The U.S. Food and Drug Administration (FDA) has granted accelerated approval for Sprycel (dasatinib), a new oral treatment for patients with chronic myeloid leukemia (CML), a rare cancer characterized by the uncontrolled growth of white blood cells. CML affects about 4,600 people annually in the United States.
In addition, the FDA gave regular approval to Sprycel for use in the treatment of adults who have Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL), a more serious form of leukemia. Both approvals are for patients who have experienced resistance or intolerance to prior therapy.
Sprycel is intended for patients with CML who are no longer responding to, or who can no longer tolerate, therapy with Gleevec (imatinib), a drug approved in 2001 for this life-threatening disease. This new treatment option works by reducing the activity of one or more proteins responsible for the uncontrolled growth of the leukemia cells. SPRYCEL treatment has been shown to reduce, and in some cases eliminate, detectable leukemia cells in the blood and bone marrow of patients with CML. As provided for under FDA accelerated approval regulations, studies are underway to demonstrate that these improved white blood cell counts also result in clinical benefit such as improved survival or improvement in leukemia-related symptoms.
"Sprycel offers an important alternative for patients with Ph + ALL whose disease has not responded to or has stopped responding to other therapies," said Dr. Steven Galson, Director of FDA's Center for Drug Evaluation and Research. "Although the long term benefits of Sprycel in CML are not yet known, early studies have suggested that Sprycel may offer a significant improvement for many patients whose disease is resistant to other therapies; however, further data from ongoing studies are needed to evaluate whether Sprycel provides an actual clinical benefit in CML."
Sprycel is considered an orphan drug for each of these indications. Under the Orphan Drug program, sponsors of medications intended for fewer than 200,000 patients in the United States can receive seven-year marketing exclusivity, tax credit for the product-associated clinical research, research design assistance by FDA and grants of up to $200,000 per year.
The approval of Sprycel is based on evidence from four single-arm studies in more than 400 patients who were no longer responsive to or tolerant of treatment with Gleevec. The efficacy of Sprycel was determined by the response rate, defined as the percent of patients in whom treatment resulted in the elimination of detectable leukemia cells or a significant reduction in the number of leukemia cells. Responses were measured primarily in the bone marrow for those patients with the earliest stage of disease, and in the blood for those patients with later stage disease. For patients with the earliest stage of CML (chronic phase), treatment with Sprycel resulted in response in 45% of patients. Response rates for patients with advanced phases of CML and for Philadelphia chromosome-positive ALL ranged from 31 to 59 percent. Most patients who had a response to Sprycel remained so six months after they began taking Sprycel.
Side effects reported in these trials included fluid retention, bleeding, diarrhea, skin rash, infections, headache, fatigue and nausea. Sprycel also frequently causes low red blood cell counts (anemia), low white blood cell counts (neutropenia) and low platelet counts (thrombocytopenia). Sprycel is manufactured by Bristol-Myers Squibb Company, Princeton, N.J.