Quantitative HBsAg Testing and the Path to Finite-Duration Therapy

"Quantitative HBsAg Testing and the Path to Finite-Duration Therapy" takes up the question of how quantitative surface antigen testing is changing eligibility for emerging therapies.

Dr. Chung turns to testing, asking Dr. Dieterich to walk through the distinction between qualitative and quantitative hepatitis B surface antigen testing and how quantitative testing may help stratify patients for emerging therapies.

Dr. Dieterich explains that his practice routinely checks ALT, AST, and AFP, along with surface antigen and antibody once or twice yearly to catch spontaneous seroconversion. With new therapies on the horizon built around quantitative surface antigen thresholds, his team now checks quantitative levels on every patient at least annually. He is encouraging the small number of untreated patients with low viral loads to start nucleoside or nucleotide analog therapy, since achieving an undetectable viral load may matter more once newer agents become available. He cites thresholds of surface antigen below 3,000 or 1,000, combined with undetectable HBV DNA on treatment, as predictive of a better chance at clearing surface antigen with emerging therapies.

Dr. Chung notes that updated AASLD/IDSA guidelines now recommend quantitative surface antigen testing in the standard workup. Dr. Dieterich says this should help identify eligible patients for new medications, and that most U.S. treaters have not routinely ordered quantitative testing, though EASL data and publicity around the update should change that.

Asked how he discusses finite-duration therapy with patients told for years they would need lifelong treatment, Dr. Dieterich says he has never framed it that way. He instead tells patients they only need treatment until their surface antigen clears, encouraging them to focus on the immunologic effect from the brain to the T cells. Citing AASLD and EASL data, he notes that patients below the 3,000 or 1,000 surface antigen thresholds have significantly better odds of clearance with new therapies. Dr. Chung calls this new hope beyond positive thinking; Dr. Dieterich agrees, adding that clinicians will use everything available in the toolbox.

Up next, in "Unmet Needs and Long-Term Antiviral Safety in Hepatitis B Care," the experts confront where current standard of care still falls short.