ERBB2 and cholangiocarcinoma: Overexpression of HER2 protein or amplification of the HER2 gene occurs in up to 20% of CCA patients and is more common in patients with pCCA and dCCA (17.4%) than in iCCA (4.8%).225–227 Dual HER2 blockade with trastuzumab and pertuzumab was evaluated in 39 patients with CCA in the phase IIa MyPathway basket study.