As patients with metastatic brain tumors also present with a high extracranial disease burden, the decrease in affinity of the TEPP-DOX-aptamer conjugate toward EpCAM (but not TfR) may be beneficial for the treatment of brain metastases since the aptamer would be expected to preferentially bind to the TfR and increase its bioavailability in the brain tumor. The gene discussed is TFRC; the disease is brain neoplasm.