Introduction: The AXIS trial established axitinib as a standard of care treatment for patients with metastatic renal cell carcinoma (mRCC) after failure of a prior tyrosine kinase inhibitor. Axitinib dosing begins at 5 mg twice daily, with escalation of doses to 7 and 10 mg after consecutive 2-week intervals if tolerated (as per the drug label). Given clinical concerns about drug-related toxicity, we have used a pragmatic strategy where dose escalations were made only after disease progression or where rapid responses were clinically required.
Methods: We performed a retrospective review of electronic health records and radiology of all patients with mRCC treated with axitinib for >2 weeks at Addenbrooke's Hospital, Cambridge, UK, over a 37 -month period to determine the clinical and radiological effects of dose escalations made according to the above strategy.
Results: 42 patients fitting these criteria were identified, 29 having ≥1 dose escalation event (DEE). 60 DEEs were identified (median of two per patient), and the objective radiological consequences of 53 DEEs could be evaluated. The disease control rate (partial response or stable disease) after the first DEE instituted for disease progression was similar to that after the second DEE (68.8% vs 70%). 56.6 % of all DEEs and 63.6 % of DEEs made as a result of disease progression resulted in disease control. The median OS from the commencement of axitinib for all dose-escalated patients was 19.9 months, and 16.5 months for the entire cohort. The mean dose (for all patients) at 90 days after starting axitinib was 5.92 mg.
Conclusion: These data suggest that dose escalation of axitinib after disease progression may be an effective dosing strategy for patients with mRCC, and this may be a preferred option in patients in whom there are particular concerns about drug-related toxicity, quality of life optimisation or healthcare-associated costs.
Keywords: axitinib; dose escalation; renal cell carcinoma; toxicity; tyrosine kinase inhibitors.