A phase III clinical trial for oblimersen (trade name: Genasense), the first "antisense" drug to be tested in chronic lymphocytic leukemia (CLL), shows promise as an adjunct therapy to chemotherapy drug fludarabine.

Oblimersen is an experimental agent that inhibits the production of a protein known as Bcl-2 in cancer cells. This protein can stop a cell from destroying itself, and is often over-expressed in cancer. As an antisense drug, oblimersen provides a complementary genetic strand to the messenger RNA that produces Bcl-2, inactivating it and preventing the protein from being produced. "It gets rid of Bcl-2, and cells that have less Bcl-2 are more sensitive to chemotherapy," O'Brien says.

According to the results, oblimersen produced a four-fold increase in CP/nPR, a clinical response defined by no definitive evidence of disease among patients who were sensitive to the chemotherapy drug fludarabine. In addition, survival was found to be three or more years in 70 percent of the patients in the oblimersen group compared with 38% in the chemotherapy-alone group. According to the researchers, oblimersen may represent a new treatment option for this subset of CLL patients whose disease has progressed, but who are still sensitive to chemotherapy.

Source: UT MD Anderson Cancer Center