ASCO: Proteomic Stratification Test Can Help Guide Second-Line Treatment of NSCLC

CHICAGO-A simple serum protein test can help guide treatment decisions between chemotherapy and erlotinib as second-line therapy for patients with non–small-cell lung cancer (NSCLC), according to results of a phase III study presented at the annual meeting of the American Society of Clinical Oncology in Chicago.

“EGFR tyrosine kinase inhibitors are more effective in NSCLC patients with EGFR activating mutations, but we know the majority of non-Asian patients with NSCLC are EGFR-wildtype or are never tested for EGFR status,” said Vanesa Gregorc, MD, of San Raffaele Scientific Institute in Milan, Italy, who presented results of the PROSE study. “For patients without EGFR activating mutations or unknown EGFR status being considering for treatment with EGFR-TKIs, there is a need for other predictive markers.”

The VeriStrat test (Biodesix) is a serum protein expression test. In the PROSE study, patients were tested prior to randomization and categorized as either VeriStrat-Good (VS-G) or VeriStrat-Poor (VS-P); they then received either erlotinib or chemotherapy with pemetrexed or docetaxel. There were 129 chemotherapy patients, with 88 (68%) classified VS-G and 41 (32%) classified VS-P; the erlotinib group had 134 patients, and 96 (72%) were VS-G and 38 (28%) were VS-P.

The median overall survival was 9 months in the entire chemotherapy group and 7.7 months in the erlotinib group, for a hazard ratio of 1.14 (95% CI, 0.88–1.49; P = 0.313). The overall survival was similar between the VS-G patients: 10.92 months in VS-G chemotherapy patients and 10.95 months in VS-G erlotinib patients.

There was a significant difference, however, between VS-P patients on either therapy. VS-P patients in the chemotherapy group survived a median of 6.38 months, compared to only 2.98 months in the VS-P group receiving erlotinib. Overall, the VeriStrat treatment interaction was significant; the test’s classification, along with ECOG performance status, were found to be significant predictors of treatment outcome.

Dr. Gregorc concluded that patients stratified as VS-P, which will make up about 30% to 35% of patients, have better survival with chemotherapy than with erlotinib. “Serum proteomic VeriStrat classification is clinically useful to guide treatment decisions in NSCLC patients with unknown or wildtype EGFR status in second-line setting,” she said.

Luis Paz-Ares, MD, PhD, of the Hospital Universitario Virgen del Rocio in Sevilla, Spain, was the Discussant for the session, and said this study suggests “we may have another useful biomarker.” The results, he said, confirm that VeriStrat is both prognostic and predictive of treatment outcome, and noted that other trials including one called EMPHASIS-lung, are ongoing to confirm the test’s utility.