Open label, Randomized, Multicentric Study to Evaluate Safety, Tolerability and Performance of mediNiK in Comparison to Standard of Care in Removal of Kidney Stones - MediNiK-02

mediNiK is an innovative two-component hydrogel system, developed for intrarenal embedding and retrieval of kidney stone fragments after ureterorenoscopy with lithotripsy (URS). This hydrogel is intended to be used when stone fragments are too small to be removed with conventional grasping tools. To evaluate safety, tolerability and performance data of mediNiK for the first time, an open-label, random-ized, multicenter study was conducted. At five sites in Germany, a total of 70 patients were examined, 65 of whom were included in the study, 32 only with standard URS procedure, and 33 with URS and subsequent mediNiK usage. At the end of the complete follow-up period, 17 (URS) and 23 (URS + mediNiK) patients remained for full analysis. Main reason for exclusion from analysis set can be attributed to protocol deviations (i.e. no stones were collected and quantified). In this study, mediNiK was shown to be safe. No incidences of device-related adverse events for either of the two groups (URS vs. URS + mediNiK) were observed. Furthermore, the occurrence of treatment-emergent adverse events following surgery was comparable between the groups. Main performance analysis of mediNiK showed a clear tendency of higher number of removed small stone fragments <1 mm (in total: 1716 stones; 74.61 per subject) compared to standard URS procedure alone (in total 209 stones; 12.29 per subject). Using more appropriate statistical methods considering the non-Gaussian distribution of stones in the patients, mediNiK even demonstrated to increase statis-tically significantly the number of removed stones, thereby proving to enable a more efficient stone removal in particular of small sized fragments. In the mediNiK group, cumulatively 2026 stones were removed, with 1492 stones < 0.5 mm, 224 stones 0.5 mm to < 1 mm, and 310 stones = 1 mm. In the URS group, cumulatively 327 stones were removed, with 194 stones < 0.5 mm, 15 stones 0.5 mm to < 1 mm, and 118 stones = 1 mm. Thus, in the mediNiK group, on average 88.1 stones of all sizes were removed per subject while only 19.2 stones were removed in the URS group. Due to the attempt to remove smaller residual fragments <1 mm that otherwise could not be grasped with the basket and the initial lack of practice with this innovative hydrogel method, the duration of pro-cedure using URS + mediNiK compared to standard URS alone differed (85.7 min vs. 66.8 min per subject). Negative effects on subjects were not observed. The ease of the kidney stone removal procedure was similar between the groups based on clinical investigator’s feedback. Thus, mediNiK did not appear to deteriorate the ease of kidney stone removal procedure. In summary, no significant differences were found with regard to safety of use. Hence, the use of mediNiK can be considered safe. Clinician responses to performance of mediNik were positive. Further analyses demonstrated that the addition of mediNiK to the standard URS procedure enables a more efficient removal in particular of stones of small sizes (<1 mm) than is currently technically possible with simple URS. A higher stone removal rate by means of mediNiK might therefore contribute to lowering recurrence rates of kidney stones, thus leading to better patient care.