HAVCR2 and acute lymphoblastic leukemia: However, most of the patients with T-ALL had low HAVCR2 mRNA expression with high TOX and TOX2 mRNA levels (75.3%, 128 of 170), and only 24.7% (42/170) of T-ALL patients had high HAVCR2 mRNA expression with high TOX and TOX2 mRNA levels in bone marrow samples (Fig. 1A).