Relapsed chronic lymphocytic leukemia (CLL) patients who had a complete response to combination therapy that included the drug oblimersen survived significantly longer than patients treated with chemotherapy alone, a team led by researchers at The University of Texas M. D. Anderson Cancer Center reports at the 49th Annual Meeting of the American Society of Hematology.
Patients who achieved a complete response with oblimersen have survived so well that a median survival time cannot yet be calculated, but it is estimated to exceed 49 months. Those who achieved complete response with chemotherapy alone had a median survival time of 35 months.
"In a relapsed population, that's excellent survival," says lead author Susan O'Brien, M.D., professor in M. D. Anderson's Department of Leukemia. "Survival is associated with achieving complete response."
The Phase III clinical trial compared a regimen of fludarabine and cyclophosphamide (F/C) with F/C plus oblimersen. Known commercially as Genasense(r), oblimersen blocks the Bcl-2 protein, which plays a critical role in progression of chronic lymphocytic leukemia (CLL), including development of resistance to treatment.
By stifling Bcl-2, researchers believe CLL becomes more vulnerable to chemotherapy such as the F/C combination.
In a paper published in the Journal of Clinical Oncology in March, O'Brien and colleagues showed that patients who received the oblimersen combination were more likely to have a complete response (20 out of 120 patients, or 17 percent, compared to 8 out of 121 patients, 7 percent, who received only the F/C chemotherapy).