Michael O'Donnell

The goal of this clinical trial is to learn whether a combination of two chemotherapy drugs, Gemcitabine and Docetaxel, can treat high-grade non-muscle-invasive bladder cancer (HG-NMIBC) in adults whose cancer failed conventional BCG therapy. The drugs are given directly into the bladder (intravesically), one immediately after the other.

The study will also assess the safety of this treatment.

The main questions it aims to answer are:

Can this drug combination effectively treat HG-NMIBC that did not respond to BCG and help prevent the cancer from coming back, offering long-term protection? What side effects or medical issues do participants experience during treatment?

Researchers will evaluate this non-surgical approach as a potential alternative to bladder removal surgery (radical cystectomy), with the goal of validating it as a bladder-sparing option in this setting.

Participants will:

* Go through a screening process, including tumor removal and imaging tests
* Receive weekly bladder treatments with Gemcitabine followed by Docetaxel for 6 weeks
* If the cancer responds, continue with similar once monthly treatments (maintenance therapy) for up to 2 years
* Attend regular check-ups, including bladder exams, urine tests, biopsies, and optional quality-of-life surveys
* Possibly receive a second 6-week treatment cycle if the cancer returns early
* Be followed for up to 5 years to monitor long-term outcomes

This is a phase II, single arm, Simon two-stage design, trial, enrolling patients with cisplatin ineligible MIBC and/or those patients who decline cisplatin based NAC.

Assess rates of pathologic downstaging and quality of life in MIBC cisplatin-ineligible/declined patients when IVC is added to gemcitabine-carboplatin NAC.

Upon successful screening and registration, enrollment to durvalumab monotherapy (cohort 1) will begin. If DLT criteria outlined in the protocol are exceeded with durvalumab monotherapy (cohort 1), the study will close. Provided the safety of durvalumab monotherapy is established, enrollment to combination regimen cohorts will proceed. Cohorts will simultaneously enroll in parallel to each other with patients assigned to cohorts based on patient slot availability and study site choice of radiation arm participation. Patient assignment to future phase 1 arms would proceed similarly.

Within BCG-containing cohorts, treatment will begin at full-dose BCG. If DLT criteria outlined in Section 5.1.4 are exceeded with full-dose BCG, a one level dose reduction of BCG will be implemented. If DLT criteria outlined in Section 5.1.4 are exceeded with reduced-dose BCG, the BCG-containing cohort will not proceed to Phase 2 of the study. Similarly, if DLT criteria outlined in Section 5.1.4 are exceeded within non-BCG containing cohorts, the non-BCG containing cohort will not proceed to phase 2 of the study. Due to the prolonged half-life of antibody therapies, no dose adjustments are planned for durvalumab in any of the cohorts.