Finally, multivariate analysis including the panel of five CTC-biomarkers in combination with the presence of bone metastasis resulted in GAPDH, NOTCH1 and PTP4A3 as independent predictors of PFS (Table 1, upper panel); GAPDH and ITGB3 showed predictive value for OS (Table 1, upper panel). Here, PTP4A3 is linked to bone metastasis.