A phase 1/2 study of EG-70 (detalimogene voraplasmid) intravesical monotherapy for patients with BCG-unresponsive non-muscle invasive bladder cancer with carcinoma in situ.

TPS4626 Background: High-risk non-muscle-invasive bladder cancer (NMIBC) is treated with adjuvant intravesical Bacille Calmette-Guérin (BCG). However, approximately 50% of patients experience recurrence and/or progression after BCG treatment and are considered unresponsive. EG-70 (detalimogene voraplasmid) is an investigational drug product that was specifically engineered for intravesical administration to elicit local stimulation of anti-tumor immune responses in the bladder and drive durable efficacy in patients with BCG-unresponsive NMIBC, while mitigating the risk of systemic toxicities from immune stimulation. The phase 1 (dose-escalation) part of the first-in-human LEGEND (NCT04752722) phase 1/2, open-label, multicenter study of EG-70 in patients with high-risk BCG-unresponsive NMIBC with carcinoma in situ (CIS) is complete: intravesical instillation of EG-70 was well tolerated with an overall complete response (CR) rate of 73%; and the recommended phase 2 dose (RP2D) was identified. Here we describe the ongoing phase 2 part of the study, which opened to enrollment in May 2023. Methods: Patient eligibility criteria: age ≥18 years; ECOG PS 0−2; BCG-unresponsive NMIBC with CIS, with or without resected coexisting papillary tumors, ineligible for, or have elected not to undergo, cystectomy; satisfactory bladder function with ability to retain study drug for ≥60 minutes. Prior checkpoint inhibitor treatment is allowed if completed within 30 days before study entry. Patients are treated with EG-70 at the RP2D (800 µg in 50 mL) by intravesical administration on weeks 1, 2, 5, and 6 of a 12-week cycle, for 4 cycles in one of two cohorts: BCG-unresponsive (Cohort 1); BCG-naïve or BCG-incompletely treated (Cohort 2). Patients in either cohort who exhibit stable disease (SD) or CR at week 12 will continue treatment until week 24; patients with progressive disease (PD) will discontinue treatment. Patients who experience or maintain CR at week 24 will receive additional cycles every 12 weeks until week 48; patients with SD or PD at week 24 will discontinue treatment. Patients with PD at any time after week 24 will discontinue treatment. Phase 2 primary objective: evaluate efficacy (CR rate at week 48) and safety of EG-70. Secondary objectives: evaluate progression-free survival, CR rate at 12, 24, 36 and 48 weeks, and duration of response. The study is being conducted in accordance with the International Conference on Harmonisation Good Clinical Practice guidelines and with the principles of the Declaration of Helsinki. All patients provide written informed consent. The ongoing, registration-enabling phase 2 portion of the LEGEND study is anticipated to recruit approximately 100 patients from sites in North America, Europe, and the Asia-Pacific region. Clinical trial information: NCT04752722 .