Patient characteristics
From March 2017 to March 2021, 2329 HCC patients were screened. A total of 499 patients met the inclusion criteria, including 296 patients in the TKI group and 203 patients in the combination group (Fig. 1). The baseline characteristics of all patients are shown in Table 1. The patients were mostly male (n = 439,78.9%), and the median age was 55 years old (IQR, 48-60). The median follow-up time in the TKI group was 6 months (IQR, 3-11), and the median follow-up time of the combination group was 5 months (IQR, 2-9). The antitumor drugs in the TKI group were mainly lenvatinib (n = 145, 48.9%) and sorafenib (n = 145, 48.9%). The combined group was dominated by lenvatinib plus sintilimab (n = 106, 52.2%) and sorafenib plus sintilimab (n = 30, 14.7%). Anti-HBV drugs were administered to all patients, mainly entecavir (n = 425, 85.1%) and tenofovir (n = 41, 8.2%). There were more local regional treatments in the TKI group than in the combination group (82.4% vs. 53.7%, P<0.001).
HBV reactivation
Among the 499 HCC patients, 138 (27.7%) had HBV reactivation according to Definition A, 70 (14%) according to Definition B and 13 (2.6%) according to Definition C. The 3-month, 6-month and 12-month cumulative incidence rates of HBV reactivation (according to Definition A) in the TKI group and combination group were 7.8%, 12.8%, 21.3%, and 9.9%, 19.2% 30.0%, respectively (Fig. 2).
HBsAg seroclearance
During the follow-up of 499 HCC patients, only 5 patients (1%) developed HBsAg seroclearance, 2 patients received TKI, and 3 patients received TKI combined with PD-1 inhibitors (Table 2). After HBsAg seroclearance, 3 patients continued to use antiviral drugs, but all 3 had HBV reactivation, which occurred with a median onset of 20 weeks (range, 15-110 weeks). At reactivation, all patients had HBV DNA >2 log increase with the baseline undetectable even though the HBsAg remained negative.
HBV pgRNA and HBsAg quantitative analysis
Sixty-three eligible patients were selected from above cohorts with plasma samples collected before and after treatment (TKI group with 19 patients, TKI plus PD-1 inhibitors group with 44 patients). There was no significant difference in baseline characteristics between the two groups (suppl. Table 1). The incidence of HBV reactivation, pg RNA and HBsAg increasing rate in the TKI combined with PD-1 inhibitors group were higher than those in the TKI group (10.5% vs. 25%, 5.3% vs. 25%, 5.1% vs. 11.4%, respectively) (suppl. Table 2).
Factors associated with HBV reactivation
Table 3 and suppl. Table 3 analyzed factors associated with HBV reactivation. The levels of HBV reactivation in the combination group were significantly higher than those in the TKI group no matter according to Definition A, Definition B or Definition C (P=0.02, P=0.01, P=0.04). The baseline levels of AFP (P=0.04) and ALT (P=0.01) showed significant differences only when Definition A was used. Additionally, HBsAb negativity was only significant when Definition B was used for reactivation (P=0.04). There was no significant difference in the HBV reactivation rate between patients with or without local treatment during TKI group and the combination group (suppl. Table 4).
In the multivariate analysis using Definition A for reactivation, combination therapy (HR 1.41, 95% CI 1.00-1.99, P=0.05), ALT>40 U/L (HR 1.50, 95% CI 1.05-2.16, P=0.03) and tumor diameter greater than 5 cm (HR 1.58, 95% CI 1.10-2.28, P=0.01) were independent risk factors for HBV reactivation. When Definition B was used, combined treatment (HR 1.78, 95% CI 1.09-2.92, P=0.02) and HBsAb negativity (HR 2.57, 95% CI 1.16-5.67, P=0.02) were independent factors. However, the combination of PD-1 inhibitors with TKI was the only significant risk factor for HBV reactivation when Definition C was used (HR 3.47, 95% CI 1.08-11.14, P=0.04).
HBV reactivation and prognosis
The constituent ratio of simultaneous tumor progression in patients with HBV reactivation is shown in Supplementary Table 5. Among 138 patients with HBV reactivation using Definition A, 79 (57.2%) had HBV reactivation and tumor progression at the same hospitalization, but the rates were higher in both the Definition B and Definition C groups (65.7% and 76.9%, respectively). The cumulative tumor progression rate and OS in patients with and without HBV reactivation were compared by log rank tests, and the risk curves are shown in Figure 3. The rate of tumor progression in both the Definition A and Definition B reactivation groups was significantly higher than that in the non-HBV reactivation group (P <0.001, P =0.008). Compared with the HBV reactivation group, the non-HBV reactivation group had longer median OS according to Definition A and Definition B, 20 months vs. 14 months (P=0.001), and 19 months versus 15 months (P=0.016). Due to insufficient cases, the survival curve of patients with reactivation according to Definition C (n = 13) was not drawn.