Transarterial Radioembolization for Hepatocellular Carcinoma with Major Vascular Invasion: A Nationwide Propensity Score-Matched Analysis with Target Trial Emulation.

PURPOSE: To examine National Cancer Database (NCDB) data to comparatively evaluate overall survival (OS) between patients undergoing transarterial radioembolization (TARE) and those undergoing systemic therapy for hepatocellular carcinoma with major vascular invasion (HCC-MVI). METHODS: One thousand five hundred fourteen patients with HCC-MVI undergoing first-line TARE or systemic therapy were identified from the NCDB. OS was compared using propensity score-matched Cox regression and landmark analysis. Efficacy was also compared within a target trial framework. RESULTS: TARE usage doubled between 2010 and 2015. Intervals before treatment were longer for TARE than for systemic therapy (mean [median], 66.5 [60] days vs 46.8 (35) days, respectively, P < .0001). In propensity-score-matched and landmark-time-adjusted analyses, TARE was found to be associated with a hazard ratio of 0.74 (95 % CI, 0.60-0.91; P = .005) and median OS of 7.1 months (95 % CI, 5.0-10.5) versus 4.9 months (95 % CI, 3.9-6.5) for systemically treated patients. In an emulated target trial involving 236 patients with unilobular HCC-MVI, a low number of comorbidities, creatinine levels <2.0 mg/dL, bilirubin levels <2.0 mg/dL, and international normalized ratio <1.7, TARE was found to be associated with a hazard ratio of 0.57 (95 % CI, 0.39-0.83; P = .004) and a median OS of 12.9 months (95 % CI, 7.6-19.2) versus 6.5 months (95 % CI, 3.6-11.1) for the systemic therapy arm. CONCLUSIONS: In propensity-score-matched analyses involving pragmatic and target trial HCC-MVI cohorts, TARE was found to be associated with significant survival benefits compared with systemic therapy. Although not a substitute for prospective trials, these findings suggest that the increasing use of TARE for HCC-MVI is accompanied by improved OS. Further trials of TARE in patients with HCC-MVI are needed, especially to compare with newer systemic therapies.

Phospholipids are A Potentially Important Source of Tissue Biomarkers for Hepatocellular Carcinoma: Results of a Pilot Study Involving Targeted Metabolomics.

BACKGROUND: Hepatocellular carcinoma (HCC) pathogenesis involves the alteration of multiple liver-specific metabolic pathways. We systematically profiled cancer- and liver-related classes of metabolites in HCC and adjacent liver tissues and applied supervised machine learning to compare their potential yield for HCC biomarkers. METHODS: Tumor and corresponding liver tissue samples were profiled as follows: Bile acids by ultra-performance liquid chromatography (LC) coupled to tandem mass spectrometry (MS), phospholipids by LC-MS/MS, and other small molecules including free fatty acids by gas chromatography-time of flight MS. The overall classification performance of metabolomic signatures derived by support vector machine (SVM) and random forests machine learning algorithms was then compared across classes of metabolite. RESULTS: For each metabolite class, there was a plateau in classification performance with signatures of 10 metabolites. Phospholipid signatures consistently showed the highest discrimination for HCC followed by signatures derived from small molecules, free fatty acids, and bile acids with area under the receiver operating characteristic curve (AUC) values of 0.963, 0.934, 0.895, 0.695, respectively, for SVM-generated signatures comprised of 10 metabolites. Similar classification performance patterns were observed with signatures derived by random forests. CONCLUSION: Membrane phospholipids are a promising source of tissue biomarkers for discriminating between HCC tumor and liver tissue.

Transcriptomics Associates Molecular Features with 18F-Fluorocholine PET/CT Imaging Phenotype and Its Potential Relationship to Survival in Hepatocellular Carcinoma.

Studies involving transcriptomics have revealed multiple molecular subtypes of hepatocellular carcinoma (HCC). Positron emission tomography/computed tomography (PET/CT) has also identified distinct molecular imaging subtypes, including those with increased and decreased choline metabolism as measured by the tissue uptake of the radiopharmaceutical 18F-fluorocholine. Gene signatures reflecting the molecular heterogeneity of HCC may identify the biological and clinical significance of these imaging subtypes. In this study, 41 patients underwent 18F-fluorocholine PET/CT, followed by tumor resection and gene expression profiling. Over- and underexpressed components of previously published gene signatures were evaluated for enrichment between tumors with high and low 18F-fluorocholine uptake using gene set analysis. Significant gene sets were enumerated by FDR based on phenotype permutation. Associations with overall survival were analyzed by univariate and multivariate proportional hazards regression. Ten gene sets related to HCC were significantly associated with high tumor 18F-fluorocholine uptake at FDR q < 0.05, including those from three different clinical molecular classification systems and two prognostic signatures for HCC that showed predictive value in the study cohort. Tumor avidity for 18F-fluorocholine was associated with favorable characteristics based on these signatures with lower mortality based on survival analysis (HR 0.36; 95% confidence interval, 0.14-0.95). Tumors demonstrating high 18F-fluorocholine uptake were also enriched for genes involved in oxidative phosphorylation, fatty acid metabolism, peroxisome, bile acid metabolism, xenobiotic metabolism, and adipogenesis. These results provide a pathobiological framework to further evaluate 18F-fluorocholine PET/CT as a molecular and prognostic classifier in HCC. SIGNIFICANCE: A pathobiological framework for HCC brings together multiple prognostically relevant gene signatures via convergence with 18F-fluorocholine PET/CT imaging phenotype.

Clinical and molecular sub-classification of hepatocellular carcinoma relative to alpha-fetoprotein level in an Asia-Pacific island cohort.

Aim: Increased serum alpha-fetoprotein (AFP) levels are associated with specific molecular sub-classes of hepatocellular carcinoma (HCC), supporting AFP as a predictive or therapeutic biomarker for precision treatment of this disease. Considering recent efforts to validate HCC molecular classification systems across different populations, we applied existing signature-based classification templates to Hawaii cohorts and examined whether associations between HCC molecular sub-class, AFP levels, and clinical features found elsewhere can also be found in Hawaii, a region with a unique demographic and risk factor profile for HCC. Methods: Whole-genome expression profiling was performed on HCC tumors collected from 40 patients following partial hepatectomy. Tumors underwent transcriptome-based categorization into 3 molecular sub-classes (S1, S2, and S3). Patient groups based on molecular sub-class and AFP level were then compared with regards to clinical features and survival. Differences associated with AFP level and other clinical parameters were also examined at the gene signature level by gene set enrichment analysis. Results: Statistically confident (false discovery rate < 0.05) sub-classifications were made in 98% (39/40) of tumors. Patient sub-groups differed significantly with regards to serum AFP level, with significantly lower levels in the S3 sub-group as compared to S1 (P = 0.048) and S2 (P = 0.010). Serum AFP > 400 ng/mL predicted significant tumor enrichment for genes corresponding to MYC target activation, high cell proliferation, poor clinical prognosis, and the S2 sub-class. AFP > 400 ng/mL and non-S3 tumor classification were found to be significant predictors of overall survival. Conclusion: Distinct sub-classes of HCC associated with different molecular features and survival outcomes can be detected with statistical confidence in a Pacific Island cohort. Molecular classification signatures and other predictive markers for HCC that are valid for all patient populations are needed to support multi-center efforts to develop targeted therapies for HCC.

[18F]Fluorocholine PET/CT Imaging of Liver Cancer: Radiopathologic Correlation with Tissue Phospholipid Profiling.

PURPOSE: [18F]fluorocholine PET/CT can detect hepatocellular carcinoma (HCC) based on imaging the initial steps of phosphatidylcholine synthesis. To relate the diagnostic performance of [18F]fluorocholine positron emission tomography (PET)/x-ray computed tomography (CT) to the phospholipid composition of liver tumors, radiopathologic correspondence was performed in patients with early-stage liver cancer who had undergone [18F]fluorocholine PET/CT before tumor resection. PROCEDURES: Tumor and adjacent liver were profiled by liquid chromatography mass spectrometry, quantifying phosphatidylcholine species by mass-to-charge ratio. For clinical-radiopathologic correlation, HCC profiles were reduced to two orthogonal principal component factors (PCF1 and PCF2) accounting for 80 % of total profile variation. RESULTS: Tissues from 31 HCC patients and 4 intrahepatic cholangiocarcinoma (ICC) patients were analyzed, revealing significantly higher levels of phosphocholine, CDP-choline, and highly saturated phosphatidylcholine species in HCC tumors relative to adjacent liver and ICC tumors. Significant loading values for PCF1 corresponded to phosphatidylcholines containing poly-unsaturated fatty acids while PCF2 corresponded only to highly saturated phosphatidylcholines. Only PCF2 correlated significantly with HCC tumor-to-liver [18F]fluorocholine uptake ratio (ρ = 0.59, p < 0.0005). Sensitivity for all tumors based on an abnormal [18F]fluorocholine uptake ratio was 93 % while sensitivity for HCC based on increased tumor [18F]fluorocholine uptake was 84 %, with lower levels of highly saturated phosphatidylcholines in tumors showing low [18F]fluorocholine uptake. CONCLUSION: Most HCC tumors contain high levels of saturated phosphatidylcholines, supporting their dependence on de novo fatty acid metabolism for phospholipid membrane synthesis. While [18F]fluorocholine PET/CT can serve to identify these lipogenic tumors, its imperfect diagnostic sensitivity implies metabolic heterogeneity across HCC and a weaker lipogenic phenotype in some tumors.

Prediction of PSA Progression in Castration-Resistant Prostate Cancer Based on Treatment-Associated Change in Tumor Burden Quantified by 18F-Fluorocholine PET/CT.

UNLABELLED: Measurements of metabolically active tumor volume (MATV) can be applied to (18)F-fluorocholine PET/CT to quantify whole-body tumor burden. This study evaluated the serial application of these measurements as systemic treatment response markers and predictors of disease progression in patients with castration-resistant prostate cancer (CRPC). METHODS: Forty-two patients completed sequential (18)F-fluorocholine PET/CT scans before and 1-3 mo after starting treatment for CRPC. Whole-body tumor segmentation was applied to determine net MATV from each scan. Changes in net MATV were evaluated as predictors of time to prostate-specific antigen (PSA) progression by Kaplan-Meier and proportional hazards regression analysis. RESULTS: Treatments consisted of chemotherapy in 16 patients, antiandrogens in 19 patients, (223)Ra-dichloride in 5 patients, and sipuleucel-T in 2 patients. A significant MATV response (defined as a ≥30% decrease in net MATV) was observed in 20 patients on the basis of in-treatment PET/CT performed an average of 51 d (median, 49 d) into treatment. Significantly longer times to PSA progression were observed in patients who exhibited an MATV response (418 d vs. 116 d, P = 0.0067). MATV response was associated with a hazard ratio of 0.246 (P = 0.0113) for PSA progression, which remained significant when adjusted for treatment type. CONCLUSION: Significant changes in whole-body tumor burden can be measured on (18)F-fluorocholine PET/CT over the course of contemporary treatments for CRPC. In this study, these changes were found to be predictive of PSA progression as a potential surrogate marker of treatment outcome. Because (18)F-fluorocholine PET/CT can also be used for localizing resistant tumors, this modality can potentially complement other measures of response in the precision management of advanced prostate cancer.

Chronic Liver Disease and the Detection of Hepatocellular Carcinoma by [(18)F]fluorocholine PET/CT.

Positron emission tomography (PET) using the radiopharmaceutical tracer fluorine-18 fluorocholine (FCh) can elucidate tumors based on differences in choline phospholipid metabolism between tumor and surrounding tissue. The feasibility of detecting hepatocellular carcinoma (HCC) using FCh PET has been shown despite constitutively high parenchymal choline metabolism in the liver. Since HCC frequently develops in the setting of chronic liver disease, we comparatively evaluated FCh PET/CT between cirrhotic and non-cirrhotic patients with HCC to investigate the effects of hepatic dysfunction on tumor detection and the tumor-to-background ratio (TBR) of FCh uptake. FCh PET/CT was performed prospectively in 22 consecutive patients with HCC (7 newly diagnosed, 15 previously treated). Of these 22 patients, 14 were cirrhotic and 8 non-cirrhotic. Standardized uptake value (SUV) measurements were obtained by region of interest analysis of the PET images. Tumor FCh uptake and the TBR were compared between cirrhotic and non-cirrhotic patients. Liver lesions were confirmed to be HCC by biopsy in 10 patients and by Barcelona criteria in 4 patients. There was correspondingly increased liver tumor FCh uptake in 13/14 of those patients, and iso-intense tumor FCh uptake (TBR 0.94) in one non-cirrhotic patient with newly diagnosed HCC. FCh PET/CT also showed metastatic disease without local tumor recurrence in 2 previously treated patients, and was negative in 6 treated patients without tumor recurrence by radiographic and clinical follow-up. Tumor maximum SUV ranged from 6.4 to 15.3 (mean 12.1) and liver TBR ranged from 0.94 to 2.1 (mean 1.6), with no significant differences between cirrhotic and non-cirrhotic patients (SUVmax 11.9 vs. 12.2, p = 0.83; TBR 1.71 vs. 1.51, p = 0.29). Liver parenchyma mean SUV was significantly lower in cirrhotic patients (6.4 vs. 8.7, p < 0.05). This pilot study supports the general feasibility of HCC detection by FCh PET/CT. However, a broad range of tumor FCh uptake was observed, and lower liver parenchymal uptake of FCh was noted in cirrhotic patients as compared to non-cirrhotic patients. Incorporating tissue profiling into future liver imaging trials of FCh PET may help determine the molecular basis of the observed variations in tumor and hepatic FCh uptake.

Volumetric modulated arc therapy planning for primary prostate cancer with selective intraprostatic boost determined by 18F-choline PET/CT.

PURPOSE: This study evaluated expected tumor control and normal tissue toxicity for prostate volumetric modulated arc therapy (VMAT) with and without radiation boosts to an intraprostatically dominant lesion (IDL), defined by (18)F-choline positron emission tomography/computed tomography (PET/CT). METHODS AND MATERIALS: Thirty patients with localized prostate cancer underwent (18)F-choline PET/CT before treatment. Two VMAT plans, plan79 Gy and plan100-105 Gy, were compared for each patient. The whole-prostate planning target volume (PTVprostate) prescription was 79 Gy in both plans, but plan100-105 Gy added simultaneous boost doses of 100 Gy and 105 Gy to the IDL, defined by 60% and 70% of maximum prostatic uptake on (18)F-choline PET (IDLsuv60% and IDLsuv70%, respectively, with IDLsuv70% nested inside IDLsuv60% to potentially enhance tumor specificity of the maximum point dose). Plan evaluations included histopathological correspondence, isodose distributions, dose-volume histograms, tumor control probability (TCP), and normal tissue complication probability (NTCP). RESULTS: Planning objectives and dose constraints proved feasible in 30 of 30 cases. Prostate sextant histopathology was available for 28 cases, confirming that IDLsuv60% adequately covered all tumor-bearing prostate sextants in 27 cases and provided partial coverage in 1 case. Plan100-105 Gy had significantly higher TCP than plan79 Gy across all prostate regions for α/ß ratios ranging from 1.5 Gy to 10 Gy (P<.001 for each case). There were no significant differences in bladder and femoral head NTCP between plans and slightly lower rectal NTCP (endpoint: grade ≥ 2 late toxicity or rectal bleeding) was found for plan100-105 Gy. CONCLUSIONS: VMAT can potentially increase the likelihood of tumor control in primary prostate cancer while observing normal tissue tolerances through simultaneous delivery of a steep radiation boost to a (18)F-choline PET-defined IDL.