Tenofovir alafenamide: An initial experience at Groote Schuur Hospital, Cape Town, South Africa

BACKGROUND

Hepatitis B virus (HBV) remains endemic in South Africa (SA), with a concomitantly high prevalence of HIV co-infection. Chronic kidney disease in these subpopulations also has a high prevalence. Tenofovir is an important component of management, but the associated risk of nephrotoxicity makes dosing a challenge in patients with impaired kidney function. A new formulation, tenofovir alafenamide fumarate (TAF), with a more favourable renal toxicity profile, is now available.

OBJECTIVES

To evaluate our initial experience of TAF use at Groote Schuur Hospital, Cape Town.

METHODS

We retrospectively reviewed patients with HBV mono-infection and HIV-HBV co-infection who were initiated on TAF since 2018. We recorded all relevant demographic, serological, virological and biochemical data from patient records. Adherence was documented by pill collection at the pharmacy.

RESULTS

A total of 26 patients were included in the evaluation, median (interquartile range (IQR)) age 48 (39 - 51) years, 73% (n=19) male, 27% (n=7) hepatitis B e-antigen-positive, and 46% (n=12) HIV co-infected. The median (IQR) duration of treatment with TAF was 13 (9 - 15) months. The median (IQR) baseline creatinine level was 180 (130 - 227) µmol/L, with significant improvement at 12 months, 122 (94 - 143) µmol/L; p=0.017. Reflecting this change, the estimated glomerular filtration rate improved significantly from baseline to month 12 (42 (25 - 52) and 51 (48 - 68) mL/min/1.73 m2, respectively; p=0.023). Similarly, serum alanine aminotransferase (ALT) normalised from a baseline of 33 (18 - 52) to 18 (15 - 24) U/L at month 12 (p=0.012). HBV DNA viral load also declined, from a baseline of log10 4.04 (2.5 - 7.8) IU/mL to a median of <log10 1.3 IU/mL at month 12. HIV viral load was less than the lower level of quantification at months 6 and 12.

CONCLUSIONS

TAF was well tolerated, with stable and significantly improving kidney function throughout a 12-month follow-up period. Serum ALT normalised, mirrored by declining HBV viral load. HIV viral load remained undetectable at 6 and 12 months.

Why is there a paucity of clinical trials in Africa?

Disproportionately few clinical trials are undertaken on the African continent, in part due to lingering neocolonial attitudes in the Global North which keep research activity primarily in developing countries, while being skeptical of the abilities of those in the Global South to undertake organized clinical studies. In the era of the COVID-19 pandemic, applicable research and clinical trials should be undertaken in relevant populations in order to extrapolate to a population level. This is all the more important in Africa, which has a rich genetic diversity. We suggest that a lack of organized research ethics committees across the continent and a deficiency of appropriate training are responsible in part for the reluctance of clinical trial organizers in the developed countries of the Global North to engage with medical leadership in Africa. We consider ways of alleviating this problem, including suggesting a pan-continental surveillance of ethics committee agendas and of training, either through the auspices of the African Union or the World Health Organization. In addition, medical leadership in African nations must be encouraged to take ownership of their medical ethics agendas to facilitate decent international clinical trial participation for the good of the continent as a whole.

COVID-19 and the liver: A 2021 update

In December 2019, a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in Wuhan, China and has since resulted in a global pandemic in excess of 165 million reported infections and 3.4 million attributable deaths. COVID-19 is primarily a respiratory illness, which may be complicated by pneumonia and acute respiratory distress syndrome. SARS-CoV-2 is also responsible for numerous extrapulmonary manifestations involving the haematologic, cardiovascular, renal, gastrointestinal and hepatobiliary, endocrinologic, neurologic, ophthalmologic and dermatologic systems. This review will discuss the pathophysiology of COVID-19; focusing on the mechanisms and outcomes of liver injury associated with COVID-19; its impact on chronic liver disease (CLD); management of CLD during the COVID-19 pandemic and the long-term impact of COVID-19 on CLD.

Efficacy and safety of glecaprevir/pibrentasvir in patients with HCV genotype 5/6: An integrated analysis of phase 2/3 studies

BACKGROUND & AIMS

Hepatitis C virus (HCV) has high genetic diversity with six major genotypes (GT) GT1-6 and global distribution. HCV GT5 and 6 are rare with < 10 million people infected worldwide. Data on direct-acting antiviral use in these rare HCV genotypes are limited. The study aimed to evaluate the efficacy and safety of glecaprevir/pibrentasvir (G/P) in a pooled analysis of phase 2/3 trials in HCV GT5 or 6-infected patients without cirrhosis or with compensated cirrhosis.

METHODS

Patients with chronic HCV GT5 or 6 infection received oral G/P (300 mg/120 mg) once daily for 8 or 12 weeks. The primary efficacy endpoint was sustained virological response at post-treatment week 12 (SVR12) in the intention-to-treat population.

RESULTS

One hundred eighty-one patients were evaluated; 56 with HCV GT5 and 125 with HCV GT6. The majority were treatment-naïve (88%) and non-cirrhotic (85%). Overall SVR12 rate with 8- or 12-week G/P treatment was 98% (178/181). Eight-week treatment with G/P yielded SVR12 rates of 95% (21/22) in HCV GT5- and 99% (69/70) in HCV GT6-infected non-cirrhotic patients. Eight- and 12-week treatment of patients with compensated cirrhosis achieved SVR12 rates of 100% (10/10) and 94% (17/18) respectively. The G/P regimen was well-tolerated; 3% (6/181) Grade 3 or higher adverse events, and no serious adverse events were attributed to G/P or led to study drug discontinuation.

CONCLUSIONS

This integrated dataset demonstrates a high SVR12 rate following 8-week G/P treatment in patients with HCV GT5 (96%) or GT6 (99%) infection without cirrhosis or with compensated cirrhosis.

Innovative strategies for the elimination of viral hepatitis at a national level: A country case series

Viral hepatitis is a leading cause of morbidity and mortality worldwide, but has long been neglected by national and international policymakers. Recent modelling studies suggest that investing in the global elimination of viral hepatitis is feasible and cost-effective. In 2016, all 194 member states of the World Health Organization endorsed the goal to eliminate viral hepatitis as a public health threat by 2030, but complex systemic and social realities hamper implementation efforts. This paper presents eight case studies from a diverse range of countries that have invested in responses to viral hepatitis and adopted innovative approaches to tackle their respective epidemics. Based on an investment framework developed to build a global investment case for the elimination of viral hepatitis by 2030, national activities and key enablers are highlighted that showcase the feasibility and impact of concerted hepatitis responses across a range of settings, with different levels of available resources and infrastructural development. These case studies demonstrate the utility of taking a multipronged, public health approach to: (a) evidence-gathering and planning; (b) implementation; and (c) integration of viral hepatitis services into the Agenda for Sustainable Development. They provide models for planning, investment and implementation strategies for other countries facing similar challenges and resource constraints.

Detection of in vivo hepatitis B virus surface antigen mutations-A comparison of four routine screening assays

An important requirement for a state-of-the-art hepatitis B surface antigen (HBsAg) screening assay is reliable detection of mutated HBsAg. Currently, there is a striking shortage of data regarding the detection rates of in vivo HBsAg mutations for these clinically important assays. Therefore, we compared the detection rates of four commercial HBsAg screening assays using a global cohort of 1553 patients from four continents with known HBV genotypes. These samples, which represent the broadest spectrum of known and novel HBsAg major hydrophilic region (MHR) mutations to date, were analyzed for the presence of HBsAg using the Roche Elecsys^® HBsAg II Qualitative, Siemens ADVIA Centaur XP HBsAg II, Abbott Architect HBsAg Qualitative II and DiaSorin Liaison^® HBsAg Qualitative assays, respectively. Of the 1553 samples, 1391 samples could be sequenced; of these, 1013 (72.8%) carried at least one of the 345 currently known amino acid substitutions (distinct HBsAg mutation) in the HBsAg MHR. All 1553 patient samples were positive for HBsAg using the Elecsys^® HBsAg II Qual assay, with a sensitivity (95% confidence interval) of 99.94% (99.64%-100%), followed by the Abbott Architect 99.81% (99.44%-99.96%), Siemens ADVIA 99.81% (99.44%-99.96%) and DiaSorin Liaison^® 99.36% (98.82%-99.69%) assays, respectively. Our results indicate that the Elecsys^® HBsAg II Qual assay exhibits the highest sensitivity among the commercial HBsAg screening assays, and demonstrate that its capacity to detect HBV infection is not compromised by HBsAg MHR mutants.

Strategies to manage hepatitis C virus (HCV) infection disease burden - volume 2

The hepatitis C virus (HCV) epidemic was forecasted through 2030 for 15 countries, and the relative impact of two scenarios was considered: (i) increased treatment efficacy while holding the treated population constant and (ii) increased treatment efficacy and increased annual treated population. Increasing levels of diagnosis and treatment, in combination with improved treatment efficacy, were critical for achieving substantial reductions in disease burden. In most countries, the annual treated population had to increase several fold to achieve the largest reductions in HCV-related morbidity and mortality. This suggests that increased capacity for screening and treatment will be critical in many countries. Birth cohort screening is a helpful tool for maximizing resources. In most of the studied countries, the majority of patients were born between 1945 and 1985.

The present and future disease burden of hepatitis C virus (HCV) infections with today's treatment paradigm - volume 2

Morbidity and mortality attributable to chronic hepatitis C virus (HCV) infection are increasing in many countries as the infected population ages. Models were developed for 15 countries to quantify and characterize the viremic population, as well as estimate the number of new infections and HCV related deaths from 2013 to 2030. Expert consensus was used to determine current treatment levels and outcomes in each country. In most countries, viremic prevalence has already peaked. In every country studied, prevalence begins to decline before 2030, when current treatment levels were held constant. In contrast, cases of advanced liver disease and liver related deaths will continue to increase through 2030 in most countries. The current treatment paradigm is inadequate if large reductions in HCV related morbidity and mortality are to be achieved.

Historical epidemiology of hepatitis C virus (HCV) in select countries - volume 2

Chronic hepatitis C virus (HCV) infection is a leading cause of liver related morbidity and mortality. In many countries, there is a lack of comprehensive epidemiological data that are crucial in implementing disease control measures as new treatment options become available. Published literature, unpublished data and expert consensus were used to determine key parameters, including prevalence, viremia, genotype and the number of patients diagnosed and treated. In this study of 15 countries, viremic prevalence ranged from 0.13% in the Netherlands to 2.91% in Russia. The largest viremic populations were in India (8 666 000 cases) and Russia (4 162 000 cases). In most countries, males had a higher rate of infections, likely due to higher rates of injection drug use (IDU). Estimates characterizing the infected population are critical to focus screening and treatment efforts as new therapeutic options become available.

Effect of liver regeneration on the pharmacokinetics of immunosuppressive drugs

In liver transplantation the graft has been known to undergo regeneration, which is associated with down-regulation of the cytochrome P450 system. The latter is involved in the metabolism of several immunosuppressive drugs. The aim of this study was to investigate the effect of liver regeneration on the pharmacokinetics (PK) of cyclosporine, rapamycin, and tacrolimus. Rats were subjected to either partial hepatectomy (PH) or sham operation (SH). Cyclosporine, rapamycin, and tacrolimus PK studies were performed at 0, 24, and 96 hours postoperatively. The areas under the curve (AUC), trough levels, and maximum concentrations (Cmax) for cyclosporine and tacrolimus were numerically higher in the animals subjected to PH. The PK studies of rapamycin were not affected by PH. These studies indicated that cyclosporine and tacrolimus metabolism may be inhibited during liver regeneration.

Effect of rapamycin on the healing of the bile duct

Besides its potent immunosuppressive properties, rapamycin also has antitumor and antifungal effects. Rapamycin also inhibits the proliferation of fibroblasts and therefore may impair the healing of various tissues. We investigated the effect of rapamycin on the healing of the bile duct anastomosis. The study was undertaken in pigs that were subjected to a laparotomy under general anesthesia. The bile duct was mobilized and divided and immediately reanastomosed. The animals were randomly allocated to receive either rapamycin or placebo. The animals were sacrificed on the postoperative day 5, then the biliary anastomosis was excised and used to determine the tensile strength, hydroxyproline levels, and the histological changes. The tensile strength and the hydroxyproline levels in the biliary anastomosis were lower in the animals treated with rapamycin. The liver function tests were normal. These studies show that rapamycin may impair the healing of the biliary anastomosis.

Restoration of liver mass after partial hepatectomy--implications for living donor liver transplantation

In living donor liver transplantation, the recipient liver undergoes more rapid regeneration than the remnant liver in the donor. In this study we investigated the factors which may be responsible for the difference in the regenerative response between the donor and the recipient. Long Evans rats were subjected to either partial hepatectomy (PH) or sham operation (SH) and were treated with liver cytosol (C) and cyclosporine (Cy). The rats were sacrificed at 24, 48, 72 and 96 hours and 1 and 2 weeks postoperatively. The livers were removed to determine the liver weight/body weight (LW/BW) ratio and the mitotic index. The mitotic index, serum aspartate transferase (AST) and serum alanine transferase (ALT), although unchanged in the SH groups, were increased in the rats treated with PH + C + Cy, and were greater than after PH only. However LW/BW ratios increased after PH but had returned to preoperative levels by 2 weeks. The changes in LW/BW ratio were not modified by the cytosol or cyclosporine.

The Effect of Rapamycin on the Healing of the Ureteric Anastomosis and Wound Healing

Rapamycin is a potent immunosuppressive agent that also inhibits fibroblastic activity and therefore may affect the healing of various tissues. The aim of this study was to investigate the effect of rapamycin on wound healing and the healing of the ureteric anastomosis. Large White/Landrace pigs were subjected to a laparotomy and division and immediate anastomosis of the ureter. The animals were randomly allocated to receive either rapamycin or placebo. The animals were sacrificed on postoperative day 5, and strips of the skin and fascia closure and the ureteric anastomosis excised and used to determine the tensile strength, hydroxyproline levels, and histological changes. The tensile strength and the hydroxyproline levels in the ureter and fascia were lower in the rapamycin-treated animals. There was no difference in the tensile strength in the skin, although the hydroxyproline levels were lower. This study shows that healing of the ureteric anastomosis and fascia and skin closure may be impaired by rapamycin.

Decreasing blood product requirements after orthotopic liver transplantation

OBJECTIVES

To document the changing blood product transfusion requirements over time during the first 50 orthotopic liver transplantation (OLT) operations performed at Groote Schuur Hospital.

DESIGN

The first 50 OLT operations were divided into three groups chronologically and blood transfusion requirements were compared across the three groups.

SETTING

Groote Schuur Hospital, Cape Town.

SUBJECTS

Forty-seven patients undergoing 50 OLT operations between October 1988 and September 1999. The majority of patients had end-stage chronic liver disease. Patients were divided chronologically into three groups of 16, 17 and 17 patients.

OUTCOME MEASURES

The number of units of blood products transfused in each group was quantified.

RESULTS

During the study period there was a significant decrease in the number of units of packed red cells, fresh frozen plasma (FFP) and platelets (but not cryoprecipitate) transfused intraoperatively. The median number of units of packed cells decreased from 13.5 in our first 16 patients (group 1) to 5.0 in our last 17 (group 3). The median number of units of platelets transfused was 9 in group 1 and 0 in groups 2 and 3. No platelets were transfused in our last 22 patients. The average cost of blood products transfused intraoperatively per patient in the three groups decreased from R13 034 in group 1 to R11 389 in group 2 to R7 396 in group 3.

CONCLUSION

The number of units of blood products transfused during OLT operations has decreased since the programme started 13 years ago. The reasons include increased experience, the use of aprotinin to block fibrinolysis and the selective use of the thromboelastogram to monitor coagulation intraoperatively. OLT need no longer be regarded as wasteful of blood resources. Use of platelets to treat thrombocytopenia need not be empirical.

Liver transplantation in children--the Red Cross War Memorial Children's Hospital experience

Liver transplantation for infants and children has been available in South Africa for more than a decade. Current concerns have shifted from an initial target of early post-transplant survival to quality of life in the long term. Since 1985, 175 infants and children have been assessed, with 104 accepted for transplantation. Fifty have had orthotopic liver transplants (OLTx), 48 (3 retransplants) in Cape Town and 2 abroad. Biliary atresia was the most frequent diagnosis (52%) followed by acute liver failure (ALF) (16%). Waiting list mortality has remained high (15%), particularly for the ALF group (50%). Thirty-four patients survive 1 month--14 years post-transplant. Early post OLTx mortality was low (7%) but late morbidity and mortality (23%) were mainly due to viral infection: de novo hepatitis B (5 patients, 2 deaths), EBV-related post-transplantation lymphoproliferative disease (PTLPD) (6 patients, 4 deaths) and CMV disease (9 patients, 4 deaths). Tuberculosis prophylaxis, required in 6 cases, resulted in major morbidity in 1. Hypertension requiring medication along with some compromise of renal function has been present in all but 2 patients. However, all those of school-going age (20) attend school normally and remain in good health and only 3 of the survivors have abnormal liver function tests. Successful liver transplantation is possible in a developing country with limited resources. Scarcity of virus-free donors (HBV and HIV) leading to waiting list mortality and infrequent retransplantation along with long-term consequences of immunosuppression (infection, lymphoma and renal toxicity) remain problems.

History of liver transplantation at the University of Cape Town and Groote Schuur Hospital

The liver transplant programme at Groote Schuur Hospital was born out of a rich history of experimental liver transplantation and an active liver clinic. Professor John Terblanche has played a key role in the initiation and success of the programme. In the first 10 years since October 1988, 41 adults have undergone liver transplantation. The cumulative graft survival rates at 1 and 5 years were 74% and 62% respectively.

Ten years of liver transplantation at Groote Schuur Hospital

INTRODUCTION

Liver transplantation has evolved from an experimental procedure to being the treatment of choice for many patients with end-stage liver disease, and is performed on a routine basis in most major centres throughout the world. However, certain situations peculiar to developing countries have a major impact on liver transplant programmes in these countries. We present the results of the liver transplant programme in Cape Town.

PATIENTS AND METHODS

All patients undergoing orthotopic liver transplantation at Groote Schuur Hospital and Red Cross War Memorial Children's Hospital were included in this report. Standard surgical techniques were used for procuring the donor liver, the recipient hepatectomy and the subsequent implantation of the liver. All patients received standardised peri-operative management; in particular, the immunosuppressive protocol consisted of cyclosporin, steroids and azathioprine. Since October 1988, 83 patients have undergone 89 orthotopic liver transplants. There were 44 adults and 39 children, the age range being from 6 months to 56 years. The commonest indications for hepatic transplantation in adults included cryptogenic cirrhosis, auto-immune hepatitis and primary sclerosing cholangitis. In children biliary atresia was the commonest cause of liver failure.

RESULTS

Of the 81 patients transplanted, 50 are alive and well with follow-up ranging from 2 months to 9.5 years. The cumulative graft survival rate was 72% at 1 year and 61% at 5 years. Six patients have undergone re-transplantation and 4 patients have had combined liver/kidney transplants. De novo hepatitis due to hepatitis B virus (HBV) has occurred in 8 patients following transplantation. Subsequent investigation has shown that 5 of the donors of these livers were hepatitis B core antibody (HBcAb)-positive, while information on the remaining 3 was not available. Tuberculosis (TB) has been a significant problem in 4 patients, with 2 deaths precipitated by anti-TB drug-induced hepatitis. Post-transplant lymphoproliferative disorder was also responsible for significant postoperative morbidity.

CONCLUSION

Orthotopic liver transplantation has been established at Groote Schuur Hospital as the treatment of choice for selected patients with chronic end-stage liver disease. However, hepatitis B and TB appear to present a problem. The particularly high prevalence of HBV carrier status in our donor population may necessitate the use of living donors in the future.

A novel high molecular weight fibrinogenase from the venom of Bitis arietans

A fibrinogenase (Ba100) with an apparent molecular mass of 100 kDa under non-reducing conditions and a pI of 5.4 was purified from the venom of the African puff adder (Bitis arietans) by fibrinogen affinity chromatography. Under reducing conditions the protease dissociates into subunits of 21 kDa and 16 kDa. N-Terminal amino acid sequencing showed these two chains to have 66.7% homology and homology to C-type lectins. The fibrinogenase activity of Ba100 cleaves the Aalpha and Bbeta chain of fibrinogen rendering the molecule unable to polymerise into fibrin clots. Ba100 inhibited platelet aggregation in platelet rich plasma, and clot formation in whole blood, in a concentration dependent manner.

The management of biliary complications following orthotopic liver transplantation

OBJECTIVE

Review of the biliary complications following orthotopic liver transplantation (OLT) at our institution, and their management and outcome.

DESIGN

Retrospective study of medical records of 63 patients who underwent 68 transplant operations.

SETTING

The Liver Transplant Unit, Groote Schuur Hospital and Red Cross War Memorial Children's Hospital, Cape Town

PATIENTS

Six patients treated for 9 biliary complications.

INTERVENTIONS

Reoperation with biliary reconstruction, or non-operative measures by either endoscopic retrograde pancreatography (ERCP) or percutaneous transhepatic cholangiography (PTC).

OUTCOME MEASURES

Clinical outcome and survival following treatment for biliary complications.

RESULTS

Biliary complications occurred in 8.8% of patients who underwent transplantation at our institution. These consisted of strictures in 4 patients (with leak in 2), bile leak in 1 patient, and unsuspected primary sclerosing cholangitis (PSC) of the recipient duct in 1 patient. The mean time interval of biliary complications following OLT was 8 weeks (range 3-16). Biliary reconstruction was required in 4 patients while 2 patients were treated by endoscopic stenting. After a mean follow-up period of 30 months (range 1-64), 4 patients remained stable, 1 patient developed progressive stricturing of the intrahepatic ducts requiring repeated PTC dilatations, and 1 patient experienced stent blockages requiring endoscopic stent changes (died of unrelated causes).

CONCLUSIONS

The rate of biliary complications following OLT at our institution compares favourably with literature reports. While biliary reconstruction is usually needed, endoscopic stenting appears effective in selected cases of biliary stricture and leak. PSC should be excluded prior to transplantation in young patients with cryptogenic cirrhosis.

Orthotopic liver transplantation at Groote Schuur Hospital

We present data on 10 patients (5 men and 5 women, aged 21-56 yrs) with end-stage liver disease or tumour who underwent orthotopic liver transplantation at Groote Schuur Hospital between October 1988 and June 1991. Standard surgical techniques were used for procuring the donor liver, the recipient hepatectomy and the implantation of the liver. The venovenous bypass method was used in all but 2 patients. Postoperative immunosuppression was usually achieved with cyclosporin, azathioprine and low-dose steroids. Six patients were treated with prophylactic OKT3. Rejection episodes were treated with bolus doses of intravenous steroids. The indications for liver transplantation included chronic active hepatitis progressing to cirrhosis (5), biliary cirrhosis in association with inflammatory bowel disease (1), sclerosing cholangitis (2), alpha 1-antitrypsin deficiency (1), and tumour (1). All patients with chronic liver disease had experienced at least one complication, examples of which included encephalopathy, bacterial peritonitis, ascites, variceal bleeding and septicaemia. Serious postoperative complications included acute rejection of the transplanted liver, renal and liver failure that responded to intensive care support and medical management. One patient died on the 11th postoperative day with complications of bleeding oesophageal ulcer, shock and fungaemia. The remaining patients are alive and well 1-31 months after transplantation.