ProNAi Therapeutics Advances Gene-Silencing Cancer Drug, Marina Biotech Provides Delivery Package

Xconomy Detroit/Ann Arbor — 

A quiet competitor in the gene-silencing game has surfaced with good news. Kalamazoo, MI-based ProNAi Therapeutics says that it’s started to treat cancer patients with its first experimental DNA interference drug, which is essentially made to specifically silence disease at the fundamental level of DNA. And the firm is relying on molecules from Bothell, WA-based Marina Biotech (NASDAQ:MRNA) to deliver the treatment where it needs to go inside cells.

ProNAi‘s drugs are at a much earlier stage in development compared with other gene-silencing methods such as antisense and RNA interference. This is an important trial for ProNAi, as it seeks to gather the first evidence that its drugs work in humans. Now, the firm is testing its lead experimental drug, PNT2258, in patients with tumors for which there are no effective treatments, according to the company. The primary goals of the trial are to show the safety and tolerable dosages of the drug, but it’s also going to give the firm its first glimpse at the effects of its treatment in patients.

The company, which has raised $17 million from investors, has taken a long road get to this point. Founded in 2004, the startup’s novel approach to silencing disease genes has been under development for about as long as RNA interference but has lacked the huge investments and notoriety enjoyed by the latter technology, said Mina Sooch, a managing partner at Apjohn Ventures and an director at ProNAi. The company got the green light from the FDA to start this trial back in March 2008, but has only recently begun enrolling patients because the firm didn’t have enough money until recently.

On the other hand, Cambridge, MA-based Alnylam Pharmaceuticals (NASDAQ:ALNY), a leading developer of RNA-interference drugs, has raised hundreds of millions of dollars and has taken at least three gene-silencing treatments into clinical trials since its founding in 2002. Of course, Craig Mello of the University of Massachusetts and Andrew Fire won a Nobel Prize in 2006 for their discovery of RNA interference, raising the profile of the gene-silencing technology to new heights. (Conversely, ProNAi’s technology was first conceived at Wayne State University by a less well-known scientist named Reza Sheiknejad, who has since moved to Iran, according to Robert Forgey, the firm’s chief operating officer.)

“We’ve spoken to all the big players in this field, and they recognize our idea of silencing genes,” Sooch said. “We’ve actually been working as long as they [RNAi groups] have with probably one-one hundredth of the research dollars.”

ProNAi is developing a drug that uses short pieces of DNA to silence disease-causing genes. A key feature of ProNAi’s treatments is that they are intended to go directly to a region of DNA in cells to block the activity of disease-related genes, while RNA-interference drugs target genetic messenger molecules (or messenger RNA) that play a key role in producing disease proteins. If that doesn’t make sense, think of the firm’s drugs as striking at a different point along a pathway of disease-gene activity than RNA-interference drugs.

While more money has been invested in RNAi than DNAi, both approaches share the same problems of how to deliver the gene-silencing treatments to cells deep in the body. To tackle this delivery challenge, ProNAi has adopted liposomal-particle delivery technology from Marina Biotech. (The Seattle-area biotech, formerly known as MDRNA, acquired the technology in July from Germany-based Novosom for $5 million in Marina common stock.) The drug-delivery technology uses fatty molecules to form liposomes. Those molecules will encapsulate ProNAi’s drug and hopefully carry them into cells, where the drug can travel into the nucleus and silence a tumor gene called Bcl-2. The gene is believed to be a culprit in tumor cell survival, and it’s been shown that it’s overactive in patients with non-Hodgkin’s lymphoma, breast tumors, and other cancers.

The Phase I trial is taking place at South Texas Accelerated Research Therapeutics in San Antonio. ProNAi’s Forgey said that the trial is expected to enroll 20 to 25 patients, and full results from the study are likely to come in the first quarter of 2012.

Meantime, Forgey has nearly finished raising $1 million to pay for the early-stage trial. He declined to disclose who is investing in the financing. Yet the firm’s previous investors include Amherst Fund, Apjohn Ventures, the Michigan Economic Development Corporation, and Sigvion Ventures.

Depending on the success of the firm’s clinical trial, ProNAi might start to attract the kind of attention that Alnylam, Merck-Sirna, and other gene-silencing firms have long enjoyed. If it shows promise, ProNAi’s DNAi won’t be such a quiet cousin to its RNA counterpart.

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