Efficacy and Safety of Plecanatide in Chinese Patients with Functional Constipation: A Phase III Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial

Background Plecanatide is a novel guanylate cyclase-C agonist for the treatment of functional constipation (FC). Its efficacy may vary across different racial populations. Objective This study aimed to comprehensively evaluate the efficacy, safety, and pharmacokinetics of plecanatide in Chinese patients with FC. Methods This phase III, randomized, double-blind, placebo-controlled trial was conducted across 40 hospitals in China. A total of 648 patients with FC were randomly assigned in a ratio of 1:1 to receive either plecanatide 3 mg or placebo for 12 weeks, followed by a 2-week follow-up. The primary efficacy endpoint was the durable overall complete spontaneous bowel movement (CSBM) response rate. Data on adverse events were collected. A post hoc logistic regression analysis was performed to identify predictors of durable overall CSBM response. Results After 12 weeks of continuous treatment, the durable overall CSBM response rates were 23.5% in the plecanatide group and 10.2% in the placebo group (p < 0.001). Plecanatide significantly increased the mean weekly frequency of CSBM (1.89 vs 0.9) and SBM (2.33 vs 1.03) compared with placebo throughout the treatment period. In addition, all other secondary efficacy endpoints showed statistically significant improvements with plecanatide compared with placebo. The most common treatment-related emergent adverse event was diarrhea, which occurred in 4.3% of plecanatide-treated patients and 0.6% of placebo-treated patients (p = 0.002). Plasma concentrations of plecanatide and its metabolite SP-338 remained below the lower limit of quantification (0.500 ng/ml) at all assessed time points. Weekly CSBM response at week 2 (odds ratio 43.476; 95% confidence interval 18.274-103.432) and baseline stool consistency (odds ratio 0.550; 95% confidence interval 0.366-0.827) were identified as effective predictors of durable overall CSBM response. Even among plecanatide non-responders, a significant improvement in SBM frequency compared with placebo was observed over the 12-week treatment period. Conclusions Plecanatide 3 mg was effective and well tolerated in the treatment of Chinese patients with FC. A weekly CSBM response at week 2 may serve as a predictor of 12-week durable overall efficacy. Patients who did not achieve the primary endpoint may still benefit from plecanatide treatment.