The Zenflow Spring System is a novel minimally invasive surgical therapy (MIST) that delivers an appropriately sized nitinol urethral expander device into the prostatic urethra displacing the lateral lobes for improved urinary flow. The ZEST pilot studies are prospective single-arm clinical studies evaluating the Zenflow Spring System for BPH. Three clinical trials were conducted using the same eligibility criteria across 4 countries (Mexico, Australia, New Zealand, Canada).
Seventy-two (72) subjects received the device. Symptom improvement was measured utilizing the International Prostate Symptom Score (IPSS) and IPSS-QOL, and functional improvement was measured by peak urinary flow rate (Qmax). Overall effectiveness measures were calculated using a mixed model repeated measures (MMRM) analysis, which incorporates within-patient correlations and missing data, and equally weighs results from each study.
Subjects treated with the Zenflow Spring showed a significant reduction in IPSS from baseline to 24 months (22.0 to 11.4), representing a 48% improvement in IPSS. IPSS QOL significantly reduced from baseline to 24 months (4.5 vs 1.85) representing a 59% improvement. Qmax increased from 10.5 mL/sec at baseline to 14.0 mL/sec at 24 months representing a 33% improvement. The responder rate at 12 and 24 months, calculated as those with at least 30% improvement in IPSS, was 75% (48/64 subjects) and 70% (39/56), respectively.
The Zenflow Spring System resulted in immediate, significant, and durable symptomatic improvements from 1 through 24 months. Subjects experienced improvements in symptoms, quality of life, maximum flow rate without any sexual dysfunction through 24 months of follow up. These results are currently being validated through a large, multi-center, prospective randomized study in the United States and Canada.
