One point to be considered is the fact that EGFR is also highly expressed in some normal tissues, such as the liver, skin, and submaxillary salivary gland. Therefore, the bioavailability of ABY-029 could be reduced as a consequence of off-target EGFR binding of the NIR probe. The results from dose escalation showed a dose-dependent ABY-029 tumor uptake (Fig. 4), which can be related to saturation of EGFR in the liver . Moreover, the fluorescence from the tumor was higher than the contralateral normal brain or brain from the rats that received sham surgery. This was true even 48 h post-injection. Thus, these results show that there is high in vivo specificity for ABY-029 uptake by tumor cells.