3561 - Comprehensive Genomic Profiling (CGP) of mixed hepatocellular cholangiocarcinomas (cHCC-CCA)

Background

cHCC-CCA is a rare primary liver carcinoma, with histologic features of both hepatocellular carcinomas (HCC) and liver cholangiocarcinomas (CCA). In order to elucidate their shared and distinctive biology, we used CGP to compare the genomic alterations (GA) of cHCC-CCA with those of HCC and CCA.

Methods

1269 HCC, 3965 CCA and 44 cHCC-CCA were assayed by hybrid capture based CGP on 0.8-1.1 Mb of the coding genome to identify GAs in exons and select introns in up to 404 genes, tumor mutational burden (TMB), microsatellite status (MSI) and % monoallelic genome (gLOH). Utilizing the significant differences in GAs, biomarkers, and demographics between HCC and CCAs (Fischer exact test, FDR < 0.05, only GAs with freq > 10% shown, Table), we built a random forest-based machine learning model to rank a cHCC-CCA specimen in the CCA-HCC spectrum (Out of Bag error rate = 12.6%, AUC = 0.94).

Results

Biomarkers exclusively associated with one disease type included IDH1 (15% in CCA vs 1% in HCC, p = 1e-57), TERT (4% in CCA vs 47% in HCC, p = 2e-273) and Hepatitis B virus (HBV, 0.8% in CCA vs 8.5% in HCC, p = 9e-42). 10/44 cHCC-CCA were classified as CCA-like (IDH1 = 4/10, HBV = 0/10, TERT = 0/10, median TMB = 0.9) and 21/44 cases as HCC-like (IDH1=0/21, HBV=5/21, TERT = 15/21, median TMB = 4). 13/44 cHCC-CCA featured ambiguous/conflicting CGP findings (IDH1=0/13, HBV=1/13, TERT = 0/13, median TMB = 4). 5/13 cHCC-CCA had a computational tumor purity < = 20% and a different 1/13 was highly contaminated, making classification difficult.Table:

677PD

Conclusions

Using a machine learning model, the prevalence and mutual exclusivity of IDH1/2, FGFR2, TERT, CTNNB1 and other key GAs, suggest that the majority of cHCC-CCA cases fall into molecular subgroups either similar to CCA or HCC. These findings suggest that cHCC-CCA is not a true disease entity but may be a conglomerate of transformed CCA and HCC.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Foundation Medicine.

Funding

Foundation Medicine.

Disclosure

K. Murugesan: Full / Part-time employment: Foundation Medicine; Shareholder / Stockholder / Stock options: Roche. M. Javle: Honoraria (self), Honoraria (institution), Advisory / Consultancy, Speaker Bureau / Expert testimony, Leadership role, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses, Shareholder / Stockholder /: Rafael Pharmaceuticals; Honoraria (self), Honoraria (institution), Advisory / Consultancy, Speaker Bureau / Expert testimony, Leadership role, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses, Shareholder / Stockholder /: Incyte; Honoraria (self), Honoraria (institution), Advisory / Consultancy, Speaker Bureau / Expert testimony, Leadership role, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses, Shareholder / Stockholder /: Pieris Pharmaceuticals; Honoraria (self), Honoraria (institution), Advisory / Consultancy, Speaker Bureau / Expert testimony, Leadership role, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses, Shareholder / Stockholder /: Merck; Honoraria (self), Honoraria (institution), Advisory / Consultancy, Speaker Bureau / Expert testimony, Leadership role, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses, Shareholder / Stockholder /: Merck Serono; Honoraria (self), Honoraria (institution), Advisory / Consultancy, Speaker Bureau / Expert testimony, Leadership role, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses, Shareholder / Stockholder /: Novartis; Honoraria (self), Honoraria (institution), Advisory / Consultancy, Speaker Bureau / Expert testimony, Leadership role, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses, Shareholder / Stockholder /: Seattle Genetics; Honoraria (self), Honoraria (institution), Advisory / Consultancy, Speaker Bureau / Expert testimony, Leadership role, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses, Shareholder / Stockholder /: QED Therapeutics; Honoraria (self), Honoraria (institution), Advisory / Consultancy, Speaker Bureau / Expert testimony, Leadership role, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses, Shareholder / Stockholder /: Bayer; Honoraria (self), Honoraria (institution), Advisory / Consultancy, Speaker Bureau / Expert testimony, Leadership role, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses, Shareholder / Stockholder /: BeiGene. A.B. Schrock: Full / Part-time employment: Foundation Medicine; Shareholder / Stockholder / Stock options: Roche. N. Ngo: Full / Part-time employment: Foundation Medicine; Shareholder / Stockholder / Stock options: Roche. G.M. Frampton: Full / Part-time employment: Foundation Medicine; Shareholder / Stockholder / Stock options: Roche. B.M. Alexander: Full / Part-time employment: Foundation Medicine; Shareholder / Stockholder / Stock options: Roche. V.A. Miller: Full / Part-time employment: Foundation Medicine. T. Bekaii-Saab: Advisory / Consultancy: Amgen; Advisory / Consultancy: Bristol-Myers Squibb; Advisory / Consultancy: Lilly; Advisory / Consultancy: Regeneron; Advisory / Consultancy: AstraZeneca; Advisory / Consultancy: Celgene; Advisory / Consultancy: NCCN; Advisory / Consultancy: Genentech/Roche; Advisory / Consultancy: Bayer; Advisory / Consultancy: Taiho Pharmaceutical; Advisory / Consultancy: Boehringer Ingelheim; Advisory / Consultancy: Sirtex Medical; Advisory / Consultancy: Pfizer; Advisory / Consultancy: Glenmark; Advisory / Consultancy: Ipsen; Advisory / Consultancy: AbbVie; Advisory / Consultancy: Incyte; Advisory / Consultancy: Imugene; Advisory / Consultancy: Immuneering. L.A. Albacker: Full / Part-time employment: Foundation Medicine; Shareholder / Stockholder / Stock options: Roche. J.S. Ross: Full / Part-time employment: Foundation Medicine; Shareholder / Stockholder / Stock options: Foundation Medicine. S.M. Ali: Shareholder / Stockholder / Stock options, Licensing / Royalties, Full / Part-time employment: Foundation Medicine; Advisory / Consultancy: Revolution Medicines; Leadership role: Incysus; Shareholder / Stockholder / Stock options: Exelixis; Shareholder / Stockholder / Stock options: Blueprint Medicines; Shareholder / Stockholder / Stock options: Agios; Shareholder / Stockholder / Stock options: Genocea Biosciences.