* Drug meant for myeloma patients who failed other medicines
* Advisers vote 11-0 in favor
* Shares of Ligand, which gets royalties, up nearly 13 pct (Adds details on data, company comment)
By Anna Yukhananov
SILVER SPRING, Md., June 20 (Reuters) - U.S. drug advisers backed Onyx Pharmaceuticals Inc's drug for patients who have failed to successfully treat their blood cancer with other medicines, making it likely the drug would secure approval from U.S. regulators.
A panel of outside advisers to the Food and Drug Administration voted unanimously to recommend approval of Onyx's drug, to be sold as Kyprolis, for treating multiple myeloma in people who have tried at least two other medicines.
The FDA usually follows panel recommendations, although it is not required to, and will make a final decision by July 27.
Multiple myeloma, a type of cancer that affects the plasma cells in bone marrow, is relatively rare in the United States but often deadly. In 2012, about 21,700 new cases of multiple myeloma will be diagnosed in the United States, and about 10,710 people will die from the disease, according to the American Cancer Society.
Analysts expect the multiple myeloma market to reach $5.4 billion by 2016, with carfilzomib - the chemical name of Kyprolis - garnering about $570 million if it is approved, according to Thomson Reuters forecasts.
Onyx shares were halted during the panel's discussion and vote. Shares of Ligand Pharmaceuticals Inc - a small biotech firm that contributed to Kyprolis and would receive royalties from its sales - closed up 12.8 percent at $14.55.
Panel members said the drug gave people another option to try to beat back the disease.
"I do think this drug is beneficial to this patient population given the limited therapeutic options available," said panel member Dr. Michael Menefee, assistant professor in hematology and oncology at the Mayo Clinic.
The Onyx drug is a proteasome inhibitor with the same mechanism of action as Takeda Pharmaceutical Co Ltd's Velcade, or bortezomib, a commonly used treatment for multiple myeloma available since 2003.
Onyx said about a fifth of all myeloma patients have cancer that no longer responds to standard drugs, leaving room for another option. The company is seeking approval in only those people who have already tried at least two other myeloma treatments, including Velcade and Celgene Corp's Revlimid or Thalomid, known chemically as thalidomide.
About 23 percent of people taking Kyprolis had some response to it during clinical trials, and the response lasted for just under 8 months.
Dr. Richard Pazdur, head of the FDA's office of oncology, said the duration of response was significant, and suggested the drug had a unique way of targeting the cancer.
Onyx submitted its application under a process known as accelerated approval, when a single clinical trial is sufficient to show benefit, as long as the company conducts a follow-up study to confirm the drug actually works. This designation is given to drugs that treat an unmet medical need.
The company tested its drug in 266 patients in a single-arm study, meaning the drug's effects were not compared to any other medicine or to a placebo.
Initial results from a larger study will be available in about a year, and Onyx is also testing the drug in newly diagnosed multiple myeloma patients.
Some panel members said they were nervous about granting approval based on such a small study, especially as the drug was linked to some serious heart, lung and liver side effects, and at least seven people died from the treatment.
In a review posted before the panel meeting, FDA staff said the study's design made it more difficult to decide if the side effects were linked to the drug, or were due to people's underlying cancer or other causes.
But patients who testified during the public comment portion of the meeting said they were happy to endure side effects in exchange for living longer.
Dr. James Omel, the patient representative on the panel, said myeloma patients constantly need new drugs once their disease changes and stops responding to older medicines.
"The thing about carfilzomib is it doesn't cure myeloma," he said. "But it will buy us precious time."
Onyx said it would work with the FDA to bring the drug to patients as quickly as possible. (Reporting by Anna Yukhananov; Editing by Gary Hill, Bernard Orr, Phil Berlowitz)