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Mirna Closes $34.5M Series C Round as microRNA Drugs Gain Investor Interest

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Mirna Therapeutics this week announced that it has closed a Series C round of financing, raising $34.5 million in what is the microRNA therapeutics field's biggest single round of private investment.

According to Mirna's top official, the cash infusion will give the firm resources enough to advance its lead drug candidate, the liver cancer treatment MRX34, through phase II testing — a key inflection point as these trials are expected to yield solid proof-of-concept data.

Coming on the heels of other recent financings, as well as Regulus Therapeutics' initial public offering earlier this month, the Series C also suggests that there is strong interest in miRNA drugs despite the highly publicized departures of two big pharmas from the oligonucleotide therapeutics space.

Mirna was founded in 2007 as a spinout of Asuragen and, unlike most other miRNA drug shops, is developing mimics of the small, non-coding RNAs, rather than inhibitors of them. With a core interest in oncology, Mirna has been primarily focused on advancing the liver cancer therapy MRX34.

The drug is a synthetic version of miR-34a, an miRNA that is down-regulated in a number of cancers and which is associated with the p53 tumor-suppressor network, formulated with Marina Biotech's Smarticle liposome particle-based delivery technology.

About a year ago, Mirna reported in vivo data showing that the drug, as well as other miRNA mimics, could significantly inhibit tumor growth (GSN 11/17/2011). That same year, the company published data showing that its miR-34a mimic reduced tumor burden in mouse lungs when administered systemically (GSN 3/24/2011).

Despite the promising findings with other compounds, Mirna has generated the most data with MRX34, while building an intellectual property portfolio around the drug (GSN 4/7/2011), and getting the drug into human testing has been a key goal for years.

The company, however, has fallen short of expectations when it comes to the timing of clinical trials. For example, in early 2010, Mirna President and CEO Paul Lammers had predicted an investigational new drug application for MRX34 would be filed with US regulators before the end of 2011 — a milestone never reached (GSN 1/14/2010).

At the same time, the company ran into difficulties getting the funding needed to begin clinical studies. In mid-2010, Lammers said Mirna was nearing the completion of a $25 million Series B round, but by early 2011, he pushed that timeline back (GSN 6/24/2010 & 1/20/2011). In the end, the Series B closed in August 2011, raising $1.5 million — just enough to carry the company through IND-enabling studies (GSN 8/25/2011).

But this week, Mirna nailed down the field's biggest single financing round to date, getting $34.5 million from existing investors, as well as new ones including Pfizer Ventures.

According to Lammers, getting such a major cash infusion stemmed from the decision that solid clinical data would be needed to drive money-making deals like product licensing arrangements and big pharma partnerships, and that meant getting into phase II.

“That's why we came up with the idea to put this kind of money together,” which is expected to fund two phase I trials and one phase II study of MRX34, he told Gene Silencing News this week.

Lammers said that Mirna aims to file an IND to begin in early 2013 a phase I safety study of MRX34 in patients with advanced solid tumors with liver involvement, with patient dosing beginning shortly thereafter. As that trial progresses, the company anticipates identifying which cancers are most responsive to the miRNA drug, and adding additional patients with those diseases.

Mirna is also planning to run a follow-on phase Ib trial, examining MRX34 in combination with standard cancer therapy, he noted.

“We think that this drug by itself will be phenomenal,” he said. “But we also know that, for many cancers, combination with either standard chemotherapy, targeted therapy, or radiation might very well [have] great promise, as well.

“We try to maximize the potential of these microRNA therapeutics,” Lammer said.

Big Money

With its Series C, Mirna has moved to the head of the pack in terms of miRNA drug companies pulling in private equity. Still, the other players in the field have attracted a lot of interest.

For instance, in April this year, Miragen Therapeutics raised $20 million in a Series B round (GSN 4/26/2012). In June, Santaris Pharma, which develops more than miRNA-targeting drugs but whose most advanced clinical candidate inhibits miR-122, pulled in $12 million in private investment (GSN 6/21/2012).

In late 2011, Groove Biopharma raised $6 million in a Series B to help fund development of its miRNA inhibitors (GSN 12/15/2011).

Most notable was Regulus' IPO this month, which raised $45 million for the company despite a reduced offering price (GSN 10/4/2012).

And while there has been some suspicion about the oligo therapeutics market since Roche and Pfizer ended their in-house work in the field, miRNA drug companies have been relatively successful in attracting partners, in addition to financing.

Regulus tops the listing with allies including Sanofi, GlaxoSmithKline, and AstraZeneca, but Miragen last year landed France's Les Laboratoires Servier as a partner for its cardiovascular programs outside the US and Japan (GSN 10/20/2011).

“There is a lot of great momentum gathering,” Lammers observed.

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