Safety and pharmacokinetics of veliparib extended-release in patients with advanced solid tumors: a phase I study

The poly(ADP-ribose) polymerase-1/2 inhibitor veliparib is active against tumors deficient in homologous DNA damage repair. The pharmacokinetics and safety of veliparib extended-release (ER) were evaluated in patients with advanced solid tumors. This phase I study assessed veliparib-ER up to 800 mg once daily or 600 mg twice daily. Dose-limiting toxicities (DLTs), recommended phase II dose (RP2D), and maximum tolerated dose (MTD) were assessed in cycle 1 and safety/tolerability during continuous administration (28-day cycles). Seventy-one patients (n = 53 ovarian, n = 17 breast, n = 1 prostate carcinoma) received veliparib; 50 had deleterious breast cancer susceptibility (BRCA) gene mutations. Single-dose veliparib-ER 200 mg (fasting) led to 58% lower peak concentration and similar area under the concentration-time curve compared with veliparib immediate-release (IR). Three patients experienced DLTs (grade 2: asthenia; grade 3: nausea/vomiting, seizure). RP2D and MTD for veliparib-ER were 400 mg BID. The most frequent adverse events (AEs) were nausea (78.9%) and vomiting (50.7%). The most common grade 3/4 treatment-related AEs were as follows: thrombocytopenia (7.0%), nausea, and anemia (4.2% each). Overall, 12 (27.3%) patients with ovarian and 10 (62.5%) patients with breast carcinoma had a partial response. Veliparib-ER, versus veliparib-IR, exhibited an improved pharmacokinetic profile and was well tolerated in patients with ovarian and BRCA-mutated breast cancers.