pg/mL; P = .01), MIG (mean 184 vs. 67 pg/mL; P = .016), and MIP-1α (mean 319 vs. 108 pg/mL; P = .02). Plasma CAFs with no detected gender differences included VEGF, bFGF, HGF, sVEGFR-2 and ICAM-1. TMAs were available from 329 archived NSCLC specimens: Gender distribution was 154 M and 175 F; histologies were 211 adenocarcinomas and 118 squamous cell carcinomas; stage (S) distribution was 206 S I, 65 S II, 36 S IIIA, and 21 S IIIB/IV. On univariate analysis, cytoplasmic pVEGFR-2 (P = .005), nuclear FGFR-2 (P = .01) and nuclear IL-8 (P = .01) expression were higher in F than in M NSCLC. Interactions between gender and the characteristics of smoking history, histologic type, tumor stage, age and race were detected for a number of CAFs. On multivariate analysis controlling for these characteristics, cytoplasmic pVEGFR-2 (P = .004) and nuclear IL-8 (P = .03) expression were higher in F NSCLC, and cytoplasmic MMP-9 (P = .015) was higher in M NSCLC. CAFs in which no gender differences were seen in the TMAs include VEGF, bFGF, HGF, EGFR, pEGFR, PDGFR-α and TGF-α. Conclusions: There are gender differences in CAFs in plasma and tumor tissue from patients with NSCLC. These findings suggest that the regulation of tumor angiogenesis is different between M and F NSCLC. These differences may contribute to the reported gender differences in benefit from anti-angiogenic agents in clinical trials.