Imatinib-induced regression of AIDS-related Kaposi's sarcoma.
OBJECTIVE
Activation of the platelet-derived growth factor (PDGF) and c-kit receptors has been proposed as important in mediating the growth of AIDS-related Kaposi's sarcoma (KS). We investigated the response of KS to the PDGF receptor (PDGFR)/c-kit inhibitor, imatinib mesylate, and investigated the effect of this therapy on critical signal transduction intermediates.


METHODS
Ten male patients with AIDS-related cutaneous KS, which progressed despite chemotherapy and/or highly active antiretroviral therapy, received imatinib mesylate administered orally, 300 mg twice daily. Clinical response was determined by serial tumor measurements. To determine biologic and histologic response, skin lesion biopsies were obtained at baseline and following 4 weeks of therapy.


RESULTS
Five of 10 participants had a partial response by tumor measurements. Biopsies after 4 weeks of therapy demonstrated histologic regression in four of six patients. Four patients' tumor biopsies were assessable for immunohistochemistry end points pre- and post-therapy. These demonstrated inhibition of PDGFR and its downstream effector, extracellular receptor kinase, which is a member of the mitogen-activated protein kinase family. The most common adverse event was diarrhea, which led to dose reduction in six patients.


CONCLUSIONS
Imatinib mesylate administered orally twice daily for AIDS-related KS results in clinical and histologic regression of cutaneous KS lesions within 4 weeks. These promising results demonstrate that inhibition of the c-kit and/or PDGF receptors may represent an effective strategy for treating KS.
Koon
Henry B
HB
Beth Israel Deaconess Medical Center, 330 Brookline Ave, CC-913, Boston, MA 02215, USA.
Bubley
Glenn J
GJ
Pantanowitz
Liron
L
Masiello
David
D
Smith
Brad
B
Crosby
Katherine
K
Proper
Joann
J
Weeden
Will
W
Miller
Thomas E
TE
Chatis
Pamela
P
Egorin
Merrill J
MJ
Tahan
Steven R
SR
Dezube
Bruce J
BJ
D017088:AIDS-Related Opportunistic Infections / Q000188:drug therapy*; D000284:Administration, Oral; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D001549:Benzamides; D001706:Biopsy; D003967:Diarrhea / Q000139:chemically induced; D005500:Follow-Up Studies; D006801:Humans; D000068877:Imatinib Mesylate; D008297:Male; D010865:Pilot Projects; D010879:Piperazines / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D019009:Proto-Oncogene Proteins c-kit / Q000187:drug effects; D011743:Pyrimidines / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D017479:Receptors, Platelet-Derived Growth Factor / Q000037:antagonists & inhibitors; D012074:Remission Induction; D012514:Sarcoma, Kaposi / Q000188:drug therapy*; D015398:Signal Transduction / Q000187:drug effects; D012878:Skin Neoplasms / Q000188:drug therapy*; D042461:Vascular Endothelial Growth Factor A / Q000097:blood
D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D042461:Vascular Endothelial Growth Factor A; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases; D019009:Proto-Oncogene Proteins c-kit; D017479:Receptors, Platelet-Derived Growth Factor