A Food and Drug Administration advisory panel Tuesday recommended that manufacturers of three biotech drugs used to treat rheumatoid arthritis warn patients about a possible link to incurable lymph cancer.
The rival drugs -- Amgen Inc.'s Enbrel, Johnson & Johnson's Remicade and Abbott Laboratories Inc.'s Humira -- are expected to have combined sales in excess of $2 billion this year and are used to treat advanced cases of the disease. The medications already are known to have serious side effects, including higher risk of infection and tuberculosis.
But the FDA panel -- outside experts who meet to review the drugs' safety -- said the link between lymphoma and the three biotech drugs wasn't clear.
Data provided by the drug companies showed that a small number of patients taking the drugs developed lymph cancer. But patients with serious rheumatoid arthritis have a higher risk of lymphoma anyway, the panel said.
"There are not enough numbers to say there's causality, but there's enough to say there may be a signal," said Dr. Steven Abramson, acting chairman of the FDA's panel and head of rheumatology and medicine at New York's Hospital for Joint Diseases.
At the same time, the panel couldn't rule out a cancer link. Clinical trials revealed that less than two dozen out of 8,000 patients treated with the drugs developed lymphoma, compared with none of the patients who received a placebo, they said.
The panel issued its recommendation at the end of a six-hour meeting in Washington. The FDA isn't required to follow the panel's advice but usually does.
Analysts said sales of the drugs probably wouldn't be affected by a warning that applies to all three medications. Michael King of Banc of America Securities said the injectable biotech drugs still compare favorably with the steroids and chemotherapy medications traditionally used to treat advanced rheumatoid arthritis.
The biotech drugs block a molecule called tumor necrosis factor that causes inflamed, painful joints. But the TNF molecule, although partly responsible for the discomfort of rheumatoid arthritis, also is useful because it helps fight infection and possibly cancer.
The recommendation is a setback for Thousand Oaks-based Amgen, which said Enbrel poses no additional lymphoma risk to patients. Dawn Vivesh, vice president of regulatory and safety for the company, said that Amgen would continue to press its case with the FDA.
"In our mind, the data does not support a warning," Vivesh said.
The FDA panel, however, found no statistical difference among cases reported for the three drugs. It said lymphoma can take many years to develop, and that patients should be followed for a long period to determine a link to the drugs. The manufacturers have agreed to track as many as 2,000 patients in clinical trials for five years, but panelist Elaine S. Jaffe of the National Institutes of Health said that was not long enough.
Just six of nearly 3,400 patients on Enbrel developed lymphoma. For Remicade, six of 2,400 patients got lymph cancer. Ten of 2,400 patients on Humira developed the disease.
The panel left it to the FDA to decide how the warning should be worded -- a matter that has marketing implications.
Thomas Schaible, vice president of the Johnson & Johnson unit that makes Remicade, said statistics should not be included. "They are not very informative and could be misleading."
On Tuesday, Amgen's stock closed at $54.12, up 27 cents on Nasdaq. Johnson & Johnson shares fell 74 cents to $51.69, and Abbott closed at $35.46, up 43 cents, both on the New York Stock Exchange.