First-in-Human Phase I Study of Minnelide in Patients With Advanced Gastrointestinal Cancers: Safety, Pharmacokinetics, Pharmacodynamics, and Antitumor Activity.

BACKGROUND: Minnelide is a water-soluble prodrug of triptolide. Triptolide is an anticancer agent that targets cancer resistance through several mechanisms. Minnelide was evaluated in a phase I study in patients with advanced GI carcinomas to establish the safety, pharmacodynamic, antitumor activity, and recommended phase II dose (RP2D). PATIENTS AND METHODS: Patients with refractory GI carcinoma and with measurable disease on CT scan were eligible. The study used a 3 + 3 dose-escalation scheme. Due to neutropenia toxicity, 2 dosing schedules were evaluated to determine the RP2D for future studies. Response was assessed using RECIST 1.1 and Choi criteria. Minnelide and triptolide PK were evaluated. Patients who completed the first 28-day treatment cycle without DLTs continued treatment until disease progression or unacceptable toxicity. RESULTS: Forty-five patients were enrolled (23 pancreatic cancer, 10 colorectal, and the remaining 9 had other GI tumors); 42 patients received at least one dose of Minnelide. Grade ≥ 3 toxicities occurred in 69% of patients, most common neutropenia (38%). 2 patients with severe cerebellar toxicity who had a 2-fold higher triptolide concentration than other participants. ORR was 4%; the disease control rate (DCR) was 54% (15/28). Choi criteria demonstrated a decrease in average tumor density in 57% (16/28) patients. CONCLUSIONS: This first-in-human, phase I clinical study identified a dose and schedule of Minnelide in patients with refractory GI cancers. The primary toxicity experienced was hematologic. Evidence of efficacy of Minnelide treatment in this group of patients was observed. The DCR ranged from ~2 to 6 months in 14/28 (50%) of evaluable patients. Studies in monotherapy and combination treatments are underway.

Triptolide and Its Derivatives as Cancer Therapies.

Triptolide, a compound isolated from a Chinese medicinal herb, possesses potent antitumor, immunosuppressive, and anti-inflammatory properties, but is clinically limited due to its poor solubility, bioavailability, and toxicity. Recently, Minnelide, a water-soluble prodrug of triptolide, was shown to have potent antitumor activity in various preclinical cancer models. Minnelide is currently in Phase II clinical trials for treatment of advanced pancreatic cancer, which has fueled increased interest in this promising agent. Here, we review the recent advances in the biological activity of triptolide and its analogs, their mechanisms of actions, and their clinical developments. A special emphasis is given to proteins and pathways within the tumor and stromal compartments that are targeted by triptolide and its analogs as well as the ongoing clinical trials.