Tobevibart-Elebsiran Sustains HDV Suppression at 96 Weeks: Tarik Asselah, MD, PhD

A combination of a monoclonal antibody and a small interfering RNA continued to outperform monotherapy in suppressing the hepatitis D virus (HDV) through 2 years of treatment, with virologic responses deepening over time rather than plateauing, according to week 96 data from the phase 2 SOLSTICE trial presented at the European Association for the Study of the Liver 2026 Congress.

Combination Advantage Holds and Widens

The separation between the combination and monotherapy arms that emerged at week 48 persisted and became more pronounced by week 96. Tobevibart plus elebsiran, dosed every 4 weeks, achieved an HDV RNA target not detected (TND)—meaning no virus was detectable by polymerase chain reaction—in 88% of evaluated patients at week 96, up from 77% at week 72. By contrast, patients on tobevibart monotherapy saw their TND rates decline from 53% at week 72 to 46% at week 96, suggesting the combination arm continued to improve while monotherapy responses leveled off.

Hepatitis B surface antigen (HBsAg) suppression told a similar story. Approximately 94% of patients on combination therapy achieved HBsAg levels below 10 IU/mL by week 72, a threshold that reflects meaningful viral control, compared with roughly 19% on monotherapy—a gap that held through week 96. Tarik Asselah, MD, PhD, professor of hepatology at Hôpital Beaujon and the University of Paris-Cité, explained that the complementary mechanisms of the 2 agents—a monoclonal antibody and a small interfering RNA—drive the divergence.

"They are complementary," he said, "so you have 2 drugs…and it persists at 96 weeks."

Durability of Response Is a Key Signal

Perhaps equally important as the magnitude of response is its durability. Among patients who achieved TND status, Asselah reported no relapses, breakthroughs, or treatment failures.

When a patient’s blood shows virus not detected, it is maintained over time, he said, which begins to address one of the central open questions from earlier data cuts about whether virologic responses would hold.

What the Data Establish and What Comes Next

Asselah characterized the SOLSTICE findings as establishing 2 things the early readouts could only suggest: high antiviral efficacy and an acceptable safety profile, with treatment-emergent adverse events being largely grades 1 to 2 and transient. He was quick to note the study's limitations as a phase 2 trial with a small sample size. Both findings now require confirmation in the ongoing phase 3 ECLIPSE program, which is currently enrolling and will serve as the definitive test of whether the combination's performance translates at scale.