A, For GIST patients (n = 8), VEGF is detectable in plasma, and there are nonsignificant trends toward decrease with therapy. B, IL8 is widely variable at baseline without any changes seen with therapy. C, For patients (n =13), median ALC at baseline =1,100; after 1 week of dasatinib = 1,300 (P = NS); dasatinib and two doses of ipilimumab = 1,550 (P = 0.04, paired t test). No relationship with clinical benefit was observed. D, Western blot analysis: Pre represents prior to treatment, post #1 is after dasatinib alone, and post #2 is after dasatinib + two doses of ipilimumab. There were 4 of 6 patients with adequate tissue for analysis. All patients had baseline expression of KIT, p-KIT, and IDO. Patients 1 and 2 had no changes after treatment (Tx) and evidence of progression. Patient 5 (duodenal GIST, exon 13 mutation) had loss of IDO expression at the second posttreatment biopsy with stable disease per RECIST, irRC, and Choi lasting 19 weeks. Patient 6 had SDH-deficient GIST with evidence of stable disease for 48 weeks without loss of IDO expression.