This observation can, on the one hand, provide an argument for anti-HER2 treatment in patients with HER2-negative primary tumors, but on the other hand, can also explain why the anti-HER2 treatment is not effective: anti-HER2 antibodies bind to the HER2-positive EVs rather than inhibiting the HER2 signal activation on the tumor cell surface [74]. The gene discussed is ERBB2; the disease is neoplasm.