– Primary endpoint met in both trials –
– Bepirovirsen demonstrated a statistically significant and clinically meaningful functional cure rate –
– Chronic hepatitis B (CHB) accounts for ~56% of liver cancer cases and affects more than 250 million people worldwide –
– Global regulatory filings planned from Q1 2026 –
Ionis Pharmaceuticals, Inc. (Nasdaq: IONS) partner GSK today announced positive results from two pivotal Phase 3 studies, B-Well 1 and B-Well 2, evaluating the safety and efficacy of bepirovirsen, an investigational antisense oligonucleotide (ASO) for the treatment of chronic hepatitis B (CHB). The studies included over 1,800 patients from 29 countries. GSK licensed bepirovirsen from Ionis and the two companies have collaborated on its development.
CHB is a major health challenge affecting over 250 million people worldwide and is the leading cause of liver cancer. The current standard of care, nucleos(t)ide analogues, often requires lifelong therapy and the functional cure rates remain low, typically only 1%. Functional cure for CHB is when the virus can no longer be detected in the blood as measured by the sustained loss of hepatitis B surface antigen (HBsAg), a viral protein that signals ongoing infection, and undetectable hepatitis B virus DNA for at least 24 weeks after a finite course of treatment. Functional cure is associated with significant reduction in the risk of long-term liver complications, including liver cancer, as well as all-cause mortality.
The B-Well studies met their primary endpoint, and bepirovirsen demonstrated a statistically significant and clinically meaningful functional cure rate. Functional cure rates were significantly higher with bepirovirsen plus standard of care compared with standard of care alone. Results were statistically significant across all ranked endpoints, including in patients with baseline surface antigen (HBsAg) ≤1000 IU/ml where an even greater effect was demonstrated. The studies demonstrated an acceptable safety and tolerability profile consistent with what was reported in other studies.
“CHB is one of the most common, persistent viral infections in the world, with currently no approved therapy that can achieve meaningful functional cure. Bepirovirsen is uniquely positioned to effectively treat CHB based on its potential to reduce the replication of hepatitis B virus, suppress hepatitis B surface antigen and stimulate the immune system,” said Brett P. Monia, Ph.D., chief executive officer, Ionis. “Today’s positive results are made possible by the strategic collaboration between Ionis and GSK, and demonstrate that bepirovirsen has the potential to bring hope to the millions of people living with CHB. This is the first of five anticipated Phase 3 readouts from Ionis’ partnered programs this year, underscoring the broad applicability of our technology.”
Full results will be submitted for presentation at an upcoming scientific congress, published in a peer-reviewed journal and used to support regulatory submissions to health authorities worldwide. If approved, bepirovirsen has the potential to become the first finite, six-month therapeutic option for CHB and to serve as a backbone for future sequential treatment strategies.
Bepirovirsen has been recognized by global regulatory authorities for its innovation and potential to address significant unmet need in hepatitis B with Fast Track designation from the US FDA, Breakthrough Therapy designation in China and SENKU designation in Japan.
GSK licensed bepirovirsen from Ionis in 2019 under a collaborative development and licensing agreement. Under the terms of the agreement, Ionis received an upfront payment, license fee and development milestone payments and is eligible to receive an additional $150 million in regulatory and sales milestone payments as well as tiered royalties of 10-12% on net sales of bepirovirsen.
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