Peptide-based tool for the rapid isolation of quiescent monocytes from peripheral blood

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SUMMARY/ABSTRACT Dendritic cell (DC) therapy represents a new and promising immunotherapeutic approach for treatment of advanced stage cancers, with DC vaccines already approved for use in advanced prostate cancer, and more than 30 DC-based vaccines in the clinical development pipeline for other cancers. In particular, the US market for cancer vaccines (including DC-based vaccines) is set to expand tremendously at a CAGR of 78.1% from $20 million in 2010 to $2 billion by 2018. This highlights the need to develop clinical grade technologies for collecting DC precursor cells and generating DCs for cancer vaccination. Typically, DCs are differentiated from monocytes, which are isolated from peripheral blood mononuclear cells using different methods including plastic adherence, counter-flow elutriation, and immunomagnetic selection or depletion of cells. Of these techniques, immunomagnetic selection of CD14+ monocytes is the most commonly employed technique in the clinic. While this technique results in a relatively pure population of monocytes as compared to the other techniques, the recovery/yield of monocytes is low. Also, the use of antibodies to purify monocytes makes it cost-prohibitive for large-scale production of monocytes. In addition, all the above mentioned techniques are unable to isolate monocytes from whole blood, and require a density-gradient step prior to isolation of monocytes, thus increasing costs, time and technical skill involved. Thus, there is an unmet need to develop a simple, rapid and efficient method capable of isolating a highly pure and quiescent population of monocytes directly from whole blood. Affinergy has identified a family of peptides that bind specifically to monocytes, while not binding to the other blood cells. When conjugated to magnetic beads, these peptides can directly isolate monocytes from whole blood, and result in high recovery and purity, without any additional processing steps. At the conclusion of Phase I, we will have established a rapid and efficient method for purifying monocytes from whole blood and demonstrated that the enriched monocytes are capable of differentiating into DCs. In Phase II, we will optimize large-scale production of peptide-conjugated beads, establish shelf-life and storage conditions and demonstrate the feasibility of our technique to purify monocytes at a larger scale.