Fig 4.

Patient-derived xenograft (PDX) –bearing mice (seven to 10 per group) treated with vehicle or dabrafenib (D) plus trametinib (T) daily for 21 days. (A) Plotted is change in PDX tumor volume after treatment, relative to initial tumor volume (all P < .001 by unpaired t test). (B) Computed tomography images showing lesion in patient who was biopsied to generate PDX pretreatment and at maximal response (weeks 32, 8, 3, and 8, respectively). First patient had spinal intramuscular mass biopsied, which regressed by 23% after 8 weeks of treatment and was not measurable by week 16 (overall best response in patient, confirmed partial response). Second patient had liver lesion biopsied, which regressed by 41% after 8 weeks of treatment (overall best response in patient, stable disease). Third patient had superficial paraumbilical nodule biopsied. This patient was not evaluable (ended study treatment because of toxicity), but imaging at week 3 showed early response in biopsied lesion. Fourth patient had posterior vaginal mass resected pretreatment, with anterior rectal recurrence by first restaging (overall best response in patient, progressive disease). If positron emission tomography was performed, maximum standardized uptake value (SUV) is noted for biopsied lesion.