PADRES: a phase 2 clinical trial of neoadjuvant axitinib for complex partial nephrectomy.

OBJECTIVE: To report the results of PADRES (Prior Axitinib as a Determinant of Outcome of Renal Surgery, NCT03438708), a study investigating neoadjuvant axitinib for tumours of high complexity with imperative indication for partial nephrectomy (PN). METHODS: We conducted a single-arm phase II clinical trial of localized (cT1b-cT3M0) clear-cell renal cell carcinoma (RCC) patients with imperative indications for nephron preservation, where PN is a high-risk procedure due to complexity (RENAL score 10-12). Axitinib 5 mg was administered twice daily for 8 weeks with repeat imaging at completion, followed by surgery. The primary outcome was successful completion of planned PN following axitinib treatment. Secondary objectives included changes in tumour diameter, RENAL nephrometry score, renal function and Response Evaluation Criteria in Solid Tumours (RECIST) v1.1, and surgical complications. RESULTS: Twenty-seven patients were enrolled (median age 69 years). Prior to therapy, twenty patients (74.0%) had ≥ clinical T3a staged tumours. Axitinib resulted in reductions in tumour diameter (7.5 vs 6.2 cm; P < 0.001) and RENAL score (11 vs 10; P < 0.001). Nine patients (33.3%) had partial response based on RECIST and nine (33.3%) were clinically downstaged. PN was performed in twenty patients (74.0%); twenty-five patients (96.2%) had negative margins. Six patients (22.2%) had Clavien III-IV complications. The median change in estimated glomerular filtration rate (preoperative to last follow-up) was 8.5 mL/min/1.73 m2 . CONCLUSION: Neoadjuvant axitnib resulted in reductions in tumour size and complexity, enabling safe and feasible PN and functional preservation in patients with complex renal masses and imperative indication.