IDO downregulation sensitized A549 xenografts to pemetrexed treatment.

A: Ten million A549 cells transfected with control shRNA (clone NC-3) or anti-IDO shRNA (clone 2–18) were injected into flanks of SCID mice. Once tumors reached ~300 mm3 animals were injected with 100,000 IU IFNγ i.p. (twice a week for four weeks) and 50 mg/kg pemetrexed i.p. (once per week for four weeks). Animals transplanted with A549 clonal cells transfected with control shRNA or anti-IDO shRNA received four weeks of IFNγ treatment alone (B) or IFNγ and pemetrexed (C). Tumor growth was monitored with caliper measurement to estimate tumor volume. *Significant difference, Student's t-test, p