These days deciding when to stop targeted treatment for chronic hepatitis B is a bigger challenge than knowing when to start, Norah A. Terrault, MD, MPH, observed at the Gastroenterology Updates, IBD, Liver Disease Conference.
That’s because the treatment paradigm is in flux. The strategy is shifting from achieving hepatitis B virus (HBV) DNA suppression through indefinite use of nucleoside analogues to striving for functional cure, which means eliminating hepatitis B surface antigen (HBsAg) and sustained inactive chronic hepatitis B off therapy. It’s a goal that recognizes that, while suppression is worthwhile because it reduces a patient’s risk of hepatocellular carcinoma, HBsAg clearance is better because it’s associated with an even lower risk of the malignancy, explained, professor of medicine and chief of gastroenterology and liver diseases at the University of Southern California, Los Angeles.
The current strategy in patients who are hepatitis B e antigen (HBeAg) positive at the outset is to treat with a nucleoside analogue until seroconversion, followed by a further year or more of consolidation therapy then treatment withdrawal. It’s a rational approach whose primary benefit is it allows identification of the roughly 50% of patients who can remain off treatment with inactive chronic hepatitis B. The other 50% – those who experience clinical relapse – will need retreatment.
Factors predictive of increased likelihood of a sustained off-treatment response include age younger than 40 years at the time of seroconversion, more than 1 year of consolidation therapy, and undetectable HBV DNA at cessation of treatment.
“In my own practice now, I actually extend the consolidation period for 2 years before I consider stopping, and I really favor doing a trial of stopping treatment in those who are younger,” Dr. Terrault said.
The biggest change in thinking involves the duration of therapy in patients who are HBeAg negative. The strategy has been to treat indefinitely unless there is a compelling reason to stop, such as toxicity, cost, or patient preference. However, it has now been demonstrated in at least nine published studies that withdrawal of therapy has a favorable immunologic effect in noncirrhotic patients with HBeAg-negative chronic hepatitis B who have been HBV DNA negative on nucleoside analogues for at least 3 years. This trial off therapy can bring major benefits because roughly 50% of patients will have sustained inactive chronic hepatitis B off-treatment and 20% of patients will become HbsAg negative with functional cure at 3-5 years of follow-up.
“This is what’s impressive: that 20% of patients have lost surface antigen, because if you continue HbeAg-negative patients on nucleoside analogue therapy, essentially none of them lose surface antigen. This is an impressive number, and you’re also able to identify about 50% of patients who didn’t need to be on treatment because they now have immune control and can remain inactive carriers off treatment,” the gastroenterologist commented.
Treatment withdrawal in HBeAg-negative patients usually is followed by disease flares 8-12 weeks later because of host immune clearance, and therein lies a problem.
“The challenge with the withdrawal strategy is these flares that appear to be necessary and important, can be good or bad, and we’re really not very good at predicting what the flare is going to look like and how severe it’s going to be,” according to Dr. Terrault, first author of the current American Association for the Study of Liver Diseaseson prevention, diagnosis, and treatment of chronic hepatitis B.
The good flares are accompanied by a reductions in HBV DNA and viral proteins, loss of HbsAg, and preserved liver function. The bad flares entail excessive host immune clearance leading to liver dysfunction or failure, with no reduction in viral proteins. The search is on for predictors of response to treatment withdrawal in HbeAg-negative patients. Potential differences in outcomes with the three available nucleoside analogues are being looked at, as are duration of viral suppression on treatment and differences in patient characteristics. A low quantitative HbsAg level at the time of drug withdrawal may also be important as a predictor of a higher likelihood of HBsAg loss over time off treatment.
“The studies that have been done are basically withdrawing everyone and then seeing what happens. I think we want to have a more refined approach,” she said.
This is an unfolding story. The encouraging news is that the drug development pipeline is rich with agents with a variety of mechanisms aimed at achieving HbsAg loss with finite therapy. Some of the studies are now in phase 2 and 3.
“We should be extremely excited,” Dr. Terrault said. “I think in the future we’re very likely to have curative therapies in a much greater proportion of our patients.”