At the start of the genomics era when the first human genome became available, it was thought that knowing our DNA code would provide sufficient biomarkers to get us a good way toward our precision medicine goal. Unfortunately, the underlying complexity of the genome (and epigenome) proved to be far more intractable than many researchers expected. It soon became clear that genomics was not the panacea we sought, but required complementation from other'omics, including (but not limited to) proteomics, metabolomics, and transcriptomics. We are now at the point where genomics discovery tools (mostly high-throughput, rapid-sequencing technologies) are reaching maturity, while proteomics and other technologies are on the upswing. The articles in this booklet describe recent advances in proteomics technologies and how they are enabling the identification of new biomarkers that researchers are optimistic will advance us well along the track to realizing our objective for precision medicine. Much work remains to be done, but there is little doubt that the wind is at our backs and the scientific discoveries coming out of this multi-omics era will benefit patients in measurable ways.

Medical research is developing an ever greater need for comprehensive high-quality data generation to realize the promises of personalized health care based on molecular biomarkers. The nucleic acid proximity-based methods proximity ligation and proximity extension assays have, with their dual reporters, shown potential to relieve the shortcomings of antibodies and their inherent cross-reactivity in multiplex protein quantification applications. The aim of the present study was to develop a robust 96-plex immunoassay based on the proximity extension assay (PEA) for improved high throughput detection of protein biomarkers. This was enabled by: (1) a modified design leading to a reduced number of pipetting steps compared to the existing PEA protocol, as well as improved intra-assay precision; (2) a new enzymatic system that uses a hyper-thermostabile enzyme, Pwo, for uniting the two probes allowing for room temperature addition of all reagents and improved the sensitivity; (3) introduction of an inter-plate control and a new normalization procedure leading to improved inter-assay precision (reproducibility). The multiplex proximity extension assay was found to perform well in complex samples, such as serum and plasma, and also in xenografted mice and resuspended dried blood spots, consuming only 1 µL sample per test. All-in-all, the development of the current multiplex technique is a step toward robust high throughput protein marker discovery and research.