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Researchers from Europe have reported that Sprycel® (dasatinib) is effective therapy for patients with Philadelphia chromosome-positive (Ph-positive) leukemia that involves the central nervous system (CNS). The details of this study appeared in an early online publication in Blood on May 13, 2008.1
Gleevec is the standard initial treatment of newly diagnosed Ph-positive chronic myeloid leukemia (PH+CML). Gleevec produces high rates of complete cytogenetic responses (70-85%) and of major molecular responses (20-40%) and has improved progression-free and overall survival. However, Gleevec does not eradicate the BCR-ABL clones in most patients as detected by polymerase chain reaction (PCR) monitoring. Furthermore, a small but significant fraction of patients will develop Gleevec-resistance or are intolerant to the drug. Patients who fail or are intolerant to Gleevec now have treatment alternatives other than allogeneic stem cell transplantation.
Sprycel and Tasigna® (nilotinib) are two new agents that have been developed for the treatment of patients with BCR-ABL-positive CML and acute lymphoblastic leukemia (ALL); these agents appear to have great promise for the treatment of patients who fail Gleevec. Sprycel and Tasigna are both approved by the U.S. Food and Drug Administration for treatment of patients who fail or are intolerant to Gleeevec. Other tyrosine kinases are under development and being tested in the clinic. Studies are beginning to determine if Sprycel or Tasigna may be superior to Gleevec for the initial treatment of newly diagnosed patients with CML.
One of the problems with Gleevec is that it does not penetrate the blood-brain barrier. Researchers involved in the current study stated that preclinical studies have shown that Sprycel is more effective than Gleevec for treatment of CNS PH+CML. They also report significant drug activity in 11 patients with CNS Ph+leukemia. All patients responded, and seven of 11 had complete, long-lasting responses. They also presented data that shows that Sprycel-treated patients can develop isolated metastases in the CNS that have resistant clones, suggesting penetrance into the CNS.
Comments: These data suggest that patients with CNS PH+CML or ALL should be treated with Sprycel.
