Swedish biotech firm Olink Biosciences has launched a new plasma biomarker-discovery service featuring a panel of 74 potential cancer protein biomarkers.
The service uses the company's proximity ligation assay-based immunoassay platform to detect protein markers in plasma volumes as small as 2 microliters. According to Olink's chief scientific officer Simon Fredriksson, this low sample requirement is a key advantage of the system, one that he expects will draw particular interest from researchers working with limited amounts of plasma.
The PLA system uses pairs of antibodies attached to unique DNA sequences to detect proteins of interest. When the antibodies bind their targets the attached DNA strands are brought into proximity and ligate, forming a new DNA amplicon that can then be quantified using real-time PCR. The quantity of the DNA corresponds to the quantity of the target protein.
Such PCR-based measurement allows for "high-throughput generation of [protein biomarker] data from very small sample volumes with very high sensitivity," Fredriksson said, offering more sensitive detection than colorimetric ELISA assays or Luminex-based assays.
The 74-protein panel's most sensitive assays can measure biomarkers in the range of tens of femtomoles, he said, while the least-sensitive measures in the 5-picomolar to 10-picomolar range. The majority of the assays in the panel are below 1 picomolar in sensitivity.
The company is also looking into quantitating the panel's biomarkers via next-generation sequencing, Fredriksson said, noting that the technique could potentially improve the platform's throughput and precision.
In a pilot study published in the January edition of Molecular & Cellular Proteomics, Olink scientists, in collaboration with a number of other academic and industry researchers, used the platform to measure protein biomarkers related to colorectal cancer in 148 biobanked plasma samples, demonstrating its ability to detect low-abundance proteins like IL-8 that have traditionally been difficult to pick up with conventional ELISA assays. The researchers also showed they could move the assay from a 9-plex to 24-plex platform without losing specificity.
Olink plans to add roughly 100 additional proteins to its discovery panel within the next year, Fredriksson told ProteoMonitor, with more assays to come after that – also to be added in chunks of roughly 100 proteins at a time.
The present 74-analyte panel is focused on cancer biomarkers, which Fredriksson called "a major opportunity." However, he added, the company would consider adding other indications in the future. He also said the company would likely package different sets of biomarkers into panels aimed at various diseases, much like biomarker firm Rules-Based Medicine, which is perhaps the dominant player in the plasma biomarker discovery space.
The main barrier to adding assays, Fredriksson said, is obtaining antibodies for use in the panel. Olink is using commercially available antibodies for the work, but, he said, all must undergo "rigorous testing for specificity and sensitivity and all the immunoassay performance parameters that one could require for validation."
In the MCP paper the authors also highlighted the "availability of binding reagents for target proteins" as a potential "limiting step," but noted that because the platform can use matched monoclonal antibodies or just a single batch of an affinity purified polyclonal antibody raised against the native antigen split in two aliquots, "the potential repertoire of multiplex PLAs should be greater than for conventional multiplex assays."
The company has yet to sign any major customers for the service, but Fredriksson said the new platform has generated "a lot of interest," particularly in the academic research community. He envisions the panels being especially useful for work involving low-volume biobanked samples.
"This is a major issue with biobanked samples," he said. "Clinical researchers collect blood from patients over many years and store them and then they way to do a biomarker study. But they have only a certain limited amount of this sample and consuming it all in one study is often a problem."
At 2 microliters, the platform's sample requirements are significantly lower than those for RBM's discovery assays, which, depending on the panel, range between 50 microliters and 750 microliters of serum or plasma. Many of RBM's panels measure considerably more than the 74 analytes currently available on the Olink platform. The company's Human DiscoveryMAP product, for instance, quantitates more than 250 different proteins.
This breadth of assays accounts for RBM's leading position in plasma biomarker discovery, said Peter Levine, CEO of diagnostics firm Correlogic, which has used RBM for plasma biomarker work related to its OvaCheck ovarian cancer diagnostic.
"They have by far the largest offering of assays," he told ProteoMonitor, adding, though, that Olink's new platform "seems to be promising."
While Olink is currently offering the platform for research use only, it's interested in applying it to diagnostics as well, Fredriksson said, noting that the company was "working with partners on developing" a version for diagnostic uses.
"We're not a diagnostics company, so we're looking for partnerships to develop this in the diagnostics space once applications emerge," he said. One such application could be improved diagnosis of colorectal cancer.
According to Fredriksson, the company's current 74-protein panel is focused on this indication to the extent that it has any focus beyond cancer generally. And in the MCP paper the authors wrote that having successfully validated the multiplexed PLA technology, "we are now initiating a large study including all the [5,165] subjects from our endoscopy study and selected analytes" with the ultimate aim of developing a diagnostic algorithm combining several protein biomarkers.
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