Sonus Pharmaceuticals yesterday began enrolling women with metastatic breast cancer for an 800-patient, $40 million trial of its leading...

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Sonus Pharmaceuticals yesterday began enrolling women with metastatic breast cancer for an 800-patient, $40 million trial of its leading chemotherapy drug candidate.

Tocosol paclitaxel, an easier to use and better tolerated version of the widely prescribed cancer treatment paclitaxel, would compete in the largest category of chemotherapy drugs.

The Bothell-based company is going up against pharmaceutical giants with established drugs and smaller biotechs pursuing new products, including Cell Therapeutics of Seattle, in a market worth an estimated $2.5 billion.

Sonus’ stock moved up more than 9 percent yesterday to close at $4. The company’s shares have traded between $2.15 and $5.04 in the past year.

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Sonus will compare how patients respond to weekly doses of Tocosol or Taxol, a market-leading product of Bristol-Myers Squibb. It will also study patient survival and the cancer’s progression over three years. Patient enrollment is expected to be complete by next summer.

Matthew Kaplan, an analyst with Punk Ziegel & Company, which has done investment banking for Sonus, said designing the trial around weekly doses of the drugs is a “pretty savvy” way to showcase one expected advantage.

The established drug Taxol is approved for dosing at three-week intervals but frequently is given on a weekly basis, he said. That intensity carries with it side effects that are usually more than a patient can handle without a break, known as a “drug holiday.”

“What Sonus has shown in their [previous] studies is that they can dose consistently without drug holidays on a weekly basis,” he said.

Sonus’ drug is designed to deliver more chemotherapy with fewer side effects.

The company says it also can be stored, transported and prepared easily and takes less time to administer: 15 minutes compared with one to three hours for competitors.

The results of the trial, to be conducted at about 150 clinical sites, will be important in distinguishing Tocosol from other taxanes, which inhibit growth of cancer cells.

Tocosol, if approved for use, would face competition not only from established products like Taxol and French pharmaceutical giant Sanofi-Aventis’ Taxotere but also from American Pharmaceutical Partners’ recently approved Abraxane, and possibly more reformulated taxane products.

“If the data they produce convinces oncologists that this is a superior alternative to Taxol and even Taxotere, they could enjoy some major success in that market,” said Vinny Jindal, a senior biotech analyst with Wedbush Morgan Securities.

Jindal covers Sonus and two of its competitors but has no financial interest in any of them.

Sonus Chief Executive Michael Martino said in an interview yesterday that he does not view the taxane market as crowded.

“Even if competitive products get approved,” he said, “there will continue to be unmet medical needs that our product addresses.”

Benjamin J. Romano: 206-464-2149 or bromano@seattletimes.com