Thesis (M. Phil.)--University of Hong Kong, 1973. / Typewritten.

Thesis (M. Phil.)--University of Hong Kong, 1982.

Thesis (Ph. D.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 167-219).

published_or_final_version / Public Health / Master / Master of Public Health

published_or_final_version / Pathology / Doctoral / Doctor of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

With the recent advances in the knowledge of hepato-carcinogenesis, there has been encouraging development in the molecular targeted therapy for patients with advanced hepatocellular carcinoma (HCC). Sorafenib, an anti-angiogenic multi-targeted receptor tyrosine kinase inhibitor, has become the standard of treatment in HCC patients with Child-Pugh A cirrhosis. Nevertheless, the benefits and safety profile of sorafenib in the majority of the unselected advanced HCC patients and other patient subgroups are still unclear. More importantly, the survival benefit associated with sorafenib use is generally modest in Asian population. Therefore, an unmet medical need remains for more effective therapeutic agents. This thesis studied the impact of molecular targeted therapy in the treatment of advanced HCC patients and it contains 10 original studies divided into six sections. The first section provides a concise overview of the epidemiology, risk factors, and current treatment options for HCC patients. Also, the molecular biology and opportunity for the use of targeted therapy in advanced HCC were discussed. The second section is about a new prognostic score system that we developed — Advanced Liver Cancer Prognostic System (ALCPS). Our study results showed that ALCPS was able to objectively estimate the 3-month survival probability of advanced HCC patients and thus could enhance patient selection for targeted therapy or clinical trials. The third section is about the use of sorafenib in the treatment of advanced HCC patients. The results of our single centre phase II study showed that sorafenib had good efficacy and acceptable tolerability in treating advanced HCC patients in hepatitis B endemic area. Furthermore, our retrospective study results confirmed that the overall survival benefits and overall treatment-related adverse events of sorafenib were comparable in elderly and young advanced HCC patients. More importantly, our other retrospective analysis showed that Child-Pugh (CP) A and CP B patients tolerated sorafenib similarly and derived similar clinical and progression-free survival benefit. Among CP B patients, most benefits were observed in patients with score 7. Nevertheless, CP B patients were more susceptible to developing cirrhotic complications. Last but not least, our study also demonstrated that drop in serum alpha-fetoprotein level > 20% in the first 6 weeks of sorafenib treatment was a useful early surrogate endpoint for evaluating antitumor response and survival benefits. All these results are instrumental in guiding future rational use of sorafenib in advanced HCC population. The fourth section is about the role of targeted therapies in treating sorafenib-refractory advanced HCC patients. In a single arm phase II study, we showed that bevacizumab and erlotinib combination was not effective in treating advanced HCC patients who had failed prior sorafenib treatment. The fifth section of the thesis comprises results of four early phase novel clinical trials that may potentially improve the therapeutic outcomes in advanced HCC patients. First, our phase I/II study demonstrated that another anti-angiogenic agent — PTK787 had encouraging and possible synergistic activity when combined with intravenous doxorubicin in treating advanced HCC patients. Second, our multi-center phase II study results demonstrated promising activity with good tolerability of a novel combination — sorafenib together with capecitabine and oxaliplatin (SECOX) in the treatment of advanced HCC patients. Third, in a phase I study, we showed that pazopanib, a novel anti-angiogenic agent, had a manageable safety profile and preliminary activity in advanced HCC patients. Moreover, pazopanib reduced tumor vessel leakage, as shown by contrast-enhanced magnetic resonance imaging indicating a direct effect on HCC vasculature that might be associated with its antitumor activity. Lastly, in another phase I study, we evaluated safety, pharmacological parameters, and potential antitumor activity of pegylated recombinant human arginase 1 (peg-rhArg1) in advanced HCC patients. Our results illustrated that arginine depletion in humans can be achieved safely with peg-rhAgr1 in a dose-response manner and peg-rhArg1 had manageable safety profile and preliminary evidence of activity in advanced HCC patients. In the last section, the future perspectives about the use of molecular targeted therapy in the treatment of advanced HCC patients were discussed. / published_or_final_version / Medicine / Master / Doctor of Medicine

Hepatocellular carcinoma (HCC) is the major type of primary liver cancer which is well-known for its high heterogenicity and metastatic potential. Despite of the current advancement in surgical resection and the availability of targeted therapy, HCC remains a barely curable and fatal disease. We previously demonstrated that deregulation of epigenetic regulators is a common event in human HCC. Herein, we identified the frequent up-regulation of the prototype of H3K9 tri-methyltransferase SUV39H1 in clinical HCCs. SUV39H1 over-expression was also significantly associated with increased Ki67 expression and the presence of venous invasion. By using both SUV39H1 over-expression and knockdown model, we consistently demonstrated that SUV39H1 contributed to HCC tumor growth and migration. Most importantly, SUV39H1 knockdown drastically suppressed in vivo tumorigenicity and extra-hepatic metastasis of HCC cells in nude mice model. These findings evidently demonstrated the oncogenic role of SUV39H1 in HCC and implied potential therapeutic targeting of SUV39H1 for HCC treatment. Molecularly, SUV39H1 knockdown HCC cell underwent morphological changes and accompanied with increased lysosomal β-galactosidase activity and elevated p21 protein and γH2AX level. This data suggested senescence induction in SUV39H1 knockdown HCC cells. SUV39H1 has been implicated in telomere regulation and transcriptional control. However, neither telomere length nor expression of tumor suppressor genes was altered in SUV39H1 knockdown HCC cells. Interestingly, we demonstrated a novel observation that SUV39H1 may potentially methylate non-histone substrates that are yet to be identified, which may contribute to the pro-tumorigenic function of SUV39H1 in HCC. We also investigated the upstream regulation of SUV39H1 and identified miR-125b as the negative post-transcriptional regulator of SUV39H1. Ectopic expression of miR-125b abolished SUV39H1 3’UTR-coupled luciferase activity and suppressed endogenous SUV39H1 at both mRNA and protein level. Clinically, miR-125b level was found inversely correlated with SUV39H1 expression. We have previously reported the frequent under-expression of miR-125b in HCC. Collectively, our data suggested that SUV39H1 up-regulation in HCC may be the sequential outcome of miR-125b down-regulation. In conclusion, we demonstrated for the first time that SUV39H1 up-regulation contributed to HCC development and metastasis, potentially via senescence evasion. SUV39H1 elevation in HCC was attributed to the loss of its negative regulator, the tumor suppressive miR-125b. / published_or_final_version / Pathology / Doctoral / Doctor of Philosophy

Background and Aim Hepatocellular Carcinoma (HCC) is the fifth most frequent malignancy worldwide with high mortality and recurrence rate. Chronic inflammation is a dominant risk factor for the malignancy and the roles of tumor associated immunological infiltrates during the disease development and progression remain unclear. The significance of alternative activated macrophages (M2) with pro-tumor phenotypes has been demonstrated in many cancers except HCC. M2 macrophages are associated with tumor angiogenesis, invasion and growth which represent a potential target to be investigated. In this study, we intend to investigate the role of M2 macrophage on HCC. Materials and Methods M2 macrophages in 100 clinical specimens collected from HCC patients were detected by immunohistochemical (IHC) staining and quantitative PCR using common macrophage markers CD14 and CD68, and M2 specific markers CD163, Scavenger receptor class A (SA) and Mannose receptor (MR). The protein and transcript expression levels were further correlated with clinical pathological parameters. Phenotypic and functional characteristics of M1 and M2 macrophages derived from THP-1 cell line were validated and their roles in promoting HCC growth and invasion were studied in vitro co-culture system and in vivo orthotopic mice model. Secretory profiles of M2 macrophages after cocultivated with HCC cells were analyzed by cytokines antibody array screening. C-C motif chemokine 22 (CCL22) was identified to be upregulated in M2 macrophages in response to HCC cells. The functional roles of the chemokine in HCC was further studied by chemotaxis and migration assay. Underlying molecular mechanisms induced by CCL22 in HCC cells were determined. Results In clinical analysis, we first discovered that macrophages were widely expressed in liver tumor comprising 10-30% of total cell population. Noteworthy, the density of a M2 macrophage marker CD163 was found to had a significant prognostic impact as an independent factor associated disease free survival (HR: 3.79; 95% CI 1.3-10.4; p<0.01). Strong expression of the CD163+ population was also correlated with poor relapse free survival, multiple tumor nodules and increased venous infiltration. In vivo studies revealed that the tumor volume injected with M2 macrophages increased 3.26-fold (1.27cm3±0.36) compared to the control group (0.39cm3±0.05) (P=0.032). In contrast, mice injected with M1 macrophages had a significant reduction of tumor volume by 2.79-fold (0.14cm3±0.02) (P=0.044). Increasing rate of lung metastases (57%) was also observed in M2 treated group compared to the control (25%) (P<0.05). In vitro, M2 macrophages increased the number of HCC cells (MHCC97L) and migration events by 1.3-fold and 3.2-fold after cocultivation compared to negative control (P<0.05). In cytokine antibody array study, M2 macrophages derived CCL22 was discovered to be strongly induced by MHCC97L. Chemotaxis analysis confirmed that CCL22 increased MHCC97L migration capacities and excess level led to increased venous infiltration in HCC patients (p<0.05). Upon addition of CCL22, the epithelial mesenchymal transition through SNAIL activation in MHCC97L was observed. Conclusion Clinical analysis and both the in vitro and in vivo studies presented here collectively illustrated the significances of M2 macrophages in promoting tumor growth and migration through CCL22-CCR4 mechanism in HCC. Targeting these M2 macrophages and associated products in situ represents a novel approach for treating the disease. / published_or_final_version / Surgery / Doctoral / Doctor of Philosophy

Bioethics has been central to living donor liver transplantation (LDLT), which mandates a high recipient benefit and an acceptably low donor risk. The double equipoise imposes the contextual features of this already technically complex treatment. This research aimed at looking into key bioethical issues of LDLT in the light of the contemporary practice standards. In adult LDLT, in order to provide a partial graft of adequate size, donor right hepatectomy is often required. This procedure pioneered by The University of Hong Kong is now being performed at many centers and by many surgeons. Through close guidance and gradual granting of surgical privilege, newer surgeons can now perform this operation safely with low blood loss (400 mL) and low complication rates ( 30%). Analysis of our series also showed that right liver donors with a smaller remnant left liver had higher peak bilirubin level and longer peak prothrombin time after the operation. Severe complications were associated with hyperbilirubinemia (p=0.031) while prolonged hospital stay was associated with prolonged prothrombin time (p=0.011) and smaller remnant left liver (p=0.036). Facts need to be known to potential right liver donors before operation. Donor left hepatectomy, which carries a lower donor risk, is more feasible for donors with a larger left liver and recipients with a smaller body size. Lowering the graft size requirement also allows more LDLTs being done using left livers. The percentages of left liver LDLTs feasible with a graft to standard liver volume (G/SLV) ≥ 40%, ≥ 35%, ≥ 30%, and ≥ 25% were 5.8%, 12.5%, 29.1%, and 62.3% respectively. For every 5% decrease in G/SLV ratio, twice as many left liver LDLTs could be performed. The 5-year survival rate was 85.7% for liver transplantation recipients with hepatocellular carcinoma (HCC) within the Up-to-7 criteria, unaffected by the presence of microvascular invasion (88.2% vs. 85.1%, p=0.652). This is comparable with that of liver resection patients with HCC without microvascular invasion (81.2%, p=0.227) but far superior to that of liver resection patients with lesions with microvascular invasion (50.0%, p<0.0001). Primary liver transplantation for HCC with microvascular invasion and within the Up-to-7 criteria in fact doubled the chance of cure as compared with liver resection. LDLT has been criticized of fast-tracking patients with more aggressive HCC for transplant. Waiting does select out patients with better survival to undergo transplantation. With careful selection though without waiting, LDLT nevertheless does not confer poorer survival. Progressive liver failure following a major hepatectomy for HCC is a known and uncommon cause of mortality. Proceeding to LDLT is an ethical challenge because of the possibility of coercion. Tumor status as confirmed by histopathological examination of resected specimens can demonstrate features of more aggressive cancer, which warns against a rescue transplantation for the increase in chance of tumor recurrence. In order to overcome ABO blood group incompatibility, paired donor interchange (between two pairs: A to B and B to A) has been practiced for the liver. The extension to matching with one pair of universal donor (O) and universal recipient (AB) was also performed at our center. The obvious biological advantage of this treatment modality has to be weighed against the potential increase in risks to patients involved. Media coverage of advances and successes in liver transplantation stimulates deceased donor organ donation (DDOD). The relation between widely reported key events and DDOD can be recognized as celebrity hero influence, medical success, or emotional response. An accountable liver transplant service answerable to the public is vital to a region where the DDOD rate is low. Selective disclosure of patient information to the media for public interest in promoting organ donation can be justified. LDLT now has a two-decade history of clinical practice. Basic and clinical research has provided a clearer picture of the efficacy and fallibility of LDLT. We can now be more accurate in defining and interpreting the applicability of LDLT for a wider spectrum of disease indications. / published_or_final_version / Medicine / Master / Doctor of Medicine