Haemoglobin level increase as an efficacy biomarker during axitinib treatment for metastatic renal cell carcinoma: a retrospective study

BACKGROUND: Axitinib is used after failure of first line treatment for metastatic renal cell carcinoma (mRCC). A known side effect is the increase of haemoglobin level (HbL) during treatment with a suspected correlation with better outcome. Our objective was to examine whether HbL increase during the first three months of axitinib treatment is associated with better prognosis. METHODS: Retrospective multicentre analysis including patients with mRCC treated with axitinib for at least three months from 2012 to 2014. Progression-free survival (PFS) was analysed by a Cox model according to gender, International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) prognostic score, high blood pressure (hBP), and maximum increase in HbL within the first three months of treatment. RESULTS: Ninety-eight patients were analysed (71% men; median age at treatment initiation: 62 years; IMDC: 24%, 50%, and 26% in the favourable, intermediate, and poor-risk group, respectively). Patients received axitinib for a median of 8 months. During the first three months, the median increase of HbL was +2.3 g/dL (−1.1; 7.2). Fifty-six (57%) patients developed hBP. In multivariate analysis, after adjustment for performance status (P < 0.0001) and gender (P = 0.0041), the combination of HbL increase ≥2.3 g/dL and any grade hBP was significantly associated with longer PFS (HR = 0.40, 95%CI [0.24; 0.68]). CONCLUSIONS: Early HbL increase during axitinib treatment combined with hBP is an independent predictive factor of PFS. These results require validation in a prospective setting.