Abstract 287P
Background
The anti-HER-2 RC48-ADC (Disitamab Vedotin) has shown promising efficacy in HER2 positive locally advanced or metastatic UC (la/mUC). Limited data support its use for patients with Her-2 low or null expression.
Methods
Patients with HER2 low (IHC1+) or null expression (IHC0) la/mUC who were treated with RC48-ADC monotherapy or in combination with programmed cell death protein 1 (PD-1) inhibitors were enrolled in this multi-center, retrospective study to evaluate the real-world antitumor effectiveness and safety.Outcomes evaluated were progression-free survival (PFS), overall survival (OS),objective remission rate (ORR), disease control rate (DCR), and adverse events.
Results
Altogether 27 patients were included. The median age was 64 (39-76)years, median range was 1.8 (0-4) and 17(63%) were male. HER2 was low expression(IHC 1+) in 19 (70.4%) patients, and null expression (IHC 0) in 8 (29.6%) patients. The primary sites were ureteral UC in 40.7%(11/27), renal pelvis UC in 33.3% (9/27), and bladder UC in 26% 7/27). Seven (26.0%) patients received RC48 alone, and 20 (74.1 %) received RC48 combined with a programmed death-1 antibody. The median follow up was 7.1month, median PFS was 7.4 months, and the median OS was not reached. The 6-month and 1-year PFS rates were 50.4% and 28.3%, respectively. The 1-year OS rate was 60.6%. Eight patients achieved a partial response, and 12 patients showed stable disease, with the ORR and DCR were 30.8% and 76.9%. The main treatment-related adverse events included anemia, nausea, hypoalbuminemia, elevated transaminases. Notreatment-related death occurred.
Conclusions
RC48-ADC shows favorable efficacy and manageable safety in metastaticUC patients with HER2 low/null expression in real-world settings, supporting its use.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.