Vitra Bioscience said last week that it has raised $5.5 million in a second round of financing and plans to use this new cash infusion to push its flagship CellCard assay technology to market.
The fundraising effort comes three years after an initial round of financing yielded a little over $9 million for the company, which at that point was called Virtual Arrays. And early last year, the Mountain View, Calif.-based company was awarded a Phase I SBIR grant by the National Cancer Institute to further develop CellCard.
Shortly thereafter, in May 2003, the company changed its name to Vitra Bioscience. However, it stuck with its original goal of commercializing CellCard as a tool for highly multiplexed cell-based assays, which the company calls CellPlex assays, primarily in drug screening.
Last week, company officials told Inside Bioassays that the most recent round of funding will not only go toward commercialization of CellCard, but will also support expansion of the company’s adjunct product offerings. According to Andrew Whitely, Vitra’s CEO, this means further developing an entire turn-key system based on CellCard, including a dispenser, plate reader, and software.
“We believed at this stage that building a turn-key solution was focused on the needs that pharmaceutical companies have today for this type of technology,” he said.
The CellCard is the core technology that gives Vitra a unique position in the cell-based assay and high-content screening marketplace, said Heidi Bullock, Vitra’s director of marketing.
“What’s really unusual and unique is the CellCard carrier, which is the cornerstone of our technology” she said. “That allows researchers to multiplex different cell types. There are technologies out there that allow multiplexing of parameters, but this enables multiplexing of cell types and parameters all within a single microtiter well.”
Each “carrier” is microscopic — about 500 by 300 microns — and is made of a proprietary material that Bullock said “is compatible with cell culture.” The surface of the cards can also be coated with matrices of various materials for specific cell or assay types, she said.
In addition, the long sides of each card have colored strips on them — two on each side — that together act as a bar code of sorts so different cards can be distinguished from one another under a microscope. Before an assay is to be performed, cells are grown on the cards to confluence, with different cell types being assigned to different color-coded cards. Bullock said Vitra provides customers with the optimal cell seeding density so that the culture achieves confluence.
The cards — now coated with cells — are deposited in a mixture in each well of a microtiter plate typically containing 96 wells. A CCD-camera-based brightfield scanner captures images of each well, and Vitra’s proprietary software recognizes the various bar codes in each well and associates them with the proper cell type, according to the company. Finally, one of a variety of assays — typically fluorescence- or luminescence-based — is performed in each well, and the reader captures images of each well again, thereby allowing researchers to see the results of an assay against several different cell types simultaneously.
The company said that researchers will not only be able to assay against ten different types of cells, but also ten of the same type of cells with each genetically engineered to express different reporter genes, such as mutant forms of specific cell surface receptor genes.
Currently, Vitra is attempting to commercialize ten classes of the cell cards (ten different bar code combinations), which allow researchers to multiplex ten different cell types. However, Bullock said, “we can obviously do much more than that … because of the many different types of combinations.” Bullock added that although Vitra will eventually produce more than ten types of cards, the company felt that ten is appropriate for the current market. “Ten seems to be the sweet spot,” she said.
And although “96 wells” and “high throughput” are usually not associated with one another, Bullock noted that the actual number of data points that researchers obtain is much greater than 96, because researchers can obtain as many as ten data points per well for a potential of 960 data points.
Because the cells are grown as they would be on a cell culture plate, any type of assay that can be performed in that environment can also be performed on the CellCard cells, Bullock said. Possible assays include, but are not limited to, proliferation, cell cycle, apoptosis, cytotoxicity, GPCRs, and kinases.
As far as competition in the marketplace goes, Whitely does not see direct competitors to the CellCard system.
“The CellCard is unique,” Whitely said. “There are other ways people are doing this type of screening, but most of it is done in a sequential manner. Our customers say the same thing. We’re not really high-throughput or high-content. We’re more high complexity or high value.”
So where will the CellCard and CellPlex assays fit into the world of drug screening? According to Whitely, it will be best used in the area of lead optimization.
“Customers are interested in this type of extremely rich data output in the lead optimization phase,” Whitely said. “We’re providing a technology that allows you to take the head libraries that will come from a primary screen — 3,000 to 5,000 compounds — and allows you to rapidly profile all of these compounds right across many targets or cell types … under identical conditions.”
Bullock added that Vitra sees the technology as being more of a follow-up to high-throughput screening groups. “HTS groups are going to generate all the hits,” she said. “And then it’s up to the secondary screening groups to … optimize these assays and get more out of the hits.”
The current protocol for such lead optimization screening is good, Bullock said, but still presents a bottleneck. “Say you have another type of imaging-based platform, and you’re looking at an assay like apoptosis in ten cell lines,” she said. “You’re going to have to do that one at a time, whereas with ours you can do it all on one plate.”
And like many companies attempting to market high-content screening tools, Vitra is attempting to address the issue of drug selectivity — an area that Whitely said researchers in the past may have overlooked a bit in favor of drug potency.
“Users of the technology are saying they really have to step up efforts in looking for selectivity in compounds these days because everybody is haunted by the very high failure rate in the clinic today,” Whitely said. “Many of these failures come because of unforeseen side effects or off-target effects that … were potentially easily screenable if the effort had been put in at an early enough stage.”
As a result, he added, rather than screening against a few different cell types, researchers have recently taken to “screening against ten or twenty, or even a hundred different cell types in order to make very good, watertight decisions about which compounds to push forward to the clinic.”
Vitra will attempt to market its assay technology as an entire platform as opposed to selling only the CellCard technology as a separate entity, Whitely said.
“We think the card technology is really a very high-value component,” Whitely said. “However, the quality that you get from these assays is all about making sure that you can establish the experiments in a robust manner in these screening environments.”
Vitra’s plate reader, dispensing technology, and software are all home-grown, the company said, and each one, particularly the software, is optimized to perform CellPlex assays. The company declined to comment on pricing at this point.
As far as a commercialization time-table goes, Whitely said that it is too early to identify a specific date, but that the company is in “heavy discussion with a number of big pharmas about evaluation and testing of the platform.