Modification of Pegasys dosing categories for alignment across pediatric studies and to conform to the recently approved pediatric dosing regimen for hepatitis C; The hepatitis B virus DNA (HBV-DNA) level required for study inclusion has been corrected; To enhance recruitment and avoid unnecessary exclusion of patient with true chronic hepatitis B (CHB) (positive hepatitis B envelope antibody [HBeAg], positive hepatitis B surface antigen [HBsAg], detectable HBV-DNA), the requirement for negative hepatitis B surface antibody (anti-HBs) and hepatitis B envelope antibody (anti-HBe) has been removed from the inclusion criteria. The diagnostic criteria of CHB does not require measurement of antibodies; The seroconversion stopping rule has been updated to reflect the full seroconversion definition of both HBsAg loss and presence of anti-HBs.

The Schedule of Assessments have been updated with respect to lactate and tyrosine-methionine-aspartate-aspartate (YMDD). These were originally only included for the Schedule of Assessments for the Pegasys + Lamivudine treatment arm, but it may be difficult to ensure drawing of baseline bloods only after randomization at site. Therefore, these parameters are identical for all patients (regardless of treatment arm), and the YMDD parameter has been moved to screening instead of baseline; Text has been added to reflect the fact that exploratory analyses may be conducted not only to ascertain the presence of YMDD mutations but others as required.

The NV25361 protocol version numbers and EUDRACT number have been amended. This study was originally an investigator-lead single-center study sponsored by King's College Hospital/King's College London (KCH/KCL) and, as such, already had a EUDRACT number assigned (2006-000977-31). The KCH/KCL protocol underwent four amendments, with the final amendment being Version 5 dated 29 April 2010. Plans were then agreed with KCH/KCL for Roche to become the study sponsor and continue the study as a multi-center study. Roche prepared a protocol amendment, which was numbered Version 1 (2 January 2013) and a new (different) EUDRACT number (2012-005356-42) was assigned. Roche then prepared a subsequent amendment, Version 2 (8 May 2013). However, the original EUDRACT number should have been maintained and the protocol version should have followed on from the latest KCH/KCL protocol version number such that the subsequent versions amended by Roche should have been Versions 6 and 7, respectively, rather than Versions 1 and 2. In the future, the protocol version numbers will continue to follow on sequentially from the KCH/KCL protocol version numbering under the original EUDRACT number assigned at the start of the study (2006-000977-31).

The Pegasys monotherapy arm has been removed. Concerns regarding the probable low response rates to treatment with Pegasys monotherapy were raised by the study Data Safety Monitoring Board (DSMB) members and potential study investigators during feasibility; Some subjects were recruited into the study under the previous single-site investigator led three-arm study, which included the Pegasys monotherapy arm, and have all now completed their treatment. Text has been included to say that these subjects will roll over into the Roche-sponsor protocol and all data will be reported when the study has been completed. The Pegasys monotherapy schedule of assessments has been updated to include the long-term follow-up period for these subjects; The primary endpoint has been changed from seroconversion to anti-HBs at 1-year post-end of treatment/end of untreated observation to loss of HBsAg at 24 weeks post-end of treatment/end of untreated observation; The secondary endpoints and schedule of assessments have been updated accordingly, and the length of the untreated observation period has been reduced from 100 weeks to 80 weeks to coincide with the earlier primary endpoint; The safety objectives of the study have been updated to clarify that assessment of AEs will include neurological and psychiatric events; For clarity, the efficacy and safety outcome measures have been updated to include the timepoints at which they will be measured; For consistency, AEs of concern have been amended to non-serious AEs of special interest; The diagnosis of CHB is defined as presence of HBsAg for 6 or more months. Hence, the inclusion criterion for positive HBsAg and HBeAg has been changed from more than 1 year to more than 6 months prior to baseline to ensure that eligible subjects diagnosed with CHB within 6-12 months are not unnecessarily excluded. The seroconversion stopping rule has been removed.

Analysis of anti-drug antibodies (ADAs) has been added as an exploratory objective in order to follow regulatory guidelines for increased level of immunogenicity testing for new indications (EMA 2008 – Guideline on immunogenicity assessment of biotechnology-derived therapeutic proteins); The Ministry of Healthcare of the Russian Federation requires completion of efficacy and safety clinical studies with Pegasys in combination with lamivudine in children with Hepatitis B aged 12 to 17 years of age prior to enrollment of children below 12 years of age. Therefore, the age inclusion criterion has been updated, specifically for Russia, to specify that only patients >/= 12 years old can be enrolled in this study; The inclusion criterion regarding informed consent has been updated to clarify that those subjects <18 years of age at baseline who are legally considered to be adults according to national legislation must consent in their own right if required by national legislation. In addition, the informed consent section has been updated to clarify that minors who attain legal adulthood during the course of the study must consent in their own right at that time, if required by national legislation.

Randomization stratification factor (HBV genotype) has been amended from ‘genotype A vs non-A’ (2 levels) to ‘genotype A vs. B/C vs. D/others’ (3 levels) to prevent any potential imbalance of HBV genotype allocation between the 2 randomized arms, since it is expected that reasonable proportions of B,C and D HBV genotypes will be recruited. Sub-analyses from the Pegasys adult immune-active CHB study) have shown different efficacy response according to HBV genotype, with response rates being similar in genotypes B and C; Pegasys dose modification guidance has been updated with recommendations for dosage modification for management of psychiatric disorders as outlined in Table 3 of the Pegasys United States Prescribing Information (USPI) dated March 2015; Assessments on sexual maturation (Tanner staging, date of menarche onset) have been added following an FDA request, and relevant section and the schedule of assessments have been updated accordingly; Pharmacokinetic (PK) sampling has been revised.

Study treatment has been modified to include entecavir as a nucleoside analogue option for the combination treatment with Pegasys. Prior to randomization investigators will choose between lamivudine or entecavir. Subjects are treated for the 8-week lead-in phase and the subsequent 48-week Pegasys-combination phase with the same nucleoside analogue throughout the study (if applicable); The Ministry of Healthcare of India required the exclusion of younger subjects from this study. Therefore, the age inclusion criterion has been updated, specifically for India, to specify that only subjects >/= 12 years old can be enrolled in this study; The inclusion criterion regarding HBV DNA level has been updated to > 20,000 IU/mL following review of published data and guidelines on the management of hepatitis B of patients with CHB in the immune-tolerant phase as well as following recommendation of Health Authorities that have evaluated this protocol; The primary analysis of the study has been updated to include the new study treatment option, Pegasys + entecavir. Furthermore testing of the primary endpoint has been updated to clarify that it is a superiority test.

Results from two multicenter clinical trials (sponsored by the National Institutes of Health [NIH]) evaluating the entecavir plus Pegasys treatment regimen in subjects with immune-tolerant chronic hepatitis B (CHB) were made available in October 2017 at the American Association for the Study of Liver Diseases Congress in Washington, USA. These two NIH studies demonstrated minimal to no efficacy of the intervention in both adult and pediatric subject populations with immune-tolerant CHB. Moreover, both studies had a similar design to Study NV25361. The conclusion was that the combination of entecavir with Pegasys, administered for up to 48 weeks, rarely led to loss of hepatitis B envelope antigen with sustained suppression of hepatitis B virus (HBV) DNA levels and was associated with frequent but not serious adverse events. The authors also concluded that more potent and more broadly targeted regimens against HBV are needed to treat children in the immune-tolerant phase of chronic HBV infection. Because of the similar study design, treatment regimen and efficacy assessments compared with these two NIH-sponsored studies, Study NV25361 was not expected to demonstrate efficacy in the target subject population. Based on the results of the NIH pediatric study and following a Pediatric Investigational Plan (PIP) modification procedure, the PDCO agreed in March 2018 to modify the PIP for Pegasys and remove Study NV25361 from the PIP commitments.

After this decision, the Sponsor terminated recruitment in the study on 28 March 2018 after enrollment of 62 patients (26 patients had been randomized to the active combination treatment, and 3 subjects had been randomized to Pegasys monotherapy before Roche became the study sponsor). This decision to terminate recruitment was also in accordance with the recommendation from the Data Safety Monitoring Board on 22 March 2018 based on the NIH results demonstrating minimal efficacy and a changed benefit-risk assessment. No specific safety concerns were identified in their scheduled review of the study. The protocol for Study NV25361 has been amended because of the expected lack of efficacy of the treatment regimen and the premature termination of recruitment.