Circulating Cell-free DNA as a Prognostic Biomarker in Patients with Advanced ALK+ Non-small Cell Lung Cancer in the Global Phase III ALEX Trial

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Clinical cancer research


INTRODUCTION: We retrospectively assessed prognostic value of circulating cell-free DNA (cfDNA) using data from the phase III ALEX study in treatment-naïve, advanced ALK+ NSCLC.

METHODS: Patients were randomized to receive twice-daily alectinib 600 mg (n = 152) or crizotinib 250 mg (n = 151). cfDNA was quantified from baseline plasma samples, with patients stratified into {less than or equal to}median and >median cfDNA biomarker-evaluable populations (BEP). Effect of cfDNA concentration on outcomes was analyzed using a Cox regression model with treatment group as covariate, and in multivariate analyses.

RESULTS: Median cfDNA concentration in the BEP was 11.53 ng/mL (n = 276). A positive correlation was found between cfDNA concentration and number of lesions, organ lesion sites, and tumor size (sum of longest diameter; all pmedian BEP were more likely to experience disease progression than the {less than or equal to}median BEP (alectinib adjusted hazard ratio [HR] 2.04 [95% confidence interval (CI): 1.07-3.89], p=0.0305; crizotinib adjusted HR 1.83 [95% CI: 1.11-3.00], p=0.0169). Median progression-free survival was longer with alectinib than crizotinib in both {less than or equal to}median and >median BEPs (pmedian versus {less than or equal to}median BEP in both treatment arms (alectinib HR 2.52 [95% CI: 1.08-5.88], p=0.0333; crizotinib HR 2.63 [95% CI: 1.27-5.47], p=0.0096).

CONCLUSION: These data suggest that plasma cfDNA concentration may have prognostic value in advanced ALK+ NSCLC. Prospectively designed studies are warranted to investigate this finding.

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ePub ahead of print