FLT3 inhibition cooperates with ATRA to rapidly restore normal hematopoiesis.

Cytology and histopathology of representative mice treated as described in the legend to Figure 6. (A-D) Bone marrow cytology. ATRA causes differentiation of leukemic immature forms/blasts to neutrophilic cells, whereas SU11657 + ATRA restores a heterogeneous bone marrow with healthy elements. (E-H) Splenic cytology. ATRA-induced differentiation is evident along with normal lymphocytes and erythroid cells. SU11657 + ATRA spleen contains many healthy small lymphocytes. (I-L) Bone marrow histopathology. Findings are consistent with those observed in cytology preparations. (M-P) Splenic histopathology. SU11657 + ATRA restores normal splenic architecture. (Q-T) Liver histopathology. ATRA and SU11657 + ATRA cause marked regression of the leukemia from the liver. Wright-Giemsa stain; original magnification × 250 (A-H). Hematoxylin and eosin stain (I-T). Original magnification × 125; insets × 250 (I-P). Original magnification × 50 (Q-T).