GSK Cuts Deal with Sino to Broaden Reach of Hepatitis B Drug

GSK Partners with Sino Biopharmaceutical for Hepatitis B Drug in China

GSK has entered into an agreement with Sino Biopharmaceutical to enhance the distribution and promotion of its experimental hepatitis B drug, bepirovirsen, in China. Under the deal, Sino's subsidiary, CTTQ, will purchase and market bepirovirsen through its network of over 5,000 medical centers for an initial five-and-a-half year term. This collaboration aims to address the significant burden of chronic hepatitis B in China, which accounts for approximately one-third of the global 250 million affected individuals. Bepirovirsen, an RNA-based medicine developed with Ionis Pharmaceuticals, is currently under regulatory priority review in China and could see U.S. approval by October 26.

• GSK's strategic partnership with Sino Biopharmaceutical's subsidiary, CTTQ, is designed to maximize access to bepirovirsen in China. CTTQ will leverage its extensive network of over 5,000 medical centers to distribute and promote the drug, ensuring broader reach for patients suffering from chronic hepatitis B infections in a region with a high disease burden. The agreement also offers GSK opportunities to evaluate Sino's early-stage pipeline for potential partnerships outside of China.
• Bepirovirsen, developed by GSK and Ionis Pharmaceuticals, is an RNA-based medicine positioned as a potential 'functional cure' for chronic hepatitis B. Clinical testing has demonstrated its ability to reduce the virus to undetectable levels within six months. The drug is currently undergoing regulatory priority review in China and has a potential U.S. approval date of October 26, with China and the U.S. representing two-thirds of the expected global market opportunity.
• Chronic hepatitis B affects over 250 million people worldwide, with China alone accounting for about a third of this global burden, according to the World Health Organization. The partnership aims to provide a new treatment option beyond lifelong antiviral drugs, addressing the high desire for treatment and the associated stigma of the disease in China, thereby helping GSK reach more patients more quickly.

Why a Functional Cure for Chronic Hepatitis B is Crucial

Current treatment approaches for chronic hepatitis B face fundamental limitations that prevent achieving functional cure in most patients. The most significant barrier is the inability to eliminate covalently closed circular DNA (cccDNA), the viral minichromosome that persists in hepatocyte nuclei and serves as the template for viral replication. While existing therapies can control infection and slow disease progression, they fall short of providing complete eradication.

• Limited therapeutic options and effectiveness: Approved treatments are restricted to interferon and nucleos(t)ide analogs, both with significant limitations - direct antiviral therapies require lifelong administration due to frequent viral rebound upon cessation, while pegylated interferon therapy achieves sustained off-treatment responses in only a minority of patients

• Persistent viral reservoir: The covalently closed circular DNA form of HBV represents the major barrier to cure, as current nucleos(t)ide analogs and interferon therapies rarely eliminate this viral minichromosome that maintains chronic infection

• Patient-specific treatment challenges: Hepatitis B e antigen positive immunotolerant patients remain at risk for developing active chronic hepatitis, yet current treatment options are ineffective for this population, and genotype C infections are more refractory to antiviral therapies than genotypes A and B

• Economic and accessibility barriers: High costs of medical care and antiviral drugs present critical obstacles, with lack of adequate reimbursement for treatment and diagnostic testing making adherence to treatment guidelines difficult in many regions

• Treatment duration uncertainty: While guidelines indicate patient selection criteria and treatment initiation timing, the optimal duration of therapy remains unclear, requiring individualized assessment that represents a significant challenge for general physicians

• Immune system dysfunction: Persistent T cell exposure to high antigen burden, particularly HBsAg, influences T cell differentiation and function, contributing to immune exhaustion that prevents natural viral clearance

Unlocking the Significant Chronic Hepatitis B Market in China

The most recent global estimates from 2022 indicate that chronic hepatitis B remains a substantial public health burden worldwide. Globally, 254 million people, representing 3.27% of the world's 7.758 billion population, were living with chronic HBV infection in 2022. In terms of new infections, there were 1.2 million new chronic HBV infections worldwide in 2022, contributing to the combined total of more than 2.2 million new chronic HBV and HCV infections. The disease burden resulted in more than 1.3 million deaths due to HBV and HCV combined, with the majority (1.1 million deaths) attributed specifically to HBV.

Geographic distribution reveals significant regional concentration of the disease burden. Five countries account for 55% of the combined global HBV and HCV burden: China leads with 83.7 million cases (27.5%), followed by India with 35.3 million cases (11.6%), Indonesia with 18.9 million cases (6.2%), Nigeria with 15.7 million cases (5.2%), and Pakistan with 12.6 million cases (4.2%). The African Region bears a disproportionate burden of new infections, accounting for 62.7% (771,000) of new chronic HBV infections in 2022. At the country level, prevalence varies dramatically from 0.1% to 35.0% depending on locality and population characteristics.

Despite the substantial disease burden, significant gaps remain in diagnosis and treatment access. Of the estimated 254 million people living with chronic HBV globally, only 34.1 million individuals were diagnosed in 2022, and merely 6.6 million received antiviral treatment. This represents a diagnosis rate of approximately 13.4% and a treatment rate of only 2.6% of the total infected population. Encouragingly, epidemiological trends from 2000-2021 show that age-standardized incidence, prevalence, and death rates from HBV-related liver disease have decreased globally, though HBV-related primary liver cancer incidence has risen in 65 countries during this period.

Bepirovirsen's Position in the RNA-based Hepatitis B Pipeline

Bepirovirsen is currently the only antisense oligonucleotide (ASO) targeting HBV mRNAs with detailed clinical trial data available in the literature. While other RNA silencers including antisense oligonucleotides and small-interfering RNAs are mentioned as forming the backbone of combination strategies for chronic hepatitis B, specific drug names and intervention models for other ASOs are not provided.

China Deal Propels Bepirovirsen Towards Hepatitis B Functional Cure

GSK's strategic alliance with Sino Biopharmaceutical for bepirovirsen in China marks a pivotal moment in the global fight against chronic hepatitis B (CHB). With China accounting for a third of the world's CHB burden, this collaboration, leveraging Sino's extensive medical network, is designed to ensure broad access for an innovative therapy addressing a significant unmet medical need. Current treatments for CHB, primarily nucleos(t)ide analogs and interferons, effectively suppress the virus but rarely achieve a functional cure, defined as sustained hepatitis B surface antigen (HBsAg) seroclearance.

Bepirovirsen, an antisense oligonucleotide (ASO) developed with Ionis Pharmaceuticals, represents a novel approach by targeting all HBV messenger RNAs. Early Phase 2 data have been encouraging, demonstrating HBsAg reductions and, notably, functional cure rates of approximately 9-10% in a subset of patients with low baseline HBsAg levels (<3000 IU/mL). This modest but significant achievement, coupled with an acceptable safety profile characterized mostly by mild-to-moderate injection site reactions and transient, self-resolving ALT flares, positions bepirovirsen as a promising candidate. The observation of ALT flares potentially correlating with HBsAg decline suggests a mechanism that might involve innate immune stimulation.

However, the path forward is not without considerations. While promising, the overall functional cure rates remain limited, and the long-term durability of responses will be critical to establish in ongoing Phase 3 trials. Efficacy appears more pronounced in patients with lower baseline HBsAg, which could influence patient selection. Furthermore, while bepirovirsen's safety profile has been favorable, the broader ASO class has, in some instances, been associated with more serious adverse events, underscoring the need for continued rigorous safety monitoring.

Strategically, the lack of pharmacokinetic drug-drug interactions with existing nucleos(t)ide analogs simplifies co-administration. The potential for sequential therapy with pegylated interferon to reduce post-treatment relapse offers a compelling combination strategy to enhance and sustain responses. The development of a prefilled syringe also streamlines administration, potentially facilitating patient self-administration. As bepirovirsen progresses through regulatory review, its success could redefine CHB treatment paradigms and further validate ASO technology in infectious diseases, moving closer to viral hepatitis elimination.