O-15 : Impact of Treatment with Tenofovir Alafenamide (TAF) or Tenofovir Disoproxil Fumarate (TDF) on Hepatocellular Carcinoma (HCC) Incidence in Patients with Chronic Hepatitis B (CHB)

Aims: Potent antiviral treatment can reduce HCC incidence in CHB patients. TAF has shown antiviral efficacy similar to TDF, with higher rates of ALT normalization and no resistance in Phase 3 studies. We evaluated the impact of TAF or TDF on HCC in the ongoing Phase 3 studies. Methods: HBeAg-positive (n=1039) and -negative (n=593) patients with HBV DNA≥20,000 IU/mL and ALT >60 U/L (males) or >38 U/L (females) were recruited from 190 sites in 20 countries and randomized (2:1) to TAF or TDF. HCC was assessed at 6-monthly intervals by hepatic ultrasonography introduced after Week 96 and throughout by local standards of care. The standardized incidence ratio (SIR) for HCC was calculated for observed cases relative to predicted risk using the REACH-B model. Results: Through 5 years of follow-up, HCC occurred in 21 patients (1.0% [11/1,093] with TAF, 1.9% [10/539] with TDF). Median (Q1, Q3) time to HCC onset was 104 (55, 191) weeks. At baseline, relative to those without HCC, patients with HCC were more likely to be older (median age 53 vs 39y; P<0.001), male (90% vs 65%; P=0.014), and cirrhotic (FibroTest ³0.75; 33% vs 9%; P<0.001). The overall SIR was significantly reduced with TAF or TDF (SIR 0.42, 95% CI 0.27-0.64). HCC incidence was significantly reduced in noncirrhotic patients (SIR 0.37, 95% CI 0.22 to 0.63), and in patients receiving TAF (SIR 0.35, 95% CI 0.19-0.62). Lack of ALT normalization at Week 24 (HR 6.90; P=0.011), cirrhosis (HR 4.18; P=0.006), baseline HBsAg level (HR 0.53; P=0.006), and baseline hypertension (HR 5.55; P<0.001) were significant predictors of HCC development by multivariable analysis. Conclusions: In CHB patients receiving TAF or TDF, the incidence of HCC was reduced comparing with expected HCC incidence from REACH-B model. In patients treated with TAF, a significant reduction in SIR was seen, whereas those treated with TDF showed a trend toward a reduction.