To this end, 4 different tumor samples of various molecular subtypes of the disease—microsatellite instability (P1), copy-number low (P2), and polymerase epsilon (POLE) ultramutated (P3), and P4 (subtype unknown)—were incubated with trastuzumab, AR9.6, or ATG-031; stained with a fluorophore-labeled secondary mAb, and evaluated via confocal microscopy (Fig. 2) (22,23). Here, POLE is linked to neoplasm.