Cabozantinib versus sunitinib as initial therapy for metastatic renal cell carcinoma of intermediate or poor risk (Alliance A031203 CABOSUN randomised trial): Progression-free survival by independent review and overall survival update

BACKGROUND: The randomised phase 2 CABOSUN trial comparing cabozantinib with sunitinib as initial therapy for advanced renal cell carcinoma (RCC) of intermediate or poor risk met the primary end-point of improving progression-free survival (PFS) as assessed by investigator. We report PFS by independent radiology review committee (IRC) assessment, ORR per IRC and updated overall survival (OS). PATIENTS AND METHODS: Previously untreated patients with advanced RCC of intermediate or poor risk by IMDC criteria were randomised 1:1 to cabozantinib 60 mg daily or sunitinib 50 mg daily (4 weeks on/2 weeks off). Stratification was by risk group and presence of bone metastases. RESULTS: A total of 157 patients were randomised 1:1 to cabozantinib (n = 79) or sunitinib (n = 78). Median PFS per IRC was 8.6 months (95% confidence interval [CI] 6.8—14.0) versus 5.3 months (95% CI 3.0—8.2) for cabozantinib versus sunitinib (hazard ratio [HR] 0.48 [95% CI 0.31—0.74]; two-sided p = 0.0008), and ORR per IRC was 20% (95% CI 12.0—30.8) versus 9% (95% CI 3.7—17.6), respectively. Subgroup analyses of PFS by stratification factors and MET tumour expression were consistent with results for the overall population. With a median follow-up of 34.5 months, median OS was 26.6 months (95% CI 14.6—not estimable) with cabozantinib and 21.2 months (95% CI 16.3—27.4) with sunitinib (HR 0.80 [95% CI 0.53—1.21]. The incidence of grade 3 or 4 adverse events was 68% for cabozantinib and 65% for sunitinib. CONCLUSIONS: In this phase 2 trial, cabozantinib treatment significantly prolonged PFS per IRC compared with sunitinib as initial systemic therapy for advanced RCC of poor or intermediate risk.