Current assessment is based on computed tomography scans, approximately 6-8 weeks after treatment. Earlier molecular predictors of response would be highly beneficial for both patients and clinicians. We have investigated whether useful protein biomarkers could be found in patient plasma, through the use of an advanced MS technique known as SRM-MS. Here, we will discuss the discovery-through-validation pipeline of identifying and validating clinically-relevant biomarkers that can be rapidly translated into the clinic. Briefly, we examined whether the type of blood collection tube would impact on SRM measurement of plasma proteins, in addition to examining the stability of the selected plasma proteome over a 19 week time-course. We then applied SRM to monitor 31 plasma proteins in a trial cohort of advanced CRC patients receiving FOLFOX chemotherapy. Our results indicated that the baseline levels of plasma vitronectin were associated with chemotherapy response, which was successfully validated in a larger patient cohort using SRM and ELISA (n=29 patients). These findings pave the way for further testing in larger cohorts and could lead to more cost-effective and rational uses of systemic chemotherapy.