Thermo Electron and Quest Diagnostics last week announced an automated, biochip-based laboratory test for the detection of cystic fibrosis gene mutations during prenatal screening.
The CF Portrait biochip is produced collaboratively by the two companies and is based on Thermo’s thin-film technology, which is used to mount assay probes on a silicon wafer. The wafer is then sliced into smaller chips, each with 64 activated spots, and the chips are placed at the bottom of a 96-well microtiter plate, where hybridization is detected by a camera that records a pattern of a purple spot against the gold background of the chip.
“We think there is a great place in the diagnostics market for low- and mid-density arrays,” said Noel Doheny, director of business development for Thermo, and the former CEO of BioStar, which was acquired by Thermo in 1998.
The BioStar unit created the technology underlying the chip, using a thin-film optics technique (Optical ImmunoAssay) that employs optically coated surfaces to provide imaging of bioanalytical reactions and measurements.
Each spot on the chip will contain probes for 25 SNPs, six other polymorphisms, and two controls. The capture oligos are less than 20 mers in length. The process, after completion, takes about a half hour per microplate, said Doheny.
The chip will be imple-mented at Quest’s Nichols Institute reference laboratory in San Juan Capistrano, Calif., and, by July 1, will be used for all CF screens performed there, the company said. The Nichols Institute will have exclusive rights to develop the biochip as part of a testing system. Financial details of the agreement were not disclosed.
Current methods, such as hybridization strips distributed by Roche, or sequencing methods from ABI, cost from $40 to $100 per assay, and this process will be dramatically less, Doheny said: “It has the potential to take zeros off what was previously charged.” However, he said he was not at liberty to disclose a price.
The CF Portrait biochip represents another small step towards moving microarray-based assays from a research tool to the financially attractive diagnostics market, a transition that not only requires a reliable instrument, but also one that is cost-effective and easy to use.
The chip enters a marketplace where demand for the CF test is spiking in response to a 2001 guideline issued by the American College of Obstetrics and Gynecology and the American College of Medical Genetics, which recommended that Caucasian couples should undergo screening for the CF genes prior to conception. Quest has seen its CF testing business increase four-fold since then.
Other companies are also seizing this market opportunity with biochip products. Healthspex, a small company in Knoxville, Tenn., is seeking to enter the CF testing market by commercializing an integrated optical biochip technology from Oak Ridge National Labs. Nanogen, of San Diego, offers analyte-specific reagents for testing CF mutations on its Nanochip electrode microarray workstation.
Thermo said it has two other assays under development.
Jorge Leon, vice president of applied genomics at Quest Diagnostics, said Quest expects DNA arrays to be one of three to four important diagnostic platforms, joining traditional ELISAs and antibody arrays, as well as fluorescent in situ hybridization and protein mass spectrometry. (BioArray News, March 29, 2002).
The global market for clinical diagnostics equipment is estimated by analysts at upwards of $13 billion globally per year, according to an April 2003 report published by Business Communications, a Norwalk, Conn., market researcher.
The technology in this chip was originally used for protein applications and took two years to adapt to DNA technology. The silicon chips are manufactured on 4x4 inch wafers and then sliced to fit into a microtiter well.
The technology is protected by a patent that was filed originally in 1985, said Doheny, and got lost in the patent office before it was granted in 1999-2000.
“It predates most array IP and gives us an ability to practice our art,” he said.