Purpose: The objectives of this study were to evaluate the tolerability and efficacy of valproic acid (VPA) and lenalidomide.
Methods: In this 3+3 design study, VPA was administered daily on a 7-day-on, 7-day-off schedule, and lenalidomide was administered daily for 28 days. Because of the response noted during the dose-escalation phase, 12 additional patients with adenoid cystic carcinoma (ACC) received the maximum tolerated dose (MTD) in a dose-expansion phase.
Results: Twenty-six patients with advanced cancer (14 men/12 women), median age of 56 years (range 38-70 years), and a median number of two prior therapies (range 0-12) were enrolled. The most common toxicities were fatigue, rash, neutropenia, thrombocytopenia, and change in mental status. Dose-limiting toxic (DLT) effects were grade III confusion (n = 3), somnolence (n = 1), and gait disturbance (n = 1). The MTD was reached at VPA 30 mg/kg and lenalidomide 25 mg. Although only two of the 12 patients from the dose-expansion phase had DLT during the first cycle at the MTD, during subsequent cycles the majority of patients required dose reduction of VPA to 5-20 mg/kg because of fatigue and drowsiness. No significant tumor reductions were noticed in patients with ACC, but seven of these patients had stable disease over four cycles. Of non-ACC patients, one patient with melanoma and one patient with parathyroid carcinoma had stable disease for six cycles and eight cycles, respectively.
Conclusions: Lenalidomide combined with VPA was well tolerated. We recommend starting VPA at 5 mg/kg and titrating upward to 20 mg/kg. No significant tumor reductions were noticed in patients with ACC.