A number of groups have retrospectively analyzed response rates in PEG-IFN cohorts with respect to on-treatment HBsAg declines. In HBeAg-positive patients, one study showed that a baseline HBsAg level < 10,000 IU/mL was associated with a higher rate of response to

PEG-IFN therapy.35 Other studies have not confirmed this observation but have reported a significant association between on-treatment levels of HBsAg and responses to PEG-IFN. A large European study of 202 patients treated with PEG-IFNα2b with or without LAM for 52 weeks showed that responders (response was defined as an HBeAg loss with HBV DNA levels < 1 × 104 copies/mL 26 weeks after treatment) experienced a more profound HBsAg decline at week 52 (3.3 versus 0.7 Rapamycin ic50 log10 IU/mL) and week 78 (3.4 versus 0.35 log10 IU/mL, P < 0.001). Moreover, any HBsAg decline at week 12 had

a positive predictive value (PPV) of 25% for a response and a PPV of 15% for HBsAg loss up to 3 years after treatment.26 A Hong Kong Poziotinib manufacturer study of 92 patients who were treated with PEG-IFNα2b with or without LAM for 32 to 48 weeks found that HBsAg levels < 1500 IU/mL at month 3 and HBsAg levels < 300 IU/mL at month 6 (21% of the patients) could predict a sustained response 12 months after treatment (the PPVs were 46% and 62%, respectively). In addition, the combination of an HBsAg level ≤ 300 IU/mL and a >1 log reduction at month 6 had a PPV of 75%.35 A small study from China showed that an HBsAg level < 1500 IU/mL at week 12 of IFNα/PEG-IFNα therapy had a PPV of 33% for HBeAg seroconversion after 24 weeks of treatment.36 Piratvisuth et al.37 reported that HBsAg levels < 1500 IU/mL at week 12 of PEG-IFNα2a treatment (23% of the patients) ADAM7 were associated with an HBeAg seroconversion rate of 57% 6 months after treatment; 18% of these patients experienced HBsAg clearance. In HBeAg-negative patients, the baseline HBsAg level could not predict the response to PEG-IFN therapy,32, 38, 39 but sustained responders had marked decreases in

their serum HBsAg levels at the end of treatment (2.1 ± 1.2 log10 IU/mL) and at week 72.38 Brunetto et al.32 further indicated that both an HBsAg level ≤ 10 IU/mL at week 48 (12% of the patients) and an on-treatment HBsAg decline > 1.1 log10 IU/mL (22% of the patients) were significantly associated with HBsAg clearance 3 years after treatment (relative risks of 22.8 and 10.8, respectively, P < 0.0001). Moucari et al.38 also found a significant association between an HBsAg decline and a sustained response; they reported that decreases of 0.5 and 1.0 log10 IU/mL at week 12 (19% of patients) and week 24 (25% of patients) of PEG-IFNα2a therapy had high PPVs (89% at week 12 and 92% at week 24).