Working… Menu

Prostate Oncologic Therapy While Ensuring Neurovascular Conservation (POTEN-C) (POTEN-C)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. Identifier: NCT03525262
Recruitment Status : Recruiting
First Posted : May 15, 2018
Last Update Posted : February 2, 2021
Boston Scientific Corporation
Information provided by (Responsible Party):
University of Texas Southwestern Medical Center

Brief Summary:

Reduction of dose to or 'sparing' of neurovascular structures during stereotactic ablative body radiotherapy (SAbR) for localized prostate cancer will improve retention of sexual potency, while retaining excellent oncologic control and other secondary health-related quality of life (HRQOL) endpoints.

Primary Objectives:

• To compare the decline in patient health-related quality of life (HRQOL) instrument-defined erectile dysfunction following stereotactic ablative body radiotherapy (SAbR) with or without neurovascular sparing

Secondary Objectives:

  • Assess acute (within 9 months of treatment) and chronic (>9 months after treatment) SAbR related GU and GI toxicities, as well as serial impact on HRQOL metrics over time
  • Assess biochemical progression free survival, local recurrence, disease-specific survival
  • Evaluate the impact of neurovascular sparing on neurovascular element dose and the impact of rectal spacer use on neurovascular element sparing
  • Evaluate quality of spacer placement and its effect on dose to neurovascular structures
  • Evaluate rate local recurrence in the area of sparing adjacent to the neurovascular elements by biopsy in those with biochemical progression.
  • Evaluate simplified 'practical' secondary HRQOL sexual potency endpoints that can be compared to prior literature.

Condition or disease Intervention/treatment Phase
Prostate Cancer Adenocarcinoma Radiation: 30Gy (Gray) planning target volume (PTV) Phase 2

Show Show detailed description

Layout table for study information
Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 120 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: A Phase II Randomized Controlled Trial of Stereotactic Ablative Body Radiotherapy (SAbR) With or Without Neurovascular Sparing for Erectile Function Preservation in Localized Prostate Cancer
Actual Study Start Date : April 24, 2018
Estimated Primary Completion Date : June 16, 2022
Estimated Study Completion Date : June 16, 2024

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Prostate Cancer

Arm Intervention/treatment
No Intervention: SAbR WITHOUT Neurovascular sparing
  • GTV represents MR defined gross radiographic disease, if identifiable.
  • CTV encompasses the full prostate. At physician's discretion, the insertion of the seminal vesicle upon the prostate on slices containing prostate may be included.
  • PTV1_30Gy will not be used or created on this arm
  • PTV2_SAbR will be generated by a 3mm expansion on the CTV. PTV2_SAbR will receive 8-9 Gy per fraction for 5 fractions (40-45 Gy).
Experimental: SAbR WITH Neurovascular sparing
  • GTV represents MR defined gross radiographic disease, if identifiable.
  • CTV encompasses the full prostate. At physician's discretion, the insertion of the seminal vesicle upon the prostate on slices containing prostate may be included.
  • PTV1_30Gy represents a 3mm expansion on the CTV, excluding the neurovascular structures on the side to be spared (left or right). PTV1 will receive 6 Gy per fraction for 5 fractions (30 Gy).
  • PTV2_SAbR will be generated by subtracting a 5mm expansion around the neurovascular elements to be spared (at least one side, left or right) from PTV1. These neurovascular structures consist of the neurovascular bundle, penile bulb, and internal pudendal arteries. PTV2 will receive 8-9 Gy per fraction for 5 fractions (40-45 Gy).
Radiation: 30Gy (Gray) planning target volume (PTV)
PTV1_30Gy represents a 3mm expansion on the prostate (and proximal seminal vesicle per physician discretion), excluding the neurovascular structures on the side to be spared (left or right). PTV1 will receive 6 Gy per fraction for 5 fractions (30 Gy).

Primary Outcome Measures :
  1. Reduction in Expanded prostate cancer index composite (EPIC) sexual function domain composite score from Baseline [ Time Frame: Mean 24-Months ]
    The Expanded prostate cancer index composite (EPIC) Health-related quality of life (HRQOL) instrument includes four sub-scales like Urinary function, Bowel habits, Sexual function, and Harmonal function. The primary outcome (sexual function) which has a range score of 0-100 from 9 questions related to ability to achieve an erection with or without aids and participate in intercourse. Higher the score represents the better outcome. Individual responses are summed for a total score of sexual function.

Secondary Outcome Measures :
  1. Acute & Delayed Genitourinary (GU) and Gastrointestinal (GI) toxicity [ Time Frame: Mean 24-Months ]
    Severity or Toxicity will be assessed according to the National Cancer Institute (NCI) Common Toxicity Criteria for Adverse Events (CTCAE), version 4.0. Dose adjustments should be made according to the system showing the greatest degree of toxicity. The consequences of gastointestinal/renal/genitourinary/sexual and reproductive toxicity should all be graded 1-5 according to the Common Terminology Criteria For Adverse Events (CTCAE), version 4.0 occurring prior to 270 days from the start of protocol treatment. Other treatment related toxicity attributed to the therapy will be captured, recorded and the consequences of should all be graded 1-5 according to the Common Terminology Criteria For Adverse Events (CTCAE). CTCAE V4.0 along with grades 1-5 is provided in the link for reference (

  2. Biochemical failure RTOG-ASTRO definition (also known as Phoenix definition) [ Time Frame: 60 Months ]
    Increase in PSA greater than 2ng/ml above the patients lowest PSA level (nadir) after treatment.

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

Layout table for eligibility information
Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  1. Age ≥ 18 years.
  2. Appropriate staging studies identifying patient as AJCC 7th edition clinical stage T1 (a, b, or c) or T2 (a, b, or c) adenocarcinoma of the prostate gland. The patient should not have direct evidence of regional or distant metastases after appropriate staging studies. See Appendix I for details on AJCC 7th Edition staging criteria. Histologic confirmation of cancer will be required by biopsy performed within 12 months of registration. T-staging may be assessed by multi-parametric imaging alone if digital rectal examination was deferred.
  3. The patient's Zubrod performance status must be 0-2 (see Appendix II for definition).
  4. The Gleason summary score should be less than or equal to 7 [Grade group 1 (Gleason 3+3=6), group 2 (Gleason 3+4=7), and group 3 (Gleason 4+3=7) are allowed]. See Appendix III for details on definitions. While a template biopsy is recommended, it is not required in the case of MRI fusion biopsy performed on all dominant MR lesions (defined as PIRADS v2 4-5).
  5. Baseline AUA symptom score ≤19 (see Appendix IV for questionnaire) without need for maximum medical therapy (specifically, not on tamsulosin 0.8mg daily)
  6. EPIC sexual domain composite score 60-100 (see Appendix V)
  7. Multi-parametric MRI evaluation of the prostate is required for this study within 12 months of registration. Gross radiographic disease on MRI (defined as PIRADS v2 score 3-5) must be > 5mm at minimum distance from at least one side's neurovascular bundle, which is typically the closest of the neurovascular elements to the prostate.
  8. The serum PSA should be less than or equal to 20 ng/ml within 90 days of registration.

    Study entry PSA must not be obtained during the following time frames: (1) 10-day period following prostate biopsy; (2) following initiation of ADT or anti-androgen therapy; (3) within 30 days after discontinuation of finasteride; (4) within 90 days after discontinuation of dutasteride; (5) within 5 days of a digital rectal examination.

  9. Ultrasound or MRI based volume estimation of prostate gland ≤ 80 grams. Cytoreduction therapy (finasteride or dutasteride only) may be considered for those with >60 gram size.
  10. All patients must be willing and capable to provide informed consent to participate in the protocol within the 30 days prior to registration

Exclusion Criteria:

  1. Subjects with clinical (digital rectal examination) evidence of extraprostatic extension (T3a) or seminal vesicle involvement (T3b). MRI evidence of equivocal/potential but not definite extraprostatic extension is allowed, as long as it is unilateral and not on the side of the gland proposed for neurovascular element sparing. In equivocal cases of potential extracapsular extension on MRI only, discretion is left to the treating physician.
  2. MRI evidence of gross disease (defined as PIRADS v2 score 3-5 lesions) ≤5mm of BOTH neurovascular bundles, which are the most proximate of the neurovascular elements planned for sparing on this protocol.
  3. Patients with all three intermediate risk factors (PSA >10 and ≤ 20, Gleason 7, clinical stage T2b-T2c) who ALSO have ≥50% of the number of their template biopsy cores positive for cancer are ineligible.
  4. Inability to undergo multi-parametric MRI.
  5. Evidence of metastatic disease. Note bone scan is not required for this study given the low-intermediate NCCN risk cohort to be enrolled.
  6. Evidence of clinical nodal involvement of the pelvis. Biopsy is required for lymph nodes over ≥1.5cm in short-axis measured size.
  7. No currently active ADT or anti-androgen therapy at time of registration is allowed. Further, no more than 3 cumulative months of prior ADT or anti-androgen therapy is allowed. If either has been used by the patient, there must be a demonstration of testosterone recovery (>50ng/dL serum blood level), EPIC sexual domain score ≥60, and at least 1 month between demonstration of testosterone recovery and study registration (any one measurement of testosterone recovery suffices).
  8. Testosterone ≤ 50 ng/dL (any one measurement >50 ng/dL suffices for inclusion) within 90 days of study entry.
  9. Subjects who have had previous pelvic radiotherapy or have had chemotherapy or surgery for prostate cancer.
  10. Subjects who have plans to receive other concomitant or post treatment adjuvant antineoplastic therapy while on this protocol including surgery, cryotherapy, conventionally fractionated radiotherapy, hormonal therapy, or chemotherapy given as part of the treatment of prostate cancer.
  11. Subjects who have undergone previous transurethral resection of the prostate (TURP) or ablative procedures to the prostate for benign prostatic hyperplasia or other conditions (i.e. cryotherapy, HIFU).
  12. Subjects who have baseline severe urinary symptoms, as defined by AUA symptom score >19 (alpha-blocker medication allowed except if taking tamsulosin 0.8mg daily at baseline which indicates compensated severe symptoms and also can affect sexual function).
  13. Subjects who have a history of significant psychiatric illness that would confound informed consent.
  14. Severe, active co-morbidity, defined as follows:

    1. Unstable angina and/or congestive heart failure requiring hospitalization within the last 6 months
    2. Myocardial infarction within the last 6 months
    3. Acute bacterial or fungal infection requiring intravenous antibiotics at time of registration
    4. Patients with active inflammatory colitis (including Crohn's Disease and ulcerative colitis) currently requiring systemic steroids and/or systemic immunosuppression are not eligible.
  15. Subjects with a known allergy to polyethylene glycol hydrogel (rectal spacer material) or contraindication to spacer products (SpaceOAR)
  16. Subjects with uncontrolled coagulation disorder which cannot be controlled with anticoagulants
  17. Men of reproductive potential who do not agree that they will use an effective contraceptive method.
  18. Men who require erectile function medication or aid to achieve an erection sufficient for intercourse. Ability to achieve erection sufficient for intercourse without medication or aid at least once time in the month prior to registration is sufficient for inclusion.
  19. Men who have clinically significant penile malformation (i.e. Peyronie's disease) or history of penile implantation are excluded
  20. If DRE is performed, patient may not have palpable disease on side of gland to be planned for neurovascular sparing. Given the poor accuracy of DRE, such a finding should be confirmed by MRI and/or biopsy to harbor actual disease before excluding a patient

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT03525262

Layout table for location contacts
Contact: Neil B Desai, MD MHS 2146458525
Contact: Samantha Mannala 2146481873

Layout table for location information
United States, Colorado
University of Colorado Hospital Recruiting
Aurora, Colorado, United States, 80045
Contact: Robyn Swing    720-848-0607   
Principal Investigator: Thomas Pugh, MD         
United States, Texas
UT Southwestern Cancer Center Recruiting
Dallas, Texas, United States, 75235
Contact: Samantha Mannala    214-648-1873   
Sponsors and Collaborators
University of Texas Southwestern Medical Center
Boston Scientific Corporation
Layout table for additonal information
Responsible Party: University of Texas Southwestern Medical Center Identifier: NCT03525262    
Other Study ID Numbers: STU 092017-018
First Posted: May 15, 2018    Key Record Dates
Last Update Posted: February 2, 2021
Last Verified: January 2021

Layout table for additional information
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
Keywords provided by University of Texas Southwestern Medical Center:
Erectile dysfunction, Neurovascular, Prostate, Rectal spacer, Radiotherapy
Additional relevant MeSH terms:
Layout table for MeSH terms
Prostatic Neoplasms
Genital Neoplasms, Male
Urogenital Neoplasms
Neoplasms by Site
Prostatic Diseases