For example, in the treatment of brain tumors, RTX was encapsulated within a biodegradable, crosslinked zwitterionic polymer to increase brain uptake through AMT.[30, 31] Further conjugation of this nanocapsule with chemokine (C‐X‐C motif) ligand 13 (CXCL13), a ligand of the chemokine receptor C‐X‐C chemokine receptor type 5 (CXCR5) expressed on lymphoma, guided RTX nanoparticles to brain metastases of primary lymphoma to enhance therapeutic efficacy (Figure 4B).[195]. Here, CXCR5 is linked to lymphoma.