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EPO Upholds Stay on Mirrx Patent Proceedings as Santaris Pushes Ahead with HCV Rx

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By Doug Macron

The European Patent Office last week upheld a request by Santaris Pharma to stay a review of a patent application at the heart of a Danish legal battle with Mirrx Pharma, stating that it would not be appropriate to make a decision on the IP until the litigation had been resolved.

"Taking all filed information and arguments into account, the [EPO's] legal division does not intend to resume proceedings … at this state," the patent office wrote in a letter to Mirrx, which owns the intellectual property.

Meanwhile, Santaris said earlier this month as part of its financial report for the first half of 2010 that its microRNA-targeting hepatitis C treatment miravirsen, whose development has become a key issue in the litigation with Mirrx, is poised to enter phase II testing before the end of the year.

Earlier this year, Santaris sued Mirrx and its founder, Thorleif Moller, for allegedly using illegally obtained trade secrets to file European patent applications on a miRNA-inhibiting technology with therapeutic applications (GSN 5/6/2010).

As part of its gambit, Santaris also successfully petitioned the EPO to stop its review of a key Mirrx patent application, EP 07817970, pending a decision on the lawsuit, which seeks ownership of the IP.

The legal row centers around Mirrx's so-called Blockmir technology, which the company describes as steric antisense oligos that bind to specific miRNA target sites, preventing regulation of a particular messenger RNA.

Blockmirs "do not recruit any cellular enzymes which mediate degradation of target mRNAs … [so if they do] bind to a non-intended RNA, it will only cause an effect if it prevents binding of a [miRNA] or another cellular factor," an unlikely event, reducing the possibility of off-target effects, the company notes.

In its lawsuit, Santaris said that Moller had at one time worked for a patent firm that filed patent applications for the company related to the use of the drug shop's locked nucleic acid technology for creating oligonucleotides capable of binding to miRNAs, and participated in the handling of at least one of the applications.

Shortly thereafter, Moller filed his own patent applications on the Blockmir technology, which are based on inventions made at Santaris, the company added.

In a court filing, Moller denied the charges and argued that Mirrx's technology is fundamentally different from the Santaris technology since it prevents a miRNA from binding to a single target, rather than all its targets. He further alleged that Santaris' suit is an attempt to gain control of a technology that would allow the company to avoid infringing IP held by competitor Regulus Therapeutics.

Both Santaris and Regulus are developing hepatitis C drugs targeting miR-122, but Regulus holds the exclusive rights to US patent No. 7,307,067, which covers the regulation of the miRNA as an HCV treatment and is fundamental for developing such a drug.

In an April letter to the EPO seeking a resumption of the patent application-review proceedings, Moller said that not only does Santaris' miravirsen (formerly SPC3649) fall under the claims in the '067 patent, but because the drug inactivates miR-122, which has been shown to be a tumor suppressor, treatment with the drug "entails a serious cancer risk."

Moller alleged that these issues came into play when Santaris partner GlaxoSmithKline opted against taking a license to miravirsen, and instead partnered with Regulus on the development of a miR-122-targeting drug for HCV (GSN 12/3/2009 & 2/24/2010).

"Thus, apparently GlaxoSmithKline did indeed come to the conclusion that [miravirsen] is dominated by IP held by Regulus," Moller wrote.

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Importantly, Moller's inventions "provide an alternative to … [miravirsen] for … HCV," but are "not covered, described, or even hinted at in any patent applications or patent preceding the earliest filing dates" of the Blockmir IP, he stated in his letter to the EPO. As such, Santaris is seeking to gain control of the Blockmir technology through litigation to save its miR-122 program.

As far as the stay on the '970 patent application, Moller told the EPO that the only advantage of its continuation would be to interrupt the time limits on filing divisional applications. While favorable since the application "can potentially be divided into hundreds of divisional applications … even this significant advantage does not come close to outweighing the disadvantages of a stay."

Lifting the stay would not adversely affect Santaris, in part, since the company aims to take control of the IP through its lawsuit.

In the end, though, the EPO has opted to leave the stay in place.

"The legal division is of the opinion that the dispute before the Danish … court is an entitlement dispute … and the balance of interests is not clearly in favor of the [intellectual property's] applicant in the sense that proceedings should be resumed," the EPO said in its letter to Mirrx. "The legal division of the EPO is neither competent nor qualified to decide which party the [patent] application might belong to or which outcome of the … dispute seems more likely."

1H 2010

While Santaris' dispute with Mirrx proceeds, so too does its development of miravirsen.

The company noted in its report for the first half of 2010 that the drug continues to be evaluated in a phase I study of healthy volunteers and that phase II development is expected to begin in the second half of 2010.

Meanwhile, the company posted a jump in losses for the first half of the year to DKK60.3 million ($10.3 million) from DKK34.4 million in the same period the year before.

Contributing to the higher losses was a rise in research and development spending to DKK77.3 million from DKK60.2 million as the company expanded its pipeline, along with a drop in revenues to DKK26.9 million from DKK28.7 million.

As of June 30, the company had cash and cash equivalents totaling DKK85.8 million, which is expected to be sufficient to fund its operations "beyond 2010," although Santaris said it has "initiated various activities related to securing future funding through partnering and/or [the issuance] of new shares."

Looking ahead, Santaris expects its full-year 2010 loss to be in the range of DKK90 million to DKK100 million.

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