Phase 2 clinical study evaluating the efficacy and safety of disitamab vedotin with or without pembrolizumab in patients with HER2-expressing urothelial carcinoma (RC48G001).

Abstract

TPS594 Background: Urothelial carcinoma (UC) is the 10th most diagnosed cancer worldwide, and nearly 50% of patients cannot tolerate the current first-line (1L) standard of care. There is a need to improve outcomes in 1L and later lines of therapy. HER2 is overexpressed in UC and may be associated with poor outcomes. Despite this, no HER2-directed therapies are currently approved for UC. Disitamab vedotin (DV; RC48-ADC) is an investigational antibody-drug conjugate comprising a novel HER2-directed monoclonal antibody, disitamab, conjugated to monomethyl auristatin E (MMAE) via a protease-cleavable mc-vc linker. DV elicits antitumor activity through multimodal mechanisms of action including MMAE-mediated direct cytotoxicity, bystander effect, and immunogenic cell death. Methods: RC48G001 (NCT04879329) is a phase 2, multi-cohort, open-label, multicenter trial to evaluate DV in patients with HER2-expressing locally advanced/metastatic UC (LA/mUC). Patients are enrolled in 3 cohorts based on prior treatment and tumor HER2 expression by immunohistochemistry (IHC) and gene amplification (via in situ hybridization [ISH]), assessed centrally. Cohorts A and B are enrolling patients who have received prior systemic therapy (1 or 2 lines, including platinum-containing chemotherapy) and whose tumors are HER2-positive (IHC 3+, or 2+ and ISH-positive) or HER2-low (IHC 2+ and ISH-negative, or IHC 1+), respectively. Cohort C is enrolling 1L treatment-naive patients in the LA/mUC setting, whose tumors have HER2-positive or HER2-low expression. Cohorts A and B will evaluate DV as monotherapy (intravenous [IV] administration, once every 2 weeks [Q2W]). Cohort C will evaluate DV (IV, Q2W) +/– pembrolizumab (IV, Day 1 of each 6-week cycle). Patients in all cohorts must have measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 and an Eastern Cooperative Oncology Group Performance Status of 0–1 in Cohorts A and B, and 0–2 in Cohort C. The primary endpoint is confirmed objective response rate (cORR) per blinded independent central review (BICR). Secondary endpoints include cORR by investigator assessment, overall survival, duration of response, progression-free survival, disease control rate per RECIST v1.1 by BICR and investigator, safety, and pharmacokinetic parameters. Enrollment for all cohorts is ongoing in North America and Europe, and planned in Latin America, Asia-Pacific, and Israel. Clinical trial information: NCT04879329 .