Antisense suffers new setback
On September 6 the Oncologic Drugs Advisory Committee of the US Food and Drug Administration (FDA) voted 7–3 not to recommend approval for Genta's Genasense for the treatment of chronic lymphocytic leukemia. It was the second such rejection of the antisense drug, after failure in melanoma in 2004, and another setback for the struggling field of antisense therapy. Although the drug, which targets Bcl-2, shrank more tumors than chemotherapy alone, patients did not live longer. Meanwhile, phase 3 trials of Genasense continues for acute myeloid leukemia. Since the 1998 FDA approval of Isis Pharmaceuticals' Vitravene (fomivirsen) for treating certain viral eye infections in AIDS patients, no other antisense drug has reached market, and the list of clinical failures is long. Several companies have exited the field. Other RNA-based therapies, especially siRNA, have now overtaken antisense in popularity. “One of these types of compounds...will make it,” predicts Brian Rye, an analyst with Janney, Montgomery Scott in Philadelphia. “I just don't know if it will be something that prospectively has got the label of antisense.” KG
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