39: Prospective noninterventional study of cabozantinib treatment following VEGF-targeted therapy in patients with advanced renal cell carcinoma: post hoc analysis of patients with concomitant radiotherapy

Background: Real-world data on cabozantinib use in patients with advanced renal cell carcinoma (aRCC) are limited. We report findings for patients from CASSIOPE (NCT03419572) who received concomitant radiotherapy; these patients are typically excluded from clinical trials.

Methods: Patients enrolled in the prospective, noninterventional CASSIOPE study (Apr 2018–May 2022) had aRCC and ≥ 1 prior vascular endothelial growth factor (VEGF)-targeted therapy (excluding cabozantinib). We present demographics, clinical characteristics, treatment patterns and safety associated with second-line (2L) or third- or later-line (≥ 3L) cabozantinib from a post hoc analysis of a subset of patients who received concomitant radiotherapy.

Results: In total, 70/679 patients (2L subgroup, n = 34; ≥ 3L subgroup, n = 36) had ≥ 1 concomitant radiotherapy. 71.4% were male, median (range) age was 61.0 (38–89) years, 82.9% had clear-cell aRCC and 74.3% had prior nephrectomy. Baseline characteristics were similar between groups. The table shows usage data. Most patients (87.1% [2L, 88.2%; ≥ 3L, 86.1%]) had a single concomitant radiotherapy, and bone was the most common site (77.1% [2L, 82.4%; ≥ 3L, 72.2%]). Most patients (78.6% [2L, 76.5%; ≥ 3L, 80.6%]) reported treatment-emergent adverse events (TEAE) in the first 6 months after initiating radiotherapy (table shows TEAEs occurring ˃ 6 months after initiation), most commonly diarrhea (24.3% [2L, 26.5%; ≥ 3L, 22.2%]), decreased appetite (17.1% [2L, 14.7%; ≥ 3L, 19.4%]), and nausea (12.9% [2L, 14.7%; ≥ 3L, 11.1%]). Any serious adverse events were reported for 28.6% of patients (2L, 26.5%; ≥ 3L, 30.6%).

Conclusions: Among patients with aRCC who received concomitant radiotherapy in real-world practice, the most common site was bone. Dose modifications were low. The most common TEAEs were consistent with the known safety profile of cabozantinib.