Abstract GS3-07: Genome-wide copy number analysis of chemotherapy-resistant metastatic triple-negative breast cancer from cell-free DNA

Introduction:

Triple-negative breast cancer (TNBC) is a poor prognosis breast cancer subset characterized by relatively few mutations but extensive copy number alterations (CNAs). Cell-free DNA (cfDNA) offers the potential to overcome infrequent tumor biopsies in metastatic TNBC (mTNBC) and interrogate the genomics of chemotherapy resistance.

Methods:

506 archival or fresh plasma samples were identified from 164 patients with mTNBC who had previously received chemotherapy. We performed low coverage whole genome sequencing to determine genome-wide copy number and estimate 'tumor fraction' of cfDNA (TFx) using our recently-developed approach, ichorCNA. In patient samples with TFx >10%, we identified regions that were significantly gained or lost using GISTIC2.0. We compared CNAs of 20 paired primary-metastatic samples and also mTNBCs from cfDNA versus primary TNBCs from TCGA and METABRIC.

Results:

We successfully obtained high quality, low coverage whole genome sequencing data for 478 (94.5%) plasma samples from 158 patients, with 1 to 14 samples per patient. TFx and copy number profiles were highly concordant with paired metastatic biopsy (n=10, range 0-7 days from biopsy to blood draw) with sensitivity of 0.86 and specificity of 0.90 and reproducible in independently-processed blood draws (TFx intraclass correlation coefficient 0.984). Median overall survival from time of first blood draw was 8 months, and TFx was highly correlated independent of primary stage, primary receptor status, age at primary diagnosis, BRCA status, and metastatic line of therapy: adjusted hazard ratio between 4th and 1st quartiles = 2.14 (95% CI 1.40-3.28; p=0.00049). 101/158 patients (63.9%) had at least one sample with TFx >10%, our threshold for high confidence CNA calls. Copy number profiles and percent genome altered were remarkably similar between mTNBCs and primary TNBCs in TCGA and METABRIC (n=433), suggesting that large-scale chromosomal events are infrequent in TNBC metastatic progression. We identified chromosomal gains that demonstrated significant enrichment in mTNBCs relative to paired primary TNBCs (n=20) and also TCGA/METABRIC, including driver genes (NOTCH2, AKT2, AKT3) and putative antibody-drug conjugate targets. Finally, we identify a novel association of gains of 18q11 and/or 19p13 with poor metastatic prognosis, independent of clinicopathologic factors and TFx.

Conclusions:

Here, we present the first large-scale genomic characterization of metastatic TNBC to our knowledge, derived exclusively from cfDNA. 'Tumor fraction' of cfDNA is an independent prognostic marker in mTNBC. Primary and metastatic TNBC have remarkably similar copy number profiles yet we identify alterations enriched and prognostic in mTNBC. Collectively, these data have potential implications in the understanding of metastasis, therapeutic resistance, and novel therapeutic targets.

Citation Format: Stover DG, Parsons HA, Ha G, Freeman S, Barry B, Guo H, Choudhury A, Gydush G, Reed S, Rhoades J, Rotem D, Hughes ME, Dillon DA, Partridge AH, Wagle N, Krop IE, Getz G, Golub TA, Love JC, Winer EP, Tolaney SM, Lin NU, Adalsteinsson VA. Genome-wide copy number analysis of chemotherapy-resistant metastatic triple-negative breast cancer from cell-free DNA [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr GS3-07.

Liver failure determines the outcome in patients of acute-on-chronic liver failure (ACLF): comparison of APASL ACLF research consortium (AARC) and CLIF-SOFA models

BACKGROUND AND AIMS

Acute-on-chronic liver failure (ACLF) is a progressive disease associated with rapid clinical worsening and high mortality. Early prediction of mortality and intervention can improve patient outcomes. We aimed to develop a dynamic prognostic model and compare it with the existing models.

METHODS

A total of 1402 ACLF patients, enrolled in the APASL-ACLF Research Consortium (AARC) with 90-day follow-up, were analyzed. An ACLF score was developed in a derivation cohort (n = 480) and was validated (n = 922).

RESULTS

The overall survival of ACLF patients at 28 days was 51.7%, with a median of 26.3 days. Five baseline variables, total bilirubin, creatinine, serum lactate, INR and hepatic encephalopathy, were found to be independent predictors of mortality, with AUROC in derivation and validation cohorts being 0.80 and 0.78, respectively. AARC-ACLF score (range 5-15) was found to be superior to MELD and CLIF SOFA scores in predicting mortality with an AUROC of 0.80. The point scores were categorized into grades of liver failure (Gr I: 5-7; II: 8-10; and III: 11-15 points) with 28-day cumulative mortalities of 12.7, 44.5 and 85.9%, respectively. The mortality risk could be dynamically calculated as, with each unit increase in AARC-ACLF score above 10, the risk increased by 20%. A score of ≥11 at baseline or persisting in the first week was often seen among nonsurvivors (p = 0.001).

CONCLUSIONS

The AARC-ACLF score is easy to use, dynamic and reliable, and superior to the existing prediction models. It can reliably predict the need for interventions, such as liver transplant, within the first week.