The immune system learned to keep the virus suppressed on its own
For the 254 million people living under the shadow of chronic hepatitis B, medicine has long offered suppression but rarely liberation. Now, a small but carefully observed trial suggests that priming the immune system with a therapeutic vaccine before delivering two complementary antivirals may produce something rarer: durable viral clearance that persists long after treatment ends. Presented at a major liver disease conference and published in Nature Medicine, the ENSURE study offers early evidence that a functional cure — once considered out of reach for most patients — may be achievable for a meaningful subset, provided the immune system has first been taught to recognize its adversary.
- Chronic hepatitis B kills 820,000 people annually, yet current therapies can suppress the virus but almost never eliminate it — leaving hundreds of millions in a permanent state of managed illness.
- The ENSURE trial revealed a striking divide: patients whose immune systems had previously responded to the BRII-179 vaccine cleared the virus at six times the rate of non-responders, 24 weeks after all treatment stopped.
- Unexpectedly, half of the durable responders had entered the study with relatively high viral loads, suggesting the vaccine-plus-antivirals strategy may reach a broader patient population than researchers initially anticipated.
- The combination therapy — vaccine, RNA-silencing drug, and interferon — was well-tolerated, and early regulatory recognition in China signals that authorities regard this approach as potentially transformative.
- Two fully enrolled Phase 2b trials, ENRICH and ENHANCE, are now racing toward 2026 readouts that will determine whether these results hold at scale and which patients stand to benefit most.
In November, researchers presented findings from ENSURE, a study testing whether a therapeutic vaccine could help the immune system do what decades of antiviral drugs have largely failed to accomplish: permanently clear hepatitis B virus from the body. The results, shared at a major liver disease conference in Washington and simultaneously published in Nature Medicine, offered cautious but meaningful grounds for optimism.
The trial enrolled 31 patients from the Asia-Pacific region who had previously received BRII-179, a vaccine designed to train the immune system to recognize and fight hepatitis B. Participants were divided by how strongly their immune systems had responded to that earlier vaccination. All 31 then received 48 weeks of combination therapy — elebsiran, which silences viral RNA, alongside pegylated interferon, a long-established antiviral.
The difference between the two groups was stark. At the end of treatment, 58 percent of prior vaccine responders had cleared hepatitis B surface antigen, the key marker of active infection, compared to just 17 percent of non-responders. Six months after treatment ended, 42 percent of responders — eight of 19 people — still showed no detectable antigen. Only one of 12 non-responders maintained that clearance. The durability of the effect suggests the immune system, once properly primed, continues suppressing the virus even without ongoing medication.
One finding surprised the researchers: half of the durable responders had entered the study with relatively elevated baseline viral loads. This hints that the approach may work across a wider range of patients than initially assumed, not just those with low viral burden at the outset. The therapy was generally well-tolerated, with no unexpected safety concerns.
Brii Biosciences is now running two larger Phase 2b trials to confirm and refine these results. ENRICH will focus on identifying which patients are most likely to respond to the vaccine, while ENHANCE will test different drug combinations and sequencing strategies — including whether the vaccine can meaningfully shorten the duration of interferon therapy. Both trials are fully enrolled, with results expected in 2026. Chinese regulators have granted breakthrough therapy designations to both BRII-179 and elebsiran, reflecting institutional confidence in the approach. Whether that confidence proves warranted depends on what the larger studies reveal about replicating what ENSURE's small cohort first made visible.
In November, researchers presented findings from an ongoing study of a new approach to treating chronic hepatitis B—one that combines a therapeutic vaccine with two other drugs and appears to produce lasting viral clearance in a meaningful portion of patients. The work, presented at a major liver disease conference in Washington and published simultaneously in Nature Medicine, suggests that this three-drug strategy might eventually allow doctors to shorten treatment timelines while achieving better outcomes than existing therapies alone.
The study, called ENSURE, enrolled 31 people in the Asia-Pacific region who had previously participated in an earlier trial of BRII-179, a vaccine designed to train the immune system to recognize and attack hepatitis B virus. Researchers divided these participants into two groups based on how well their immune systems had responded to the vaccine in the prior study. The responders—those who had generated strong antibody responses—numbered 19. The non-responders numbered 12. All of them then received 48 weeks of combination treatment with elebsiran, a drug that silences viral RNA, and pegylated interferon, a traditional antiviral therapy.
The results showed a stark difference between the two groups. At the end of treatment, 58 percent of the vaccine responders had cleared hepatitis B surface antigen, the viral marker that indicates active infection. Only 17 percent of non-responders achieved this milestone. More importantly, the benefit persisted. Six months after treatment ended, 42 percent of the responders—eight out of 19 people—still showed no detectable hepatitis B surface antigen. Among non-responders, only one of 12 maintained this clearance. The durability matters because it suggests the immune system, once primed by the vaccine, continues to suppress the virus even after the drugs are stopped.
One detail stood out to the researchers: half of the responders who maintained viral clearance six months post-treatment had started the study with relatively high baseline viral loads, between 1,514 and 3,086 IU/mL. This suggests the vaccine approach might work across a broader range of patients than initially expected, including those with more advanced viral burden. The combination therapy was generally well-tolerated, with no unexpected safety signals.
The implications are significant for a disease that affects more than 254 million people worldwide. Chronic hepatitis B kills roughly 820,000 people annually from liver complications. In China alone, 87 million people carry the chronic infection. Current treatments can suppress the virus but rarely eliminate it entirely. A functional cure—where the virus is cleared and doesn't return—remains elusive for most patients. This trial suggests that by first using the vaccine to sensitize the immune system, then hitting the virus with two complementary drugs, researchers might achieve that goal in a subset of carefully selected patients.
Brii Biosciences, the company developing BRII-179, is now running two larger Phase 2b trials to confirm and refine these findings. One study, called ENRICH, will focus on identifying which patients are most likely to respond to the vaccine. The other, ENHANCE, will test different combinations and sequences of the three drugs—whether they should be given together or in stages, and whether the vaccine truly allows for shorter courses of the expensive interferon therapy. Both trials are fully enrolled. Results are expected in 2026. The company received breakthrough therapy designations from Chinese regulators for both BRII-179 and elebsiran, a signal that authorities view the approach as potentially transformative. What happens next depends on whether these larger studies replicate what the smaller ENSURE cohort has shown: that the right combination of vaccine and antivirals, given to the right patients, can produce durable freedom from hepatitis B.
Citações Notáveis
The difference in hepatitis B surface antigen clearance rates observed at treatment end was maintained through 24 weeks of follow-up, supporting the potential for more rapid and durable viral loss and potentially shorter pegylated interferon treatment duration.— David Margolis, Chief Medical Officer of Brii Bio
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Why does it matter that these patients maintained viral clearance six months after stopping treatment?
Because hepatitis B is a virus that hides in the liver and can rebound if you're not constantly suppressing it. Most current drugs work like a lid on a pot—they keep the virus down, but the moment you stop taking them, it boils over again. If these patients stayed clear six months out, it suggests their immune system learned to keep the virus suppressed on its own. That's the difference between managing a disease and actually curing it.
The study mentions that responders had higher baseline viral loads than non-responders. Isn't that backwards?
It is counterintuitive. You'd expect people with less virus to do better. But what it tells us is that the vaccine isn't just working in easy cases. It's working in people whose bodies are carrying a heavier viral burden. That's what makes it potentially applicable to more patients in the real world.
What's the practical difference between a 58 percent clearance rate at the end of treatment and a 42 percent rate six months later?
The drop-off is real—some people's immune systems couldn't hold the line after the drugs stopped. But 42 percent sustained clearance is still remarkable for a disease where functional cure has been nearly impossible. And the researchers think they can improve that number by optimizing which patients get the vaccine and how the drugs are sequenced.
Why are they running two more trials instead of just moving to the final phase?
Because they need to understand the mechanism better. One trial is specifically designed to identify which patients will respond to the vaccine before they get the full three-drug regimen. The other is testing whether the vaccine actually allows them to use less interferon—a drug that's expensive and has significant side effects. If they can prove that, it changes the treatment landscape.
Is 42 percent a success?
In the context of hepatitis B, yes. This is a disease where most people never clear the virus. Forty-two percent of carefully selected patients achieving durable clearance is genuinely novel. But it's also why they need the larger trials—to see if that number holds up and whether it can be improved.