- Grade >/= 3 thrombocytopenia (platelets <50 * 10(9)/L) after the first 4 weeks of therapy with the tyrosine kinase inhibitor. Thrombocytopenia must be either recurrent (i.e., second or greater episode of grade >/= 3 thrombocytopenia) or having required dose reductions of the tyrosine kinase inhibitor.