REtrieval of Transurethrally Resected Intact En-bloc Vesical Tumors Using a Retrieval Device for Bladder Tumors (RETRIEVE-BT)

REtrieval of Transurethrally Resected Intact En-bloc Vesical Tumors Using a Retrieval Device for Bladder Tumors - A Prospective Multicenter Feasibility Study

Bladder cancer is the most common malignancy of the urinary tract, and approximately 75% of cases are non-muscle invasive (NMIBC) at diagnosis. The standard treatment is transurethral resection of the bladder tumor (TURBT). En bloc resection (EBR-T), in which the tumor is removed in one intact piece rather than fragmented, offers superior pathological specimen quality and may reduce the need for repeat resections. However, extracting the intact specimen from the bladder through the urethra remains a critical technical challenge, particularly for larger tumors.

CURTIS (Urotech GmbH) is a CE-marked retrieval device consisting of a hydrophilic-coated bag that can be opened and closed via a handpiece, enabling controlled capture and safe transurethral extraction of the resected tumor specimen.

This study aims to evaluate the technical feasibility of CURTIS-assisted intact specimen retrieval following en bloc transurethral resection of primary NMIBC. The central question the study seeks to answer is: in what proportion of cases can CURTIS successfully retrieve an intact en bloc resected bladder tumor, and what is the maximum tumor size for which intact retrieval remains feasible?

Study Overview

• Status: Not yet recruiting
• Conditions: Bladder Cancer; Bladder Cancer TNM Staging Primary Tumor (T) T1
• Intervention / Treatment: Device: CURTIS retrieval device

Detailed Description

Here is the Detailed Description for ClinicalTrials.gov:

Study Design The RETRIEVE-BT Trial is a prospective, multicenter, single-arm, non-randomized feasibility study conducted at multiple urological centers. No control group or randomization is applied, as the study is designed to characterize the technical performance of the CURTIS device under real-world clinical conditions rather than to test a comparative efficacy hypothesis.

The CURTIS Device CURTIS (Urotech GmbH, Achenmühle, Germany) is a CE-marked medical device specifically developed for transurethral retrieval of intact bladder tumor specimens following en bloc resection. The device consists of a hydrophilic-coated retrieval bag that can be opened and closed via a handpiece, enabling controlled capture and safe transurethral extraction of the resected specimen. It is used within its approved intended purpose as defined by EU MDR 2017/745.

Surgical Procedure All procedures are performed under general or spinal anesthesia. En bloc transurethral resection is carried out using a standard resectoscope with an appropriate electrode (e.g., bipolar hook, J-electrode, or needle electrode). A circumferential incision is made in healthy urothelium approximately 3-5 mm lateral to the visible tumor margin, followed by en bloc dissection at the submucosal or muscularis propria level. Once the specimen is fully detached from the bladder wall, CURTIS-assisted retrieval is attempted according to the manufacturer's instructions for use. If retrieval with CURTIS is unsuccessful, conversion to an alternative extraction method is performed at the surgeon's discretion and documented.

Data Collection and Follow-up Data are collected prospectively via an electronic Case Report Form (eCRF). Intraoperative variables recorded include retrieval success or failure, reason for failure if applicable, total procedure time, and dedicated retrieval time. Resected specimens are processed by the local pathology department according to institutional standards; pathological variables include specimen dimensions, muscularis propria presence, pathological T-stage, histological grade (WHO 2022), and resection margin status. Postoperative complications are documented according to the Clavien-Dindo classification until hospital discharge. No additional study-specific outpatient follow-up visits are required.

Statistical Approach This is a pilot feasibility study; the statistical approach is primarily descriptive. The primary endpoint will be reported as an observed proportion with exact 95% Clopper-Pearson confidence interval. A predefined technical feasibility rate of ≥80% is the threshold indicating clinical utility. Secondary endpoints will be analyzed descriptively. A threshold analysis will be applied to identify the maximum tumor size associated with successful intact retrieval.

• Study Type: Interventional
• Enrollment (Estimated): 75
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Yannic T PD Dr. Volz, M.D.; Phone Number: +4989440071357; Email: yannic.volz@med.uni-muenchen.de

Study Locations

• Denmark
  • Aarhus, Denmark, 8200
    • Department of Urology, Aarhus University Hospital, Aarhus
    • Contact: Pernille S Kingo; Email: pernking@rm.dk
  • Roskilde, Denmark, 4000
    • Zealand University Hospital, Roskilde
    • Contact: Juan L. Vasquez; Email: julv@regionsjaelland.dk
• Germany
  • Bavaria
    • Augsburg, Bavaria, Germany, 86156
      • Urologie, Universitätsklinikum Augsburg
      • Contact: Roman Mayr, M.D., Prof.; Email: roman.mayr@uk-augsburg.de
    • Erlangen, Bavaria, Germany, 91504
      • Universtitätsklinikum Erlangen
      • Contact: Christian Fiebig, M.D.; Email: Christian.Fiebig@uk-erlangen.de
    • Munich, Bavaria, Germany, 80639
      • Urologie, Barmherzige Brüder Krankenhaus München
      • Contact: Alexander Prof. Karl, M.D., Prof.; Email: Alexander.Karl@barmherzige-muenchen.de
      • Sub-Investigator: Theresa Kahl, M.D.
    • Munich, Bavaria, Germany, 81377
      • Urologische Klinik und Poliklinik, LMU Klinikum
      • Contact: Yannic Volz, M.D.; Email: yannic.volz@med.uni-muenchen.de
    • Munich, Bavaria, Germany, 81675
      • Urologische Klinik, Klinikum Rechts der Isar
      • Contact: Michael Straub, M.D.; Email: michael.straub@tum.de
      • Sub-Investigator: Fabian Horné, M.D.
    • Nuremberg, Bavaria, Germany, 90419
      • Klinik für Urologie, Klinikum Nürnberg, Campus Nord
      • Contact: Gloria Zeitler, M.D.; Email: Gloria.Zeitler@klinikum-nuernberg.de
• Greenland
  • Nuuk, Greenland, 3900
    • Department of Surgery, Queen Ingrid's Hospital
    • Contact: Jørgen B Jensen; Email: jb@skejby.net

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age ≥18 years at the time of enrollment
• Suspected primary non-muscle invasive bladder cancer (NMIBC; stage pTa or pT1) based on cystoscopic assessment, with no radiological or clinical evidence of muscle-invasive disease
• Solitary or multiple bladder tumors with an estimated largest diameter of ≤50 mm based on flexible or rigid cystoscopic assessment (or cross-sectional imaging if available)
• Clinical indication for elective transurethral resection of the bladder tumor, planned to be performed as en-bloc resection
• Written informed consent obtained prior to any study-related procedure
• Ability to understand the study procedures and willingness to comply with study requirements

Exclusion Criteria:

• Known or clinically suspected muscle-invasive bladder cancer (MIBC; cT2 or higher) based on cystoscopy or imaging
• Recurrent bladder tumor (prior history of bladder tumor resection within the past 24 months)
• Active untreated urinary tract infection at the time of surgery (requiring postponement and re-evaluation)
• Uncorrectable coagulopathy or anticoagulation that cannot be safely paused perioperatively
• Severe urethral stricture precluding standard resectoscope passage
• Inability to provide written informed consent (e.g., due to cognitive impairment or language barrier without translation support)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: En-Bloc Retriever Arm; En-bloc resection and retrieval of the tumor with CURTIS device	Device: CURTIS retrieval device; After successful en-bloc resection, the tumor is retrieved using the novel retrieval device, where the tumor is catched with a bag and removed through the urethra

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Technical Feasibility Rate of CURTIS-Assisted Intact Specimen Retrieval	Proportion of enrolled patients in whom the CURTIS device enables complete, intact retrieval of the en-bloc resected bladder tumor specimen without fragmentation within the bladder or urethra. A case is classified as a technical success if the entire resected specimen is extracted through the urethra in one piece using the CURTIS device. Cases requiring conversion to an alternative retrieval method (e.g., piecemeal extraction, Ellik evacuator, endoscopic bag) are classified as technical failures.	Intraoperatively (single assessment at the time of specimen retrieval during the index surgical procedure)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Maximum Retrievable Tumor Size	Largest tumor diameter (in mm) at which successful intact retrieval using CURTIS was achieved, used to define a clinically meaningful upper size limit for CURTIS-assisted EBR-T.	Intraoperatively (measured at time of specimen retrieval)
Proportion of Specimens Containing Muscularis Propria (Detrusor Muscle)	Proportion of retrieved specimens containing detrusor muscle on pathological examination.	Perioperative/Periprocedural
Proportion of Specimens Permitting Complete Pathological T-Stage Assessment	Proportion of retrieved specimens allowing complete pathological T-stage assessment (pTa/pT1/pT2+).	Perioperative/Periprocedural
Proportion of Specimens Permitting Histological Grading	Proportion of retrieved specimens permitting grading according to WHO 2022 classification.	Perioperative/Periprocedural
Proportion of Specimens Permitting Resection Margin Assessment	Proportion of retrieved specimens permitting assessment of horizontal and vertical resection margin status.	Perioperative/Periprocedural
Total Procedure Time	Time from cystoscope insertion to complete specimen extraction and withdrawal of all instruments.	Intraoperatively (during the index surgical procedure)
Retrieval Time	Time from completion of en-bloc resection (detachment of tumor from bladder wall) to complete specimen extraction through the urethra.	Intraoperatively (during the index surgical procedure)
Perioperative Complication Rate (Clavien-Dindo Classification)	All intraoperative and postoperative complications occurring from the start of the procedure until hospital discharge, up to 30 postoperative days, classified according to the Clavien-Dindo classification system.	From start of procedure until hospital discharge, up to 30 days postoperatively

Collaborators and Investigators

• Sponsor: Ludwig-Maximilians - University of Munich
• Investigators: Principal Investigator: Yannic T Volz, M.D., Urologische Klinik und Poliklinik, LMU Klinikum München

Study record dates

Study Major Dates

• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): December 30, 2026
• Study Completion (Estimated): March 31, 2027

Study Registration Dates

• First Submitted: August 7, 2026
• First Submitted That Met QC Criteria: August 11, 2026
• First Posted (Actual): August 13, 2026

Study Record Updates

• Last Update Posted (Actual): August 17, 2026
• Last Update Submitted That Met QC Criteria: August 13, 2026
• Last Verified: August 1, 2026

More Information

Terms related to this study

• Keywords: bladder cancer; TUR-BT; transurethral resection of bladder tumor; urothelial cell cancer; en-bloc; retrieval
• Additional Relevant MeSH Terms: Urogenital Diseases; Urogenital Neoplasms; Neoplasms by Site; Neoplasms; Male Urogenital Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urologic Neoplasms; Urinary Bladder Diseases; Urinary Bladder Neoplasms
• Other Study ID Numbers: 26-0559

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Not able due to ethical and legal obligations

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No