UPDATE 2-US panel rejects Cell Therapeutics lymphoma drug

* Panel votes 9-0 that company trial was inadequate

* FDA usually follows panel recommendations

* Shares fall 57 percent (Adds panel member, company comments, share movement)

GAITHERSBURG, Md., March 22 (Reuters) - Cell Therapeutics CTIC.O suffered a setback on Monday as a U.S. advisory panel said the company had not collected enough data to win clearance for an experimental lymphoma drug.

Advisers to the Food and Drug Administration, in a 9-0 vote, said the company’s single trial of pixantrone was inadequate to back marketing approval.

“I don’t see this as being a well-designed or well-executed study,” said Dr. Wyndham Wilson, a panel member and a lymphoma specialist at the National Cancer Institute.

The company’s shares fell 57 percent to 39 cents in afternoon Nasdaq trading. Shares had been halted ahead of the panel vote.

The panel decision makes it unlikely the FDA will approve pixantrone without additional data. The agency usually follows panel recommendations, and FDA scientists who spoke to the committee also were critical of the company’s study.

Cell Therapeutics wants to sell pixantrone under the name Pixuvri for treating non-Hodgkin’s lymphoma that has stopped responding to other treatments. The blood cancer affects about 66,000 Americans annually.

The company said pixantrone offered an effective therapy for patients whose cancer worsened after at least two prior chemotherapy regimens. Patients at that stage have no approved treatments and often live less than six months.

In the Cell Therapeutics study of 140 patients, 20 percent had a major decrease in their disease if they got pixantrone, compared to about 6 percent with a different medicine.

“It is clear to me pixantrone provides an important benefit in these very poor prognosis patients,” said Dr. John Leonard, a cancer specialist at Weill Cornell Cancer Center and a Cell Therapeutics consultant.

But FDA reviewers questioned the company’s conclusions. They said the study tested less than half the number of people originally planned and included just eight U.S. patients. The agency also said heart damage and decreased white blood cells were more common with pixantrone versus other cancer drugs.

Despite their concerns, several panel members said they saw signs the drug could be helpful and urged additional study.

“This drug has some activity. I don’t think anybody on this committee would debate that point. The population enrolled in this study, however, doesn’t reflect the U.S. population of lymphoma patients,” said Dr. Mikkael Sekeres, an oncologist at the Cleveland Clinic.

In a statement after the panel vote, Cell Therapeutics Chief Executive James Bianco said the company was “committed to working closely with the FDA to address the committee’s comments as quickly as we can.”

“We continue to believe that pixantrone should be considered as a treatment option for patients” with aggressive NHL, he said.

A final FDA ruling is due by April 23. Swiss drugmaker Novartis NOVN.VX has an option for a worldwide license to develop and sell the drug.

Reporting by Lisa Richwine