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MO21 - Prognostic and Predictive Biomarkers V - EGFR (ID 98)
- Event: WCLC 2013
- Type: Mini Oral Abstract Session
- Track: Medical Oncology
- Presentations: 1
MO21.01 - Randomized Proteomic Stratified Phase III Study of Second Line Erlotinib (E) versus Chemotherapy (CT) in Patients with Inoperable Non-Small Cell Lung Cancer (PROSE): VeriStrat analysis of longitudinal samples (ID 3122)
10:30 - 12:00 | Author(s): D. Ghio
2nd-line therapy for advanced NSCLC patients (pts) after progression on platinum-based regimens typically employs CT or E. A test for optimizing choice of treatment in these pts is of clinical value. VeriStrat (VS) is a serum protein test that assigns "good" (VSG) or "poor" (VSP) classification and has demonstrated prognostic and predictive utility. PROSE is a multicenter prospective randomized biomarker validation trial, designed to evaluate the ability of VS to predict survival in 2nd- line NSCLC pts treated with E or CT. As reported at 2013 ASCO1, PROSE met its primary endpoint of demonstrating significant treatment*VS interaction with a p value of 0.031, with VSG pts deriving similar overall survival (OS) benefit from both treatments (hazard ratio (HR) for E=1.06; p=0.71) and VSP pts benefitting more from CT than E (HR for E=1.72; p=0.02). Previous studies in EGFR-TKI-treated pts have shown that at progression around 30% of pre-treatment VSG pts have changed classification to VSP2. The present report discusses the exploratory analysis of longitudinal VS classifications generated during the PROSE study.
Of the 263 pts in the PROSE primary analysis population, 89 provided serum samples during treatment and 108 at progression, with 47 pts providing both. VS testing was performed on these longitudinal samples blinded to all clinical and treatment outcomes and pts and physicians remained blinded to VS results.
VSG or VSP classifications were obtained for 89 pts from treatment samples (67 VSG / 22 VSP) and 107 pts (one sample was classified as indeterminate) from progression samples (59 VSG / 48 VSP). In pts with matched baseline and progression samples, the percentage of VSG classifications was lower at progression (55%) than at baseline (77%) (p < 0.001 ). Twenty eight pts (34%) classified at baseline as VSG changed to VSP at progression, in line with previous studies2, and this did not show any significant dependence on treatment. When treated with E, pts whose classification changed from VSG at baseline to VSP during treatment (n=6) had inferior PFS to the 25 pts who remained VSG (p=0.001, median PFS: 3.6 and 7.7 months (mos), respectively). Patients whose classification changed from VSG at baseline to VSP at progression on E (n=18) had numerically inferior OS (median 10.0 mos) compared with the 31 pts who remained VSG at progression (median 14.6 mos) and significantly superior OS (median 5.0 mos) compared with the 10 pts who were VSP at both time points (p<0.001).
The observed changes in VS classification at progression demonstrate the importance of obtaining a VS result prior to each line of therapy for which erlotinib is considered as a therapeutic option. The proportion of patients who are good candidates for erlotinib therapy (VSG) decreases from 2[nd] to 3[rd] line and the possible impact of this on treatment sequencing and monitoring for 2[nd] and higher line advanced NSCLC pts merits further studies.
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