A new clinical study has shown that imatinib mesylate (Gleevec) has activity in AIDS-related Kaposi's sarcoma (KS). Imatinib inhibits important pathways that spur cancer growth, resulting in the regression of KS tumors within 4 weeks in some patients. The study will be published November 30 in the Journal of Clinical Oncology (JCO).
"Imatinib is a targeted therapy originally shown to be effective in treating chronic myelogenous leukemia and gastrointestinal stromal tumors. This study and others are showing that the drug is also active in other cancers that express some of the same proteins," said Henry B. Koon, MD, Instructor of Medicine, Beth Israel Deaconess Medical Center/Harvard Medical School in Boston, and lead author of the study. "Studies like this one represent an exciting time in oncology, when our understanding of the development of diseases like KS coincide with the availability of effective treatments. Further research on imatinib in KS patients will be needed to determine appropriate dosing schedules."
Kaposi's sarcoma is an AIDS-defining illness characterized by soft purplish lesions on the skin, mucous membranes, and internal organs. Although the incidence of KS has declined dramatically in the developed world since the advent of highly active antiretroviral therapies (HAART), it remains a significant cause of morbidity and mortality for AIDS patients in the United States and a major cause of mortality in the third world, given the limited number of effective treatments for KS.
Researchers examined the response of Kaposi's sarcoma to imatinib, a drug known to inhibit the PDGF-R and/or c-kit pathways that are responsible for the growth of other cancers, such as chronic myelogenous leukemia, gastrointestinal stromal tumors (GIST), and bone sarcomas of the head and neck. Given that PDGF-R and c-kit also play a role in the development of KS, researchers theorized that imatinib may be an effective strategy for treating the disease.