Role of ErbB family receptor tyrosine kinases in intrahepatic cholangiocarcinoma

Table 1 Rodent models of intrahepatic cholangiocarcinoma constitutively overexpressing ErbB2/Neu in cancerous epithelium

Model	Tumor			ErbB2/Neu			Tyrosine phosphorylation	Ref.
	Development time	Incidence (%)	Classification	c-erbB-2/neu	mRNA	Protein
Furan rat model	> 1 yr	70-100	Intestinal-type cholangiocarcinoma	Wild-type/non-amplified	Increased	Increased	Increased	[63,64]
Thioacetamide rat model	16-22 wk	100	Intestinal-type cholangiocarcinoma	NA	NA	Increased	NA	[65]
P53 deficiency/CCl4 mouse model	≥ 16 wk	40	Ductal cholangiocarcinoma	NA	NA	Increased	NA	[66]
Rat BDEneu orthotopic cell transplantation model	4 wk	100	Ductal cholangiocarcinoma	Mutated	Increased	Increased	Increased	[68,69]

NA: Not assessed.

Table 2 Selected anti-cancer agents targeting ErbB family receptors

Agent	Class/Type	Target	Route of administration	Development stage	Ref.
Trastuzumab (Herceptin)	Recombinant humanized mAb	Extracellular domain of ErbB2	Intravenous infusion	Approved (ErbB2-positive breast cancer)	[150-152]
Pertuzumab (Omnitarg, 2C4)	Recombinant humanized mAb	Dimerization domain of ErbB2	Intravenous infusion	Phase II/III	[151,153,154]
Cetuximab (Erbitux, C225)	Recombinant human/mouse chimeric mAb	Extracellular domain of EGFR	Intravenous infusion	Approved (EGFR-positive metastatic colorectal cancer and squamous cell carcinoma head and neck cancer)	[151,155-157]
Panitumumab (ABX-EGF, Vectibix)	Fully human mAb	Extracellular domain of EGFR	Intravenous infusion	Approved (EGFR-positive metastatic colorectal cancer)	[157-159]
Matuzumab (EMI-72000)	Recombinant humanized mAb	Extracellular domain of EGFR	Intravenous infusion	Phase I/II	[157,159,160]
MDX-447	Humanized bispecific mAb	Extracellular domain of EGFR and high affinity IgG receptor CD64	Intravenous infusion	Phase I/II	[157,161]
Gefitinib (Iressa)	Anilinoquinazoline/Reversible TKI	EGFR tyrosine kinase	Oral	Limited approval (NSCLC)	[157,162-164]
Erlotinib (Tarceva)	Anilinoquinazoline/Reversible TKI	EGFR tyrosine kinase	Oral	Approved (NSCLC and pancreatic cancer)	[153,155,157,165,166]
Lapatinib (Tykerb, GW572016)	Thiazolylquinazoline/Reversible TKI	EGFR and ErbB2 tyrosine kinases	Oral	Approved (ErbB2-positive advanced metastatic breast cancer)	[157,166-169]
PKI-166	Pyrrolopyrimidine/Reversible TKI	EGFR and ErbB2 tyrosine kinases	Oral	Phase I	[153,155,157,166,170]
BMS-599626	Pyrrolotriazine/Reversible TKI	EGFR and ErbB2 tyrosine kinases	Oral	Phase I	[171,172]
EKB-569 (Pelitinib)	Cyanoquinoline/Irreversible TKI	EGFR tyrosine kinase	Oral	Phase I/II	[157,166,173]
BIBW-2992	Anilinoquinazoline/Irreversible TKI	EGFR and ErbB2 tyrosine kinases	Oral	Phase I/II	[168,174]
CI-1033 (Canertinib)	Anilinoquinazoline/Irreversible TKI	Pan-ErbB tyrosine kinases	Oral	Phase I/II	[153,157,164,168]
HKI-272	Cyanoquinoline/Irreversible TKI	Pan-ErbB tyrosine kinases	Oral	Phase I/II	[153,164,168,175]

mAb: Monoclonal antibody; TKI: Tyrosine kinase inhibitor; EGFR: Epidermal growth factor receptor; NSCLC: Non-small cell lung cancer.

Table 3 Preclinical biological effects of ErbB RTK inhibitors alone or combined with other target-based treatments for biliary tract cancer cells

Agent	Target	Experimental condition	Biliary cancer cell line/tumor	Biological effects	Ref.
Gefitinib	EGFR	Cell culture	HAG-1 human gallbladder adenocarcinoma cell line	Dose-dependent in vitro cell growth inhibition by arresting cells in G0/G1, followed by progressive cell apoptosis; inhibition of EGFR phosphorylation and of Erk1/2 and Akt activation; decreased cyclin D1 mRNA and induced accumulation of p27 protein, a negative cell cycle regulator	[176]
Gefitinib + Ionizing radiation	EGFR	Cell culture	HuCCT1 human intrahepatic cholangiocarcinoma cell line; TFK-1 human bile duct carcinoma cell line	Gefitinib induced increase in radiosensitivity of HuCCT1 and TFK-1 cells	[177]
Cetuximab + erlotinib	EGFR	Cell culture and subcutaneous tumor xenografts in athymic nude mice	HuCCT1 cell line	Combined treatment with cetuximab blunted erlotinib-induced EGFR up-regulation and regulated in HuCCT1 growth inhibition and apoptosis in vitro and HuCCT1 tumor growth arrest in vivo	[178]
Gefitinib + CI-1040	EGFR + MEK-Erk1/2	Cell culture and subcutaneous tumor xenografts in athymic nude mice	HuCCT1 cell line	Drug combination significantly more effective than single agent treatments in suppressing both in vitro and in vivo tumor cell growth; combination treatment dramatically decreased phosphorylation levels of EGFR and Erk1/2 in cultured cells and in xenografted tumors, whereas HuCCT1 cells were found to be resistant to treatments with gefitinib or CI-1040 alone	[179]
Lapatinib	EGFR/ErbB2	Cell culture	Rat C611B and human HuCCT1 cholangiocarcinoma cell lines	Lapatinib was demonstrated to be a potent inhibitor of C611B and HuCCT1 cholangiocarcinoma cell growth in vitro by a mechanism involving inhibition of EGFR and ErbB2 activation, suppression of p42/44 MAPK and Akt phosphorylation, and induction of apoptosis	[180]
NVP-AEE788	EGFR/ErbB2 and VEGFR-2	Cell culture and subcutaneous tumor xenografts in athymic nude mice	EGI-1, TFK-1, CC-SW-1, CC-LP-1 and SK-ChA-1 human extrahepatic bile duct cancer cell lines; MZ-ChA-1 and MZ-CA-2 human gallbladder adenocarcinoma cell lines	NVP-AEE788 more efficacious than the EGFR RTK inhibitors gefitinib and erlotinib in suppressing in vitro cell growth; EGI-1 tumors in mice treated with NVP-AEE788 had significantly reduced volume and mass compared with those in placebo-treated mice, while erlotinib was without effect in inhibiting in vivo tumor growth; main mechanisms of NVP-AEE788 drug action were suppression of Erk1/2 phosphorylation, induced apoptosis, and inhibition of tumor angiogenesis	[181]
Emodin + Celecoxib	ErbB2 +COX-2	Cell culture	C611B rat intrahepatic cholangiocarcinoma cell line	Emodin and celecoxib combined to synergistically suppress anchorage-dependent and anchorage-independent cell growth in vitro through a mechanism involving enhanced inhibition of ErbB2 activation, decreased phospho-Akt, and enhanced caspase-9 and -3 activation, resulting in significantly increased apoptosis	[75]
Gefitinib or GW2974	EGFR	BK5.erbB2 transgenic mice constitutively expressing wild-type rat ErbB2	Gallbladder adenocarcinoma	Both agents produce significant chemopreventative and therapeutic effects in reducing gallbladder adenocarcinoma incidence, which was associated with prominent decreases in both the phosphorylation and protein levels of EGFR and ErbB2, with significantly decreased Erk1/2 acitivity and with a reduction in COX-2 protein levels in BK5.erbB2 mouse gallbladders	[182]
	EGFR/ErbB2

RTK: Receptor tyrosine kinase; EGFR: Epidermal growth factor receptor; VEGFR-2: Vascular endothelial growth factor receptor-2; COX-2: Cyclooxygenase-2.

Table 4 Outcomes of ErbB-targeted therapies in patients with advanced biliary cancer

Assessable patients	Tumor	ErbB status	ErbB inhibitor	Target	Administration	Response	Ref.
40	Unresected or metastatic biliary tract cancers (gallbladder, intra- and extrahepatic bile duct)	29/36 (81%) assessable tumor samples positive for EGFR expression	Erlotinib	EGFR	Single agent	PR-3 patients; SD-17 patients; median time to disease-progression of 2.6 mo	[185]
1	Metastatic cholangiocarcinoma	Negative EGFR expression in tumor	Cetuximab	EGFR	In combination with 5'flurouracil, folic acid, and radiotherapy	PR in intra-chemotherapeutic state	[186]
1	Unresected cholangiocarcinoma with peritoneal carcinomatosis	Positive EGFR expression in tumor	Cetuximab	EGFR	In combination with gemcitabine	PR with 30% reduction in hepatic mass and disappearance of peritoneal carcinomatosis as shown by computed tomography	[187]
9	Unresected cholangiocarcinoma with disease progression after at least 3 cycles of gemcitabine-oxaliplatin	9/9 (100%) tumor samples positive for EGFR expression, with all being negative for membranous ErbB2	Cetuximab	EGFR	In combination with gemcitabine-oxaliplatin	After 6 mo, CR-1 patient; PR-1 patient; SD-1 patient; progressive disease-6 patients; all patients relapsed, with a median time to disease progression of 4 mo	[188]
17	Unresected advanced biliary tract cancers (gallbladder, bile duct)	Not reported	Lapatinib	EGFR/ErbB2	Single agent	No observed responses; 5 patients with SD; cohort closed due to no noted lapatinib activity	[189]
6 with biliary tract cancers out of a total of 34 with various types of solid tumors	Advanced cholangiocarcinoma (5) or gallbladder cancer (1)	Not investigated	Lapatinib	EGFR/ErbB2	In combination with oxaliplatin/5-flurouracil/leucovorin	PR-1 patient with cholangiocarcinoma and 1 patient with gallbladder cancer	[190]

CR: Complete response; PR: Partial response; SD: Stable disease.

Table 5 Factors affecting ErbB-targeted therapies for intrahepatic cholangiocarcinoma and other biliary tract cancers

Factors
Patient selection and sampling size
Suboptimal drug dosing and/or scheduling
Tumor microenvironment and bioavailability
Intratumoral heterogeneity in receptor expression and activation
Receptor dynamic effects
Mutational effects
Different mechanisms of acquired resistance
Constitutive overexpression of ErbB family ligands
Co-activation of multiple receptor tyrosine kinases resulting in signaling redundancy and interplay
Lack of uniform biomarkers to effectively predict therapeutic response
Co-morbid disease and toxicity