List agrees that MDS patients with a 5q minus deletion are generally lower risk and have a better prognosis than other MDS patients. But that doesn't mean 5q minus patients aren't sick or at risk for death; he cites statistics from medical literature that show these patients, even though they have a low-grade disease, can still have an annual mortality rate as high as 10%.
If List's historical mortality statistics are accurate, then the 7% death rate in the Revlimid study -- again, assuming that analysis is confirmed -- may not be all that unusual. But there are other published medical studies of MDS 5q minus patients that show a longer survival. A study published this year in the medical journal Leukemia by Dr. AAN Giagounidis of St. Johannes Hospital in Germany found median survival of 146 months, or more than 12 years, for this population of MDS patients. That's roughly double the median survival implied by List's 10%-per-year annual mortality statistic.
The best way to measure efficacy and safety of any drug, of course, is to conduct a large, randomized, controlled study in which some patients receive the drug and others receive a placebo. However, that is something Celgene chose not to do with Revlimid in these low-grade MDS patients. If the death rate in the Revlimid study does become a point of concern for regulators, the lack of good control data in which to assess Revlimid's safety might be the factor that forces the FDA to delay approval.
The outlook for Revlimid in low-grade MDS patients is further clouded by the fact that these patients can be treated with blood transfusions or with Vidaza, a drug marketed by Pharmion (PHRM) that was approved earlier this year for all forms of MDS.Celgene spokesman Gill says it is a mistake to consider 5q minus MDS patients less sick or not in urgent need of new therapies like Revlimid, and he cites a specific example: An MDS patient with the missing 5q gene identified by Celgene required weekly blood transfusions in order to keep his MDS under control. After taking Revlimid for two years, this patient is completely free of the need for transfusions and expects to live a normal, healthy life as long as he continues to take Revlimid, says Gill. List believes Revlimid is an active drug and approvable by the FDA. "This will be a good package for possible approval, there is nothing excessive here at all." Celgene has previously stated that it would release data from an analysis of this phase II Revlimid study in 5q minus MDS patients at a corporate event planned in conjunction with the American Society of Hematology annual meeting, which runs Dec. 4-7. But since this particular Revlimid data presentation will not be under the formal auspices of the medical meeting, the breadth and depth of the information Celgene will release is not clear.