Rini BI et al. - In a study to assess the use of sunitinib or sorafenib in pts with metastatic renal cell carcinoma (RCC), it was found that macrocytosis was a common occurrence after treatment with sunitinib but not sorafenib in pts with metastatic RCC. Sunitinib-induced macrocytosis is reversible with drug discontinuation Methods
A retrospective review of all pts with metastatic RCC who were treated with sunitinib or sorafenib for at least 3 months was undertaken
Complete blood count (CBC) data including red blood cell indices were recorded at baseline, after 3 months of therapy, and at the end of treatment
Results
61 pts were treated with sunitinib and 37 pts were treated with sorafenib with available CBC data
In pts treated with sunitinib, median corpuscular volume (MCV) increased significantly at 3 months vs baseline and continued to increase throughout treatment
Pts who developed hypothyroidism had a larger MCV increase at 3 months than pts who remained euthyroid, although macrocytosis was observed in pts without hypothyroidism
10 pts discontinued sunitinib therapy, and MCV decreased in all pts within 2 to 4 months, without further intervention
Bone marrow analysis of 4 pts revealed a hypocellular bone marrow with trilineage hematopoiesis and no evidence of metastasis
