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Digital PCR a Priority for RainDance Following $37.5M Financing


By Ben Butkus

RainDance Technologies this week said that it has closed a $37.5 million Series D financing round, and that it will use part of the proceeds to ramp up development and commercialization of its digital PCR platform.

If development occurs as planned, the company hopes to be taking pre-orders for the product by the end of this year, RainDance President and CEO Roopom Banerjee told PCR Insider this week.

In the meantime, RainDance is busy forging collaborations with academic and industrial entities to further refine the technology and identify and develop new applications in the areas of oncology, infectious disease, and immune monitoring, Banerjee said.

RainDance will also use its most recent cash infusion to drive new applications for its commercial targeted sequencing and sequence-enrichment products in the medical genetics and research markets; and to develop a product for single-cell genetic analysis. The company said it will also use the funds to develop and to grow its global sales and support infrastructure.

At the core of all of RainDance's current and future products is its RainStorm technology, which uses oil and surfactant chemistry to generate picoliter-volume droplets at a rate of 10 million per hour with as little as 1 percent variation in droplet size.

The company's flagship product, the RDT 1000, uses the RainStorm technology to amplify hundreds to thousands of genomic loci with high specificity and uniformity for targeted resequencing applications.

Last summer, Banerjee suggested in an interview with PCR Insider that the company was considering applying its microdroplet technology in the area of digital PCR, a technique in which a nucleic acid sample is partitioned into small, individual PCR reaction volumes. This allows the amplification of extremely small amounts of genetic material such as single transcripts or DNA from single cells, which can be useful for applications such as rare event detection and copy number variation analysis (PCR Insider, 7/8/2010).

At the time, Banerjee was somewhat coy about his company's foray into this area, saying that RainDance had to that point demonstrated feasibility of digital PCR in house and was "actively looking" at the space. This week, in the wake of its Series D financing, Banerjee confirmed that digital PCR is now one of several new product priorities for the company.

"We have largely been in stealth mode, because we wanted to make sure we had the kind of claims and performance and capabilities that would give us a large and sustainable lead in the market for the foreseeable future," Banerjee said this week. "I think we've certainly validated that."

Banerjee said that the company plans to launch a new instrument for digital PCR at a price point that is "very competitive with other leading solutions on the market." Until late last year, Fluidigm had been the only real player in the digital PCR space, with its microfluidic array technology. However, other recent entries into the field include platforms from Life Technologies, which leverages technologies acquired from several companies; and QuantaLife, which uses emulsion-generated microdroplet technology.

According to Banerjee, RainDance is in the process of developing a single-molecular digital PCR instrument that enables interrogation of more than 1 million droplets at a time with between five and six logs of dynamic range.

"When you look at [Fluidigm, Life Technologies, and QuantaLife] in terms of sensitivity, they all claim sort of in the one-in-3,000 to one-in-10,000 sensitivity range; and we're talking about coming out of the gates at between one in 100,000 and one in a million sensitivity. That's where we get the five or six logs of dynamic range. There is no other technology out there today that can achieve that level of resolution."

Banerjee said the upshot of this is a "significant difference" in the ability to resolve mutants from wild types in a heterogeneous background, which is the sweet-spot application for digital PCR.

"Also, this is true single-molecule, and absolute quantitation, because we generate drops one at a time, but obviously at very high speeds," Banerjee added. "But we also count and visually quantitate every individual droplet one at a time." This capability is important for CNV analysis, certain gene expression applications, certain structural variation applications, "and potentially even for microRNA analysis," Banerjee said.

To complement its microdroplet-generation technology, RainDance has over the last several years developed proprietary "high-end optics" around which the company has filed intellectual property claims. "We've worked with outside engineers … to really advance the state of our technology there," he said. "Our system, because of the small droplet size, high speed, and ultra-sensitive resolution, does require very high-end optics in terms of detection."

RainDance has not disclosed a development and commercialization timeline for the digital PCR platform, "although we have a very well-defined plan in place," Banerjee said. At the JP Morgan Global Healthcare Conference earlier this month in San Francisco, Banerjee told potential investors that the company would likely unveil more details about the product in November around the American Society for Human Genetics annual meeting.

"We anticipate that we will be taking pre-orders by the end of the year," he added.

Banerjee said that the development of RainDance's digital PCR platform is on "a parallel path" with its other new product areas, such as a single-cell analysis platform and new applications for targeted sequencing and sequence enrichment.

"The move to digital PCR and ultimately single-cell analysis really represents the future of the company," Banerjee said. "The targeted resequencing market is very attractive because it allows us to leverage the strength and growth in the next-generation sequencing market, and lets us take advantage of the fact that we can generate 2 million PCR reactions in the space that's normally doing one."

To illustrate this point, Banerjee reiterated data he presented at the JP Morgan Healthcare Conference. "To put this into perspective, in order to do 2 million reactions it would take you 200,000 thermal cyclers working with 96 samples per cycler, and it would take eight straight weeks running 24/7 and would cost $1 million." Banerjee said that for targeted resequencing applications, RainDance's technology enables the same number of reactions "in one test tube, in 45 minutes, for under $500."

RainDance's Series D financing was co-led by new investor Quaker Bio Ventures and existing investor Mohr Davidow Ventures. Existing investors Alloy Ventures and Acadia Woods also participated in the round.

As part of the transaction, Sherrill Neff from Quaker Bio Ventures and Jeffrey Samberg from Acadia Woods will join RainDance's board of directors.

Have topics you'd like to see covered in PCR Insider? Contact the editor at bbutkus [at] genomeweb [.] com.