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Gastroenterology and hepatology
Protocol
Study protocol for a prospective, multicentre, phase II trial on endoscopic treatment using two fully covered self-expandable metallic stents for benign strictures after hepaticojejunostomy
  1. Yuki Kawasaki1,2,
  2. Susumu Hijioka1,
  3. Yoshikuni Nagashio1,
  4. Akihiro Ohba1,
  5. Yuta Maruki1,
  6. Kotaro Takeshita1,
  7. Tetsuro Takasaki1,
  8. Shin Yagi1,
  9. Daiki Agarie1,
  10. Yuya Hagiwara1,
  11. Hidenobu Hara1,
  12. Kohei Okamoto1,
  13. Daiki Yamashige1,
  14. Souma Fukuda1,
  15. Masaru Kuwada1,
  16. Shunsuke Kondo1,
  17. Chigusa Morizane1,
  18. Hideki Ueno1,
  19. Takuji Okusaka1
  1. 1Department of Hepatobiliary and Pancreatic Oncology, National Cancer Center Hospital, Chuo-ku, Japan
  2. 2Showa University Koto Toyosu Hospital, Koto-ku, Japan
  1. Correspondence to Dr Susumu Hijioka; shijioka{at}ncc.go.jp

Abstract

Introduction The current endoscopic treatment for postoperative benign hepaticojejunostomy anastomotic stricture (HJAS) has a high technical success rate and is highly effective in the short term. However, long-term results have shown a high rate of stenosis recurrence, which indicates an insufficient response to treatment. Three prospective studies on fully covered self-expandable metallic stent (FC-SEMS) treatment for benign HJAS used the stenosis resolution rate as the primary endpoint, and no study has yet used the long-term non-stenosis rate (at 12 months) as the primary endpoint.

Methods and analysis We launched the ‘saddle-cross study’, which will be conducted as a multicentre, prospective intervention of endoscopic treatment using two modified FC-SEMSs (BONASTENT️ M-Intraductal) that have been improved for benign stenosis in patients with benign HJAS, with the long-term non-restenosis rate (at 12 months) as the primary endpoint. This study aims to evaluate the long-term non-restenosis rate (at 12 months) and safety of the saddle-cross technique for benign HJAS. We plan to enrol 50 participants.

Ethics and dissemination This study has been approved by the Certified Review Board of the National Cancer Center, Japan (CRB3180009). The results will be reported at various conferences and published in international peer-reviewed journals.

  • GASTROENTEROLOGY
  • Endoscopy
  • Hepatobiliary disease
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This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

https://doi.org/10.1136/bmjopen-2023-078967

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    STRENGTHS AND LIMITATIONS OF THIS STUDY

    • No prospective studies have used long-term non-stricture rate as the primary endpoint in the treatment of benign bile duct stricture.

    • The sample size required for a comparative study is enormous, and this trial is intended to be a validation study with many cases.

    • This treatment procedure is limited to patients in whom the hepaticojejunostomy anastomotic stricture can be reached via the transgastrointestinal route.

    Introduction

    Hepaticojejunostomy anastomotic stricture (HJAS) is a late complication that has been reported to occur in 3%–12% of patients undergoing pancreaticoduodenectomy.1–3 Postoperative transgastrointestinal endoscopic treatment for benign HJAS includes balloon dilation alone and temporary multiple biliary plastic or metal stenting. To date, the standard treatment in Japan is balloon dilation alone or temporary multiple biliary plastic stenting in addition to balloon dilation.

    The technical success rate of these treatments has been reported to be 86.8%–100%.4–8 In balloon dilation alone, the non-restenosis rate at 12 months has been reported to be 67.3%.4–6 In a report by Tomoda et al, the non-restenosis rate with multiple biliary plastic stenting combined with balloon dilation was 75% at 12 months.8

    Recent studies have examined the efficacy of temporary implantation of fully covered self-expandable metallic stents (FC-SEMSs) for the treatment of benign bile duct strictures.9–15 These reports suggest that the temporary placement of an FC-SEMS is effective in improving the long-term non-stenosis rate and reducing the number of endoscopic procedures. The non-restenosis rate after the temporary placement of an FC-SEMS was 76.9% at 12 months, as reported by Devière et al.14

    More recently, a new FC-SEMS (BONASTENT️ M-Intraductal, Standard Sci-Tech, Seoul, South Korea) with convex margins at both ends, a smaller central diameter, a cross-wired structure, and a 10 cm long lasso that was introduced for benign stenoses, has been improved and applied for benign bile duct strictures.13

    In a report by Sato et al on FC-SEMS placement for benign HJAS, the modified FC-SEMS (BONASTENT️ M-Intraductal) was placed in 20 patients, and the metallic stent was removed after 3 months.15 In that report, the non-restenosis rate at 12 months was 87.5% (7/8), and long-term follow-up results from studies involving more patients are required.

    We previously reported the results of the endoscopic treatment of 20 cases of benign HJAS using two modified FC-SEMSs (BONASTENT️ M-Intraductal, saddle-cross technique).16 Technical and clinical success was achieved in all cases (20/20). Stenosis resolution was achieved at stent removal in all patients, and the non-restenosis rate at 12 months was 89.5% (17/19), achieving long-term patency in a larger number of cases than those reported previously. However, those results were from a single-centre, retrospective study; therefore, there is insufficient evidence to support the results of this treatment. Three prospective studies on FC-SEMS treatment of benign HJAS have been published,12 17 18 all of which used the stenosis resolution rate as the primary endpoint, and no study has yet used the long-term non-stenosis rate (at 12 months) as the primary endpoint.

    Therefore, we launched the ‘saddle-cross study’, which will be conducted as a multicentre, prospective, intervention of endoscopic treatment using two modified FC-SEMSs in patients with benign HJAS, with the long-term non-restenosis rate (at 12 months) as the primary endpoint.

    Methods and analysis

    Patient and public involvement

    In developing the protocol, the Certified Review Board at the National Cancer Center, Japan, reviewed the purpose and process of the study and whether the terminology was easy to understand for patients, with a representative from the public involved in the review process, and revised the implementation plan and explanatory documents.

    Objectives

    In this study, two modified FC-SEMSs (BONASTENT️ M-intraductal) will be used for the endoscopic treatment of benign HJAS to evaluate the clinical efficacy and safety of the treatment.

    Study setting

    This is a multicentre prospective study, and the planned treatment procedures after enrolment are shown in figure 1.

    Figure 1
    Figure 1

    CONSORT flow chart for a single-arm, open-label, phase II clinical trial on endoscopic treatment using two FC-SEMS for benign strictures after hepaticojejunostomy: The saddle-cross study. FC-SEMS, fully covered self-expandable metallic stent; HJAS, hepaticojejunostomy anastomotic stricture; IV-EUS, interventional endoscopic ultrasound; PTCD, percutaneous transhepatic cholangio-drainage. The CONSORT flow chart is a diagram that describes the cases excluded and the reasons for their exclusion at all stages of subject enrollment, allocation, follow-up, and analysis.

    Eleven facilities in Japan will be participating in this study, including the National Cancer Center Hospital, Japan, International University of Health and Welfare, Mita Hospital, Mie University Hospital, Fukuoka University Hospital, Kumamoto University Hospital, Dokkyo Medical University Saitama Medical Center, Tokyo Metropolitan Bokuotoh Hospital, Saitama Medical Center Jichi Medical University, Saiseikai Kawaguchi General Hospital, Subaru Health Insurance Society Ota Memorial Hospital and Keiyu Hospital. Patients who meet the eligibility criteria at each facility will be introduced to the study using an explanatory document, and those who will give their consent will be enrolled.

    Endpoints

    Primary endpoint and key secondary endpoint

    The purpose of this study is to evaluate the long-term non-restenosis rate (at 12 months) and safety of the saddle-cross technique for benign HJAS. The primary endpoint is the long-term non-restenosis rate (at 12 months), and the key secondary endpoint is the adverse event rate.

    Secondary endpoints

    In our pilot study, we achieved technical and clinical success in all patients. In this prospective multicentre study, the secondary endpoints are the (1) clinical success rate of endoscopic HJAS dilatation with two modified FC-SEMSs, (2) technical success rate of endoscopic HJAS dilatation with two modified FC-SEMSs, (3) procedure time, (4) time to restenosis, (5) rate of spontaneous stent dislodgment and (6) time to stenosis recurrence in cases of spontaneous stent dislodgment, for comparisons with the conventional standard treatment and to evaluate efficacy.

    Eligibility criteria

    1. We will be enrolling patients who meet criteria 1–7.

      1. No tumour is found at the anastomotic site on imaging (contrast-enhanced CT or MR cholangiopancreatography (MRCP)), no hepatic duct stone is found, and benign HJAS is suspected (regardless of patients who have previously received treatment for benign HJAS, except for those who have been treated with the saddle-cross technique).

      2. Cholangitis that meets any of the following criteria within 28 days before enrolment: (1) fever, (2) abdominal pain and (3) hepatic dysfunction conforming to any of the following: (a) total bilirubin level of >1.5 mg/dL, (b) aspartate transaminase level of >100 U/L or (c) alanine transferase level of >100 U/L.

      3. The patient meets the indications for the saddle-cross technique, except for the necessary endoscopic retrograde cholangiopancreatography findings during surgery or CT and MRCP findings.

      4. No bleeding tendency (platelet count of ≥50 ×109/L and prothrombin activity at 50%).

      5. Eastern Cooperative Oncology Group Performance Status: 0, 1 or 2.

      6. Age ≥20 years

      7. The patient’s free and voluntary written consent to participate in the study has been obtained.

    2. The indications for the saddle-cross technique are as follows.

    This study treatment consists of the placement of two modified FC-SEMSs in the standard technique for the treatment of benign HJAS. The procedural aspect of the placement of two modified FC-SEMSs will be limited to patients who meet the following criteria on cholangiography based on CT, MRI and endoscopic retrograde cholangiopancreatography.

    1. Surgical anastomosis is a one-hole.

    2. The severity of HJAS is defined based on the anastomotic diameter as follows: normal >8 mm; mild ≤8 and 6<mm; moderate ≤6 and 2≤mm or severe < 2 mm. The indication for this study procedure is the presence of moderate or severe stenosis. In normal cases, only biliary angiography will be performed; in mild cases, only balloon dilation will be performed.

    3. Patients undergoing periodic replacement of a plastic stent (standard therapy) will also be eligible. The indication in such cases will be moderate or severe stenosis at the time of the initial treatment.

    4. The distance from the HJAS to the porta hepatis, where the right and left bile ducts are located, from the anastomosis to the confluence of the anterior and posterior regional branches in the case of left hepatic lobectomy, or to the confluence of B2 and B3 in the case of right hepatic lobectomy, is <1.5 cm.

    5. If a small number of small stones are present, it is acceptable to perform a one-time study treatment. If many stones are present, balloon dilation of the anastomosis (≤8 mm is preferred; however, a larger dilation may be acceptable depending on the size of the stones), stone lithotripsy, endoscopic nasobiliary drainage or plastic stenting should be performed. After confirming the absence of adverse events associated with stone lithotripsy, a two-stage trial will be performed. Similarly, if there is a possibility of malignant recurrence, it is acceptable to perform a histological examination, endoscopic nasobiliary drainage, or plastic stenting, and confirm benign results before conducting a two-stage trial (two-stage here refers to any case in which the patient received the first treatment before study enrolment and a second treatment after enrolment, as well as any case in which the patient received the first or second treatment after study enrolment).

    Exclusion criteria

    Patients who meet criteria 1–3 will be excluded.

    1. The physician determines that the participant’s enrolment in the study is inappropriate.

    2. A classification of ‘severe’ in the severity classification of acute cholangitis (diagnostic criteria and severity follow Tokyo Guidelines 201819).

    3. Evident intrahepatic stones on CT or MRI (for patients with bile duct stones on CT or MRI, enrolment in the study will be considered after stone removal).

    Trial examination

    The study treatment procedure is described below:

    1. Preparation for routine biliopancreatic endoscopy.

    2. Insertion of a forward-viewing scope (colonoscope or balloon endoscope for small intestine).

    3. After reaching the HJA, the anastomosis will be observed. Whether the anastomosis is moderately or severely stenosed with a diameter of ≤6 mm will be confirmed. In normal cases, only biliary angiography will be performed, and in cases of mild stenosis, only balloon dilation will be performed (the size of the balloon dilation will be at the discretion of the physician in charge at each institution). Histology will be performed when malignant recurrence is suspected (even if malignancy is suspected, it is permissible to perform an exploratory study procedure, as it is possible to remove it).

    4. A catheter will be inserted into the HJAS formed in one hole with a 0.025-inch or 0.018-inch hydrophilic guide wire.

    5. Cholangiography will be performed to confirm the bile duct formation. At this time, the distance from the HJAS to the porta hepatis will be confirmed, where the right and left bile ducts are confluent, from the anastomosis to the confluence of the anterior and posterior regional branches in the case of left hepatic lobectomy, and to the confluence of B2 and B3 in the case of right hepatic lobectomy is <1.5 cm.

    6. Balloon dilation of the HJAS will be performed using a balloon catheter of ≤8 mm.

    7. A guidewire will be placed in each bile duct where the placement of the modified FC-SEMS is planned.

    8. A modified FC-SEMS (BONASTENT️ M-Intraductal) 8 mm in diameter and 30 mm in length will be placed along the guidewire that has been placed.

    9. The stent placement results in good contrast outflow in the bile duct will be confirmed. If the bile ducts are obstructed by the modified FC-SEMS and there is poor outflow, an additional plastic stent will be placed in the bile duct with poor outflow.

    10. Under fluoroscopy, the absence of intra-abdominal leakage of contrast and free air will be confirmed.

    11. The surgeon will endoscopically confirm the location of the two modified FC-SEMSs and the absence of bleeding and terminate the procedure.

    12. The absence of spontaneous dislodgement of the modified FC-SEMS will be confirmed by abdominal radiography on the day after treatment and after 2 weeks.

    13. The inserted modified FC-SEMS will be endoscopically removed between days 30 and 90. Even in the case of spontaneous dislodgement, endoscopic observation will be performed 30–90 days after the placement of the modified FC-SEMS to confirm the resolution of the anastomotic stenosis.

    14. After 6 and 12 months of study treatment, patients will be evaluated using blood tests and abdominal contrast-enhanced CT (MRCP or simple CT are also acceptable) to check for recurrent stenosis.

    Definition

    Benign HJAS requiring treatment is defined as the presence of stenosis at the bile duct jejunal anastomosis on endoscopic imaging in the absence of malignant findings on CT/MRI and other findings, such as abdominal pain, fever and liver dysfunction, as described in eligibility criteria 1 and 2. Stenosis improvement after HJAS treatment is defined as an endoscopic anastomotic opening of at least 8 mm and a good contrast outflow. The diameter of the intrahepatic bile duct after treatment is not relevant, as it may be enlarged due to a postoperative dilated common bile duct caused by abnormal pancreaticobiliary confluence. If endoscopic imaging shows improvement of stenosis but residual findings, such as abdominal pain, fever and liver dysfunction, are suggestive of cholangitis, then the condition is defined as an adverse event of retrograde cholangitis due to overdilation of the HJAS.

    Study design and statistical analysis

    In previous studies, the long-term non-restenosis rate (at 12 months) with standard treatment in patients with benign HJAS ranged from 14.3% to 67.3% in the balloon dilation group4 8 and 75% in the plastic stent group.4 In our pilot study using the modified FC-SEMS, the long-term non-restenosis rates (at 12 months) were 76.9% in the balloon dilation group14 and 87.5% in the plastic stent group.15 Based on the above-mentioned findings, we set the threshold for the long-term non-restenosis rate (at 12 months) at 75%. Moreover, based on the findings of our pilot study, we set the expected long-term restenosis-free rate (at 12 months) at 90%.

    Assuming unilateral α=0.05 and 1−β=0.8, the required number of patients would be 45. The number of cases was set at 50 to allow for ineligible cases, inability to reach the HJAS via the transgastrointestinal tract, and normal or mild stenosis at the HJAS. The clinical hypothesis of this study is that the long-term restenosis-free rate (at 12 months) should exceed the threshold of 75%. If the long-term non-restenosis rate (at 12 months) is greater than 43/50 cases (86%) in this sample, the 90% CI will be 75.3 to 93.2, and the lower limit of the 90% CI will exceed the threshold of 75%; therefore, the study will meet the primary endpoint.

    A higher than moderate degree of HJAS is not common, and a large number of patients would be required for a randomised trial of standard and trial treatments. Therefore, based on the feasibility of the trial and the results of the retrospective study at our institution, we decided to conduct a single-arm study.

    Discussion

    The standard endoscopic treatment for benign HJAS has a high technical success rate if anastomosis can be achieved. However, treatment techniques have not yet been established. To improve a patients’ quality of life, single procedure treatments to resolve stenosis and to achieve long-term non-stenosis are needed. The median time from surgery for patients in whom anastomotic stenosis appeared in our previous study16 was 24 months. Together with the subsequent course of events, there is a significant need to seek long-term non-restenosis results. The standardised procedure is also expected to reduce adverse events and improve technical and clinical success. For patients who have undergone multiple endoscopic procedures and repeated hospitalisations, this increased treatment option is expected to improve their quality of life and contribute to healthcare economics by eliminating multiple procedures and endoscopies.

    In Japan, endoscopic treatment using metallic stents for benign bile duct strictures has not yet been approved under the Pharmaceutical Affairs Law. The Clinical Trial Act in Japan, with specified clinical trials, will clarify the clinical results of the use of biliary metallic stents for benign HJAS. Validation studies will help provide evidence for the use of biliary metallic stents for the treatment of benign stenosis in the guidelines.

    Ethics and dissemination

    The study has been approved by the Certified Review Board at the National Cancer Center, Japan (CRB3180009) and was published in the Japan Registry of Clinical Trials on 4 January 2023, under the clinical research protocol number jRCTs032220556 (https://jrct.niph.go.jp/re/reports/detail/69056). The study was initiated at the same time as the publication in jRCT. The committee reviewed the rules governing the study design, ethics, study safety and conflict of interest management at all participating facilities. The results will be reported at various conferences and published in international peer-reviewed journals.

    Ethics statements

    Patient consent for publication

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    Footnotes

    • Contributors All authors were involved in designing the trial. YK, SH, YN, AO, YM, KT, TT, SY, DA, YH, HH, KO, DY, SF, MK, SK, CM, HU and TO wrote the protocol. YK drafted the manuscript. All authors reviewed and revised the paper and approved the submission of this version of the manuscript.

    • Funding This study receives support from the National Cancer Center Research and Development Fund, Japan(2022-A-5).

    • Competing interests None declared.

    • Patient and public involvement Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the Methods section for further details.

    • Provenance and peer review Not commissioned; externally peer reviewed.