Macrocytosis as a potential parameter associated with survival after tyrosine kinase inhibitor treatment

Aim of the study As a rise in mean corpuscular volume (MCV) of the erythrocyte is frequently seen during treatment with imatinib and sunitinib, we investigated whether macrocytosis (MCV > 100 fl) also occurs as a class effect in other tyrosine kinase inhibitors (TKIs) and whether occurrence of macrocytosis is associated with outcome.
Materials and methods In 533 patients, using 5 TKIs, we investigated if macrocytosis and an increase in MCV were associated with progression-free survival and overall survival (OS) in specific tumour-treatment combinations.
Results Macrocytosis as well as an increase in MCV from baseline of >10 fl (ΔMCV +10 fl), when included as a time-dependent covariate, were associated with improved OS in patients with renal cell cancer (RCC) treated with sunitinib (macrocytosis, hazard ratio [HR] = 0.61, p = 0.031, and ΔMCV +10 fl, HR = 0.58, p = 0.016).
Conclusion In sunitinib-treated patients with RCC, the occurrence of macrocytosis, or a substantial increase in MCV levels after start of treatment, could potentially serve as a positive prognostic factor for survival, if validated prospectively.