HBV screening, best practice advisories, and HBV vaccination
Screening for both HBV reactivation and HBV risk factors is the first step in preventing reactivation in patients undergoing therapy for NHL.28,30,53 Organizational policies on screening have significantly increased screening rates over the last 6 years from 20% to 90% at large oncology centers in the US.24,28 Policies on screening modalities are also gradually shifting from a targeted approach to a universal approach.
A targeted screening approach for patients undergoing chemo-immunotherapy on the basis of HBV risk status is limited since chronic hepatitis may be asymptomatic, and sufficient information may not be elicited during initial patient encounters to adequately assess the risk of HBV infection.54,55 On the other hand, universal HBV screening for all patients newly diagnosed with cancer who require chemo-immunosuppressive therapy results in a more direct reduction in reactivation rates.24 In the US, hospital-enforced universal screening policies in some large cancer treatment centers provide evidence that increasing pre-therapy screening and prophylaxis for HBV can result in zero-to-minimal cases of HBV reactivation.28,53 Currently, the National Comprehensive Cancer Network (NCCN) recommends that all patients receiving an anti-CD20 antibody should be screened for HBV prior to exposure to the agent.56 Screening should be for both HBsAg and anti-HBc since HBV DNA undetected in serum can persist in tissues11,56,57 and the antigen may be absent in indolent cases of HBV.58 Patients who are found to be positive for either should be considered for HBV prophylaxis prior to chemo-immunosuppressive therapy.
According to clinical opinion in the oncologic literature, there is clear consensus on adopting screening to identify patients who are at high risk of HBV and also candidates for anti-CD20 monoclonal antibody. There are differences in opinion regarding the necessity to screen all patients who will receive chemotherapy irrespective of HBV risk status. Guidelines from the American Gastroenterological Association (AGA),26 the European Association for the Study of Liver Disease (EASL),59 the American Society of Clinical Oncology (ASCO),53 and the Asian-Pacific Association for the Study of the Liver (APASL)60 recommend that low and high risk patients receiving chemotherapy or immunotherapy should be considered for testing and prophylaxis. On the other hand, the NCCN57 and the American Association for the Study of Liver Diseases (AASLD)61 suggested excluding from screening, patients with low risk of HBV and candidates for cancer therapy associated with low risk of reactivation, because supporting evidence was insufficient. A tenable explanation for the disparity in screening approach may be consideration given to patients from regions with high HBV prevalence. At this time, clinicians should determine if screening for HBV is needed in each individual patient receiving chemotherapy. In the future, we hope that better data are available to help allocate resources for patients in need of HBV screening prior to chemotherapy.53
Improved coordination of primary care and specialist healthcare professional services is required to screen promptly all patients at risk of HBV infection irrespective of negative cancer status. Screening prescription by healthcare professionals to patients, prior to immunosuppressive therapy still needs to be enhanced.54,55,62 Improved screening rates to prevent HBV reactivation can be achieved with improved data management and alert systems integrated into existing electronic medical records.55,63 Between 2012 and 2013, a cancer center study showed the role of a best practice advisory (alert system) incorporated in the computerized physician order entry (CPOE) application in increasing HBV screening rates prior to therapy. At the end of the program, the study reported an improved screening rate for patients treated with biologic agents from < 50% to > 85%.63 Since prior HBV infection prior HBV infection is a baseline risk factor for HBV reactivation, prevention efforts need to maintain a clear distinction between identifying risk factors for HBV reactivation and for HBV infection.28,36 Notable risk factors for HBV infection include groups such as healthcare workers, injecting drug users, recipients of blood products or dialysis, household contacts of people with chronic HBV infection, incarcerated persons, people with multiple sex partners, men who have sex with men, and unvaccinated or partially vaccinated travelers to high endemic regions.36 Low and intermediate endemic countries require catch-up immunization targeted at these high risk groups. In addition, programs that mandate HBV vaccination for entry into schools, colleges, and work-places remain an effective strategy to reduce HBV infection in low-intermediate endemic regions.36
The Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control (CDC) recommends universal vaccination of individuals, especially male adults, who test positive, since the risk of hepatitis B remains highest in this group.36 This recommendation is important because adult males have a higher incidence of NHL compared to women of the same age group.8,9,64 For children, universal vaccination at childbirth with follow-up remains appropriate for high endemic (>8%) regions. On a global scale, newborns who received a birth dose of HBV vaccine increased from 27% to 38% between 2006 and 2014. Birth cohorts who received three doses in 2008 and 2014 increased from 69% to 82%. Although these data indicate that HBV vaccination rates are rising, there is still room for improvement in high endemic areas.1,65 Since the last two decades, the CDC has recommended routine post-vaccination tests for anti-HBs and annual booster doses for sustained immunity among high risk groups and immunocompromised persons.66 Therefore, targeted and universal vaccination efforts should not wane, because the risk of exposure to HBV continues to persist.
Reactivation prophylaxis and therapy
HBV seropositive individuals who require chemotherapy or anti-CD20 antibody therapy should be started on antivirals in a timely manner. Globally, lamivudine has been the most utilized nucleos(t)ide analogue for the prevention of HBV reactivation during chemo-immunotherapy.33,67–70 Prognosis of patients with lamivudine following HBV reactivation remains favorable, despite few cases of viral resistance.71 Newer nucleos(t)ide are now favored in reactivation management.71–75 Newer nucleos(t)ide analogues, such as entecavir, adefovir, and tenofovir, have been used because of their lower viral resistance.27,57 In a notable study, Li and others compared entecavir with lamivudine as prophylaxis for hepatitis B reactivation in lymphoma patients undergoing chemotherapy. The entecavir group exhibited a significantly lower rate of HBV reactivation (0% vs 12.4%, p = 0.024) and a lower incidence of aborted chemotherapy compared to the lamivudine group (5.9 vs 20.2%, p = 0.042).74
The stage of NHL disease is a useful criterion when considering use of nucleos(t)ide analogues. Studies have shown that the efficacy of entecavir is higher than that of lamivudine, especially in advanced disease.72,76 In advanced diffuse large B-cell lymphoma (DLBCL), Huang and colleagues compared entecavir and lamivudine and demonstrated that there was a lower reactivation rate (6.6% vs 30%; difference, 23.4% [95% CI, 10.2% to 36.6%]; p = .001) and premature chemotherapy cessation (1.6% vs 18.3%; difference, 16.7% [95% CI, 6.4% to 27.0%]; p = .002) with entecavir compared to lamivudine.72 Importantly, despite the lower risk of viral resistance with tenofovir, adefovir, and entecavir compared to lamivudine,77 these newer agents on rare occasions were associated with mild renal dysfunction with long-term use.20,78,79 Therefore, dosage of these agents needs to be adjusted in renal impairment, and renal function should be assessed at least every 3 months.57,79
Another study that explored steroid-free chemotherapy in the prevention of HBV reactivation in NHL reported a lower incidence and severity of reactivation when compared to steroid-containing chemotherapy.80 Despite the overall survival rate, which was higher in the steroid-containing group, a limitation of this approach may be deciding between survival following rituximab-containing therapy and the risk of HBV reactivation. Finally, more studies are needed to understand the efficacy of antivirals when both rituximab and steroids are used.81
Therapeutic intervention for HBV reactivation in aggressive lymphomas/NHL is indicated in instances such as missed HBV status and failed or interrupted prophylactic therapy.27,82–84 Failure of prophylactic lamivudine may result in withdrawal hepatitis, viral breakthrough, or mortality from liver failure.85,86 Predictors of lamivudine failure in a study include: elevated baseline HDV DNA titer (≥ 2,000 IU/mL) (hazard ratio [HR], 9.94; p = 0.0063) and the use of rituximab (HR, 3.19; p = 0.027) for viral breakthrough, while for withdrawal hepatitis, a high baseline HBV DNA titer (HR, 5.90; p = 0.007), liver cirrhosis (HR, 10.4; p = 0.002), and distant metastasis (HR, 5.14; P = 0.008) were independent risk factors.86 Therapeutic interventions also depend on the presence of secondary liver failure and prognosis of the lymphoma. Newer antivirals may be used where liver failure is absent.27,75 For patients with HBV reactivation resulting in liver failure, the AGA recommends liver transplantation.26,75 Favorable outcomes were recorded in patients who underwent liver transplantation and antiviral therapy, having established prior complete remission of disease and a favorable prognosis of the lymphoma type.75,87
Based on better outcomes from recent data, recent ASCO and NCCN guidelines on HBV reactivation recommend, when possible, that patients who are HBV positive (HBsAg-positive and/or anti-HBc positive) and require chemo-immunotherapy should be placed on prophylaxis with entecavir for the duration of treatment.53,61 Other agents, including tenofovir and lamivuidine, can also be used, but there may be more resistance to lamivudine therapy. Newer antiviral medications are readily favored considering the relatively high barrier to viral resistance compared to lamivudine for both prophylactic and therapeutic purposes. The literature suggests that prophylaxis against rituximab associated HBV-reactivation should be extended up to 12 months following oncologic therapy and should be combined with HBV viral load surveillance every 3 months.30,53,57 Although NCCN warns against lamivudine as a routine prophylactic agent due to risk of viral resistance, AASLD, EASL, ASIF, and APASL recommend lamivudine as a viable prophylactic agent based on its pharmaco-economic and safety profiles.59–61,88 Specifically, the AASLD endorses lamivudine when the planned duration of chemotherapy is less than 12 months and entecavir or tenofovir for chemotherapy lasting beyond 12 months.20,61,89 In addition, the EASL advocates for use of baseline HBV DNA < 2,000 IU/mL for initiating lamivudine while values > 2,000 IU/mL are indications for prescribing entecavir or tenofovir.59 In addition, the APASL and ASIF recommend lamivudine for treatment-naïve patients with evident or impending hepatic derangement.60,88 We urge clinicians to follow HBV seropositive patients closely while using novel agents for NHL, to ensure that reactivation does not occur. Clinicians should also remember to screen patients for HBV who are receiving chemotherapy without rituximab, if they are at high risk for reactivation. If a patient is positive for HBV, then prophylaxis should be initiated. The literature remains unclear at this time whether universal screening for HBV should be done in all patients receiving chemotherapy.
There are groups of patients in whom routine antiviral therapy may not be indicated. These groups include patients who do not meet the criteria for reactivation (the rise in HBV DNA < 10-fold in patients with past or latent infection, ALT level < three times the upper limit of normal), younger patients in the immune-tolerant phase (normal ALT levels despite positive HBsAg and HBV DNA and minimal hepatic inflammation), and patients in the inactive carrier phase. In addition, patients are considered low risk with agents such as low dose corticosteroids or immunosuppressive agents (e.g., azathioprine and 6-mercaptopurine), and may be excluded from routine antiviral prophylaxis. Further research is needed to assess the risk in these patients.30,53,90
Lastly, critical consideration should be given to factors that may impact the potential outcomes of prophylactic and therapeutic interventions for HBV reactivation. These factors include cost of newer antivirals, liver transplant cost, medication adherence, development of mutant HBV, adverse effects of therapy, and a prolonged monitoring period.68,83,84,91 Further studies are needed to better understand these issues. Table 2 provides a summary of the modalities for preventing HBV reactivation.
Table 2.Modalities for preventing HBV reactivation
Reactivation Prevention Modality | Key Characteristics | References |
| Indication/Advantages | Drawbacks | |
Pre-NHL therapy screening | | | |
Targeted screening | Screen NHL patients receiving anti-CD20 antibody with + HBV risk status | Missed cases (asymptomatic HBV infection) | 53,61,62 |
Universal screening | Screen all patients receiving anti-CD20 antibody irrespective of HBV risk status | False HBV positive cases Added cost to therapy | 26,59,60,63 |
Best Practice Advisory (EHR alert system) | Increase HBV screening rates | Implementation cost | 56,64 |
HBV Vaccination | | | |
Catch-up vaccination | Low NHL endemic regions Reduced HBV reactivation rates | Missed cases | 36,54,66 |
Universal vaccination | High endemic regions Reduced HBV reactivation rates | Surveillance cost | 1,36,54,66 |
Reactivation Prophylaxis | | | |
Entecavir | Agent of choice in advanced disease. Least viral resistance | Expensive Renal insufficiency (rare) | 61,72,73,74,78 |
Lamivudine | Most used and studied agent. Cheapest | Withdrawal hepatitis Lamivudine failure (Viral resistance, viral breakthrough) | 31,32,33,34,55,68,71,85,89 |
Adefovir | Less viral resistance | Expensive Renal dysfunction (rare) Hypophosphatemia (rare) | 27,76,80,81 |
Tenofovir | Least viral resistance | Expensive Renal dysfunction (rare) Hypophosphatemia (rare) | 19,27,70,71 |
Low dose/steroid free chemo-immunotherapy | Reduced incidence of reactivation | Potentially adverse survival outcomes from undertreated NHL disease | 83,84 |
Reactivation Treatment | | | |
Lamivudine | Most used agent globally | Risk of acquired viral resistance | 33,59,60,69,70,91 |
Newer antivirals (Entecavir, Adefovir, Tenofovir) | Lamivudine failure. Liver failure must be absent | Depends on prognosis of lymphoma type | 27,53,61,68,77 |
Liver transplantation | If liver failure is present with HBV reactivation | Depends on cost, disease prognosis and post-transplant sequelae | 26,75 |