Effects of imatinib mesylate on adenoid cystic carcinomas

Adenoid cystic carcinomas (ACCs) are rare tumors which most often arise in the salivary glands. They have a propensity for local relapse and tend to metastasize, frequently with a protracted clinical course. A substantial fraction of the tumors expresses c-Kit or the platelet-derived growth factor receptor beta (PDGFRbeta), both targets for imatinib mesylate. No standard systemic therapy is known for these neoplasms.

c-kit and PDGFRbeta-expression were determined by immunohistochemistry. Four patients with distant metastases and with at least one positive result were treated with 400 mg imatinib mesylate once daily and their response assessed.

c-Kit and PDGFRbeta expressions were variable among the tumor samples. Toxicity was mild. No remissions were observed.

These data support that c-Kit or PDGFRbeta expression per se are not prognostic for the therapeutic response of metastasized ACCs to imatinib mesylate.