COBRA

• Research type

  Research Study

• Full title

  Combination chemotherapy versus Bacillus Calmette-Guérin (BCG) for high-risk non-muscle invasive bladder cancer– a phase III multi-centre randomised controlled trial (COBRA)

• IRAS ID

  1008661

• Contact name

  Steven Penegar

• Contact email

  cobra-icrctsu@icr.ac.uk

• Sponsor organisation

  The Institute of Cancer Research

• Research summary

  Why is the COBRA study being done?
  We want to find out if a new treatment – Gem-Doce – could be an option for people with early bladder cancer.
  The normal treatment – BCG – has been used for over 40 years. It causes side effects like bladder pain and flu-like symptoms. Most people do not complete a full treatment course.

  Even after BCG treatment, cancer returns for up to half of people. One in five have progression of their cancer, requiring major surgery to remove their bladder (cystectomy). Identifying an effective, better tolerated alternative to BCG is deemed critical by patient support organisations.

  The main aim of COBRA is to test if Gem-Doce is similarly successful to BCG in preventing early bladder cancer returning. We will also look at the side effects and costs of both treatments, and ask participants about treatment’s impact on their quality of life.

  What is being tested?
  People who join the COBRA study will either have BCG or Gem-Doce treatment. Both treatments are put into peoples’ bladders. Treatments are given regularly at hospital over two years. Everyone will have regular check-ups for five years. These are the same as the check-ups they would have if they did not join the study.

  Who can join the study?
  Up to 520 people with a new diagnosis of early bladder cancer, who would otherwise be treated with BCG, will be invited to join the study.

  Where is the study taking place?
  The COBRA study is taking place at up to 50 NHS hospitals across the United Kingdom.

  How long will the study last?
  People will be invited to join COBRA for 4 years. We will collect information about how everyone is doing for 2 more years after enrolment has ended. We hope to have results available 7 years after the study starts.

• REC name

  South Central - Hampshire B Research Ethics Committee

• REC reference

  25/SC/0262

• Date of REC Opinion

  21 Oct 2025

• REC opinion

  Further Information Favourable Opinion