D43 - Capecitabine and Regorafenib-related increased mean corpuscular volume of red blood cell may be a predictive marker of treatment response and survival in patients with metastatic colorectal cancer

Abstract

Background: Erythrocyte mean corpuscular volume (MCV) increase has been described in patients treated with capecitabine. Moreover, tyrosine kinase inhibitors have been shown to induce macrocytosis in patients with renal cancer cell and gastrointestinal stromal tumors, presumably via the inhibition of erythroid progenitor cells of the bone marrow. Therefore, the aim of our study was to evaluate the potential association of the erythrocyte MCV increase with tumor response and survival in patients with metastatic colorectal cancer (mCRC) treated with capecitabine and regorafenib. Patients and methods: A retrospective review of 30 patients with mCRC who were treated with capecitabine or regorafenib for at least 3 months at the Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Sant'Orsola-Malpighi Hospital, Bologna, Italy. Complete blood count (CBC) including red blood cell indices were recorded at baseline and after 4, 8 and 12 weeks from capecitabine or regorafenib treatment. Results: Baseline MCV levels and MCV levels after 4, 8 and 12 weeks were registered for each patient treated with capecitabine or regorafenib. Median ΔMCV [(post-treatment MCV values after 12 weeks) - (baseline MCV values)] was calculated. Patients were grouped according to ΔMCV into two groups in order to carry out survival analysis and correlation with tumor response. Moreover, univariate and multivariate analysis was performed to investigate if MCV increase was independently associated with favorable survival outcomes. Conclusions: Erythrocyte MCV increase may be used as a predictive marker for treatment response, PFS and OS in patients with mCRC treated with capecitabine or regorafenib. In the future, response to TAS-102 (trifluridine-tipiracil) and MCV increase will be also evaluated.