Translational research (TR) results from pointbreak: A randomized, open-label, phase III study of pemetrexed (Pem)+carboplatin (Cb)+bevacizumab (Bev) followed by maintenance pem+bev (Pem Arm) versus paclitaxel (Pac)+cb+bev followed by maintenance bev (Pac Arm) in patients (pts) with stage IIIB or IV nonsquamous non-small cell lung cancer (ns-NSCLC).

Abstract

8086 Background: Results of PointBreak were previously reported. Correlative tissue TR results are presented. Methods: Of 939 pts in the intent-to-treat population (ITT), 211 (22.5%) signed TR consent forms and had evaluable samples. Specimens were analyzed for: Epidermal Growth Factor Receptor (EGFR) mutations by polymerase chain reaction (n=132); thyroid transcription factor-1 (TTF-1) (n=205), thymidylate synthase (TS) (n=189), and folate receptor-alpha (FR-α) (n=180) by immunohistochemistry (IHC) (H-scores range, 0-300). H scores were dichotomized based on positive (>0)/negative (=0) cutpoint. Adjusted Cox/logistic regression determined correlations between overall survival (OS), progression-free survival (PFS), response rate (RR), and dichotomous IHC markers. A 2-sided test with α = 0.05 and 0.1 evaluated treatment and interaction effects, respectively. Results: Median (m) OS and mPFS were similar in the ITT and TR populations for both arms. 11/132 (8.3%) pts had activating EGFR mutations. For TS or FR-α, no significant between-arm differences in OS, PFS and RR were seen. 139/205 (67.8%) pts had positive TTF-1 (TTF-1+). TTF-1+ pts, compared with TTF-1-, independent of treatment, had significantly longer mOS (14.9 vs 8.7 mos, HR 0.48, p<0.001), mPFS (6.9 vs 4.5 mos, HR 0.62, p=0.006), and higher RR (38.9% vs 19.7%, OR 2.68, p=0.008). For TTF-1+ pts, compared with Pac arm, Pem arm had longer mOS (17.6 vs 12.8 mos, HR=0.7, p=0.08; interaction p=0.12) and mPFS (7.3 vs 5.8 mos, HR=0.78, p=0.20; interaction p=0.261); although not statistically significant. Conclusions: The number of pts with EGFR mutations was too small to draw conclusions. No significant between-arm differences for TS and FR-α were seen. Longer survival in TTF-1+ pts suggests TTF-1 expression is prognostic. Additional studies will be needed to better understand trends favoring pem for survival among TTF-1+ pts and other prognostic and/or predictive relationships of these markers. Clinical trial information: NCT00762034.