Hepatitis B Virus Screening Before Cancer Chemotherapy in Taiwan: A Nationwide Population-Based Study

Background: Reactivation of the hepatitis B virus (HBV) during cancer chemotherapy is a severe and sometimes fatal complication. In 2009, the National Health Insurance (NHI) in Taiwan recommended and reimbursed screening for HBV infection and prophylactic antiviral therapy before cancer chemotherapy. In this study, we determined the HBV screening rate in patients with cancer undergoing chemotherapy in Taiwan.Methods: We retrospectively collected data from the National Health Insurance Research Database on patients who received systemic chemotherapy for solid or hematologic cancers from January 2000 through December 2012. We defined HBV screening based on testing for serum HBsAg within 2 years of the first chemotherapy commencement. We calculated overall and annual HBV screening rates in all patients and subgroups of age, gender, cancer type, hospital level, physician's department, and implementation of NHI reimbursement for HBV screening before cancer chemotherapy.Results: We enrolled 379,639 patients. The overall HBV screening rate was 45.9%. The screening rates were higher in males, those with hematological cancer, those at non-medical centers and medical departments. The HBV screening rates before (2000–2008) and after the implementation of NHI reimbursement (2009–2012) were 38.1 and 57.5%, respectively (p < 0.0001). The most common practice pattern of HBV screening was only HBsAg (64.6%) followed by HBsAg/HBsAb (22.1%), and HBsAg/HBcAb/HBsAb (0.7%) (p < 0.0001). The annual HBV screening rate increased from 31.5 to 66.3% (p < 0.0001). The screening rates of solid and hematological cancers significantly increased by year; however, the trend was greater in solid cancer than in hematological cancer (35.9 and 26.2%, p < 0.0001).Conclusions: The HBV screening rate before cancer chemotherapy was fair but increased over time. These figures improved after implementing a government-based strategy; however, a mandatory hospital-based strategy might improve awareness of HBV screening and starting prophylactic antiviral therapy before cancer chemotherapy.

Prophylactic Antiviral Therapy in Low-Risk Patients infected with the Hepatitis B Virus with Solid Tumors

IntroductionThis study aimed to evaluate the prophylactic antiviral therapy in low-risk patients with the Hepatitis B Virus (HBV) infections during chemotherapy.Material and methodsFrom January 2011 to March 2018, HBsAg-positive patients were analyzed in this retrospective study. The HBV reactivation, related hepatitis, chemotherapy delay, and fulminant hepatic failure in low-risk patients between the prophylactic anti-HBV therapy (prophylaxis group) and the non-prophylactic anti-HBV therapy group (control group) were compared.ResultsThere were 68 patients in the prophylaxis group and 102 patients in the control group. The rusult showed that the HBV reactivation was not significantly different between the prophylaxis group and the control group (P=0.741). Three and 5 patients with HBV-related hepatitis were detected in the prophylaxis and control groups, respectively. Moreover, 2 and 4 patients with HBV activation-related chemotherapy delay were detected in the two groups, respectively, without any significant difference (P>0.05). Multivariate analysis showed that HBV DNA titer was associated with HBV reactivation in low-risk patients (P=0.001).ConclusionsProphylactic antiviral therapy might not reduce the HBV reactivation of low-risk solid malignancies (non-HCC, non-hematological lymphatic cancer, and HBV DNA titer <100 IU/ml). For low-risk patients, monitoring the HBV DNA titers and liver function tests in the follow-up observations might be an optimal and cost-effective strategy.

Success of prophylactic antiviral therapy for SARS-CoV-2: Predicted critical efficacies and impact of different drug-specific mechanisms of action

Repurposed drugs that are safe and immediately available constitute a first line of defense against new viral infections. Despite limited antiviral activity against SARS-CoV-2, several drugs are being tested as medication or as prophylaxis to prevent infection. Using a stochastic model of early phase infection, we evaluate the success of prophylactic treatment with different drug types to prevent viral infection. We find that there exists a critical efficacy that a treatment must reach in order to block viral establishment. Treatment by a combination of drugs reduces the critical efficacy, most effectively by the combination of a drug blocking viral entry into cells and a drug increasing viral clearance. Below the critical efficacy, the risk of infection can nonetheless be reduced. Drugs blocking viral entry into cells or enhancing viral clearance reduce the risk of infection more than drugs that reduce viral production in infected cells. The larger the initial inoculum of infectious virus, the less likely is prevention of an infection. In our model, we find that as long as the viral inoculum is smaller than 10 infectious virus particles, viral infection can be prevented almost certainly with drugs of 90% efficacy (or more). Even when a viral infection cannot be prevented, antivirals delay the time to detectable viral loads. The largest delay of viral infection is achieved by drugs reducing viral production in infected cells. A delay of virus infection flattens the within-host viral dynamic curve, possibly reducing transmission and symptom severity. Thus, antiviral prophylaxis, even with reduced efficacy, could be efficiently used to prevent or alleviate infection in people at high risk.

Management of Hepatitis B Virus in Allogeneic Hematopoietic Stem Cell Transplantation

The high morbidity of HBV reactivation following allogeneic hematopoietic stem cell transplantation (allo-HSCT) is partially due to the intense immunologic potency of complex therapeutic regimens, the use of antithymocyte globulin and calcineurin inhibitors to prevent graft versus-host disease (GVHD), prolonged immune reconstitution, and hematological malignancies infected with hepatitis B virus (HBV). Immunosuppression results in the reactivation of HBV replication from covalently closed circular DNA (cccDNA) residing in hepatocytes. However, the role of viral mutations during HBV reactivation needs to be validated. All individuals scheduled to receive allo-HSCT or wish to donate stem cells should be screened for hepatitis B surface antigen (HBsAg), antibodies to hepatitis B core (anti-HBc), and HBV-DNA. HBsAg-positive recipients of allo-HSCT have a high risk of HBV reactivation; thus, they should receive prophylactic antiviral therapy. The high barrier to resistance nucleos(t)-ide analogs (NAs) seems to be superior to the low barrier agents. Resolved-HBV recipients have a lower risk of HBV reactivation than HBsAg-positive recipients. Although prophylactic antiviral therapy remains controversial, regular monitoring of alanine transaminase (ALT) and HBV-DNA combined with preemptive antiviral treatment may be an optimized strategy. However, optimal antiviral therapy duration and time intervals for monitoring remain to be established. Accepting stem cells from HBsAg-positive donors is associated with a risk of developing HBV-related hepatitis. The overall intervention strategy, including donors and recipients, may decrease the risk of HBV-related hepatitis following HSCT from HBsAg positive stem cells. In this review, we summarize the issues of HBV in allo-HSCT, including HBV reactivation mechanism, HBsAg-positive recipients, HBV-resolved infection recipients, and donor-related factors, and discuss their significance.

Predicted success of prophylactic antiviral therapy to block or delay SARS-CoV-2 infection depends on the targeted mechanism

Repurposed drugs that are immediately available and have a good safety profile constitute a first line of defense against new viral infections. Despite a limited antiviral activity against SARS-CoV-2, several drugs serve as candidates for application, not only in infected individuals but also as prophylaxis to prevent infection establishment. Here we use a stochastic model to describe the early phase of a viral infection. We find that the critical efficacy needed to block viral establishment is typically above 80%. This value can be improved by combination therapy. Below the critical efficacy, establishment can still sometimes be prevented; for that purpose, drugs blocking viral entry into target cells (or equivalently enhancing viral clearance) are more effective than drugs reducing viral production or enhancing infected cell death. When a viral infection cannot be prevented because of high exposure or low drug efficacy, antivirals can still delay the time to reach detectable viral loads from 4 days when untreated to up to 30 days. This delay flattens the within-host viral dynamic curve, and possibly reduces transmission and symptom severity. These results suggest that antiviral prophylaxis, even with reduced efficacy, could be efficiently used to prevent or alleviate infection in people at high risk. It could thus be an important component of the strategy to combat the SARS-CoV-2 pandemic in the months or years to come.

Pharmacotherapy-Induced Hepatitis B Reactivation Among Patients With Prior Functional Cure: A Systematic Review

Objective: To describe and quantify the incidence and morbidity of hepatitis B reactivation (HBVr) secondary to pharmaceutical agents (eg, rituximab, tumor necrosis factor inhibitors, direct-acting antivirals [DAAs] for hepatitis C) among patients with previously resolved hepatitis B infection. Data Sources: The MEDLINE database was searched from inception through July 2018 using the terms hepatitis B + ( reactivation OR [drug or drug class linked to HBVr]). Study Selection and Data Extraction: Relevant English-language cohort studies or randomized trials quantifying the incidence of HBVr secondary to pharmacotherapy among patients negative for hepatitis B surface antigen and DNA and positive for hepatitis B core antibody were included. Data Synthesis: Among 2045 articles, 102 met inclusion criteria. Receipt of rituximab was associated with the highest risk of HBVr (for oncological indication: 6.2% rate [225/3601 patients]) and subsequent hepatitis (up to 52.4% of all HBVr cases). Biologic agents for autoimmune disease were uncommonly associated with HBVr (2.4%, 56/2338), with only 4 cases of hepatitis, all attributable to rituximab. Reactivation caused by DAAs was rare (0.3%, 28/8398), with no cases of hepatitis. Relevance to Patient Care/Clinical Practice: This review compares and contrasts the incidence and clinical relevance of HBVr for various pharmacotherapies among patients with functionally cured hepatitis B, with discussion of appropriate risk mitigation strategies. Conclusions: Among patients with prior functional cure of hepatitis B, prophylactic antiviral therapy is recommended with rituximab administration irrespective of indication because of a high risk for HBVr-associated morbidity. Enhanced monitoring alone is reasonable for patients receiving nonrituximab biologics or DAAs.