Antitumor activity of imatinib in progressive, highly expressing KIT adenoid cystic carcinoma of the salivary glands: A phase II study

Abstract

6086 Background: Adenoid cystic carcinoma (ACC) of the salivary glands is a rare orphan disease of the head and neck usually resistant to conventional chemotherapy, that was found to express KIT in 87% (39/45) of cases in our institutions. Methods: This study explored the antitumor effects of imatinib given at 800 mg daily in a phase II study for patients (pts) with recurrent or metastatic ACC failing locoregional treatments, presenting CT-scan documented progressive disease and highly (50–100% of tumor cells) expressing KIT. Primary endpoint of this study was time to tumor progression, secondary endpoints were tumor response and safety. Results. Since 2004, 17 pts (M/F: 5/12, median age 48, range 33–71) were included. Target lesions were pulmonary metastasis (13 pts), renal metastasis (1 pt), locoregional (2 pts) and pulmonary + locoregional (1 pt) recurrences. Previous treatment with chemotherapy was reported in 5 pts. Median duration of treatment was 6 months (range, 1–14 months). Toxicity was mild to moderate except for 2 pts who had grade 3–4 anemia/neutropenia and asthenia requiring dose reduction and early study withdrawal, respectively. Among 15 evaluable pts with tumor progression at study entry, 5 pts were stable after 6+, 8, 9, 12+ and 18+ months of follow-up and 2 pts displayed partial responses of 42% and 35% (RECIST). These objective responses were associated with early symptomatic improvement (dyspnea/pain) and occurred in platinum- resistant pulmonary metastasis and a radiation-pre-treated locoregional recurrence, lasting 14 months and 9+ months, respectively. Final accrual and TTP determinations are ongoing. Conclusion. Although sporadic, objective responses can be observed in patients with progressive ACC treated with imatinib as well as long-lasting tumor stabilisations. No significant financial relationships to disclose.