(UroToday.com) The 2024 GU ASCO annual meeting featured a urothelial carcinoma session and a presentation by Dr. Haoyang Liu discussing real-world results of a study assessing RC48-ADC versus BCG in adjuvant treatment of high-risk non-muscle-invasive bladder cancer (NMIBC) with HER2 over-expression. Bladder cancer ranks as the tenth most prevalent malignancy globally, with NMIBC accounting for approximately 75% of cases. Patients diagnosed with high-risk NMIBC face a tough prognosis, characterized by a 5-year disease progression rate of up to 40%. Currently, the standard treatment for high-risk NMIBC involves TURBT followed by adjuvant intravesical BCG therapy. However, BCG infusion therapy is associated with prolonged duration, substantial costs, and a high frequency of toxic side effects.
RC48-ADC, a novel humanized anti-HER2 antibody conjugated with monomethyl auristatin E, has shown promising efficacy with a manageable safety profile in patients with locally advanced or metastatic urothelial carcinoma in a Phase II clinical trial (NCT03507166). Therefore, investigating the therapeutic potential of RC48-ADC in high-risk NMIBC patients holds significant clinical importance.
This study was a retrospective analysis of patients diagnosed with high-risk NMIBC exhibiting HER2 overexpression (≥ HER2 2+) who underwent adjuvant therapy with either RC48-ADC, a HER2-targeting antibody-drug conjugate, or BCG, at the West China Hospital of Sichuan University between 2019 and 2023. The primary study endpoint was the 12-month recurrence-free survival rate, with safety assessments as secondary endpoints.
A total of 30 patients diagnosed with high-risk NMIBC displaying HER2 overexpression were included in the study. Following TURBT, eleven patients received adjuvant therapy with RC48-ADC, while nineteen received adjuvant therapy with BCG. The median follow-up duration for patients receiving RC48-ADC and BCG adjuvant therapy was 7.3 and 16.4 months, respectively. Among patients treated with RC48-ADC, the 12-month recurrence-free survival rate was 100%, with one out of the 11 patients experiencing relapse after 14.2 months of RC48-ADC adjuvant therapy. In the BCG-treated group, the 12-month recurrence-free survival rate was 57.6%. However, Kaplan-Meier analysis revealed no statistically significant difference between these two groups (p = 0.22):
In the RC48-treated group, the most commonly reported treatment-related adverse events included alopecia (45.5%), arthralgia (18.2%), and nausea (18.2%). A total of 27.7% of patients experienced grade 3 treatment-related adverse events, including alopecia, rash, and hypoesthesia, with no observations of grade 4 or grade 5 treatment-related adverse events.
Dr. Liu concluded this presentation by discussing real-world results of a study assessing RC48-ADC versus BCG in adjuvant treatment of high-risk NMIBC with HER2 over-expression with the following take-home points:
- RC48-ADC demonstrates promising efficacy with a manageable safety profile as an adjuvant therapy in patients with high-risk NMIBC
- RC48 may be an alternative adjuvant therapy for BCG in terms of the 12-month recurrence-free survival rate
Presented by: Haoyang Liu, Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Sichuan, China
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Associate Professor of Urology, Georgia Cancer Center, Wellstar MCG Health, @zklaassen_md on Twitter during the 2024 American Society of Clinical Oncology Genitourinary (ASCO GU) Cancers Symposium, San Francisco, CA, January 25th – January 27th, 2024