Timed sequential therapy of the selective T-type calcium channel blocker mibefradil and temozolomide in patients with recurrent high-grade gliomas
Holdhoff M, Ye X, Supko JG, Nabors LB, Desai AS, Walbert T, Lesser GJ, Read WL, Lieberman FS, Lodge MA, Leal J, Fisher JD, Desideri S, Grossman SA, Wahl RL, and Schiff D. Timed sequential therapy of the selective T-type calcium channel blocker mibefradil and temozolomide in patients with recurrent high-grade gliomas. Neuro Oncol 2017; 19(6):845-852.
Background: Mibefradil (MIB), previously approved for treatment of hypertension, is a selective T-type calcium channel blocker with preclinical activity in high-grade gliomas (HGGs). To exploit its presumed mechanism of impacting cell cycle activity (G1 arrest), we designed a phase I study to determine safety and the maximum tolerated dose (MTD) of MIB when given sequentially with temozolomide (TMZ) in recurrent (r)HGG.
Methods: Adult patients with rHGG ≥3 months from TMZ for initial therapy received MIB in 4 daily doses (q.i.d.) for 7 days followed by standard TMZ at 150-200 mg/m2 for 5 days per 28-day cycle. MIB dose escalation followed a modified 3 + 3 design, with an extension cohort of 10 patients at MTD who underwent 3'-deoxy-3'-18F-fluorothymidine (18F-FLT) PET imaging, to image proliferation before and after 7 days of MIB.
Results: Twenty-seven patients were enrolled (20 World Health Organization grade IV, 7 grade III; median age 50 y; median KPS 90). The MTD of MIB was 87.5 mg p.o. q.i.d. Dose-limiting toxicities were elevation of alanine aminotransferase/aspartate aminotransferase (grade 3) and sinus bradycardia. The steady-state maximum plasma concentration of MIB at the MTD was 1693 ± 287 ng/mL (mean ± SD). 18F-FLT PET imaging showed a significant decline in standardized uptake value (SUV) signal in 2 of 10 patients after 7 days of treatment with MIB.
Conclusions: MIB followed by TMZ was well tolerated in rHGG patients at the MTD. The lack of toxicity and presence of some responses in this selected patient population suggest that this regimen warrants further investigation.
Medical Subject Headings
Adult; Aged; Aged, 80 and over; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Calcium Channels, T-Type; Dacarbazine; Female; Follow-Up Studies; Glioma; Humans; Male; Maximum Tolerated Dose; Mibefradil; Middle Aged; Neoplasm Grading; Neoplasm Recurrence, Local; Survival Rate; Temozolomide; Young Adult