Chemotherapy-Induced Hepatitis B Reactivation in Lymphoma Patients With Resolved HBV Infection: A Prospective Study

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1 VIRAL HEPATITIS Chemotherapy-Induced Hepatitis B Reactivation in Lymphoma Patients With Resolved HBV Infection: A Prospective Study Chiun Hsu, 1,2 Hsiao-Hui Tsou, 3 Shyh-Jer Lin, 4 Ming-Chung Wang, 5 Ming Yao, 6 Wen-Li Hwang, 7 Woei-Yau Kao, 8 Chang-Fang Chiu, 9 Sheng-Fung Lin, 10 Johnson Lin, 11 Cheng-Shyong Chang, 12 Hwei-Fang Tien, 6 Tsang-Wu Liu, 3 Pei-Jer Chen, 6,13 and Ann-Lii Cheng, 1,2 on behalf of the Taiwan Cooperative Oncology Group Fatal hepatitis B virus (HBV) reactivation in lymphoma patients with resolved HBV infection (hepatitis B surface antigen [HBsAg] negative and hepatitis B core antibody [anti-hbc] positive) can occur, but the true incidence and severity remain unclear. From June 2009 to December 2011, 150 newly diagnosed lymphoma patients with resolved HBV infection who were to receive rituximab-chop (cyclophosphamide, doxorubicin, vincristine, prednisolone)-based chemotherapy were prospectively followed. HBV DNA was checked at baseline, at the start of each cycle of chemotherapy, and every 4 weeks for 1 year after completion of rituximab-chop chemotherapy. Patients with documented HBV reactivation were treated with entecavir at a dosage of 0.5 mg/day for 48 weeks. HBV reactivation was defined as a greater than 10-fold increase in HBV DNA, compared with previous nadir levels, and hepatitis flare was defined as a greater than 3-fold increase in alanine aminotransferase (ALT) that exceeded 100 IU/L. Incidence of HBV reactivation and HBV-related hepatitis flares was 10.4 and 6.4 per 100 person-year, respectively. Severe HBV-related hepatitis (ALT >10-fold of upper limit of normal) occurred in 4 patients, despite entecavir treatment. Patients with hepatitis flare exhibited significantly higher incidence of reappearance of HBsAg after HBV reactivation (100% vs. 28.5%; P ). Conclusion: In lymphoma patients with resolved HBV infections, chemotherapy-induced HBV reactivation is not uncommon, but can be managed with regular monitoring of HBV DNA and prompt antiviral therapy. Serological breakthrough (i.e., reappearance of HBsAg) is the most important predictor of HBV-related hepatitis flare. (HEPATOLOGY 2014;59: ) See Editorial on Page 2062 Hepatitis B virus (HBV) reactivation and hepatitis flare induced by cytotoxic chemotherapy is common in cancer patients suffering chronic HBV infections. We and other investigators have demonstrated, through randomized, clinical trials, the preventive effect of lamivudine on chemotherapy-induced HBV reactivation in non-hodgkin s lymphoma (NHL) patients who tested positive for HBV surface antigen (HBsAg). 1,2 Therefore, antiviral therapy is now routinely Abbreviations: Abs, antibodies; ALT, alanine aminotransferase; anti-hbc, hepatitis B core antibody; anti-hbs, hepatitis B surface antibody; CHOP, cyclophosphamide, doxorubicin, vincristine, prednisolone; CI, confidence interval; DOX, doxorubicin; ECOG, Eastern Cooperative Oncology Group; PFS, progression-free survival; HBeAg, hepatitis B e antigen; HBsAg, hepatitis B surface antigen; HBV, hepatitis B virus; HR, hazard ratio; IV, intravenously; NHL, non-hodgkin s lymphoma; OS, overall survival; PCR, polymerase chain reaction; ULN, upper limit of normal. From the 1 Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan; 2 Graduate Institute of Oncology, National Taiwan University College of Medicine, Taipei, Taiwan; 3 National Health Research Institutes, Miaoli, Taiwan; 4 Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan; 5 Kaohsiung Chang-Gung Memorial Hospital, Kaohsiung, Taiwan; 6 Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan; 7 Taichung Veterans General Hospital, Taichung, Taiwan; 8 Tri-Service General Hospital, Taipei, Taiwan; 9 China Medical University Hospital, Taichung, Taiwan; 10 Kaohsiung Medical University Chung-Ho Memorial Hospital, Kaohsiung, Taiwan; 11 Mackay Memorial Hospital, Taipei, Taiwan; 12 Changhua Christian Hospital, Changhua, Taiwan; and 13 Hepatitis Research Center, National Taiwan University College of Medicine, Taipei, Taiwan. Received April 18, 2013; accepted August 23, This study was supported by grant T1408 from the Taiwan Cooperative Oncology Group of the National Health Research Institutes, Taiwan. The funding source played no direct role in the design and conduct of the study; the collection, management, analysis, and interpretation of the data; or the preparation, review, or approval of the manuscript. 2092

2 HEPATOLOGY, Vol. 59, No. 6, 2014 HSU ET AL recommended for HBsAg-positive cancer patients who receive immunosuppressive therapy. 3,4 Cancer patients with resolved HBV infection (i.e., patients who are negative for HBsAg, but positive for antisurface [anti-hbs] or anti-core [anti-hbc] antibodies [Abs]) still carry a risk of chemotherapy-induced HBV reactivation. Although most of the reported cases of HBV reactivation in this patient population were self-limited, fulminant hepatitis and hepatitis-related mortality were occasionally noted All previous studies of cancer patients with resolved HBV infection were retrospective and differed from one another in methods of diagnosis of HBV reactivation, length of follow-up after chemotherapy, tumor types, and intensity of chemotherapy. Introduction of monoclonal Abs, such as rituximab and alemtuzumab, for lymphoma treatment may markedly increase the incidence and severity of HBV reactivation. 5 These Abs can produce long-term immune suppression and increase the risk of opportunistic viral or fungal infection. 12 A combination of rituximab and cytotoxic chemotherapy, which is the standard regimen for patients with diffuse large B-cell lymphoma and follicular lymphoma, 13 has also been observed to increase the risk of HBV reactivation and hepatitis flare in patients with resolved HBV infection. 8,9 In HBV-endemic areas such as Taiwan, approximately 60% of the adult population suffer resolved HBV infections. Therefore, chemotherapy-induced HBV reactivation should be a critical healthcare concern. 14 Moreover, the incidence of HBV reactivation in this patient population may have been substantially underestimated in previous studies because in those studies quantification of HBV DNA was performed retrospectively only for patients who developed hepatitis after chemotherapy. 15,16 Therefore, this prospective study sought to clarify the incidence, severity, and clinical course of HBV reactivation in lymphoma patients with resolved HBV infection who were undergoing standard chemotherapy. Patients and Methods Patients and Study Design. This prospective study ( identifier: NCT ) was conducted in 11 medical centers in Taiwan. The standard treatment for lymphoma patients in the participating centers was generally based on the guidelines recommended by the National Comprehensive Cancer Network. The study protocol was approved by the ethics committee of the National Health Research Institutes, Taiwan, and the institutional review boards of the participating centers. Patients with newly diagnosed, histologically proven diffuse large B-cell or follicular B-cell NHL, for which rituximab-chop (cyclophosphamide, doxorubicin, vincristine, prednisolone)-based chemotherapy is considered the treatment of choice, were eligible if they were positive for serum anti-hbc and negative for HBsAg. Patients who were positive for HBsAg or antihepatitis C Ab were excluded. Other major eligibility criteria included an age of over 18 years, an Eastern Cooperative Oncology Group (ECOG) performance score of 0-2, adequate bone marrow and liver function (absolute neutrophil count 1,500/mm 3, platelet 100,000/mm 3, bilirubin >2.5 mg/dl, and serum alanine aminotransferase (ALT) <3 times upper limit of normal [ULN]), and no history of other major systemic diseases. The following is a typical course of rituximab- CHOP chemotherapy used in this study: rituximab 375 mg/m 2 intravenously (IV), day 1; cyclophosphamide 750 mg/m 2 IV, day 1; doxorubicin (DOX) 50 mg/m 2 IV, day 1; vincristine 14 mg/m 2 (maximal 2 mg) IV, day 1; and prednisolone 40 mg/m 2 /day per oral, days 1-5. Treatment cycles were repeated every 3 weeks. Variations in treatment, including types of anthracyclines (DOX vs. epirubicin), the dosage and route of steroids, and the total number of cycles of chemotherapy, are acceptable, provided that the variations are considered according to the institutional standard of care for the particular patients. Modification of chemotherapy dosage and the use of component therapy or granulocyte colony-stimulating factor were performed according to the patients adverse events. Evaluation of treatment response was performed according to treatment guidelines. 17 Definition of HBV Reactivation and Hepatitis Flare. The primary endpoint of this study was the incidence of HBV reactivation, defined as a greater than 10-fold increase, compared with previous nadir Address reprint requests to: Pei-Jer Chen, M.D., Ph.D., Hepatitis Research Center, National Taiwan University College of Medicine, 7 Chung-Shan South Road, Taipei, Taipei 100, Taiwan. peijerchen@ntu.edu.tw; fax: ; or Ann-Lii Cheng, M.D., Ph.D., Department of Oncology, National Taiwan University Hospital, 7 Chung-Shan South Road, Taipei 100, Taiwan, alcheng@ntu.edu.tw; fax: Copyright VC 2014 by the American Association for the Study of Liver Diseases. View this article online at wileyonlinelibrary.com. DOI /hep Potential conflict of interest: Dr. Cheng consults for Eisai and advises Daiichi Sankyo. Additional Supporting Information may be found in the online version of this article.

3 2094 HSU ET AL. HEPATOLOGY, June 2014 Fig. 1. Flow chart of patient enrollment and follow-up. levels, of HBV DNA, during rituximab-chop chemotherapy and within 1 year after the final course of rituximab-chop chemotherapy. HBV DNA levels were checked at baseline and at the start of every new cycle of rituximab-chop chemotherapy. After completion of rituximab-chop chemotherapy, HBV DNA levels were measured every 4 weeks for 1 year. HBV DNA levels were quantified using real-time polymerase chain reaction (PCR) with the lower limit of HBV DNA detection at 1,000 copies/ml. 18 If baseline HBV DNA levels were below the detection limit, HBV reactivation was defined as an increase of HBV DNA to greater than 10,000 copies/ml. If an HBV DNA increase was observed during follow-up, but the magnitude was less than 10 times the previous nadir level, serum samples were collected every week until the next scheduled blood sampling to check liver function and HBV DNA. Upon diagnosis of HBV reactivation based on HBV DNA elevation, patients were treated with 0.5 mg of entecavir daily for 48 weeks. HBV DNA, HBsAg, and hepatitis B e antigen (HBeAg) were measured every 4 weeks during entecavir treatment. To evaluate the effects of the sensitivity of the HBV DNA quantification on the HBV reactivation diagnosis, the collected serum samples were re-tested using a

4 HEPATOLOGY, Vol. 59, No. 6, 2014 HSU ET AL Table 1. Clinical Characteristics of the Enrolled Patients Assay #1 (LLOQ 1000 Copies/mL)* Assay #2 (LLOQ 300 Copies/mL)* Characteristic All Patients (n 5 150) HBV Reactivation (1) HBV Reactivation (2) HBV Reactivation (1) HBV Reactivation (2) (n 5 17) (n 5 133) P Value z (n 5 27) y (n 5 116) y P Value z Age in years, median (range) 61 (27-84) 58 (27-83) 61 (32-84) (27-84) 60 (32-83) 0.08 Sex (%) M 81 (54) 8 (47) 73 (55) (59) 65 (56) 0.83 F 69 (46) 9 (53) 60 (45) 11 (41) 51 (44) ECOG performance score (%) 0/1 142 (95) 16 (94) 126 (95) (85) 112 (97) (5) 1 (6) 7 (5) 4 (15) 4 (3) Histological diagnosis (%) Diffuse large cell type 128 (85) 13 (76) 115 (86) (89) 99 (85) 0.77 Follicular type 22 (15) 4 (24) 18 (14) 3 (11) 17 (15) Ann Arbor stage (%) I 28 (19) 4 (23) 24 (18) (18) 22 (19) 0.91 II 48 (32) 3 (18) 45 (34) 10 (37) 37 (32) III 35 (23) 3 (18) 32 (24 5 (18) 29 (25) IV 39 (26) 7 (41) 32 (24) 7 (26) 28 (24) LDH >ULN (%) 89 (59) 13 (76) 76 (57) (56) 67 (58) 0.83 Baseline ALT, IU/L (median/range) 19 (4-109) 18 (6-79) 19 (4-109) (6-79) 20 (4-109) 0.63 Primary extranodal disease (%) 41 (27) 4 (23) 37 (28) (22) 33 (28) 0.63 B symptoms (%) 35 (23) 5 (29) 30 (23) (26) 26 (22) 0.80 Baseline HBV DNA detectable (%) 5 (3) 0 (0) 5 (4) (7) 0 (0) 0.03 Anti-HBs (1) (%) 116 (77) 9 (53) 107 (80) (59) 95 (82) 0.02 Anti-HBe (1) (%) 59 (39) 6 (35) 53 (40) (37) 48 (41) 0.83 *Assay #1 was used to diagnose HBV reactivation and determine the timing of antiviral therapy. Assay #2 was done after completion of patient enrollment using the collected serum samples and HBV reactivation was retrospectively determined. Seven patients had no samples left for test by assay #2. Comparison between patients with or without HBV reactivation. Fisher s exact two-sided test was used for categorical variables and Wilcoxon s test for continuous variables. Abbreviations: LLOQ, lower limit of quantification; M, male; F, female; LDH, lactate dehydrogenase. second PCR assay (RealTime HBV assay; Abbott Laboratories, Abbott Park, IL). The lower limit of detection of this assay was set at 75 IU/mL (300 copies/ ml) because of the limited sample availability in this study. HBV reactivation was retrospectively determined. If the baseline HBV DNA level was undetectable, HBV reactivation was diagnosed if the follow-up HBV DNA test was positive. If the baseline HBV DNA level was detectable, a greater than 10-fold increase from baseline levels was required for an HBV reactivation diagnosis. The secondary endpoints of this study included the incidence of hepatitis flare, defined as a greater than 3- fold increase of serum ALT level that exceeded 100 IU/L, the incidence of severe hepatitis, defined as a hepatitis flare with an ALT increase to more than 10- fold ULN or bilirubin to more than 1.5-fold ULN, and the progression-free survival (PFS) and overall survival (OS) of patients. The data and safety monitoring committee of the Taiwan Cooperative Oncology Group reviewed the safety data of this study every 6 months. Statistical Analysis. We planned to enroll 150 patients in 3 years, based on the estimated annual incidence of 68 per 100,000 persons for NHL patients in Taiwan and a proportion of 50% of anti-hbc positivity in the general population. 14,19 Categorical variables were compared using Fisher s exact test. Continuous variables were compared using Wilcoxon s rank-sum test. Survival was calculated using Kaplan-Meier s method and compared using the log-rank test. Uniand multivariate analyses were performed using Cox s proportional hazards model to identify predictors of OS and PFS. Variables with P values <0.10 in univariate analysis and variables of clinical interest were evaluated using multivariate analysis. Statistical analyses were performed using SAS software (v.8.2; SAS Institute, Inc., Cary, NC). Results Patient Characteristics. From June 2009 to December 2011, 150 patients were enrolled (Fig. 1). The clinical characteristics of the patients are

5 2096 HSU ET AL. HEPATOLOGY, June 2014 Fig. 2. Patterns of HBV reactivation. (A) HBV reactivation during rituximab-chop chemotherapy without hepatitis flare. Both HBsAg and HBeAg became positive after HBV reactivation. (B) HBV reactivation after completion of rituximab-chop chemotherapy with hepatitis flare. Only HBsAg became positive after reactivation. (C) A patient with a second episode of HBV reactivation after completion of the designated entecavir treatment, which was presumably induced by second-line chemotherapy. The patient s HBsAg remained negative during follow-up, whereas HBeAg became positive. (D) A patient with delayed hepatitis flare after HBV reactivation. The hepatitis flare occurred at the time of HBsAg seroconversion and was considered HBV related. summarized in Table 1. Distribution of age, sex, and Ann Arbor stage of this cohort was similar to those reported in the general population in Taiwan (Bureau of Health Promotion, Department of Health, Taiwan). 19 A total of 910 cycles of rituximab-chop chemotherapy were administered (median, 6 cycles/ patient; range, 1-9). As of April 1, 2013, the median follow-up of this patient cohort was 27.4 months (range, ). HBV Reactivation and HBV-Related Hepatitis Flares. HBV reactivation occurred in 17 patients. Clinical characteristics were similar between patients with and without HBV reactivation, except that patients with HBV reactivation were less likely to test positive for anti-hbs at baseline (Table 1). Median time from the start of chemotherapy to HBV reactivation was 21.0 weeks (range, ). Serum HBsAg became positive in 12 of the 17 patients with documented HBV reactivation, whereas HBeAg became positive in 7. Nine episodes of HBV reactivation occurred during rituximab-chop chemotherapy, 3 occurred during second-line or further chemotherapy with other regimens, and 6 occurred during follow-up (Fig. 2). For the 6 episodes of HBV reactivation that occurred during follow-up, median time from the start of the final cycle of chemotherapy to documentation of HBV reactivation was 4.88 months (range, ). Hepatitis occurred in 26 patients, 10 of which were HBV-related hepatitis flares. Median time from diagnosis of HBV reactivation to occurrence of hepatitis flares was 49 days (range, ). Severe hepatitis (ALT levels higher than 10-fold ULN) occurred in 7 patients. The median value of the highest ALT levels during hepatitis flares was 238 IU/L (range, 101-2,592). Four of the ten HBV-related hepatitis flares were considered severe, despite entecavir treatment. HBV-related hepatitis flares resulted in delay in rituximab-chop chemotherapy in 2 patients by 1 and 2.6 weeks, respectively. Other possible causes of hepatitis included chemotherapy (rituximab-chop chemotherapy or second-line chemotherapy upon tumor progression; 10 patients), infection (3 patients), fatty liver (2 patients), and tumor progression (1

6 HEPATOLOGY, Vol. 59, No. 6, 2014 HSU ET AL Fig. 3. PFS (A) and OS (B) for patients with or without HBV reactivation. *Log-rank test. patient). No HBV-related fulminant hepatitis or hepatitis-related death occurred during the study period. Incidence of HBV reactivation and HBVrelated hepatitis flares were 10.4 and 6.4 per 100 person-year, respectively. Dose intensity of chemotherapy has previously been considered an important risk factor for HBV reactivation. 5,8 However, in the present study, dose reduction or delay of chemotherapy did not influence risk of HBV reactivation (Supporting Table 1). Response to Chemotherapy. One hundred and thirty-eight patients had measurable tumors at time of enrollment. The objective response rate was 76.8% (95% confidence interval [CI]: ), with 59 complete and 47 partial responses. Reasons for discontinuing rituximab-chop chemotherapy included completion of assigned treatment (124 patients), poor response to rituximab-chop chemotherapy (11 patients), treatment-related adverse events (12 patients), patient refusal (1 patient), and other reasons (hip fracture, 1 patient; occurrence of lung cancer, 1 patient). As of April 1, 2013, the estimated 3-year PFS rate was 67.3% (95% CI: ) and the 3-year OS rate was 72.9% (95% CI: ). The objective response rate to rituximab-chop did not differ significantly between patients with or without HBV reactivation (Supporting Table 2). Patients with HBV reactivation were associated with a poorer OS and PFS rates (Fig. 3). For the univariate analysis, the hazard ratio (HR) was 1.93 (95% CI: ; P ) and 1.72 (95% CI: ; P ) for OS and PFS, respectively (Supporting Tables 3 and 4). Multivariate analysis indicated that the objective response to rituximab-chop chemotherapy was the only independent predictor of PFS (HR 0.09, 95% CI: , P < 0.001). Independent predictors of OS included objective response to rituximab-chop chemotherapy (HR 0.10, 95% CI: , P < 0.001) and high baseline LDH (HR 5.10, 95% CI: , P ). Serious adverse events associated with rituximab-chop chemotherapy that occurred in more than 10% of patients included febrile neutropenia (27 patients) and infection (32 patients). Effects of the Sensitivity of HBV DNA Assay on Diagnosis of HBV Reactivation and Hepatitis Flare. By using the more sensitive HBV DNA assay (Table 1, assay #2), HBV reactivation was diagnosed in 27 patients (Table 1). For the 17 patients who had been diagnosed with HBV reactivation by using the in-house assay (Table 1, assay #1), HBV reactivation can be diagnosed by a median of 11.8 weeks (range, ) earlier when using assay #2. Of the 10 additional HBV reactivation episodes diagnosed using assay #2, only one was associated with hepatitis flare. Patients with hepatitis flare exhibited a far higher incidence of reappearance of HBsAg after HBV reactivation (100% vs. 28.5%; P ), whereas other clinical characteristics did not differ significantly between patients with or without hepatitis flare

7 2098 HSU ET AL. HEPATOLOGY, June 2014 Table 2. Effects of the Sensitivity of HBV DNA Assay on Diagnosis of HBV Reactivation and Hepatitis Flare Assay #1 (LLOQ 1,000 Copies/mL) (n 5 17) Assay #2 (LLOQ 300 Copies/mL) (n 5 27) HBV reactivation 100 person-year HBV reactivation with hepatitis flare 100 person-year Hepatitis Flare (1) (n 5 10) Hepatitis Flare (2) (n5 7) P Value Hepatitis Flare (1) (n5 10) Hepatitis Flare (2) (n5 17) P Value Timing of reactivation During R-CHOP 3 6 During follow-up 5 1 During second-line treatment 2 1 Reappearance of HBsAg after HBV reactivation 10 2 Reappearance of HBeAg after HBV reactivation < (Tables 1 and 2 and Supporting Table 5). HBsAg seroconversion was associated with higher HBV DNA and ALT levels during HBV reactivation (Supporting Table 6). Median time from the documented HBV DNA reactivation to HBsAg seroconversion was 14 days (range, 7-151) and median time from HBV DNA reactivation to hepatitis flare was 49 days (range, ).The objective response rate to rituximab-chop chemotherapy, PFS, and OS did not differ significantly between patients with or without HBV reactivation (see Supporting Fig. 1). Discussion In this study, lymphoma patients with resolved HBV infection were prospectively monitored for HBV reactivation during and after first-line rituximab- CHOP chemotherapy. HBV reactivation in patients with resolved HBV infection is an important healthcare concern in HBV endemic areas because approximately 60% of the general population is negative for HBsAg, but positive for anti-hbc, and fatal fulminant hepatitis because of HBV reactivation has been reported. The patient population, chemotherapy regimen, and follow-up schedule in this study are homogenous, compared with previous retrospective studies. Therefore, the clinical patterns described in this study may help design future monitoring and preventive strategies. Our data indicate that in this patient population, HBV reactivation induced by rituximab-chop chemotherapy is not uncommon. However, we did not observe any baseline clinical features predictive for HBV reactivation, except that patients who experienced HBV reactivation were less likely to have positive anti-hbs at baseline. Therefore, monthly monitoring of HBV DNA levels for all patients during and after rituximab-chop chemotherapy and antiviral therapy upon detection of HBV reactivation is a reasonable option for this patient population. In this study, we measured HBV DNA levels before the start of every cycle of chemotherapy and every 4 weeks for 1 year after completion of rituximab-chop chemotherapy. This approach appears reasonable because no hepatitis-related death was observed in patients, and only 2 required delay of chemotherapy because of HBV reactivation. HBV DNA levels should also be monitored regularly if patients receive second-line or further chemotherapy. This strategy of regular monitoring cannot be adopted across the board unless physicians are fully aware of the potential life-threatening consequence of hepatitis flares and all patients can be monitored as regularly as in this study. Awareness of this complication in anti-hbc-positive patients must be addressed, even in areas with low anti-hbc positivity. Universal screening of HBV serological markers, including HBsAg and anti-hbc, should be performed in lymphoma patients who will receive rituximab-containing chemotherapy. This recommendation has been included in the guidelines from major societies of liver study. 3-5 It should also be included in guidelines from oncology societies to improve physician awareness and patient safety. An alternative approach is routine prophylactic antiviral therapy, starting with rituximab-chop

8 HEPATOLOGY, Vol. 59, No. 6, 2014 HSU ET AL chemotherapy. This strategy may effectively prevent HBV reactivation and avoid the inconvenience of repeated HBV DNA monitoring. 20 Future studies to identify host and viral factors that can help predict the occurrence of hepatitis flares will help design tailored preventive strategies. 21,22 Prophylactic antiviral therapy can be used for patients with high risk of HBV reactivation, such as those with negative anti-hbs or positive HBV DNA at baseline, whereas regular monitoring can be used for patients with low risk. The effect of the different approaches on clinical outcome and their cost-effectiveness, particularly in HBVendemic areas, requires further investigation. A vital concern of HBV DNA monitoring in this patient population is the criteria for diagnosis of HBV reactivation and for starting antiviral therapy. In the retrospective series of Hui et al., patients were treated with lamivudine upon being diagnosed with hepatitis flare. Three of the eight patients with HBV-related hepatitis flare developed fulminant hepatitis and 1 died of liver failure. 8 This is consistent with our previous study, which revealed that therapeutic antiviral therapy upon detection of HBV-related hepatitis flare did not change the clinical course of HBV reactivation. 1 Hui et al. therefore recommended a 100-fold increase in HBV DNA as the standard to start antiviral therapy. Our data indicate that by using the more sensitive HBV DNA assay, HBV reactivation can be diagnosed earlier and more patients will be diagnosed for HBV reactivation. Whereas patients may benefit from an earlier start of antiviral therapy, certain HBV DNA increases may be clinically nonsignificant even without antiviral therapy. Therefore, both the potential efficacy and cost-effectiveness of the various treatment approaches should be considered to establish the criteria for diagnosis of HBV reactivation and for starting antiviral therapy. A further concern is the effect of HBV reactivation on the clinical outcome of lymphoma patients. Although HBV-related fulminant hepatitis or hepatitisrelated death was not observed during the study period, our series did show a trend of poorer PFS and OS in patients with HBV reactivation. However, the patient number in this study is too small to form any conclusions. Studies with far larger sample size are required to clarify the effect of HBV reactivation and interaction with other pertinent prognostic factors on clinical outcome. It remains to be explored whether specific host factors, such as genetic polymorphisms of the human leukocyte antigen alleles, may modulate both the clinical course of viral infection and response to anticancer therapy. 23,24 In conclusion, the results of this study indicate that in lymphoma patients with resolved HBV infection, HBV reactivation induced by rituximab-chop chemotherapy is not uncommon and clinically significant. The evidence calls for a universal screening for HBV serological markers for lymphoma patients before starting chemotherapy. Although regular monitoring with prompt antiviral therapy upon HBV DNA reactivation is a reasonable approach, this approach can only be adopted if patients can be very closely followed to avoid life-threatening hepatitis flares. Acknowledgment: The authors thank Ms. Mei-Hsing Chuang and Ms. Yueh-Ling Ho, Taiwan Cooperative Oncology Group, for their help in data management, statistical analysis, and administrative support. The authors also thank the following coinvestigators for their help in patient enrollment, treatment, and follow-up: Shang-Ju Wu, Ruey-Long Hong, Wen- Chien Chou, Jih-Luh Tang, Shang-Yi Huang (National Taiwan University Hospital, Taipei, Taiwan), Ching-Liang Ho, Tsu-Yi Chao, (Tri-Service General Hospital), Yi-Chang Liu (Kaohsiung Memorial University Hospital), Tseng-Hsi Lin, Young-Sen Yang (Taichung Veterans General Hospital), Ming-Sun Yu (Kaohsiung Veterans General Hospital), Ming-Chih Chang, Ruey-Kuen Hsieh (Mackay Memorial Hospital), Woei-Chung Lo, Su-Peng Yeh, Chen-Yuan Lin, Ching-Yun Hsieh, Chin-Chan Lin, Hsuan-Yu Lin (China Medical University Hospital), Chuan-Cheng Wang (Changhua Christian Hospital), Wen-Tsung Huang (Chi Mei Medical Center, Liou-Ying Campus), and Sung-Nan Pei (Chang Gung Memorial Hospital, Kaohsiung). The authors also thank Bristol-Meyer- Squibb, Taiwan, for support of the HBV DNA assay and the Liver Disease Prevention and Treatment Foundation, Taiwan, for logistic support. References 1. Hsu C, Hsiung CA, Su IJ, Hwang WS, Wang MC, Lin SF, et al. A revisit for prophylactic lamivudine for chemotherapy-associated hepatitis B reactivation in non-hodgkin s lymphoma: a randomized trial. HEPATOLOGY 2008;47: Lau GK, Yiu HH, Fong DY, Cheng HC, Au WY, Lai LS, et al. Early is superior to deferred preemptive lamivudine therapy for hepatitis B patients undergoing chemotherapy. Gastroenterology 2003;125: Lok ASF, Mcmahon BJ. Chronic hepatitis B. HEPATOLOGY 2007;45: European Association for the Study of the Liver: EASL clinical practice guidelines: management of chronic hepatitis B. J Hepatol 2009;50: Yeo W, Johnson PJ. Diagnosis, prevention and management of hepatitis B virus reactivation during anticancer therapy. 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