Individualised axitinib regimen for patients with metastatic renal cell carcinoma after treatment with checkpoint inhibitors: a multicentre, single-arm, phase 2 study.

BACKGROUND: Checkpoint inhibitor therapy is a standard of care for patients with metastatic renal cell carcinoma. Treatment options after checkpoint inhibitor therapy include vascular endothelial growth factor receptor (VEGF-R) tyrosine kinase inhibitors, although no prospective data regarding their use in this setting exist. Axitinib is a VEGF-R inhibitor with clinical data supporting increased activity with dose titration. We aimed to investigate the activity of dose titrated axitinib in patients with metastatic renal cell carcinoma who were previously treated with checkpoint inhibitor.

METHODS: We did a multicentre, phase 2 trial of axitinib given on an individualised dosing algorithm. Patients at least 18 years of age with histologically or cytologically confirmed locally recurrent or metastatic renal cell carcinoma with clear cell histology, a Karnofsky Performance Status of 70% or more, and measurable disease who received checkpoint inhibitor therapy as the most recent treatment were eligible. There was no limit on number of previous therapies received. Patients received oral axitinib at a starting dose of 5 mg twice daily with dose titration every 14 days in 1 mg increments (ie, 5 mg twice daily to 6 mg twice daily, up to 10 mg twice daily maximum dose) if there was no axitinib-related grade 2 or higher mucositis, diarrhoea, hand-foot syndrome, or fatigue. If one or more of these grade 2 adverse events occurred, axitinib was withheld for 3 days before the same dose was resumed. Dose reductions were made if recurrent grade 2 adverse events despite treatment breaks or grade 3-4 adverse events occurred. The primary outcome was progression-free survival. Analyses were done per protocol in all patients who received at least one dose of axitinib. Recruitment has been completed and the trial is ongoing. This trial is registered with ClincalTrials.gov, number NCT02579811.

FINDINGS: Between Jan 5, 2016 and Feb 21, 2018, 40 patients were enrolled and received at least one dose of study treatment. With a median follow-up of 8·7 months (IQR 3·7-14·2), the median progression-free survival was 8·8 months (95% CI 5·7-16·6). Fatigue (83%) and hypertension (75%) were the most common all-grade adverse events. The most common grade 3 adverse event was hypertension (24 patients [60%]). There was one (3%) grade 4 adverse event (elevated lipase) and no treatment-related deaths occurred. Serious adverse events that were likely related to therapy occurred in eight (20%) patients; the most common were dehydration (n=4) and diarrhoea (n=2).

INTERPRETATION: Individualised axitinib dosing in patients with metastatic renal cell inoma previously treated with checkpoint inhibitors did not meet the prespecified threshold for progression free survival, but these data show that this individualised titration scheme is feasible and has robust clinical activity. These prospective results warrant consideration of axitinib in this setting.

FUNDING: Pfizer.