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Signatope Partners With CPATH to Apply Immuno-MS Approach to Drug Toxicity Testing


NEW YORK (GenomeWeb) – Protein analytics firm Signatope is applying its amino acid motif-specific antibody technology to identifying and measuring protein biomarkers for drug development.

The Reutlingen, Germany-based company announced last week a collaboration with the Predictive Safety Testing Consortium (PSTC) of the Critical Path Institute, a nonprofit public-private partnership with the US Food and Drug Administration based in Tucson, Arizona, to develop markers of drug-induced toxicity. The parties aim to establish the ability of certain protein markers to improve the usefulness of existing preclinical safety models and to develop standardized assays for those markers in various species, including humans.

The agreement calls for Signatope to develop assays for nine potential toxicity markers and test them in several hundred samples, said Oliver Pötz, founder and CEO of the company.

Signatope was launched in 2016 to commercialize the Signabodies technology developed by Pötz and Thomas Joos, the company's head of business development, at the Natural and Medical Sciences Institute (NMI) at the University of Tübingen. Signabodies are antibodies that, rather than binding to a specific epitope on a particular protein, bind short (four amino acid) protein terminal sequences that are shared across multiple proteins. As opposed to a conventional antibody, a Signabody thus detects classes of proteins rather than single, specific proteins.

By combining Signabody detection with mass spec analysis, the company is able to measure a variety of proteins with a single affinity reagent, which can significantly reduce assay development time and costs.

Pötz noted that a major advantage of the approach in drug toxicity testing is the fact that the same reagent can be used to measure target protein markers across different model species.

"Usually these [terminal sequences] are conserved across species, and so we can use the same antibodies across species," he said, adding that this was key to the PSTC's interest in the company's technology. "We can use the same assay setup for [markers of] drug-induced organ injury to run animal samples and human samples at the end of the day."

Signatope uses protein sequence analysis to identify short stretches of amino acids that are conserved across species and groups of proteins and then develops antibodies to those sequences. Those antibodies, or Signabodies, as the company terms them, can detect proteins of interest, with mass spec used after the antibody assay to identify the specific protein a researcher is looking to measure.

This allows Signatope to offer assays to a large number of different proteins without having to develop an equivalently large catalog of antibodies. According to the company, its current collection of reagents numbers in the hundreds and covers roughly 6,000 different proteins. Development of an assay to a protein covered by its reagent collection takes around two months.

In addition to the PSTC work, the company has used its technology to study candidate biomarkers for drug-induced kidney injury in collaboration with Johnson & Johnson, Joos said. He added that the company expects to participate in another collaboration between the PSTC and various pharma firms on drug toxicity biomarkers that is slated to launch next year.

Signatope is also using its technology to analyze drug metabolizing enzymes and transporters to support drug metabolism and pharmacokinetics work in drug development, Pötz said.

"Here we are using this approach to pull down protein families, for instance cytochrome P450 enzymes, and then we can measure the abundance of those proteins in human hepatocytes, which are usually used to measure the induction of those enzymes," he said. This is normally done by measuring gene expression, he added, but the company is offering a service for cytochrome P450 quantification at the protein level.

In a study published in April in the journal Drug Metabolism and Disposition, Pötz, Joos and their colleagues demonstrated the use of the approach to quantify a panel of 14 cytochrome P450 enzymes and nine transporter proteins in liver tissue homogenates and microsomes.

Key to the assay's usefulness is its sensitivity, Pötz said. In their paper, the researchers were able to run their analysis on less than 10 µg of extracted protein, which allowed them to run it in a 96-well-plate format, reducing costs and increasing throughput.

In addition to its pharma work, Signatope is also looking to move into food testing, Pötz said. The company is currently involved in a project at the NMI to develop protein biomarker assays for detecting forbidden bovine bone or blood meal in animal feed. This month, the company and its collaborators published a study in the Journal of Agricultural and Food Chemistry detailing a mass spec immunoassay using a Signabody capable of detecting alpha-2-macroglobulin peptides from eight different species that could be useful for analyzing the components of fish feed used in aquaculture.

That followed a study published in Analytical Chemistry in March in which the company described an assay for identifying illegal processed animal proteins in supposedly plant-based cattle feed.

Signatope uses Thermo Fisher Scientific Q Exactive instruments for its assays, running them in parallel-reaction monitoring mode, and is able to run around 300 samples per instrument per week, Joos said.

The company currently has ten employees, two of whom are funded by the NMI through an incubator program that the firm is part of. Last year, it received €600,000 ($707,000) in seed funding from German venture investor High-Tech Gründerfonds, with the potential to receive an additional €2 million. Signatope is also funded by a €1.49 million GO-Bio phase 2 grant from the German Federal Ministry of Education and Research as well as by revenues from its pharma service work.