Dense monocular depth estimation for stereoscopic vision based on pyramid transformer and multi-scale feature fusion

Stereoscopic display technology plays a significant role in industries, such as film, television and autonomous driving. The accuracy of depth estimation is crucial for achieving high-quality and realistic stereoscopic display effects. In addressing the inherent challenges of applying Transformers to depth estimation, the Stereoscopic Pyramid Transformer-Depth (SPT-Depth) is introduced. This method utilizes stepwise downsampling to acquire both shallow and deep semantic information, which are subsequently fused. The training process is divided into fine and coarse convergence stages, employing distinct training strategies and hyperparameters, resulting in a substantial reduction in both training and validation losses. In the training strategy, a shift and scale-invariant mean square error function is employed to compensate for the lack of translational invariance in the Transformers. Additionally, an edge-smoothing function is applied to reduce noise in the depth map, enhancing the model's robustness. The SPT-Depth achieves a global receptive field while effectively reducing time complexity. In comparison with the baseline method, with the New York University Depth V2 (NYU Depth V2) dataset, there is a 10% reduction in Absolute Relative Error (Abs Rel) and a 36% decrease in Root Mean Square Error (RMSE). When compared with the state-of-the-art methods, there is a 17% reduction in RMSE.

Multi-region sampling with paired sample sequencing analyses reveals sub-groups of patients with novel patient-specific dysregulation in Hepatocellular Carcinoma

BACKGROUND

Conventional differential expression (DE) testing compares the grouped mean value of tumour samples to the grouped mean value of the normal samples, and may miss out dysregulated genes in small subgroup of patients. This is especially so for highly heterogeneous cancer like Hepatocellular Carcinoma (HCC).

METHODS

Using multi-region sampled RNA-seq data of 90 patients, we performed patient-specific differential expression testing, together with the patients' matched adjacent normal samples.

RESULTS

Comparing the results from conventional DE analysis and patient-specific DE analyses, we show that the conventional DE analysis omits some genes due to high inter-individual variability present in both tumour and normal tissues. Dysregulated genes shared in small subgroup of patients were useful in stratifying patients, and presented differential prognosis. We also showed that the target genes of some of the current targeted agents used in HCC exhibited highly individualistic dysregulation pattern, which may explain the poor response rate.

DISCUSSION/CONCLUSION

Our results highlight the importance of identifying patient-specific DE genes, with its potential to provide clinically valuable insights into patient subgroups for applications in precision medicine.

Extending surgical resection for hepatocellular carcinoma beyond Barcelona Clinic for Liver Cancer (BCLC) stage A: A novel application of the modified BCLC staging system

503

Background: Intermediate hepatocellular carcinoma is a heterogenous group of disease. We aimed to prognosticate survival after surgical resection of HCC stratified by stage with amalgamation of the modified Barcelona Clinic Liver Cancer (BCLC) staging system and location of tumour. Methods: This single-institutional retrospective cohort study included patients with HCC who underwent surgical resection between 1st January 2000 to 30th June 2016. Participants were divided into 6 different subgroups based on the Milan Criteria (MC), the “Up-to-7” criteria, and location of lesions: A-u) Within MC with Unilobar lesions; A-b) Within MC + Bilobar lesions; B1-u) Out of MC + within Up-To-7 + Unilobar lesions; B1-b) Out of MC + within Up-to-7 + Bilobar lesions; B2-u) Out of MC + Out of Up-To-7 + Unilobar lesions; B2-b) Out of MC + Out of Up-To-7 + Bilobar lesions. A separate survival analysis was conducted for solitary HCC lesions according to three subgroups: A-S (Within MC); B1-S (Out of MC + within Up-To-7); B2-S (Out of MC + out of Up-To-7). The respective primary and secondary time-to-event outcomes were overall survival (OS) and recurrence-free survival (RFS). Results: 794 of 1043 patients with surgical resection for HCC were analysed. Groups A-u (64.6 %), A-b (58.4 %) and B1-u (56.2 %) had 5-year cumulative overall survival (OS) rates above 50% after surgical resection and median OS exceeding 60 months (P=0.0001). The 5-year cumulative recurrence-free survival rates (RFS) were 40.4% (group A-u), 38.2% (group A-b), 36.3% (group B1-u), 24.6% (group B2-u), and 7.3% (group B2-b)(P=0.0001). For solitary lesions, the 5-year OS for the subgroups were A-S (65.1%), B1-S (56.0%) and B2-S (47.1%) (P=0.0003). Compared to A-S, there was also a significant trend towards relatively poorer OS as the lesion sizes increased in B1-S (HR 1.46, 95%CI 1.03 – 2.08) and B2-S (HR 1.65, 95%CI 1.25 – 2.18). Conclusions: We adopted a novel approach combining the modified BCLC B sub-classification and dispersion of tumour to show that surgical resection may be curative in a select subgroup of patients with intermediate HCC that fall outside BCLC Stage A, specifically those with unilobar lesions and are within the “up-to-7” criteria. Furthermore, We found that size prognosticates resection outcomes in solitary tumours.

IFNγ-IL-17+ CD8 T cells contribute to immunosuppression and tumor progression in human hepatocellular carcinoma

IL-17-producing CD8 (Tc17) T cells have been shown to play an important role in infection and chronic inflammation, however their implications in hepatocellular carcinoma (HCC) remain elusive. In this study, we performed cytometry by time-of-flight (CyTOF) and revealed the distinctive immunological phenotypes of two IFNγ⁺ and IFNγ^- Tc17 subsets that were preferentially enriched in human HCC. Single-cell RNA-sequencing analysis further revealed regulatory circuits governing the different phenotypes of these Tc17 subsets. In particular, we discovered that IFNγ^- Tc17 subset demonstrated pro-tumoral characteristics and expressed higher levels of CCL20. This corresponded to increased tumor infiltration of T regulatory cells (Treg) validated by immunohistochemistry in another independent HCC cohort, demonstrating the immunosuppressive functions of IFNγ^- Tc17 subset. Most importantly, higher intra-tumoral proportions of IFNγ^- Tc17 were associated with poorer prognosis in patients with HCC and this was further validated in The Cancer Genome Atlas (TCGA) HCC cohort. Taken together, this compendium of transcriptomic and proteomic data of Tc17 subsets sheds light on the immunosuppressive phenotypes of IFNγ^- Tc17 and its implications in HCC progression.

Hypoxia-driven immunosuppression by Treg and type-2 conventional dendritic cells in HCC

BACKGROUND AND AIMS

Hypoxia is one of the central players in shaping the immune context of the tumor microenvironment (TME). However, the complex interplay between immune cell infiltrates within the hypoxic TME of HCC remains to be elucidated.

APPROACH AND RESULTS

We analyzed the immune landscapes of hypoxia-low and hypoxia-high tumor regions using cytometry by time of light, immunohistochemistry, and transcriptomic analyses. The mechanisms of immunosuppression in immune subsets of interest were further explored using in vitro hypoxia assays. Regulatory T cells (Tregs) and a number of immunosuppressive myeloid subsets, including M2 macrophages and human leukocyte antigen-DR isotype (HLA-DR^lo ) type 2 conventional dendritic cell (cDC2), were found to be significantly enriched in hypoxia-high tumor regions. On the other hand, the abundance of active granzyme B^hi PD-1^lo CD8⁺ T cells in hypoxia-low tumor regions implied a relatively active immune landscape compared with hypoxia-high regions. The up-regulation of cancer-associated genes in the tumor tissues and immunosuppressive genes in the tumor-infiltrating leukocytes supported a highly pro-tumorigenic network in hypoxic HCC. Chemokine genes such as CCL20 (C-C motif chemokine ligand 20) and CXCL5 (C-X-C motif chemokine ligand 5) were associated with recruitment of both Tregs and HLA-DR^lo cDC2 to hypoxia-high microenvironments. The interaction between Tregs and cDC2 under a hypoxic TME resulted in a loss of antigen-presenting HLA-DR on cDC2.

CONCLUSIONS

We uncovered the unique immunosuppressive landscapes and identified key immune subsets enriched in hypoxic HCC. In particular, we identified a potential Treg-mediated immunosuppression through interaction with a cDC2 subset in HCC that could be exploited for immunotherapies.

Limited liver resections in the posterosuperior segments: international multicentre propensity score-matched and coarsened exact-matched analysis comparing the laparoscopic and robotic approaches

Background

Limited liver resections (LLRs) for tumours located in the posterosuperior segments of the liver are technically demanding procedures. This study compared outcomes of robotic (R) and laparoscopic (L) LLR for tumours located in the posterosuperior liver segments (IV, VII, and VIII).

Methods

This was an international multicentre retrospective analysis of patients who underwent R-LLR or L-LLR at 24 centres between 2010 and 2019. Patient demographics, perioperative parameters, and postoperative outcomes were analysed; 1 : 3 propensity score matching (PSM) and 1 : 1 coarsened exact matching (CEM) were performed.

Results

Of 1566 patients undergoing R-LLR and L-LLR, 983 met the study inclusion criteria. Before matching, 159 R-LLRs and 824 L-LLRs were included. After 1 : 3 PSM of 127 R-LLRs and 381 L-LLRs, comparison of perioperative outcomes showed that median blood loss (100 (i.q.r. 40–200) versus 200 (100–500) ml; P = 0.003), blood loss of at least 500 ml (9 (7.4 per cent) versus 94 (27.6 per cent); P < 0.001), intraoperative blood transfusion rate (4 (3.1 per cent) versus 38 (10.0 per cent); P = 0.025), rate of conversion to open surgery (1 (0.8 per cent) versus 30 (7.9 per cent); P = 0.022), median duration of Pringle manoeuvre when applied (30 (20–46) versus 40 (25–58) min; P = 0.012), and median duration of operation (175 (130–255) versus 224 (155–300); P < 0.001) were lower in the R-LLR group compared with the L-LLR group. After 1 : 1 CEM of 104 R-LLRs with 104 L-LLRs, R-LLR was similarly associated with significantly reduced blood loss and a lower rate of conversion to open surgery.

Conclusion

Based on a matched analysis of well selected patients, both robotic and laparoscopic access could be undertaken safely with good outcomes for tumours in the posterosuperior liver segments.

Extending Surgical Resection for Hepatocellular Carcinoma Beyond Barcelona Clinic for Liver Cancer (BCLC) Stage A: A Novel Application of the Modified BCLC Staging System

Objective

We aimed to prognosticate survival after surgical resection of HCC stratified by stage with amalgamation of the modified Barcelona Clinic Liver Cancer (BCLC) staging system and location of tumour.

Methods

This single-institutional retrospective cohort study included patients with HCC who underwent surgical resection between 1st January 2000 to 30th June 2016. Participants were divided into 6 different subgroups: A-u) Within MC with Unilobar lesions; A-b) Within MC + Bilobar lesions; B1-u) Out of MC + within Up-To-7 + Unilobar lesions; B1-b) Out of MC + within Up-to-7 + Bilobar lesions; B2-u) Out of MC + Out of Up-To-7 + Unilobar lesions; B2-b) Out of MC + Out of Up-To-7 + Bilobar lesions. A separate survival analysis was conducted for solitary HCC lesions according to three subgroups: A-S (Within MC); B1-S (Out of MC + within Up-To-7); B2-S (Out of MC + out of Up-To-7).

Results

A total of 794 of 1043 patients with surgical resection for HCC were analysed. Groups A-u (64.6%), A-b (58.4%) and B1-u (56.2%) had 5-year cumulative overall survival (OS) rates above 50% after surgical resection and median OS exceeding 60 months (P = 0.0001). The 5-year cumulative recurrence-free survival rates (RFS) were 40.4% (group A-u), 38.2% (group A-b), 36.3% (group B1-u), 24.6% (group B2-u), and 7.3% (group B2-b)(P=0.0001). For solitary lesions, the 5-year OS for the subgroups were A-S (65.1%), B1-S (56.0%) and B2-S (47.1%) (P = 0.0003). Compared to A-S, there was also a significant trend towards relatively poorer OS as the lesion sizes increased in B1-S (HR 1.46, 95% CI 1.03–2.08) and B2-S (HR 1.65, 95% CI 1.25–2.18).

Conclusion

We adopted a novel approach combining the modified BCLC B sub-classification and dispersion of tumour to show that surgical resection in intermediate stage HCC can be robustly prognosticated. We found that size prognosticates resection outcomes in solitary tumours.

Trajectory of immune evasion and cancer progression in hepatocellular carcinoma

Immune evasion is key to cancer initiation and later at metastasis, but its dynamics at intermediate stages, where potential therapeutic interventions could be applied, is undefined. Here we show, using multi-dimensional analyses of resected tumours, their adjacent non-tumour tissues and peripheral blood, that extensive immune remodelling takes place in patients with stage I to III hepatocellular carcinoma (HCC). We demonstrate the depletion of anti-tumoural immune subsets and accumulation of immunosuppressive or exhausted subsets along with reduced tumour infiltration of CD8 T cells peaking at stage II tumours. Corresponding transcriptomic modification occur in the genes related to antigen presentation, immune responses, and chemotaxis. The progressive immune evasion is validated in a murine model of HCC. Our results show evidence of ongoing tumour-immune co-evolution during HCC progression and offer insights into potential interventions to reverse, prevent or limit the progression of the disease.

Dynamic phenotypic heterogeneity and the evolution of multiple RNA subtypes in hepatocellular carcinoma: the PLANET study

Intra-tumor heterogeneity (ITH) is a key challenge in cancer treatment, but previous studies have focused mainly on the genomic alterations without exploring phenotypic (transcriptomic and immune) heterogeneity. Using one of the largest prospective surgical cohorts for hepatocellular carcinoma (HCC) with multi-region sampling, we sequenced whole genomes and paired transcriptomes from 67 HCC patients (331 samples). We found that while genomic ITH was rather constant across stages, phenotypic ITH had a very different trajectory and quickly diversified in stage II patients. Most strikingly, 30% of patients were found to contain more than one transcriptomic subtype within a single tumor. Such phenotypic ITH was found to be much more informative in predicting patient survival than genomic ITH and explains the poor efficacy of single-target systemic therapies in HCC. Taken together, we not only revealed an unprecedentedly dynamic landscape of phenotypic heterogeneity in HCC, but also highlighted the importance of studying phenotypic evolution across cancer types.

Radioembolisation with Y90-resin microspheres followed by nivolumab for advanced hepatocellular carcinoma (CA 209-678): a single arm, single centre, phase 2 trial

BACKGROUND

Therapeutic synergism between radiotherapy and immune checkpoint blockade has been observed in preclinical models of hepatocellular carcinoma. We aimed to study the safety and efficacy of sequential radioembolisation with yttrium-90-resin microspheres (Y90-radioembolisation) followed by nivolumab in patients with advanced hepatocellular carcinoma.

METHODS

Patients with Child-Pugh A cirrhosis and advanced hepatocellular carcinoma not suitable for curative surgery were treated with Y90-radioembolisation followed by intravenous nivolumab 240 mg 21 days after Y90-radioembolisation and every 2 weeks thereafter. The primary endpoint, assessed in the per-protocol population, was the objective response rate, determined by RECIST version 1.1, defined as the proportion of patients with a confirmed complete or partial response observed for lesions both within and outside the Y90-radioembolisation field. This study is registered with ClinicalTrials.gov, NCT03033446 and has been completed.

FINDINGS

40 patients were enrolled, of whom 36 received Y90-radioembolisation followed by nivolumab. One (3%) patient had a complete response and ten (28%) had a partial response; the objective response rate was 30·6% (95% CI 16·4-48·1). The most common treatment-related adverse events of any grade were pruritus (18 [50%] of 36 patients) and maculopapular rash (13 [36%]). Two (6%) patients experienced grade 3-4 treatment-related adverse events: one patient had a grade 3 increase in alanine aminotransferase levels, grade 3 bilirubin increase, and grade 4 increase in aspartate aminotransferase levels, while the other had a grade 3 maculopapular rash. Five (14%) patients had a treatment-related serious adverse event (Steven-Johnson syndrome, hepatitis E infection, fever, liver abscesses, and ascites).

INTERPRETATION

Y90-radioembolisation followed by nivolumab resulted in an encouraging objective response rate in patients with advanced hepatocellular carcinoma, although the activity observed was not as high as the study was powered for. This strategy should be further evaluated in patients with Barcelona Clinic Liver Clinic (BCLC) stage B hepatocellular carcinoma that is ineligible or refractory to transarterial chemoembolisation and patients with BCLC C disease without extrahepatic spread.

FUNDING

National Medical Research Council Singapore, Bristol-Myers Squibb, Sirtex.

Resected pancreatic adenocarcinoma: An Asian institution's experience

BACKGROUND

Pancreatic adenocarcinoma (PDAC) is highly lethal. Surgery offers the only chance of cure, but 5-year overall survival (OS) after surgical resection and adjuvant therapy remains dismal. Adjuvant trials were mostly conducted in the West enrolling fit patients. Applicability to a general population, especially Asia has not been described adequately.

AIM

We aimed to evaluate the clinical outcomes, prognostic factors of survival, pattern, and timing of recurrence after curative resection in an Asian institution.

METHODS AND RESULTS

The clinicopathologic and survival outcomes of 165 PDAC patients who underwent curative resection between 1998 and 2013 were reviewed retrospectively. Median age at surgery was 62.0 years. 55.2% were male, and 73.3% had tumors involving the head of pancreas. The median OS of the entire cohort was 19.7 months. Median OS of patients who received adjuvant chemotherapy was 23.8 months. Negative predictors of survival include lymph node ratio (LNR) of >0.3 (HR = 3.36, P = .001), tumor site involving the body or tail of pancreas (HR = 1.59, P = .046), presence of perineural invasion (PNI) (HR = 2.36, P = .018) and poorly differentiated/undifferentiated tumor grade (HR = 1.86, P = .058). The median time to recurrence was 8.87 months, with 66.1% and 81.2% of patients developing recurrence at 12 months and 24 months respectively. The most common site of recurrence was the liver.

CONCLUSION

The survival of Asian patients with resected PDAC who received adjuvant chemotherapy is comparable to reported randomized trials. Clinical characteristics seem similar to Western patients. Hence, geographical locations may not be a necessary stratification factor in RCTs. Conversely, lymph node ratio and status of PNI ought to be incorporated.

Clinicopathological-Associated Regulatory Network of Deregulated circRNAs in Hepatocellular Carcinoma

Simple Summary

Here, we present a novel strategy to identify key signatures of clinically-relevant co-expressed circRNA-mRNA networks in pertinent cancer-pathways that modulate the prognosis of HCC patients, by integrating clinicopathological features, circRNA and mRNA expression profiles. Five master circRNAs were identified and experimentally demonstrated to upregulate proliferate and promote transformation. Through further integration with miRNA-expression profiles, clinically-relevant competing-endogenous-RNA (ceRNA) networks of circRNA-miRNA-mRNAs were constructed. The most up-regulated nodal-circRNA, circGPC3 was experimentally demonstrated to up-regulate cell-cycle, migration and invasion. circGPC3 was found to act as a sponge of miR-378a-3p to regulate ASPM expression and modulate cell transformation. These 5 nodal circRNAs has potential to be good prognostic biomarkers with good prognostic performance. circGPC3 has great potential to be a promising non-invasive prognostic biomarker for early HCC. We have thus demonstrated the robustness of bioinformatically-predicted master circRNAs in clinically-relevant, circRNA-mRNA networks, underscoring the important roles that these identified deregulated key/master circRNAs play in HCC.

Abstract

Hepatocellular carcinoma (HCC) is one of the most common and lethal cancers worldwide. Here, we present a novel strategy to identify key circRNA signatures of clinically relevant co-expressed circRNA-mRNA networks in pertinent cancer-pathways that modulate prognosis of HCC patients, by integrating clinic-pathological features, circRNA and mRNA expression profiles. Through further integration with miRNA expression profiles, clinically relevant competing-endogenous-RNA (ceRNA) networks of circRNA-miRNA-mRNAs were constructed. At least five clinically relevant nodal-circRNAs, co-expressed with numerous genes, were identified from the circRNA-mRNA networks. These nodal circRNAs upregulated proliferation (except circRaly) and transformation in cells. The most upregulated nodal-circRNA, circGPC3, associated with higher-grade tumors and co-expressed with 33 genes, competes with 11 mRNAs for two shared miRNAs. circGPC3 was experimentally demonstrated to upregulate cell-cycle and migration/invasion in both transformed and non-transformed liver cell-lines. circGPC3 was further shown to act as a sponge of miR-378a-3p to regulate APSM (Abnormal spindle-like microcephaly associated) expression and modulate cell transformation. This study identifies 5 key nodal master circRNAs in a clinically relevant circRNA-centric network that are significantly associated with poorer prognosis of HCC patients and promotes tumorigenesis in cell-lines. The identification and characterization of these key circRNAs in clinically relevant circRNA-mRNA and ceRNA networks may facilitate the design of novel strategies targeting these important regulators for better HCC prognosis.

Time-varying prognostic effects of primary tumor sidedness and grade after curative liver resection for colorectal liver metastases

BACKGROUND

The veracity of the proportional hazards (PH) requirement is rarely scrutinized in most areas of cancer research, although fulfilment of this assumption underpins widely-used Cox survival models. We sought to critically appraise the existence of prognostic factors with time-dependent effects and to characterize their impact on survival among CLM patients.

METHODS

Consecutive patients who underwent liver resection with curative intent for CLM at the Singapore General Hospital were identified from a prospectively-maintained database. We evaluated PH of 55 candidate variables, and parameters which departed significantly from proportionality were included in Cox models that incorporated an interaction term to account for time-dependent effects. As sensitivity analyses, we fitted Weibull mixture 'cure' models to handle long plateaus in the tails of survival curves, and also analyzed the restricted mean survival time.

RESULTS

318 consecutive patients who underwent curative liver resection for CLM between Jan 2000 and Nov 2016 were included in this analysis. Hazard ratios for tumor grade (poorly-versus well- and moderately-differentiated) were found to decrease from 3.135 (95% CI: 1.637-6.003) at 12 months to 2.048 (95% CI: 1.038-4.042) after 24 months, and ceased to be significant at 26 months. Compared to left-sided tumors, a right-sided tumor location was found to portend worse prognosis for the first 10 months after resection but subsequently confer a survival benefit due to a crossing of survival curves. Corroborating this observation, long-term cure fractions were estimated to be 25.5% (95% CI: 17.4%-33.6%) and 34.2% (95% CI: 17.4%-50.9%) among patients with left-sided and right-sided primary disease respectively.

CONCLUSION

Primary tumor sidedness and grade appear to exert time-varying prognostic effects in CLM patients undergoing curative liver resection.

Highly deregulated lncRNA LOC is associated with overall worse prognosis in Hepatocellular Carcinoma patients

Although numerous long non-coding RNAs (lncRNAs) were reported to be deregulated in Hepatocellular Carcinoma (HCC), experimentally characterized, and/or associated with patient's clinical characteristics, there is, thus far, minimal concerted research strategy to identify deregulated lncRNAs that modulate prognosis of HCC patients. Here, we present a novel strategy where we identify lncRNAs, which are not only de-regulated in HCC patients, but are also associated with pertinent clinical characteristics, potentially contributing to the prognosis of HCC patients. LOC101926913 (LOC) was further characterized because it is the most highly differentially expressed amongst those that are associated with the most number of clinical features (tumor-stage, vascular and tumor invasion and poorer overall survival). Experimental gain- and loss-of-function manipulation of LOC in liver cell-lines highlight LOC as a potential onco-lncRNA promoting cell proliferation, anchorage independent growth and invasion. LOC expression in cells up-regulated genes involved in GTPase-activities and downregulated genes associated with cellular detoxification, oxygen- and drug-transport. Hence, LOC may represent a novel therapeutic target, modulating prognosis of HCC patients through up-regulating GTPase-activities and down-regulating detoxification, oxygen- and drug-transport. This strategy may thus be useful for the identification of clinically relevant lncRNAs as potential biomarkers/targets that modulate prognosis in other cancers as well.

Minimally invasive versus open right anterior sectionectomy and central hepatectomy for central liver malignancies: a propensity-score-matched analysis

BACKGROUND

The utility of minimally-invasive liver resection (MILR) for deep centrally located tumours (CLT) remains controversial. We aimed to review our institution's experience and outcomes with minimally invasive central hepatectomy (CH) and right anterior sectionectomy (RAS) for CLT in a propensity score-matched (PSM) analysis.

METHODS

Retrospective review of a prospectively maintained surgical database revealed 23 patients who underwent MILR (6 CH, 17 RAS) and 53 patients who underwent open liver resection (OLR; 24 CH, 29 RAS) for CLT. PSM in a 1:1 ratio identified two groups of patients with similar baseline clinicopathological characteristics. Peri-operative outcomes were then compared.

RESULTS

There was one laparoscopic-assisted, one robot-assisted and two laparoscopic-converted-open procedures in the MILR cohort. Across the unmatched cohort, there was only one mortality (MILR) and five patients with major morbidity (all OLR). MILR was associated with a longer operating time (P < 0.001), but shorter post-operative hospital stay (P = 0.002) and decreased morbidity (P = 0.018) in the unmatched cohort. Examination of peri-operative outcomes after PSM revealed that MILR was similarly associated with a longer operating time (P = 0.001) and shortened post-operative hospital stay (P = 0.043). OLR was associated with a significantly reduced application of Pringle manoeuvre (P = 0.004). There were no significant differences between MILR and OLR with regards to blood loss, blood transfusions, morbidity and margin status in the PSM analysis.

CONCLUSION

MILR for CLT is safe and feasible when performed by experienced surgeons. It is associated with shorter hospital stays but at the expense of longer operation times and more frequent application of Pringle manoeuver.

Intratumoural immune heterogeneity as a hallmark of tumour evolution and progression in hepatocellular carcinoma

The clinical relevance of immune landscape intratumoural heterogeneity (immune-ITH) and its role in tumour evolution remain largely unexplored. Here, we uncover significant spatial and phenotypic immune-ITH from multiple tumour sectors and decipher its relationship with tumour evolution and disease progression in hepatocellular carcinomas (HCC). Immune-ITH is associated with tumour transcriptomic-ITH, mutational burden and distinct immune microenvironments. Tumours with low immune-ITH experience higher immunoselective pressure and escape via loss of heterozygosity in human leukocyte antigens and immunoediting. Instead, the tumours with high immune-ITH evolve to a more immunosuppressive/exhausted microenvironment. This gradient of immune pressure along with immune-ITH represents a hallmark of tumour evolution, which is closely linked to the transcriptome-immune networks contributing to disease progression and immune inactivation. Remarkably, high immune-ITH and its transcriptomic signature are predictive for worse clinical outcome in HCC patients. This in-depth investigation of ITH provides evidence on tumour-immune co-evolution along HCC progression.

Outcome of minimally invasive liver resection for extrapancreatic biliary malignancies: A single-institutional experience

Background:

Minimally invasive liver resection (MILR) has been increasingly adopted over the past decade, and its application has been expanded to the management of extrapancreatic biliary malignancies (EPBMs). We aimed to evaluate the peri- and post-operative outcome of patients undergoing MILR for suspected EPMB.

Methods:

Forty-four consecutive patients who underwent MILR with a curative intent for EPBM at Singapore General Hospital between 2011 and 2018 were identified from a prospectively maintained surgical database. Clinical and operative data were analysed and compared to provide information and make comparisons on peri- and post-operative outcomes.

Results:

A total of 26, 5 and 13 patients underwent MILR for intrahepatic cholangiocarcinoma (ICC), perihilar cholangiocarcinoma (PHC) and gallbladder carcinoma (GBCA), respectively. Six major hepatectomies were performed, of which one was laparoscopic assisted and another was robot assisted. Ten patients underwent posterosuperior segmentectomies. There was one open conversion. The mean operative time was 266.5 min, and the mean blood loss was 379 ml. The mean length of hospital stay was 4.7 days with no incidences of 30- and 90-day mortality. The rate of recurrence-free survival (RFS) was 75% (at least 12-month follow-up). There was a significantly higher rate of robot-assisted procedures in patients undergoing MILR for GBCA/PHC as compared to ICC (P = 0.034). Patients undergoing posterosuperior segmentectomies required longer operative time (P = 0.018) with an increased need for (P = 0.001) and duration of (P = 0.025) Pringles manoeuvre. There were no differences in operative time, blood loss, morbidity, mortality or RFS between the above groups.

Conclusion:

Minimally invasive surgery can be adopted safely with a low open conversion rate for EPBMs.

Comparison between long and short-term venous patencies after pancreatoduodenectomy or total pancreatectomy with portal/superior mesenteric vein resection stratified by reconstruction type

Background

Venous reconstruction has been recently demonstrated to be safe for tumours with invasion into portal vein and/or superior mesenteric vein. This study aims to compare the patency between various venous reconstructions.

Methods

This is retrospective study of 76 patients who underwent pancreaticoduodenectomy or total pancreatectomy with venous reconstruction from 2006 to 2018. Patient demographics, tumour histopathology, morbidity, mortality and patency were studied. Kaplan-Meier estimates were performed for primary venous patency.

Results

Sixty-two patients underwent pancreaticoduodenectomy and 14 underwent total pancreatectomy. Forty-seven, 19 and 10 patients underwent primary repair, end-to-end anastomosis and interposition graft respectively. Major morbidity (Clavien-Dindo >grade 2) and 30-day mortality were 14/76(18.4%) and 1/76(1.3%) respectively. There were 12(15.8%) venous occlusion including 4(5.3%) acute occlusions. Overall 6-month, 1-year and 2-year primary patency was 89.1%, 92.5% and 92.3% respectively. 1-year primary patency of primary repair was superior to end-to-end anastomosis and interposition graft (primary repair 100%, end-to-end anastomosis 81.8%, interposition graft 66.7%, p = 0.045). Pairwise comparison also demonstrated superior 1-year patency of primary repair (adjusted p = 0.037). There was no significant difference between the cumulative venous patency for each venous reconstruction method: primary repair 84±6%, end-to-end anastomosis 75±11% and interposition graft 76±15% (p = 0.561).

Conclusion

1-year primary venous patency of primary repair is superior to end-to-end anastomosis and interposition graft.

Adoption of Robotic Liver, Pancreatic and Biliary Surgery in Singapore: A Single Institution Experience with Its First 100 Consecutive Cases

INTRODUCTION

Presently, robotic hepatopancreatobiliary surgery (RHPBS) is increasingly adopted worldwide. This study reports our experience with the first 100 consecutive cases of RHPBS in Singapore.

METHODS

Retrospective review of a single-institution prospective database of the first 100 consecutive RHPBS performed over 6 years from February 2013 to February 2019. Eighty-six cases were performed by a single surgeon.

RESULTS

The 100 consecutive cases included 24 isolated liver resections, 48 pancreatic surgeries (including 2 bile duct resections) and 28 biliary surgeries (including 8 with concomitant liver resections). They included 10 major hepatectomies, 15 pancreaticoduodenectomies, 6 radical resections for gallbladder carcinoma and 8 hepaticojejunostomies. The median operation time was 383 minutes, with interquartile range (IQR) of 258 minutes and there were 2 open conversions. The median blood loss was 200ml (IQR 350ml) and 15 patients required intra-operative blood transfusion. There were no post-operative 90-day nor in-hospital mortalities but 5 patients experienced major (> grade 3a) morbidities. The median post-operative stay was 6 days (IQR 5 days) and there were 12 post-operative 30-day readmissions. Comparison between the first 50 and the subsequent 50 patients demonstrated a significant reduction in blood loss, significantly lower proportion of malignant indications, and a decreasing frequency in liver resections performed.

CONCLUSION

Our experience with the first 100 consecutive cases of RHPBS confirms its feasibility and safety when performed by experienced laparoscopic hepatopancreatobiliary surgeons. It can be performed for even highly complicated major hepatopancreatobiliary surgery with a low open conversion rate.

Changing trends and outcomes associated with the adoption of minimally invasive pancreatic surgeries: A single institution experience with 150 consecutive procedures in Southeast Asia

BACKGROUND

Minimally invasive pancreatic surgeries (MIPS) are increasingly adopted worldwide. However, it remains uncertain if these reported experiences are reproducible throughout the world today. This study examines the safety and evolution of MIPS at a single institution in Southeast Asia.

METHODS

This is a retrospective review of 150 consecutive patients who underwent MIPS between 2006 and 2018 of which 135 cases (90%) were performed since 2012. To determine the evolution of MIPS, the study population was stratified into 3 equal groups of 50 patients. Comparison was also made between pancreatoduodenectomies (PD), distal pancreatectomies (DP) and other pancreatic surgeries.

RESULTS

One hundred and fifty patients underwent MIPS (103 laparoscopic, 45 robotic and 2 hand-assisted). Forty-three patients underwent PD, 93 DP and 14 other MIPS. There were 21 (14.0%) open conversions. There was an exponential increase in caseload over the study period. Comparison across the 3 time periods demonstrated that patients were significantly more likely to have a higher American Society of Anesthesiologists score, older, undergo PD and a longer operation time. The conversion rate decreased from 28% to 0% and increased again to 14% across the 3 time periods. Comparison between the various types of MIPS demonstrated that patients who underwent PD were significantly older, more likely to have symptomatic tumours, had longer surgery time, increased blood loss, increased frequency of extended pancreatectomies, increased frequency of hybrid procedures, longer post-operative stay, increased post-operative morbidity rate and increased post-operative major morbidity rate.

CONCLUSION

The case volume of MIPS increased rapidly at our institution over the study period. Furthermore, although the indications for MIPS expanded to include more complex procedures in higher risk patients, there was no change in key perioperative outcomes.

Impact of multidisciplinary tumour boards (MTB) on the clinicopathological characteristics and outcomes of resected colorectal liver metastases across time

Background

Resection of colorectal liver metastases (CLM) has been established as the standard of care. This study aims to compare the change in clinicopathological characteristics of patients who underwent curative resection of CLM across two time periods—2000 to 2010 (P1) and 2011 to 2016 (P2) and evaluate the prognostic impact of these characteristics on survival outcomes.

Methods

Patients who undergo liver resection for CLM at Singapore General Hospital from January 2000 to December 2016 were identified from a prospectively maintained database. The primary end point was overall survival.

Results

There were 183/318 (57.5%) patients and 135/318 (42.5%) patients in P1 and P2, respectively. There was a lower proportion of patients who had nodal metastases from primary colorectal cancer and clinical risk score (CRS) less than 3 in P2 when compared to P1. There was no difference in survival between both time periods. Independent predictors of survival for the cohort were CEA levels ≥ 200 ng/ml, primary tumour grade and lymph nodal status. Independent predictors of poor survival in P1 were poorly differentiated colorectal cancer and nodal metastases while in P2, independent predictors of poor survival were multiple liver metastases and nodal metastases.

Conclusion

Nodal metastases from primary colorectal cancer are an independent predictor of poor survival across time for resectable CLM. Although there is no difference in survival between the two time periods, patients with multiple liver metastases should be carefully considered prior to surgery as it is also an independent predictor of overall survival.

Effect of remote ischemic preConditioning on liver injury in patients undergoing liver resection: the ERIC-LIVER trial

OBJECTIVE

Novel hepatoprotective strategies are needed to improve clinical outcomes during liver surgery. There is mixed data on the role of remote ischemic preconditioning (RIPC). We investigated RIPC in partial hepatectomy for primary hepatocellular carcinoma (HCC).

METHODS

This was a Phase II, single-center, sham-controlled, randomized controlled trial (RCT). The primary hypothesis was that RIPC would reduce acute liver injury following surgery indicated by serum alanine transferase (ALT) 24 h following hepatectomy in patients with primary HCC, compared to sham. Patients were randomized to receive either four cycles of 5 min/5 min arm cuff inflation/deflation immediately prior to surgery, or sham. Secondary endpoints included clinical, biochemical and pathological outcomes. Liver function measured by Indocyanine Green pulse densitometry was performed in a subset of patients.

RESULTS

24 and 26 patients were randomized to RIPC and control groups respectively. The groups were balanced for baseline characteristics, except the duration of operation was longer in the RIPC group. Median ALT at 24 h was similar between groups (196 IU/L IQR 113.5-419.5 versus 172.5 IU/L IQR 115-298 respectively, p = 0.61). Groups were similar in secondary endpoints.

CONCLUSION

This RCT did not demonstrate beneficial effects with RIPC on serum ALT levels 24 h after partial hepatectomy.

Early Prediction of Post-hepatectomy Liver Failure in Patients Undergoing Major Hepatectomy Using a PHLF Prognostic Nomogram

BACKGROUND

Liver resection (LR) is the main modality of treatment for hepatocellular carcinoma (HCC) and colorectal liver metastasis (CRLM). Post-hepatectomy liver failure (PHLF) remains the most dreaded complication. We aim to create a prognostic score for early risk stratification of patients undergoing LR.

METHODOLOGY

Clinical and operative data of 472 patients between 2000 and 2016 with HCC or CRLM undergoing major hepatectomy were extracted and analysed from a prospectively maintained database. PHLF was defined using the 50-50 criteria.

RESULTS

Liver cirrhosis and fatty liver were histologically confirmed in 35.6% and 53% of patients. 4.7% (n = 22) of patients had PHLF. A 90-day mortality was 5.1% (n = 24). Pre-operative albumin-bilirubin score (p = 0.0385), prothrombin time (p < 0.0001) and the natural logarithm of the ratio of post-operative day 1 to pre-operative serum bilirubin (SB) (ln(_POD1Bil/_pre-opBil); p < 0.0001) were significantly independent predictors of PHLF. The PHLF prognostic nomogram was developed using these factors with receiver operating curve showing area under curve of 0.88. Excellent sensitivity (94.7%) and specificity (95.7%) for the prediction of PHLF (50-50 criteria) were achieved at cut-offs of 9 and 11 points on this model. This score was also predictive of PHLF according to _PeakBil > 7 and International Study Group for Liver Surgery criteria, intensive care unit admissions, length of stay, all complications, major complications, re-admissions and mortality (p < 0.05).

CONCLUSIONS

The PHLF nomogram ( https://tinyurl.com/SGH-PHLF-Risk-Calculator ) can serve as a useful tool for early identification of patients at high risk of PHLF before the 'point of no return'. This allows enforcement of closer monitoring, timely intervention and mitigation of adverse outcomes.

Pre-operative Imaging Characteristics in Histology-Proven Resected Intrahepatic Cholangiocarcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) are the most common primary liver cancers. With the increasing incidence of ICC over the past two decades in Asia, it is essential to differentiate between HCC and ICC. However, ICC may mimic the radiological appearance of HCC on computed tomography scans (CT) and magnetic resonance imaging (MRI), leading to misdiagnosis of ICC. The objective of this study is to evaluate and describe the association of specific pre-operative imaging characteristics (arterial enhancement, portal venous washout) in patients with histologically proven resected ICC in our centre.

METHODS

Data on patients with histology-proven ICC and mixed hepatocellular-cholangiocarcinomas (HCC-CC) who had undergone surgical resection at Singapore General Hospital (SGH) were identified from a prospectively maintained database. Pre-operative cross-sectional imaging reports were analysed.

RESULTS

Ninety-one patients underwent resection between 1 January 2000 and 31 December 2016. Among those with no risk factors for HCC, a significant percentage of patients with ICC (24.3%) show imaging characteristics of both arterial phase hyperenhancement and non-peripheral venous washout. Among patients with risk factors for HCC, between 20.0 and 33.3% of patients with pure ICC fulfilled the imaging criteria for HCC, and this proportion was generally even higher in the mixed HCC-CC group.

CONCLUSIONS

A significant proportion of patients with pure ICC showed pre-operative imaging characteristics which fulfilled the diagnostic criteria for HCC. The differential of ICC should be borne in mind in populations where both malignancies are endemic.

A phase II open-label, single-center, nonrandomized trial of Y90-radioembolization in combination with nivolumab in Asian patients with advanced hepatocellular carcinoma: CA 209-678

4590

Background: Nivolumab (N) and Y90-radioembolization (RE) are both therapeutic options in advanced hepatocellular carcinoma (aHCC). Increasing evidence suggests that radiotherapy synergizes with immune checkpoint inhibitors to augment anti-tumour effects. Methods: Eligible Child-Pugh A aHCC patients (pts) were treated with Y90-RE followed by N 240mg, 21 days after Y90-RE and every 2 weeks thereafter. Pre- and on-treatment tumor biopsies together with circulating biomarkers were obtained. Primary end-point was overall response rate (ORR) (per RECIST v 1.1). Overall response was defined as the composite overall response observed for the lesions within Y90-RE field and outside Y90-RE field. Key secondary end points included disease control rate (DCR), progression free survival (PFS), overall survival (OS), and safety. 36 evaluable pts were needed to assess whether the addition of N improved the ORR of Y90-RE from 21% to 41% as determined by Simon two-stage optimal design with 80% power and one sided significance level of 0.05. Results: Forty pts were enrolled of which 36 were evaluable. At baseline: 63.9% were HepB in aetiology; 63.9% BCLC stage C; 47.2% had AFP > 400ng/mL; number of liver lesions – median 5 (range 1- 20); size of largest liver lesion – median 80mm (range 14-177mm); 27.8% had prior TACE; and 13.9% had prior systemic therapy. ORR was 31% (95% CI 16.4 - 48.1%). Eight out of 11 responders had not progressed at study cut-off. DCR was 58.3%. 81% of target lesions within Y90-RE field regressed. With a median follow up of 16.4 months, median PFS and OS were 4.6 months (95% CI 2.3m - 8.4m) and 15.1 months (95% CI 7.8m - NE) respectively. Six- and 12-month PFS rates were 44.2% (95% CI 27.3% - 59.9%) and 26.1% (95% CI 11.2% - 43.8%) respectively. Overall, N+ Y90-RE was well tolerated and safe; only 11% had grade 3/4 treatment related adverse events (AEs). Responders demonstrated significant alterations of LIF, MIG and Eotaxin3 levels in the pre-treatment cytokine analyses. Conclusions: Combination N+Y90-RE resulted in an encouraging ORR of 31% (95% CI 16.4 - 48.1%) in aHCC. 81% of target lesions within Y90-RE field regressed suggesting synergy in combining Y90-RE with nivolumab. This combination is safe and tolerable with low G3/4 treatment related AEs of 11%. Further biomarker analyses will be presented at the meeting. Clinical trial information: NCT03033446 .

Novel method of intraoperative liver tumour localisation with indocyanine green and near-infrared imaging

INTRODUCTION

Fluorescence imaging (FI) with indocyanine green (ICG) is increasingly implemented as an intraoperative navigation tool in hepatobiliary surgery to identify hepatic tumours. This is useful in minimally invasive hepatectomy, where gross inspection and palpation are limited. This study aimed to evaluate the feasibility, safety and optimal timing of using ICG for tumour localisation in patients undergoing hepatic resection.

METHODS

From 2015 to 2018, a prospective multicentre study was conducted to evaluate feasibility and safety of ICG in tumour localisation following preoperative administration of ICG either on Day 0-3 or Day 4-7.

RESULTS

Among 32 patients, a total of 46 lesions were resected: 23 were hepatocellular carcinomas (HCCs), 12 were colorectal liver metastases (CRLM) and 11 were benign lesions. ICG FI identified 38 (82.6%) lesions prior to resection. The majority of HCCs were homogeneous fluorescing lesions (56.6%), while CLRM were homogeneous (41.7%) or rim-enhancing (33.3%). The majority (75.0%) of the lesions not detected by ICG FI were in cirrhotic livers. Most (84.1%) of ICG-positive lesions detected were < 1 cm deep, and half of the lesions ≥ 1 cm in depth were not detected. In cirrhotic patients with malignant lesions, those given ICG on preoperative Day 0-3 and Day 4-7 had detection rates of 66.7% and 91.7%, respectively. There were no adverse events.

CONCLUSION

ICG FI is a safe and feasible method to assist tumour localisation in liver surgery. Different tumours appear to display characteristic fluorescent patterns. There may be no disadvantage of administering ICG closer to the operative date if it is more convenient, except in patients with liver cirrhosis.

Expression of CD38 on Macrophages Predicts Improved Prognosis in Hepatocellular Carcinoma

Background: CD38 is involved in the adenosine pathway, which represents one of the immunosuppressive mechanisms in cancer. CD38 is broadly expressed across immune cell subsets, including human macrophages differentiated in vitro from monocytes, but expression by tissue-resident macrophages remains to be demonstrated. Methods: Tissue samples were obtained from 66 patients with hepatocellular carcinoma (HCC) from Singapore and analyzed using immunohistochemistry. Tumor-infiltrating leukocytes (TILs) were further examined using DEPArray™, and the phenotype of freshly isolated TILs was determined using flow cytometry. Results: CD38 was frequently co-expressed with the macrophage-specific marker CD68. CD38⁺CD68⁺ macrophage density was associated with improved prognosis after surgery, while total CD68⁺ macrophage density was associated with poor prognosis. DEPArray™ analysis revealed the presence of large (>10 μm), irregularly shaped CD45⁺CD14⁺ cells that resembled macrophages, with concurrent CD38⁺ expression. Flow cytometry also revealed that majority of CD14⁺HLA-DR⁺ cells expressed CD38. Conclusion: CD38 expression was clearly demonstrated on human macrophages in an in vivo setting. The positive association identified between CD38⁺ macrophage density and prognosis may have implications for routine diagnostic work.

Outcome of minimally-invasive versus open pancreatectomies for solid pseudopapillary neoplasms of the pancreas: A 2:1 matched case-control study

Backgrounds/Aims

Solid pseudopapillary neoplasm (SPPN) is typically seen in young healthy females who would likely benefit from minimally-invasive pancreatectomy (MIP). A few comparative studies have suggested that MIP is associated with favorable outcomes when compared to the open approach for SPPN. This study aims to mitigate potential selection bias by performing a matched case-control study comparing MIP vs open pancreatectomy (OP) for SPPN.

Methods

We performed a single-institution retrospective electronic chart review of all patients who underwent surgery for pathologically confirmed SPPN between 2000 and 2017. A 2:1 matched comparison using age, gender, tumor size and the type of pancreatectomy was performed between OP and MIP.

Results

A total of 40 patients with a median age of 40.3 years (range 16.5-64.4) and female sex predominance (n=34, 85.0%) underwent surgery during the study period. Nine patients underwent MIP. Matched comparison between 18 OP and 9 MIP demonstrated that MIP was associated with a longer median operating time (305 vs 180 min, p=0.046) and shorter median postoperative stay (6 vs 9 days, p=0.015). There were no significant differences in intraoperative blood loss, blood transfusion requirements, postoperative morbidity (including postoperative pancreatic fistula) and mortality, resection margins, lymph node yield and long-term survival.

Conclusions

MIP is a safe and viable option in the management of SPPN with the benefit of a shorter postoperative length of stay at the expense of a longer operation time. There was no significant difference in oncologic outcomes between both groups of patients.

Liver Resection for Nonalcoholic Fatty Liver Disease-Associated Hepatocellular Carcinoma

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD)-related hepatocellular carcinoma (HCC) is on the rise worldwide, but data on long-term outcomes after curative operations are limited. The primary aim of this study was to characterize the perioperative and long-term outcomes after liver resection. The secondary aim was to investigate the influence of the histologic severity of nonalcoholic steatohepatitis and its impact on perioperative outcomes and long-term survival.

METHODS

A total of 996 patients who underwent liver resection for HCC in our institution were analyzed. Patients were categorized into subgroups of NAFLD vs non-NAFLD HCC based on histologic evidence of hepatic steatosis. Comparisons of patients' demographic, clinical, and surgical characteristics; postoperative complications; and survival outcomes were performed.

RESULTS

Eight hundred and forty-four patients had non-NAFLD HCC and 152 patients had NAFLD HCC. Comorbidities were significantly more common in the NAFLD group (p < 0.0001). In the non-NAFLD group, larger median tumor size, higher liver cirrhosis, and lower median neutrophil to lymphocyte ratio were observed (p < 0.0001). The NAFLD group had a greater amount of intraoperative blood loss, more postoperative complications, and longer length of stay. Five-year overall survival was significantly better in the NAFLD group (p = 0.0355). Significant factors that contribute to poorer survival outcomes include age, congestive cardiac failure, Child-Pugh's class B, cirrhosis, tumor size, multinodularity, and R1 resection. For NAFLD group, patients with abnormal parenchyma showed poorer survival and 5-year overall survival rates (64.8% vs 75.6%; p = 0.2291).

CONCLUSIONS

Nonalcoholic fatty liver disease-related HCC is associated with greater surgical morbidity and post-hepatectomy liver failure. Despite this, long-term survival outcomes are favorable compared with non-NAFLD etiologies.

Circulating microRNAs as Potential Diagnostic and Prognostic Biomarkers in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer with high mortality, due to late diagnosis and limited treatment options. Blood miRNAs, which circulate in a highly stable, cell-free form, show promise as novel potential biomarkers for early detection of HCC. Whole miRNome profiling was performed to identify deregulated miRNAs between HCC and normal healthy (NH) volunteers. These deregulated miRNAs were validated in an independent cohort of HCC, NH and chronic Hepatitis B (CHB) volunteers and finally in a 3^rd cohort comprising NH, CHB, cirrhotic and HCC volunteers to evaluate miRNA changes during disease progression. The associations between circulating miRNAs and liver-damage markers, clinicopathological characteristics and survival outcomes were analysed to identify prognostic markers. Twelve miRNAs are differentially expressed between HCC and NH individuals in all three cohorts. Five upregulated miRNAs (miR-122-5p, miR-125b-5p, miR-885-5p, miR-100-5p and miR-148a-3p) in CHB, cirrhosis and HCC patients are potential biomarkers for CHB infection, while miR-34a-5p can be a biomarker for cirrhosis. Notably, four miRNAs (miR-1972, miR-193a-5p, miR-214-3p and miR-365a-3p) can distinguish HCC from other non-HCC individuals. Six miRNAs are potential prognostic markers for overall survival.

Multidimensional analyses reveal distinct immune microenvironment in hepatitis B virus-related hepatocellular carcinoma

BACKGROUND AND AIMS

Chronic inflammation induced by chronic hepatitis B virus (HBV) infection increases the risk of hepatocellular carcinoma (HCC). However, little is known about the immune landscape of HBV-related HCC and its influence on the design of effective cancer immunotherapeutics.

METHODS

We interrogated the immune microenvironments of HBV-related HCC and non-viral-related HCC using immunohistochemistry and cytometry by time-of-flight (CyTOF). On identifying unique immune subsets enriched in HBV-related HCC, we further interrogated their phenotypes and functions using next-generation sequencing (NGS) and in vitro T-cell proliferation assays.

RESULTS

In-depth interrogation of the immune landscapes showed that regulatory T cells (T_REG) and CD8⁺ resident memory T cells (T_RM) were enriched in HBV-related HCC, whereas Tim-3⁺CD8⁺ T cells and CD244⁺ natural killer cells were enriched in non-viral-related HCC. NGS of isolated T_REG and T_RM from HBV-related HCC and non-viral-related HCC identified distinct functional signatures associated with T-cell receptor signalling, T-cell costimulation, antigen presentation and programmed cell death protein 1 (PD-1) signalling. T_REG and T_RM from HBV-related HCC expressed more PD-1 and were functionally more suppressive and exhausted than those from non-virus-related HCC. Furthermore, immunosuppression by PD-1⁺ T_REG could be reversed with anti-PD-1 blockade. Using multiplexed tissue immunofluorescence, we further demonstrated that T_REG and T_RM contributed to overall patient survival: T_REG were associated with a poor prognosis and T_RM were associated with a good prognosis in HCC.

CONCLUSION

We have shown that the HBV-related HCC microenvironment is more immunosuppressive and exhausted than the non-viral-related HCC microenvironment. Such in-depth understanding has important implications in disease management and appropriate application of immunotherapeutics.

Rare case of gallbladder mucocele causing gastric outlet obstruction treated with cholecystectomy

INTRODUCTION

Gallstone(s) impacted at the distal small bowel causing intestinal obstruction as a result of cholecystoenteric fistula is a well-known, albeit uncommon surgical condition. The rare Bouveret's Syndrome, which refers to the proximal impaction of gallstone(s) in the duodenum or pylorus resulting in the gastric outlet obstruction (GOO), has also been described in the literature. However, gallbladder mucocele with extrinsic compression of the duodenum and/or pylorus causing GOO is a separate entity that is extremely rare.

PRESENTATION OF CASE

A patient who presented with loss of appetite and weight, with intermittent vomiting over a course of eight months was found to have GOO secondary to extrinsic duodenal compression from a large gallbladder mucocele. Surgical intervention in the form of cholecystectomy was performed, and the patient's symptoms resolved post-operatively.

DISCUSSION

We describe an extremely rare case of GOO, which can be easily corrected with cholecystectomy. Removal of the gallbladder removes the root cause of the issue, and should be first line therapy unless the patient is unfit for surgery.

CONCLUSION

This extremely rare cause of GOO should be recognized, and treated promptly with surgery if possible.

Laparoscopic Liver Resection Difficulty Score-a Validation Study

OBJECTIVE(S)

The technical complexity of laparoscopic liver resection (LLR) poses unique challenges distinct from open surgery. An objective scoring system was developed that preoperatively quantifies the difficulty of LRR to help guide surgeon decision-making regarding the feasibility and safety of minimally invasive approaches. The aim of this multiinstitutional study was to externally validate this scoring system.

METHODS

Patients who underwent LLR at two institutions were reviewed. LLR difficulty score (LDS) was calculated based on patient, tumor, and anatomic characteristics by two independent, blinded hepatobiliary surgeons. Surrogates of case complexity (e.g., conversion rate, operative time) were used for validation of this index.

RESULTS

From 2006 to 2016, 444 LLR were scored as low (n = 94), intermediate (n = 98), and high difficulty (n = 152) with respective conversion rates of 5.3%, 15.7%, and 25%. Cases of higher LDS correlated with larger mean blood loss (203 ml vs. 331 ml vs. 635 ml). Mean operative and Pringle maneuver used were associated with increasing LDS (155 min vs. 202 min vs. 315 min and 14.4% vs. 29.7% vs. 45.1% respectively). These operative surrogates of difficulty correlated significantly with the LDS (all p < 0.0001).

CONCLUSIONS

This comprehensive external validation of the LDS is robust and applicable in diverse patient populations. This LDS serves as a useful objective predictor of technical difficulty for LLR to help surgeons in selecting patients according to their individual operative experience and is valuable for preoperative risk estimation and stratification in randomized trials.

Using δ13C of Levoglucosan As a Chemical Clock

Compound specific carbon isotopic measurements (δ¹³C) of levoglucosan were carried out for ambient aerosol sampled during an intensive biomass burning period at different sites in Guangdong province, China. The δ¹³C of ambient levoglucosan was found to be noticeably heavier than the average δ¹³C of levoglucosan found in source C3-plant-combustion samples. To estimate the photochemical age of sampled ambient levoglucosan, back trajectory analyses were done. The origin and pathways of the probed air masses were determined, using the Lagrangian-particle-dispersion-model FLEXPART and ECMWF meteorological data. On the other hand, the isotopic hydrocarbon clock concept was applied to relate the changes in the field-measured stable carbon isotopic composition to the extent of chemical processing during transport. Comparison of the photochemical age derived using these two independent approaches shows on average good agreement, despite a substantial scatter of the individual data pairs. These analyses demonstrate that the degree of oxidative aging of particulate levoglucosan can be quantified by combining laboratory KIE studies, observed δ¹³C at the source and in the field, as well as back trajectory analyses. In this study, the chemical loss of levoglucosan was found to exceed 50% in one-fifth of the analyzed samples. Consequently, the use of levoglucosan as a stable molecular tracer may underestimate the contribution of biomass burning to air pollution.

A retrospective review of correlative radiological assessment and surgical exploration for hilar cholangiocarcinoma

Backgrounds/Aims

Hilar cholangiocarcinomas (HCCAs) are tumors that involve the biliary confluence; at present, radical surgery offers the only chance of long-term survival, but this can be challenging given the complexity of the hilar anatomy. Blumgart and Jarnagin described a preoperative staging system that incorporates the effect of local tumor extent and its impact on adjacent structures and that has been demonstrated to correlate better with actual surgical resectability. The primary aim of this study is to describe the correlation between preoperative Blumgart-Jarnagin staging and its correlation with surgical resectability.

Methods

Patients who underwent surgical resection for hilar cholangiocarcinoma at Singapore General Hospital between January 1, 2002, and January 1, 2013, were identified from a prospectively maintained institutional database. All patients were staged based on the criteria described by Blumgart and Jarnagin. Correlation with surgical resectability was then determined.

Results

A total of 19 patients were identified. Overall resectability was 57.8% (n=11). Patients with Blumgart-Jarnagin stage T1 had the highest rates of resectability at 80%; patients with stage T2 and T3 disease had resectability rates of 25% and 40% respectively. Median overall survival was 13.6 months.

Conclusions

The Blumgart-Jarnagin staging system is useful for predicting tumor resectability in HCCA.

Predictors of post-hepatectomy liver failure in patients undergoing extensive liver resections for hepatocellular carcinoma

Backgrounds/Aims

To determine the prevalence of post-hepatectomy liver failure/insufficiency (PHLF/I) in patients undergoing extensive hepatic resections for hepatocellular carcinoma (HCC) and to assess the predictive value of preoperative factors for post-hepatectomy liver failure or insufficiency (PHLF/I).

Methods

A retrospective review of patients who underwent liver resections for HCC between 2001 and 2013 was conducted. Preoperative parameters were assessed and analyzed for their predictive value of PHLF/I. Definitions used included the 50–50, International Study Group of Liver Surgery (ISGLS) and Memorial Sloan Kettering Cancer Centre (MSKCC) criteria.

Results

Among the 848 patients who underwent liver resections for HCC between 2001 and 2013, 157 underwent right hepatectomy (RH) and extended right hepatectomy (ERH). The prevalence of PHLF/I was 7%, 41% and 28% based on the 50–50, ISGLS and MSKCC criteria, respectively. There were no significant differences in PHLF/I between RH and ERH. Model for End-Stage Liver Disease (MELD) score and bilirubin were the strongest independent predictors of PHLF/I based on the 50–50 and ISGLS/MSKCC criteria, respectively. Predictive models were developed for each of the criteria with multiple logistic regression.

Conclusions

MELD score, bilirubin, alpha-fetoprotein and platelet count showed significant predictive value for PHLF/I (all p<0.05). A composite score based on these factors serves as guideline for physicians to better select patients undergoing extensive resections to minimize PHLF.

Abstract 5725: Systematic identification of tumour-specific neoantigens(by whole-genome sequencing) and correlation between tumour neoantigen burden, PD-L1 expression and immune infiltrates in 158Asian colorectal cancers

Background: Somatic mutations are attractive therapeutic targets for “individualized neoantigen vaccines” because of lack of host central tolerance and reduced risk of autoimmunity. Here, we perform large-scale-omic analyses to assess the neoantigen landscape of colorectal cancer (CRC), a cancer largely refractory to immune-checkpoint inhibition.

Methods: We performed whole genome sequencing (WGS) (60x tumor, 30x normal) and deep whole transcriptomic sequencing (RNA-Seq) (∼200x106 reads per tumor) on 158 colorectal cancers of which 32 are microsatellite instability high (MSI-H) tumours and 126 are microsatellite stable (MSS). Whole exome sequencing (200x tumor, 100x normal) was also performed on 120 tumours. HLA typing, somatic mutations, gene expression and neoepitope predictions were computationally evaluated. Inferred HLA-A alleles were orthogonally validated with Pacbio long-read sequencing. Tissue microarrays (TMAs) with tumour core, tumour edge and normal adjacent tissue of these 158 CRCs were constructed. Histopathological analyses using multiplex immunohistochemistry (mIHC) to simultaneously evaluate 7 markers, i.e. cytokeratin (CK), CD3, CD8, FOXP3, CD68, PD-L1, DAPI, have been performed.

Results: The most common HLAs were, by allele count: A*11:01: 56; A*33:03: 38; B*58:01: 33; B*46:01: 29; B*40:01: 26; C*01:02: 41; C*07:02: 33. Inferred HLA-A alleles from WGS data was largely concordant (&gt;90%) with Pacbio long-read sequencing. There were a median of 2,850 (1229-6909) [MSI] & 213 (27-13,835) [MSS] coding variants, from which 10,487 (4,307-27,365) [MSI] & 726.5 (50-59,096) [MSS] possible neoepitopes were derived, after accounting for epitope processing, the normal proteome and general population variome based on dbSNP, Of these, 5,707 (2,608-15,218) [MSI] & 320 (14-25,243) [MSS] neoepitopes are expressed (based on RNA-Seq). Epitope prediction algorithms revealed a median of 423 (17-1,056) [MSI] & 26 (0-1,102) [MSS] bound & expressed neoepitopes. 5 MSS tumors did not have any predicted bound nor expressed neoepitopes, 112 of 126 (89%) of MSS tumors had at least 5 predicted bound, expressed neoepitopes. Histopathological correlations between extent of immune infiltrates in fixed tissues, tumour PD-L1 expression and neoantigen burden is ongoing.

Conclusions: There is substantial variability in the neoantigen landscape amongst MSI & MSS CRCs. MSI contains multiple-fold higher neo-antigens. Amongst MSS tumours, 89% of patients have at least 5 predicted bound and expressed neo-epitopes that could be targeted in neoantigen-based vaccines for personalized immunotherapy.

Citation Format: Si-Lin Koo, Joe Poh Sheng Yeong, Andy Nguyen, Clarinda Wei Ling Chua, J Zachary Sanborn, Steve Benz, Wah Siew Tan, Choong Leong Tang, Su Yan, Min Hoe Chew, Brian Goh, Chung Yip Chan, Xiao Qing Koh, Alexander Lezhava, Tony Kiat Hon Lim, Shahrooz Rabizadeh, Anders Skanderup, Iain Beehuat Tan. Systematic identification of tumour-specific neoantigens(by whole-genome sequencing) and correlation between tumour neoantigen burden, PD-L1 expression and immune infiltrates in 158Asian colorectal cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5725.

BCLC subclassification and tumour characteristics to provide prognostication of outcomes in an Asian population of locally advanced hepatocellular carcinoma treated using selective internal radiation therapy with Yttrium-90

443

Background: Selective internal radiation therapy (SIRT) with Yttrium-90 (Y90) is preferentially used in locally advanced hepatocellular carcinoma (HCC) patients in the Barcelona clinic liver cancer (BCLC) B or C cohort. However, the BCLC B cohort has a wide heterogeneity. To address this, Bolondi et al. proposed a BCLC B subclassification system. Additionally, the BCLC C cohort is also diverse in their Child-Pugh (CP) stage and extent of portal vein thrombosis (PVT). The effect of these subclassifications on survival outcomes has not been studied in HCC patients treated using SIRT. Methods: 392 HCC patients treated using SIRT from 1st January 2008 to 17th March 2017 were analyzed. These patients were classified according to the proposed subclassification system for the BCLC B cohort, and CP stage for the BCLC C cohort, and their survival outcomes reviewed. Results: 293 patients met the study’s inclusion criteria. For B1/B2/B3/B4/ C CP-A and C CP-B, the median OS was 48.3/28.7/14.4/13.7/12.8 and 6.6 months respectively. Overall comparison between the subgroups for median OS reached statistical significance (p < 0.001). The Cox proportional-hazards regression analysis found that tumour location defined as unilobar or bilobar disease significantly influenced median OS. In the BCLC C cohort, the extent of portal vein invasion significantly influenced median OS (p < 0.001). For the BCLC C CP-A group, median OS for segmental/sectoral branch invasion, right and/or left portal vein invasion and main portal vein trunk invasion was 24.1, 12.8 and 6.5 months respectively. Conclusions: Bolondi et al.’s subclassification system optimizes prognostic prediction by reducing the clinical heterogeneity in BCLC B HCC patients treated using SIRT. However tumour location, unaccounted for in the proposed subclassification, is also an important prognosticator. For the BCLC C cohort CP stage, extent of PVT, and tumour location were important predictors of treatment outcomes.

Surgical management decreases disease recurrence risk in recurrent pyogenic cholangitis

BACKGROUND

Recurrent pyogenic cholangitis (RPC) has a high risk of disease recurrence. We present our experience with RPC and examine the factors associated with disease recurrence.

METHODS

We performed a retrospective review of all patients with RPC treated at two tertiary institutions between January 1990 and December 2013. Patients with liver atrophy and/or abscess were categorized as being associated with parenchymal disease (PD).

RESULTS

We studied 157 patients with a median age of 59.0 (interquartile range (IQR): 47.0-70.0) years and a median follow-up duration of 71.0 (IQR: 26.0-109.0) months. There were 64 (40.8%) and 93 (59.2%) patients with and without associated PD, respectively. Disease recurrence rate was 43.9% in our overall cohort through the course of follow-up. Surgical treatment was an independent prognostic factor for decreased disease recurrence risk (hazard ratio (HR) 0.40, 95% confidence interval (CI) 0.18-0.87, P = 0.021). Stratified analysis revealed that liver resection was prognostic for lower risk of disease recurrence among patients with PD (HR 0.38, 95% CI 0.15-0.94, P = 0.036), while biliary bypass was prognostic for lower risk of disease recurrence among patients without PD (HR 0.30, 95% CI 0.15-0.61, P = 0.001). The overall post-operative complication rate among surgically treated patients was 31.1%, and the presence of bilobar stones was found to be independently associated with higher odds of post-operative complications (odds ratio 3.51, 95% CI 1.26-9.81, P = 0.017).

CONCLUSION

Surgical treatment is associated with decreased recurrence risk in RPC, but with significant post-operative morbidity. Where surgery is deemed appropriate, patients with and without PD are likely to benefit from liver resection and biliary bypass, respectively.

Spontaneous regression of pancreatic cancer: A case report and literature review

INTRODUCTION

Spontaneous regression of cancer is defined as the partial or complete disappearance of malignant disease without treatment, or in the presence of therapy that is deemed inadequate to exert an influence on malignant disease, as composed by Tilden Everson and Warren Cole in the 1960s. It has been a topic of major interest in the field of medical and surgical oncology. It is poorly understood and scantily documented. Factors associated and postulated pathogeneses are at best, hypothetical.

PRESENTATION OF CASE

We report a case of spontaneous resolution of a head of pancreas carcinoma in a 77-year-old gentleman after a myocardial infarction event delayed planned surgery.

DISCUSSION

A literature review of previously reported cases of spontaneous regression of pancreatic cancer was performed. The possible predisposing factors to spontaneous regression of pancreatic and other forms of malignancies was reviewed.

CONCLUSION

This is a novel case of spontaneous regression of pancreatic carcinoma after an episode of myocardial infarction. The pathophysiology to spontaneous resolution of cancer is not well understood, may be multifactorial and requires further study.

A Retrospective Review of the Diagnostic and Management Challenges of Mirizzi Syndrome at the Singapore General Hospital

BACKGROUND

Mirizzi syndrome (MS) occurs when gallstone impaction in Hartmann's pouch results in extrinsic obstruction of the common bile duct, and fistulation may occur.

METHODS

We retrospectively reviewed electronic records of patients surgically treated for MS from November 2001 to June 2012. Patient presentations, diagnostic methods, treatments and complications were recorded.

RESULTS

Sixty-four patients were grouped according to a classification proposed by Beltran et al. [World J Surg 2008; 32: 2237-2243]. Forty-three (66.2%), 18 (27.7%) and 3 (4.6%) patients were classified as types I, II, and III respectively. Magnetic-resonance-cholangiopancreaticography was the most sensitive imaging modality, suggesting MS in 24 (88.9%), followed by CT scan (40%) and ultrasonography (11.4%). Forty-four underwent Endoscopic-retrograde-cholangiopancreaticography and 29 (65.9%) suggested the presence of MS. MS was accurately diagnosed pre-operatively in 48 (73.8%) patients. In type I, 40 (93.0%) patients underwent cholecystectomy, while 3 required hepaticojejunostomy. In type II, 12 (66.7%) underwent cholecystectomy and 5 (27.8%) required hepatico-enteric anastomosis. In type III, 1 underwent cholecystectomy and 2 (66.7%) required hepatico-enteric anastomosis. Laparoscopic cholecystectomy was attempted in 20 (30.8%) patients and 13 (65.0%) required conversion. Twenty-nine (44.6%) underwent intra-operative-cholangioscopy, 30 (46.2%) underwent intra-operative-cholangiogram and 41 (63.1%) underwent intra-operative T-tube placement. Six (9.2%) experienced intra-operative complications, 12 (18.5%) experienced post-operative complications and 10 (15.4%) experienced late complications.

CONCLUSION

MS is a challenging condition and multimodal diagnostic approach has the greatest yield in achieving accurate pre-operative diagnosis. If suspicion is high, a trial of laparoscopic dissection with low threshold for open conversion is recommended.

Prediction of Hepatocellular Carcinoma Recurrence Beyond Milan Criteria After Resection: Validation of a Clinical Risk Score in an International Cohort

OBJECTIVE

This study aims to validate a previously reported recurrence clinical risk score (CRS).

SUMMARY OF BACKGROUND DATA

Salvage transplantation after hepatocellular carcinoma (HCC) resection is limited to patients who recur within Milan criteria (MC). Predicting recurrence patterns may guide treatment recommendations.

METHODS

An international, multicenter cohort of R0 resected HCC patients were categorized by MC status at presentation. CRS was calculated by assigning 1 point each for initial disease beyond MC, multinodularity, and microvascular invasion. Recurrence incidences were estimated using competing risks methodology, and conditional recurrence probabilities were estimated using the Bayes theorem.

RESULTS

From 1992 to 2015, 1023 patients were identified, of whom 613 (60%) recurred at a median follow-up of 50 months. CRS was well validated in that all 3 factors remained independent predictors of recurrence beyond MC (hazard ratio 1.5-2.1, all P < 0.001) and accurately stratified recurrence risk beyond MC, ranging from 19% (CRS 0) to 67% (CRS 3) at 5 years. Among patients with CRS 0, no other factors were significantly associated with recurrence beyond MC. The majority recurred within 2 years. After 2 years of recurrence-free survival, the cumulative risk of recurrence beyond MC within the next 5 years for all patients was 14%. This risk was 12% for patients with initial disease within MC and 17% for patients with initial disease beyond MC.

CONCLUSIONS

CRS accurately predicted HCC recurrence beyond MC in this international validation. Although the risk of recurrence beyond MC decreased over time, it never reached zero.