Efficacy of sacituzumab govitecan after enfortumab vedotin in advanced urothelial carcinoma: Analysis of the UNITE study.

BACKGROUND

Sacituzumab govitecan (SG) is an antibody-drug conjugate used for advanced urothelial carcinoma (aUC) refractory to platinum-based chemotherapy and immune checkpoint inhibitors (ICI). Real-world data are needed to better define SG outcomes, particularly following treatment with enfortumab vedotin (EV). In this analysis, we aim to evaluate efficacy of SG after EV and assess putative biomarkers associated with outcomes.

METHODS

In the UNITE retrospective study, we identified patients who received ≥1 SG cycle after therapy with EV. Observed response rate (ORR) was assessed in evaluable patients and correlated with baseline clinical characteristics and biomarkers. ORRs were compared using logistic regression, while progression free survival (PFS) and overall survival (OS) from SG start were estimated via Kaplan-Meier and Cox proportional hazard (PH) model. Biomarkers of response were evaluated in multivariate Cox PH models after accounting for relevant clinical variables.

RESULTS

Among 107 patients treated with SG after EV, 97 (91%) had NGS data. Median age was 69 years, 73% were male, 33% had ≥4 prior lines of therapy, and 42% received G-CSF. ORR was 18% (95% CI: 10%-26%), median PFS 3.2 months, and median OS 6.0 months. In patients with disease control on EV, ORR was 22% compared to 8% in primary progressors on EV. No significant associations were found between molecular biomarkers and SG outcomes in the multivariate analysis.

CONCLUSION

SG showed modest activity after EV in heavily pretreated patients with aUC. ORR with SG after EV was lower than reported in phase 2 and phase 3 clinical trials for SG in the postplatinum/ICI setting.