Hepatitis B in immunosuppressed cancer patients: Pathogenesis, incidence and prophylaxis

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1 Critical Reviews in Oncology/Hematology 87 (2013) Hepatitis B in immunosuppressed cancer patients: Pathogenesis, incidence and prophylaxis Mario Mandalà a,, Stefano Fagiuoli b, Daniela Francisci c, Raffaele Bruno d, Barbara Merelli a, Luisa Pasulo b, Carlo Tondini a, Roberto Labianca a, Fausto Roila e a Unit of Medical Oncology, Papa Giovanni XXIII Hospital, Bergamo, Italy b Division of Gatroenterology and Hepatology, Papa Giovanni XXIII Hospital, Bergamo, Italy c Infectious Disease Clinic, S. Maria della Misericordia Hospital, Perugia, Italy d Division of Infectious and Tropical Diseases, IRCCS San Matteo Hospital, University of Pavia, Pavia, Italy e Medical Oncology, Santa Maria Hospital, Terni, Italy Accepted 18 December 2012 Contents 1. Introduction Incidence and risk factors of hepatitis B reactivation Oncologic patients Hematological patients HBV reactivation in anti-hbc-positive patients HBV screening before chemotherapy or immunosuppressive therapy Prophylactic drugs Clinical trials in oncology and hematology setting Management of immunosuppressed patients with solid tumors Management of immunosuppressed hematologic patients Unsolved issues in the current literature Conclusions Reviewers References Biography Abstract Background: Hepatitis B virus (HBV) reactivation in immunosuppressed cancer patients is a serious clinical problem for HBV carriers undergoing chemotherapy, because it may result in severe liver injury and prevent completion of life-saving treatment of the underlying malignant disease. Design: We reviewed the literature on the incidence, pathogenesis and management of hepatitis B in immunosuppressed cancer patients. The role of primary prophylaxis has also been reviewed. Results: Patients with a previous HBV infection (negative for hepatitis B surface antigen [HBsAg], and positive for both hepatitis B core antibody [anti-hbc] and/or hepatitis B surface antibody [HBsAb]) can experience HBV reactivation. All guidelines support screening of patients with cancer who are about to undergo potentially immunosuppressive therapy, even if the ASCO provisional clinical opinion considers the screening for patients at heightened risk for chronic HBV infection or if undergoing highly immunosuppressive therapy, as hematopoietic cell transplantation and regimens including rituximab. Several meta-analyses support the prophylactic role of lamivudine in preventing HBV reactivation. Most of studies evaluated retrospectively or, if prospectively designed, compared the effect of prophylactic antiviral therapy against historical controls. Corresponding author at: Unit of Clinical and Translational Research, Division of Medical Oncology, Department of Oncology and Hematology, Largo Barozzi 1, Ospedali Riuniti Bergamo, Bergamo, Italy. Tel.: ; fax: address: mariomandala@tin.it (M. Mandalà) /$ see front matter 2012 Elsevier Ireland Ltd. All rights reserved.

2 M. Mandalà et al. / Critical Reviews in Oncology/Hematology 87 (2013) Conclusion: Screening for HBV should be considered before chemotherapy. Prophylaxis with lamivudine can reduce the incidence of HBV reactivation as well as HBV-related morbidity and mortality. Unsolved issues include the role of antiviral agent with higher potency and less resistance, how to monitor patients for reactivation and when to stop prophylaxis Elsevier Ireland Ltd. All rights reserved. Keywords: Hepatitis B; Cancer; Pathogenesis; Prophylaxis; Therapy 1. Introduction Hepatitis B is a major health problem worldwide with a prevalence that varies according to geographic area [1]. It has been reported that about 2 billion people show serological evidence of prior or current hepatitis B virus (HBV) infection and among those million are chronic carriers. Before the introduction of vaccination programs, 20% and <1% of the population in the Asia-Pacific region and Australia, respectively, were hepatitis B surface antigen (HBsAg) positive [1 3]. Although the incidence of acute HBV infection has declined significantly as a result of universal infant vaccination in the United States and in Western Europe, chronic infections are still prevalent in these countries due to several factors, including the immigration from areas where HBV is endemic, perinatal transmission, transmission among household contacts, and risk behaviors. In regions with low prevalence like North America and Western Europe infection leads to acute HBV-related disease more often in the adolescent and adult population and symptoms include jaundice and nausea. Chronic hepatitis B is defined as HBsAg > 6 months with or without sustained increase in aminotransferase. Up to 20% of the chronic persistent hepatitis cases progress to cirrhosis [3]. The natural course of chronic HBV infection is determined by the interplay between virus replication and host immune responses, and the outcome of chronic HBV infection acquired early in life can be generally divided into three distinct phases: immune tolerance phase (high viral loads, normal serum ALT levels, and near-normal liver histology), immune clearance phase (hepatitis B e antigen (HBeAg)- positive, fluctuating serum ALT levels, and fluctuating serum viral loads), and low-replication phase (HBeAg negative, viral load < 4 log 10/ml, and normal ALT levels) [4]. There are 3 virological features for HBV carriers: active carrier, inactive carrier, anticore or anti-hbc (antibody to hepatitis B core antigen)-positive (Table 1). It is well understood that HBV persists for decades in patients following recovery from acute hepatitis B infection during which it is controlled by the immune system. Because of this interaction, situations that lead to immunosuppression in patients with chronic HBV infection may alter the natural history of this infection and give rise to the phenomenon of reactivation. There is not a uniform definition of reactivation in different guidelines, however, one that is commonly used is the following: the presence of hepatitis as suggested by an ALT > 2 ULN in combination with either an abrupt rise in HBV replication of 1 log 10 or an absolute value greater than 20,000 IU/ml [4]. Both events occur in a patient with a previous inactive HBV infection (an inactive carrier state or a patient with resolved hepatitis) [4]. HBV reactivation can occur in situations in which HBV replication increases; the most common causes of HBV reactivation are the immunosuppression regimens adopted in solid organ transplantation, chemotherapy for onco-hematological diseases and immunosuppressive drugs used in the treatment of autoimmune diseases [5 10]. During the immunosuppression phase there is a sharp increase in viral replication and progressive infection of a larger number of hepatocytes. After reconstitution of the immunocompetence, the immune system reactivates against the infected hepatocytes and a severe hepatitis episode can develop. In most cases reactivation occurs during this recovery phase from immunosuppression, one week to 3 months after discontinuation of cytotoxic chemotherapy or immunosuppressive agents and less frequently at the time of the enhanced replication during massive immunosuppression [3]. In HBV carriers (occult or overt) the following virological events should be considered as clinically relevant: (1) in anti-hbc subjects the re-emergence of HBsAg (seroreversion); (2) in inactive carriers the appearance of a significant viremia ( 20,000 IU/ml) (reactivation), as this is frequently associated with liver damage due to HBV; (3) in active carriers the persistence of a significant viremia ( 20,000 IU/ml in HBeAg positive patients and >2000 IU/ml in HBeAg negative subjects with chronic hepatitis) (activity), as this is frequently associated with progression of liver damage due to HBV; (4) in all the virological categories (whether or not during prophylaxis or therapy with antivirals), the increase in at least one logarithm of HBV DNA, compared to its nadir, reconfirmed in two consecutive serum tests during monitoring (virologic breakthrough) [7]. The importance of reactivation of hepatitis B rests on its potential severity and the ease of its prevention with prophylactic oral antiviral therapy. The clinical features of HBV reactivation vary from asymptomatic hepatitis to fulminant hepatic failure leading to death [3]. The delayed recognition of reactivation and its complex virological and biological features can often cause clinical consequences. There is a need

3 14 M. Mandalà et al. / Critical Reviews in Oncology/Hematology 87 (2013) Table 1 Virological categories. Active carrier Inactive carrier Anti-HBc positive (anticore) Virological categories HBsAg Positive Positive Negative HbeAg Positive or negative Negative Negative AntiHBs Negative Negative Positive or negative AntiHBc Positive Positive Positive HBV DNA serum ,000 IU/ml <2000 IU/ml Negative (>90%) ALT Persistently or intermittently increased Persistently normal Persistently normal HBV DNA tissue Positive Positive Positive Liver damage Yes (>90%) No (>90%) No for a wider awareness of reactivation of hepatitis B, when it occurs and how it should be prevented or managed. This review summarizes the recent advances in this area with regards to the incidence and risk factors of HBV reactivation as well as the prevention and management in cancer patients receiving cytotoxic chemotherapy for solid and hematologic tumors. For this purpose we performed an extensive Medline and Cancerlit literature review ( ). Various combinations of search terms were used depending on the requirements of the database being searched. These terms included hepatitis B virus or HBV in combination with immunosuppressed cancer patients and incidence, pathogenesis, management primary prophylaxis, lamivudine, guidelines, reactivation. In addition, we researched manually all relevant review articles and the references of the retrieved papers. Finally, trials were excluded if relevant data could not be extracted. 2. Incidence and risk factors of hepatitis B reactivation Because serial HBV DNA monitoring is not widely performed in patients receiving chemotherapy outside the setting of clinical trials, the recorded incidence of HBV reactivation is likely to have been underestimated in many studies. Indeed, one trial demonstrated that using the above definition of reactivation hepatitis with conventional monitoring of HBV DNA [i.e. at the time of alanine aminotransferase (ALT) rise], the incidence of HBV reactivation was 24% in chronic carriers of HBV receiving chemotherapy for breast cancer, whereas with serial HBV DNA monitoring, 41% of patients were identified as having HBV reactivation [11]. Chemotherapy is highly immunosuppressive and may cause flares of HBV in people who carry HBsAg in their serum [3]. Flares can occur despite normal serum ALT levels before chemotherapy is started [12 14] and may lead to high HBV-related morbidity and mortality [15]. Since cancer is an important leading cause of death, a large proportion of the population may undergo chemotherapy during their lifetime [7]. Therefore, even with a relatively low prevalence of the HBsAg carrier state, prevention of chemotherapy-induced HBV reactivation is an important medical problem and a public health concern. The problem is more critical in areas of the world where HBV infection is endemic [16,17]. Rituximab is a human-mouse chimeric monoclonal antibody that targets the B-cell CD20 cell surface protein and has become essential for the treatment of B-cell non-hodgkin s lymphoma [18 20]. Rituximab has been found to induce durable B-cell depletion. Although lysis of HBV-infected hepatocyte killing is mainly mediated by CD8-cytotoxic T-cell immunity, B cells may also act as antigen-presenting cells and prime cytotoxic T-cellspecific responses in HBV infection [21 24]. Increasing evidence has linked rituximab to viral infections including herpes simplex virus, cytomegalovirus, parvovirus B19, adenovirus [25]. Moreover, the pathophysiology of rituximab-induced viral infections is unclear. The mechanism underlying HBV reactivation that follows rituximab treatment is likely to be more complex than simple B-cell depletion. Stasi et al. [26] demonstrated that rituximab treatment leads to significant changes in T-lymphocyte activity, including increased Th1/Th2 and Tc1/Tc2 ratios, increased expression of Fas ligand on Th1 and Th2 cells, and expansion of oligoclonal T cells. A role for the importance of B lymphocytes in HBV reactivation may also be in part related to reduction of anti-hbv antibodies [i.e. HBsAb (hepatitis B surface antibody)-positive] caused by rituximab and the associated host immunity balance. Tsutsumi et al. [27] showed that despite serum immunoglobulin levels remained constant through treatment, HBsAb titers significantly decreased with rituximab therapy. However, rituximab induces profound and prolonged B-cell depletion binding the CD20 antigen, which is expressed not only on neoplastic B cells but also on normal B lymphocytes. As B lymphocytes act as antigenpresenting cells for CD8-positive cytotoxic T cells that limit the expansion of HBV infection in hepatocytes, depletion of B lymphocytes by rituximab may result in defective T- cell responses to HBV, thereby allowing replication of the virus. Use of corticosteroids in many chemotherapy protocols may also play a role in the expansion of HBV, because HBV-DNA contains a glucocorticoid response element that facilitates HBV replication [28,29]. In patients with chronic hepatitis B, long-term prednisolone treatment increases levels of HBsAg, anti-hbc, and

4 M. Mandalà et al. / Critical Reviews in Oncology/Hematology 87 (2013) HBV DNA in hepatocytes and decreases T-cell function. A withdrawal of prednisolone means an intense rebound in cytotoxic T-cell function that coincides with a surge in serum aminotransferases and a decrease in the level of HBsAg and HBV DNA. Immunosuppression is thought to enhance viral replication with a subsequent spread in hepatocyte infection. In addition, corticosteroids may cause a direct reactivation of the latent HBV infection. The findings of corticosteroid responsive element in HBV DNA and the demonstration that glucocorticoids specifically activate HBV gene expression in cultured human hepatocellular carcinoma cells lend support to the direct reactivation theory. Sporadic retrospective clinical studies also indicate that steroid-free chemotherapeutic regimens reduce the risk of hepatitis flares of HBV carriers [30] Oncologic patients Yeo et al. [11], in a prospective study, reported HBsAg seropositive breast cancer patients treated with conventional chemotherapy. The main objectives were to investigate whether serial HBV DNA monitoring could improve the diagnostic accuracy of diagnosing HBV reactivation compared with conventional monitoring of HBV DNA (i.e. at the time of ALT rise). Overall 41 patients were studied. Ten developed HBV reactivation by conventional monitoring criteria (24%), but with serial HBV DNA monitoring, seven additional patients (17/41: 41%) were diagnosed when increased HBV DNA levels were detected before, but not concomitant with, clinical hepatitis. Premature termination of chemotherapy or delay in treatment schedules occurred in 71% of the patients who developed viral reactivation, as compared to 33% in those who did not develop the condition. Furthermore lung and gastrointestinal cancer, as well as breast cancer patients treated with cyclophosphamide, vincristine, adriamicin, methotrexate and fluorouracil and folinic acid, respectively, are associated with the occurrence of reactivation, as reported from several diverse case studies, ranging between 20% and 40% [31 33]. The highest rates of HBV reactivation have been reported in patients with breast cancer (41%) [11]. However, a prospective study highlighted that the degree of immunosuppression as a result of the treatment could be a more significant factor than the type of malignancy per se in the development of HBV reactivation [34]. In breast cancer patients receiving conventional cytotoxic chemotherapy, Yeo et al. identified treatment with anthracyclines as well as steroids and a detectable HBV DNA (viral load) prior chemotherapy as main risk factors for HBV reactivation [34]. It must be noted that different studies have applied different assays in measuring viral load, and this lack of standardization may have limited the correct understanding of the problem [34]. Jang et al. have shown that transarterial chemolipiodolization (TACL) can reactivate HBV, and HBeAgpositive hepatocellular carcinoma (HCC) patients receiving TACL should be closely monitored for HBV reactivation [35]. Among 83 patients undergoing TACL, HBV reactivation occurred in 28 (33.7%) patients, and HBeAg seropositivity was the only independent predictor of HBV reactivation. Three (10.7%) of them died of hepatic decompensation resulting from HBV reactivation. The authors have also evaluated the efficacy of preemptive lamivudine therapy in reducing hepatitis due to HBV reactivation in patients with HCC undergoing TACL. A total of 73 consecutive HCC patients undergoing TACL were prospectively and randomly assigned to receive lamivudine 100 mg daily from the start of TACL (preemptive group) or not (control group). During the study, 11 (29.7%) of 37 patients in the control group and 1 (2.8%) of 36 patients in the preemptive group developed hepatitis due to HBV reactivation. In addition, there were significantly more incidences of overall hepatitis and severe grade of hepatitis in the control group. At multivariate Cox regression model, a baseline HBV DNA level of more than 10 4 copies/ml was the only independent predictor of hepatitis due to HBV reactivation during TACL. In conclusion, in this study, preemptive lamivudine therapy demonstrated excellent efficacy in reducing hepatitis due to HBV reactivation and hepatic morbidity during TACL [35] Hematological patients Approximately 70 80% of malignant lymphomas are of B cell origin, and >90% of B cell lymphomas express CD20 on the cell surface. CD20 is an appropriate target molecule because it is not shed, modulated or internalized. The introduction of rituximab into the therapeutic regimens has dramatically improved the prognosis of CD20- positive lymphoma patients, but it has been associated with HBV reactivation. Re-initiated HBV replication and increasing levels of serum HBV-DNA have been reported following systemic chemotherapy, especially those involving rituximab-containing regimens, even in patients with resolved HBV infections [21]. In a multi-institutional phase II trial for patients with relapsed or refractory B cell lymphoma, rituximab was shown to almost completely deplete normal mature B cells for an average period of 6 9 months [36]. Recovery to normal levels may take 9 12 months. Before rituximab, 24 53% of HBsAg-positive patients on cancer chemotherapy experienced HBV reactivation. Accordingly, Yeo and Johnson [5] reported that HBV reactivation occurred in 24% of HBsAg-positive lymphoma patients who received systemic chemotherapy. Lok et al. [9] reported reactivation in 48% HBsAg-positive patients with malignant lymphoma following systemic chemotherapy. Lau et al. [37] conducted a randomized trial in 30 HBsAg-positive lymphoma patients either receiving or not receiving anti-viral drug prophylaxis during systemic chemotherapy. They found no reactivation in patients receiving prophylaxis, but 8 of 15 (53%) patients without prophylaxis had HBV reactivation. More recently, Pei et al. [38] reported an extremely high incidence of HBV reactivation in HBsAg-positive lymphoma

5 16 M. Mandalà et al. / Critical Reviews in Oncology/Hematology 87 (2013) patients receiving rituximab-containing chemotherapy. Without prophylaxis in this setting, HBV reactivation occurred in 8 of 10 (80%) patients. Several trials have considered hepatitis reactivation with rituximab. In the study by Yeo on HBsAg-negative/anti-HBc-positive diffuse large B-cell patients, the objectives were to determine the rate of HBV reactivation in patients treated with rituximab containing chemotherapy and to compare the reactivation rate with the rate of patients treated with conventional chemotherapy without rituximab. The findings revealed that the incorporation of rituximab was significantly associated with the development of HBV reactivation [21]. In this study on HBV reactivation in 80 HBsAgnegative lymphoma patients receiving R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone)-like or CHOP-like regimens, three important risk factors were identified, namely, male gender, absence of anti-hbs at diagnosis of lymphoma and the use of rituximab [21]. HBV reactivation occurred in five (6.25%) of these patients, with four receiving antivirals and one patient dying of hepatitis. All 5 patients were anti-hbc-positive and HBsAb-negative and had received R-CHOP. Thus, of 21 anti-hbc-positive patients receiving R-CHOP, five (23.8%) showed HBV reactivation. Therefore, not only HBsAgpositive patients, but also some HBsAg-negative patients, including anti-hbc-positive and/or anti-hbs-positive and/or HBV-DNA-positive patients, should be considered at high risk for HBV reactivation following rituximab plus-steroid combination chemotherapy. Also, Hui et al. [39] reported that of 244 HBsAg-negative lymphoma patients receiving systemic chemotherapy, eight (3.3%) developed HBV reactivation and all of them were either anti-hbc-positive and/or anti-hbs-positive. Moreover, the incidence of HBV reactivation in the rituximab-plussteroid combination group was higher, namely, 12.2% (6/49 patients) than that in other combination therapy groups, in which it was only 1.0% (2/195 patients). Multivariate analysis demonstrated that rituximab-plus-steroid combination chemotherapy was a risk factor for HBV reactivation in HBsAg-negative patients. Less is known about other monoclonal antibodies including Alentuzumab (anti-cd52) and Infliximab (anti-tnf). Nonetheless, it is known that all these agents can lead to profound and long-lasting immune-suppression, which may be responsible for post-treatment HBV reactivation [40,41]. Esteve et al. indicated that patients with Crohn s disease who are candidates for infliximab therapy should be tested for hepatitis B serological markers before treatment and considered for prophylaxis of reactivation using antiviral therapy if positive [42]. Furthermore, the risk of HBV reactivation tends to be more frequent in patients with hematological malignancies in particular with lymphomas [14,43,44] and in those undergoing hematopoietic stem cell transplantation (HSCT) [45], due to the fact that these patients are often subject to intense myelosuppressive treatment regimens and these malignancies, per se, are often associated with an immunecompromised status. In HBsAg positive patients receiving intensive cytoreductive therapy and high- dose chemotherapy prior to HSCT, the HBV reactivation rates are on average about 50% [45]. In patients undergoing autologous hematopoietic cell transplantation (HCT), the risk of hepatitis flare due to HBV reactivation was found to be as high as 33 fold in HBsAgpositive than in HBsAg-negative patients [12]. Furthermore HBsAg-positive patients with detectable serum HBV DNA before HCT (on Digene assay) had a nine-fold higher risk of hepatitis due to HBV reactivation than HBsAg-positive patients with no detectable serum HBV DNA. A high HBV DNA level (>10 5 copies/ml) has been reported to be one of the most important risk factors for HBV reactivation. Actually, Hui et al. examined the serological and liver related outcome of 803 consecutive patients who received allogeneic HSCTs, with a median follow-up period of 83 months (range, months). Late HBV-related hepatitis occurred in 2 of the 721 HBsAg-negative recipients compared with 16 of the 82 HBsAg-recipients after HSCT (0.3% versus 19.5%; P < by log-rank). The study showed that longterm hepatic complications occur in a significant proportion of HBsAg-positive patients after HSCT [45]. Moreover, the incidence, risk factors and course of HBV reactivation after HSCT in HBsAg-negative/anti-HBcpositive recipients are not well known (Table 2) HBV reactivation in anti-hbc-positive patients Reactivation of HBV due to chemotherapy mainly occurs in HBsAg-positive patients but can also be observed in serologically recovered HBsAg-negative patients with anti- HBc positivity and/or anti-hbs positivity [21,38], but this occurs less commonly than in patients who are HBsAgpositive. However, with the recent increased use of rituximab [21], reports of HBV reactivation after treatment with this agent in patients with resolved HBV infections have also increased. Based on case series, nearly 20% of patients died of hepatic failure. HBV reactivation has also been associated with HSCT in patients with hematologic malignancies with resolved HBV infections [46]. The discovery that HBV can persist for decades after clinical recovery from acute hepatitis B, despite the presence of serum HBsAb, has provided insights into the pathogenesis of HBV reactivation in patients who are HBsAg negative prior to chemotherapy or immunosuppressive therapy [47,48]. The persistence of HBV, decades after clinical recovery, suggests that recovery from acute hepatitis B infection does not represent a complete elimination of the virus. HBV replication has been shown to persist in the liver and in peripheral blood mononuclear cells of most HBsAg negative/anti-hbc positive patients who have apparently cleared HBV infection. These patients are referred to as having occult HBV infection. By definition, occult hepatitis B (OBI) is characterized by the persistence of HBV-DNA in the

6 M. Mandalà et al. / Critical Reviews in Oncology/Hematology 87 (2013) Table 2 Trials on the HBV reactivation in hematopoietic stem cell transplantation. Study (reference) Number of patients Duration of follow up, months Lau [12] HBsAg+ (A) 37 HBsAg (B) 77 HBsAg or antihbs (C) HBVDNA+: 10 (D) HBVDNA : 109 (E) Hui [45] HBsAg (A) 82 HBsAg+ (B) Moses [41] 15 8/10 anti-hbc+ recipients: lamivudine prophylaxis (A) 0/5 anti-hbc-recipients: no prophylaxis (B) Hui [79] 54 HBsAg+ 25: No anti-hbv therapy (A) 29: Anti-HBV therapy (B) Giaccone [80] Patients treated with lamivudine: 11/25 anti-hbc+ (A) 2/2 HBsAg+ (B) 3/3 anti-hbc HbsAg, transplanted from HBsAg+ donors (C) 25 (range: ) 83 (range: ) % HBV reactivation or acute hepatitis A: 11/23 (47.8%) B + C: 2/114 (1.75%) P = D: 9/10 (90%) E: 4/109 (4%) P < A: 0.3% B: 19.5% P < A: 2/8 B: 0/5 174 A: 12/25 (48%) B: 2/29 (6.9%) P = (range: 17 55) Abbreviations: HBsAg: hepatitis B surface antigen; HBV-DNA: hepatitis B virus DNA; anti-hbc: antibody to hepatitis B core antigen; anti-hbv therapy: anti hepatitis B virus therapy. Definitions: Lau [12] A: HBsAg positive patients without prophylaxis; B: HBsAg negative patients without prophylaxis; C: HBsAg negative or antihbs negative patients without prophylaxis; D: HBVDNA positive on Digene assay; E: HBVDNA negative on Digene assay. Hui [45] A: HBsAg patients; B: HBsAg+ patients. Moses [41] A: anti-hbc+ recipients who received lamivudine prophylaxis; B: anti-hbc recipients who did not receive lamivudine prophylaxis. Hui [79] A: patients who did not receive anti-hbv therapy; B: patients who received anti-hbv therapy. Giaccone [80] A: anti-hbc+ patients; B: HBsAg+ patients; C: anti-hbc HBsAg transplanted from HBsAg+ donors patients. A: 0% B: 0% C: 0% liver tissue (and in some cases also in the serum) in absence of HBsAg [48]. According to the HBV serological profile, OBI may be antibody (anti-hbc alone or together with anti-hbs) positive (seropositive OBI) or antibody negative (seronegative OBI). The molecular basis of the occult infection is strictly related to the conversion of the 3 Kb relaxed circular genome into a covalently closed-circular DNA (cccdna), a long lived HBV replicative intermediate that persists in the cell nuclei as a stable chromatinized episome and that serves as template for gene transcription. The stability and long-term persistence of viral cccdna molecules together with the long half-life of hepatocytes imply that HBV infection, once it has occurred, may possibly continue for life. Thus, the occult infection appears to be mostly due to a strong suppression of viral replication and gene expression affecting viruses, whose genetic variability is comparable to that of HBV strains from individuals with overt chronic HBV infection [48]. OBI may impact in several different clinical contexts including the risk of HBV transmission with transfusion or transplantation, and endogenous viral reactivation. The gold standard test for detection of occult infection is the amplification of HBV DNA. However, the anti-hbc represents a qualified candidate as a surrogate for DNA amplification, or for increasing overall sensitivity when assessing the risk of occult hepatitis in peripheral blood. The risk of occult hepatitis associated with anti-hbc seropositivity has been demonstrated extensively, and the presence of anti-hbc can be considered a sentinel marker occult HBV infection [49]. Occult HBV infection is a world-wide diffused entity, although its distribution may reflect the general prevalence of the HBV in the various geographic areas and in the various populations. There is a fairly general agreement in considering hepatitis C virus (HCV) infected patients as the category of individuals with the highest prevalence of occult HBV [50]. In particular, HBV DNA is detectable in about one-third of HBsAg negative HCV carriers in the Mediterranean basin, and this prevalence is even higher in Far East Asian countries [48]. Moreover, a high prevalence has been reported in individuals at high risk of parenteral-transmitted infections, with 45% in intravenous drug addicts in Baltimore and 51% in hemophiliacs in Japan [48]. On the contrary, the studies

7 18 M. Mandalà et al. / Critical Reviews in Oncology/Hematology 87 (2013) performed up to now on hemodialysis patients provide widely divergent results, reporting a prevalence of occult HBV that ranges from 0% to 36% [51,52]. The published prevalence in HIV positive individuals ranges from 0% to 89% [53]. Among the blood donors, this OBI appears to have a rare occurrence in the Western world, whereas it is frequently detected in the developing countries [48]. With regard to the general population, in a study evaluating the occult HBV prevalence in HBsAg negative residents of a Canadian Inuit community, Minuk et al. detected HBV DNA in 18% of anti-hbc positive subjects and in 8% of HBV seronegative individuals, respectively [54], whereas Kim et al. found occult HBV in 31 of 195 (16%) Korean HBV/HCV negative healthy subjects [55], and Hui et al. detected occult HBV genomes in 19 out of 124 (15.3%) healthy hematopoietic stem cell donors from Hong Kong [56]. In anti-hbc-positive patients immunosuppression can allow active viral replication to start again, resulting in the re-emergence of HbsAg. This clinical scenario is referred to as reverse seroconversion or seroreversion. Thus, immunosuppressive therapy may result in HBV reactivation, even in individuals who are anti-hbc and/or anti-hbs positive. The immunocompromised state due to malignancy and chemotherapy may result in enhanced replication of existing low levels of HBV, which leads to rapid destruction of infected hepatocytes upon the recovery of the immune function, resulting in HBV-related hepatitis flare. Even though Yeo et al. did not define varying degrees in the level of immunosupression, they reported the incidence of seroreversion in HBsAg-negative diffuse large-cell B lymphoma patients treated with chemotherapy (cyclophosphamide, doxarubin, vincristine, and prednisone) who received rituximab versus those who did not receive rituximab [21]. Eighty patients were HBsAg negative. Forty-six patients (44.2%) were HBsAg negative/anti-hbc positive; 25 of these patients were treated with CHOP, and none had HBV reactivation. In contrast, among the 21 patients treated with R-CHOP, five developed HBV reactivation, including one patient who died of hepatic failure. Exploratory analysis identified male sex, absence of anti-hbs, and use of rituximab to be predictive of HBV reactivation. Hence, among HBsAg-negative/anti-HBc-positive DLBCL (diffuse large B cell-lymphoma) patients treated with R-CHOP, 25% developed HBV reactivation. Koo et al. showed that the rate of HBV reactivation is low in patients who are HBsAg negative/anti-hbc positive receiving rituximab-based combination chemotherapy without concomitant antiviral prophylaxis (4%). However, elderly patients, particularly those without anti-hbs, seemed particularly at risk [57]. Viganò et al. evaluated a total of 50 HBsAg-negative/anti- HBc-positive HSCT recipients with onco-hematological diseases. During 17 months of follow-up, six (12%) patients had seroreverted to HBsAg, 7 32 months after HSCT, with 1- and 5-year cumulative rates of 13% and 22%. Patients with chronic onco-hematological disease and long-lasting immunosuppression following HSCT had a higher risk of HBsAg seroreversion independently of serum HBV DNA levels at HSCT. HBsAg-negative/anti-HBc-positive HSCT recipients with chronic onco-hematological disease carry a significant risk of HBsAg seroreversion and HBeAg-positive chronic hepatitis B, independently of serum levels of HBV DNA at transplantation [58] (Table 3). The increased risk associated with corticosteroids is thought to be due to both the immunosuppressive effect and direct stimulation of viral replication via a glucocorticoid responsive receptors on HBV surface [59]. All the available data clearly suggest that reactivation can occur at any time during chemotherapy or after it, during the recovery phase of the immune system s reconstitution. This can lead to poor outcomes, hepatic flares, liver failure, and death. Given the significant risk of viral reactivation and its life-threatening sequelae, monitoring and prophylactic strategy have been recommended for preventing from the reactivation of HBV during and after chemotherapy. It is important to identify these patients accurately so that effective prophylaxis or oral antiviral therapy can be promptly initiated. 3. HBV screening before chemotherapy or immunosuppressive therapy Most guidelines endorse recommendations that are in agreement [7,60 64]: all patients with cancer who are about to undergo potentially immunosuppressive therapy should be screened for HBsAg, anti-hbc, and HBsAb. A concomitant exhaustive evaluation of liver functional status and staging should be adopted. The choice between prophylaxis and treatment of HBV depends on the definition of the combination of virological and hepatological status of the patient [60,61]. Recommendations from ASCO [62] are state that only patients who undergo highly immunosuppressive regimens (i.e., stem cell transplants or treatment with rituximab) and patients at risk for HBV should be tested, and screening should only be for HBsAg and anti- HBc. Although there is agreement on the importance of antiviral prophylaxis, ASCO does not advocate the use of all 3 screening tests. The ASCO provisional clinical opinion recommends that oncologists screen patients at risk for HBV infection, thus taking the time to find out if patients show risk factors for HBV infections. Scottish Viral Hepatitis group and the Scottish diagnostic virology group recommend to screen all patients undergoing chemotherapy for hematological malignancies for HBsAg, anti-hbc [63]. The European Association for the Study of the Liver recommends that all candidates for chemotherapy and immunosuppressive therapy should be screened for HBsAg and anti-hbc prior to initiation of treatment [64]. The Italian Association for the Study of the Liver [7], for patients with solid tumors, recommends HBsAg only as

8 M. Mandalà et al. / Critical Reviews in Oncology/Hematology 87 (2013) Table 3 Trials assessing the implication of anti-hbc positivity. Study (reference) Number of patients Diagnosis Treatment Reactivation (%) Matsue [29] anti-hbc+ (A) 174 anti-hbc (B) Koo [57] 62 HBsAg /anti-hbc+ 48/62 R-CHOP (A) CD20+ B-cell lymphoma Rituximab A: 8.9% B: 0% B-cell lymphoma R-CHOP A: 4% Viganò [58] 50 HBsAg /anti-hbc+ Hematological malignancies HSCT 12% Ceneli [81] 90 HSCT Hematological malignancies HSCT 0% 14 HBsAg /anti-hbc+ Borentain [82] 84 HBsAg /antihbc+ Hematological malignancies HSCT (A)Rituximab (B) 8.3% A: 42.9% B: 57.1% Hammond [83] 61 HBsAg /anti-hbc+ HSCT 19.7% Ji [84] 88 HBsAg /anti-hbc+ 43/88 R-CHOP (A) B-cell lymphoma R-CHOP (A) A: 2.3% Abbreviations: Anti-HBc: antibody to hepatitis B core antigen; HBsAg: hepatitis B surface antigen; HSCT: Hematopoietic Stem Cell Transplant. Definitions: Matsue [29] A: anti-hbc+ patients; B: anti-hbc patients. Koo [57] A: patients who received R-CHOP chemotherapy (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone). Borentain [82] A: patients who received HSCT (Hematopoietic Stem Cell Transplant); B: patients who received rituximab. Ji [84] A: patients who received R-CHOP chemotherapy (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone). basal screening, because the clinical significance of isolate anti-hbc positivity in patients with solid tumors is unclear and there are no clinical evidences of higher risk of HBV reactivation in patients with isolated anti-hbc positivity in comparison with patients without serum markers of HBV infection. Screening clinical recommendations of several international associations are reported in Table 4. HBsAg-positive candidates for chemo- and immunosuppressive therapy should be tested for HBV DNA levels, although in the literature few studies have been conducted to evaluate the use of HBV DNA as a screening before chemotherapy [32,65]. Moreover, the clinical evidence does not provide enough information to determine the optimal frequency and duration of such HBV-DNA monitoring. Recently, aiming at investigating the current practice among oncologists regarding HBV screening and antiviral prophylaxis in candidates for chemotherapy, a survey was sent to the American Medical Association-registered oncologists [66]. Of the total respondents, 20% reports never screening for HBV prior to initiating therapy, 38% screens if the patient shows risk factors or a history of hepatitis, 30% screens if liver tests are abnormal, 11% screens occasionally on a random basis and 13% screens every patient for HBV. A recent paper highlighted concerns regarding HBV screening in oncologic patients and concluded that universal screening for hepatitis B virus (HBV) is not cost-effective in patients with solid tumors who undergo chemotherapy [67]. Testing may be adopted if it is limited to selected patient subpopulations or if it is simplified. Using an incremental cost-effectiveness ratio threshold of $50,000 (Australian dollars, which are nearly equivalent to American dollars) per life-year saved, the authors showed that universal HBV screening was not cost-effective for adjuvant treatments ($88,224/life-year; 13% probability of being cost-effective), palliative treatments ($1,344,251/life-year; 0%), or all patients ($149,857/life-year; 1%). However, this study did not consider important costs such as hospitalization, time lost from work, treatment delays related to hepatitis reactivation, and other factors. Furthermore focusing the screening on selected patient subpopulations, which refers to patient ethnicity may be potentially dangerous since the lack of large population-based studies and the current prevalence of HBV reactivation in patients undergoing cancer treatment is unclear. Clearly, in areas of high HBV endemicity all patients should be screened for HBsAg and anti-hbc prior to immunosuppressive chemotherapy. Recently, Zurawska et al. developed a decision model to compare the clinical outcomes and costs of three screening strategies for patients with lymphoma before R-CHOP: screening all patients for HbsAg, screening patients identified as being at high risk for HBV reactivation and screening no one. The results shown that screening all patients for HBV reduces the rate of HBV reactivation (10-fold) and is less costly than screening only high-risk patients or screening no patients [68]. Furthermore, although there are not large population based studies evaluating the role of screening in cancer patients, it s important to highlight that the cost of screening for HBsAg is relatively low whereas the clinical consequences of reactivation can be life-threatening. 4. Prophylactic drugs Nucleoside analogs (NASs) have become widely accepted for prophylaxis of reactivation of HBV in clinical practice. There are 5 nucleos(t)ides analogs (NASs) potentially currently available for hepatitis B carriers receiving immunosuppressive therapy: lamivudine, adefovir-dipivoxil, entecavir, telbivudine and tenofovir. Lamivudine is a pyrimidine nucleoside analog that inhibits binding of nucleosides to the HBV polymerase [69,70].

9 20 M. Mandalà et al. / Critical Reviews in Oncology/Hematology 87 (2013) Table 4 Screening for hepatitis B in cancer patients receiving immunosuppressive therapy. Scientific society Recommendation Oncologic Hematologic AASLD [61] HBsAg, anti-hbc HBsAg, anti-hbc EASL [64] HBsAg, anti-hbc HBsAg, anti-hbc CDC [85] HBsAg, anti-hbc, HBsAb HBsAg, anti-hbc, HBsAb Scottish Liver Society [63] None HBsAg, HBcAb NIH Consensus [86] HBsAg HBsAg Italian Guidelines [7] HBsAg HBsAg, anti-hbc, HBsAb ASCO [62] Only patients who undergo certain highly cytotoxic or immunosuppressive therapies (i.e., stem cell transplants or treatment with rituximab) and patients at risk for HBV (HBV infection or prior exposure to HBV): HBsAg, anti-hbc APASL [87] HBsAg HBsAg Canadian Guidelines [88] HBsAg, anti-hbc, HBsAb HBsAg, anti-hbc, HBsAb Abbreviations: HBsAg: hepatitis B surface antigen; anti-hbc: antibody to hepatitis B core antigen; HBsAb: hepatitis B surface antibody. AASLD [61]: American Association for the Study of Liver Diseases, EASL [64]: European Association for the Study of Liver Diseases, CDC [85]: Centers for Disease Control and Prevention, ASCO [62]: American Society of Medical Oncology, NIH Consensus [86]: National Institute of Health consensus, consensus.nih.gov; APASL [87]: The Asian Pacific Association for the Study of the Liver, Canadian Guidelines [88]: Generally, lamivudine is effective at lowering HBV viral load. However, HBV becomes resistant to lamivudine, with the prevalence of its resistance approaching 70% in four years. Furthermore, the development of lamivudine resistance also increases the likelihood of resistance to other antiviral agents, and may compromise the response to other drugs, including adefovir, entecavir and telbivudine. Adefovir dipivoxil is a purine nucleotide analog [71]. It is not a highly potent agent and its slow antiviral activity can delay, but not achieve a complete viral suppression in the majority of patients, this way increasing the risk for developing viral resistance. Entecavir is a selective guanosine analog and is the most potent inhibitor of HBV DNA replication currently available [70,72]. It can suppress viral replication more effectively than lamivudine in treatment-naïve patients in both HBeAgpositive and HBeAg-negative subjects. Telbivudine is a pyrimidine nucleoside analog with potent antiviral efficacy against HBV [73]. Telbivudine suppresses HBV replication more effectively than lamivudine. It is more potent than lamivudine and can be used in patients with high viral loads. However, as with lamivudine, inadequate suppression of the virus in cases of high viral load is associated with development of significant rates of resistance [73]. Tenofovir is a purine analog, interferes with the action of the DNA polymerase, which is involved in the formation of viral DNA [74] Clinical trials in oncology and hematology setting Over the past decade, it has been recognized that HBV reactivation and its associated fatality during chemotherapy can be prevented effectively by adopting a prophylactic strategy. Lamivudine appears to be safe and cost-effective. The published experience in the prevention and treatment of HBV reactivation is almost entirely limited to lamivudine (Tables 5 and 6). A systematic review assessed the effect of preventive lamivudine on hepatitis B reactivation during chemotherapy [69]. This research revealed that preventive lamivudine reduces the risk for HBV-related hepatitis by 79% or more. In addition, preventive lamivudine may reduce the risk for HBV-related hepatic failure and death in patients who result to be positive for HBsAg and receive chemotherapy. Several strategies employing lamivudine have been proposed to deal with chemotherapy-induced HBV reactivation: prophylaxis, targeted prophylaxis and treatment of active HBV disease. In patients at high risk of HBV reactivation antiviral prophylaxis therapy should be started pre-emptively prior or together with chemotherapy, since this reduces the risk and severity of reactivation hepatitis and allows chemotherapy to be completed. The optimal duration of preventive lamivudine therapy has not been conclusively determined yet, although maintenance lamivudine for 6 months after discontinuing chemotherapy has been recommended [9,14,75]. This strategy has been shown effective both demonstrated in lymphoma and breast cancer patients as well as in retrospective and prospective trials [76,77]. Although lamivudine therapy reduces the risk, HBV reactivation and death remain a possibility [21]. The efficacy of long-term lamivudine therapy is limited by the appearance of antiviral resistance [3]. For these reasons, preventive use of recently available, potent anti-hbv agents (such as entecavir, telbuvidine, adefovir, and tenofovir) might be preferable to further reduce the risk for morbidity and mortality in high-risk patients [78]. These newer agents, however, are more expensive than lamivudine, and their long-term safety is less well defined. Large, prospective, and well-designed randomized, controlled studies are needed to address this issue. Although results of the research synthesis provide important evidence that supports the use of preventive lamivudine in a chemotherapy setting, several limitations exist. The clinical trials included were limited by small sample sizes; heterogeneity of patient populations, baseline demographic characteristics or viral-host factors, and type of chemotherapeutic regimens used; and variable

10 M. Mandalà et al. / Critical Reviews in Oncology/Hematology 87 (2013) Table 5 Trials on the prophylaxis of hepatitis B (HBsAg positive): solid tumors. Study (reference) Number of patients Chemotherapy Duration of prophylaxis % HBV reactivation or acute hepatitis Prospective randomized trials Long [77] 42 Breast cancer 21 Lamivudine (A) 21 No prophylaxis (B) Jang [35] 73 HCC 37 Lamivudine (A) 36 No prophylaxis (B) Prospective trial with historical control Yeo [76] 92 Breast cancer 31 Lamivudine (A) 61 Historic control (B) Yeo [89] 37 Nasopharyngeal carcinoma 16 Lamivudine (A) 21 Historic control (B) Anthracycline, anthracycline-taxanes based Day 1 to 2 months after CT A: 0% B: 28.6% P = TACL Day 1 to 12 months after TACL A: 2.8% B: 29.7% P = Anthracycline, non anthracycline based taxanes Day 1 to 2 months after CT A: 6.5% B: 31.1% P = Cisplatinum based Prior to and until 8 week after CT A: 0% B: 28.6% P = Retrospective trials Dai [90] 11 Breast cancer Anthracycline-based Day 1 to 1 month after CT 0% Dai [91] 6 Breast cancer Anthracycline-based Day 1 to 1 month after CT 0% Yun [92] 131 Breast cancer 55 Lamivudine (A) 76 No prophylaxis (B) Sohn [93] 169 Breast cancer 41 Lamivudine (A) 128 No prophylaxis (B) Nagamatsu [94] 17 HCC HBeAg+ 8 Lamivudine (A) 9 No prophylaxis (B) Anthracycline-based Day 1 to 2 months after CT A: 9% B: 33% Anthracycline-based Day 1 to 2 months after CT A: 2.4% B: 14.1% TACL NR A: 0/8 B: 6/9 Abbreviations: HCC: hepatocellular carcinoma; TACL: transarterial chemo-lipiodolization using epirubicin (50 mg/m 2 ) and cisplatin (60 mg/m 2 ) in a mixture of lipiodol (5 10 ml). Definition: Long [77], Jang [35], Yun [92], Sohn [93] and Negamatsu [94] A: patients who received lamivudine; B: patients who did not receive prophylaxis. Yeo [76] and Yeo [89] A: patients who received lamivudine; B: historical controls who underwent chemotherapy without prophylactic lamivudine. duration of treatment and follow-up, all of which may limit the overall treatment effects. Most studies were retrospective cohort studies or prospective cohort studies that had either a historical or a concurrent control group. Despite these limitations, the treatment effect was in favor of preventive lamivudine therapy. Large, randomized, controlled studies are needed to establish the exact duration of preventive anti-hbv therapy and to define the clinical role and efficacy of newer anti-hbv agents, such as entecavir, telbuvidine, adefovir, and tenofovir Management of immunosuppressed patients with solid tumors In HBsAg positive patients is mandatory useful to evaluate liver function tests (LFTs) and serum HBV-DNA levels before starting chemotherapy in order to differentiate active carrier from and inactive carrier (Fig. 1a, Table 7). For active carriers therapy with more potent NASs (entecavir or tenofovir) is indicated, with the aim of controlling the disease pre- and post-treatment. For inactive carriers undergoing adjuvant or neo-adjuvant chemotherapy definite prophylaxis with lamivudine should be adopted and should be continued for the entire treatment and for 6 12 months after the end of the chemotherapy (Table 7). However, data are still insufficient to define the optimal duration of prophylactic antiviral therapy. Premature withdrawal of lamivudine could lead to a rapid rebound of viral replication, resulting in HBV-related mortality. On the other hand, prolonged use of lamivudine in absence of viral replication is not associated with an increasing likelihood of developing lamivudine-resistance HBV variants with YMDD mutants. Many guidelines differ in the duration of treatment, from at least 3 to 12 months after completion of chemotherapy. The European Association for the Study of the Liver recommends that HBsAg-positive candidates for chemotherapy and immunosuppressive therapy should be tested for HBV DNA levels and should receive pre-emptive NASs administration during therapy regardless of HBV DNA levels and for 12 months after cessation of therapy [64]. The American Society of Clinical Oncology suggests that, when evidence for chronic HBV infection is found, antiviral therapy before and throughout the course of chemotherapy may be considered to reduce the risk of HBV reactivation, although evidence from controlled trials of this approach is limited [62].