United Therapeutics Drops Ovarian Cancer Compound Following Phase III Failure

With cancer pipeline empty, firm tells DAILY it will focus mainly on planned 2008 NDA for hypertension treatment Viveta.

United Therapeutics Corp. announced Dec. 5 that it has ceased development of advanced ovarian cancer agent OvaRex (oregovomab) after two Phase III trials of the therapy failed to reach statistical significance.

Oregovomab is one of five investigational immunotherapeutic monoclonal antibodies the Silver Spring, Md., company's Unither Pharmaceuticals subsidiary licensed in 2002 from AltaRex Medical Corp.

Unither Deputy General Counsel and Senior VP-Investor Relations Andy Fisher told the "The Pink Sheet" DAILY his firm has given up on the entire platform of antibodies acquired in that deal and will terminate the licensing agreement.

The decision leaves the company's pipeline without any oncology therapies, Fisher conceded, but the firm still will pursue the cancer market.

"The short answer is we look at different opportunities all the time and different diseases, and oncology is definitely an area we want to stay involved in," he said. "Our company mission statement is to develop therapies in areas of unmet medical need and specifically in orphan conditions, and that squarely fits within the oncology area."

Unither conducted two identical Phase III trials, IMPACT I and IMPACT II, designed to confirm data from a prior Phase II study that indicated the compound could extend the time-to-relapse in ovarian cancer patients who had completed front-line therapy successfully.

The randomized, double-blind, placebo-controlled studies enrolled 367 patients during the so-called "watchful waiting" period following carboplatin and paclitaxel-based chemotherapy. The results showed no significant difference between the control group and those receiving oregovomab, however.

The company said further review of the trial data is ongoing and full results will be presented at an upcoming medical meeting and published in a peer-reviewed journal.

In a Dec. 6 statement, Unither Senior VP-Clinical R&D Christopher Nicodemus called the outcome surprising.

"The IMPACT trials, which were well designed and rigorously conducted, indicate that the approach of triggering tumor-specific immunity using a murine monoclonal antibody has its challenges," he said.

United Therapeutics said it is determining the exit costs of dropping the investigational antibodies program. The company has roughly $7 million in assets related to the program that are subject to write-down during the fourth quarter of 2007.

With the termination of OvaRex, United Therapeutics' main focus going forward will be preparing an NDA for Viveta , the inhaled version of its treprostinil compound Remodulin , for pulmonary arterial hypertension. The company currently markets treprostinil sodium in injectable and intravenous form for PAH.

Last month, United Therapeutics reported that a Phase III trial (TRIUMPH-1) of Viveta demonstrated efficacy by measuring the change in six-minute walking distance at 12 weeks of peak exposure, relative to baseline, 10 to 60 minutes after inhalation of the drug.

"The outcome was highly statistically significant, so we are in the process of preparing a filing that we would hope to be able to submit to the FDA sometime before June 2008," Fisher told the DAILY.

If approved, Viveta will join Remodulin as add-on therapy for PAH, he explained, rather than competing directly with first-line drugs.

"I don't think an inhaled therapy like Viveta is positioned in the PAH marketplace as a competitor to the front-line oral therapies available like Tracleer [Actelion's bosentan] or Revatio [Pfizer's sildenafil] or Letairis [Gilead's ambrisentan]," Fisher said. "It's more accurate to say that doctors will likely use it as a second-line therapy or as an add-on therapy to those frontline therapies. In fact, that's how we studied it, as an add-on therapy or in combination with some of those oral treatments."

-Joseph Haas ([email protected])