The Appeal of Genasense: The drug, the data, and the tangled web that its FDA review has become

At some point—probably in the very near future—there will be a final decision by the U.S. Food and Drug Administration (FDA) about whether Genta’s antisense agent Genasense® (oblimersen sodium) will be approved for the treatment of relapsed/refractory chronic lymphocytic leukemia (CLL). In the meantime, the review process has become an increasingly tangled web of data, assertions, and upset. Many healthcare professionals feel that the drug warrants approval and that the FDA’s treatment of Genasense has been too harsh.

Among the concerns raised by the ODAC members was their preference for progression-free survival (PFS) as an endpoint. The committee also asserted that the patients likely to benefit had not been clearly identified, and that the potential number of patients who would benefit did not warrant the approval of an expensive drug.

According to Genta, and many CLL experts, the FDA’s rejection of Genasense at that time was, simply, wrong. Patients have voiced their concerns, too.

According to the most recent findings (ASH abstract 751), which have been submitted to the FDA as part of the appeal, patients in the triple combination arm achieved a complete response (CR) rate of 17 percent, compared with a CR rate of 7 percent among patients treated with chemotherapy alone, a statistically significant difference.

The new data may be enough to warrant approval by the FDA. But the larger question of whether the agent should have been approved in the first place still looms, as do issues other than data that may have influenced the original decision.

Regardless of the outcome, the saga of Genasense raises crucial questions about the FDA review process. These issues extend well beyond this one drug: as is widely known, the FDA review of Dendreon’s immunotherapy Provenge® is now under serious investigation.

In its genuine efforts to ensure drug safety, is the FDA preventing drugs from reaching the patients who could be helped? Are there political reasons behind the FDA’s decisions to approve or reject drugs, and if so, what are they? Are drug applications such as these being used to set a precedent, rather than being evaluated for their own merit? Is the FDA weighing cost too heavily in its considerations of benefit?

Numerous CLL patients have already been helped by Genasense, and there is a clear desire among experts and patients alike that this drug be made available. At some point, the outcome of the Genasense application will be made clear. But its hard-to-treat side effects—the questions and issues raised during the review process—remain.

Note: A full length version of this article was published in the January issue of OBR.

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