Title: Utilising a hybrid blood collection regime of remote dried blood spot sampling and in-clinic venipuncture to maximize data output in clinical trials

Abstract

Whilst liquid blood sampling enables the most comprehensive analysis of biomarkers and their source in different blood components, this approach is logistically more challenging in the context of clinical trials and can become difficult and expensive to manage in large studies. Alternatively, dried blood spot (DBS)sampling can be performed by the participants themselves and can be done remotely. This enables both increased numbers of participants and more frequent sampling, which, for longitudinal studies, should increase the chance of detecting biomarker changes as they are occurring. Studies requiring large sample quantities, such as proteomics, has traditionally been limited by the small volumes of blood captured. However, modern advances in the sensitivity of multiplexed analytical techniques have made DBS a compelling sampling platform. This makes DBS a hugely valuable addition to traditional bio specimen collection in trials. Our laboratory is employing a hybrid blood collection regime for longitudinal studies that includes both liquid blood collected in clinic and DBS collected at home between clinic visits. To maximise the data points collected from a single sample, we have also developed a series of methods to sequentially extract and fractionate proteins from DBS. Using these methods, we have demonstrated thedetection and robust quantitation of up to 1,600 proteins from mass spectrometry analysisof dried whole blood, a significant increase compared with analysis of undepleted plasma. In fact, some proteins not previously reported in blood have been detected with this approach. In a pilot study of lung cancer, liquid blood analysis revealed 12 significantly differentproteins compared to the control group and DBS analysis revealedan additional 19 differentially expressed markers. This sampling regime is an excellent research tool that, in our trials, has reduced the logistical burden of frequent venepuncture sampling and has increased the quality and breadth of data that can easily be collected from a single participant.