Vir Biotechnology’s Hepatitis B Data Offers Hope, But Financial Struggles Weigh on Stock

Vir Biotechnology’s recent announcement of preliminary 24-week post-treatment data from its MARCH Phase 2 study for the combination of tobevibart and elebsiran has reignited interest in its chronic hepatitis B (CHB) program. The results suggest the regimen may offer a path to functional cure for a subset of patients, particularly those with low baseline hepatitis B surface antigen (HBsAg) levels. However, the modest efficacy rates, coupled with Vir’s financial woes and unresolved partnership needs, cast doubt on the treatment’s commercial viability.

Study Findings: A Nuanced Path Forward

The MARCH study evaluated tobevibart (an immunostimulatory Toll-like receptor 7/8 agonist) and elebsiran (an antisense oligonucleotide targeting hepatitis B virus RNA) with or without pegylated interferon alpha (PEG-IFNα). Key efficacy endpoints focused on HBsAg loss (seroclearance) and functional cure—defined as undetectable HBsAg and HBV DNA 24 weeks after stopping treatment.

• Functional cure rates reached 11-15% in patients with baseline HBsAg <1,000 IU/mL, rising to 13% with PEG-IFNα when allowing transient viral blips.
• HBsAg seroclearance occurred in 17-21% of this subgroup, but only 4-10% of the broader cohort achieved functional cure, highlighting the importance of baseline HBsAg levels.

The safety profile remained consistent with prior trials, with no new risks identified. However, Vir emphasized that Phase 3 development for CHB would proceed only with a global partner, which remains unsecured. This dependency underscores the high hurdle Vir faces in advancing the program.

Financial Strains and Stock Performance

Despite the scientific progress, Vir’s stock has struggled. Year-to-date through May 2025, shares fell 23.3%, far outpacing the S&P 500’s 4.7% decline. This underperformance reflects broader concerns:

• Q1 2025 financials revealed a net loss of $121 million, compared to $65 million in Q1 2024, with revenue collapsing to $3 million from $56 million as a GSK collaboration expired.
• The company’s cash runway, extended to mid-2027, depends on cost-cutting measures like facility closures and layoffs—a stark reminder of its precarious financial state.

Analysts have been unsparing. Zacks Investment Research assigned a Hold rating, citing missed earnings (a -6% earnings surprise) and revenue falling 85% below estimates. The firm noted Vir had “no earnings beats in the last four quarters,” underscoring investor skepticism.

Pipeline Challenges and Strategic Risks

While the CHB program dominates headlines, Vir’s broader pipeline offers limited near-term catalysts. Oncology candidates like VIR-5818 and VIR-5500 remain in early trials, and the hepatitis delta (CHD) program—where the combo achieved complete viral suppression in most patients—faces smaller market opportunities.

The lack of a CHB partner looms largest. Without a strategic alliance to share Phase 3 costs, Vir’s financial flexibility may be insufficient to pursue late-stage development. Competitors like Gilead Sciences, with its approved HBV therapies, already dominate the space, raising questions about the combination’s differentiation.

Conclusion: Scientific Progress vs. Execution Risks

Vir’s MARCH data marks a milestone in tackling HBV’s toughest challenge: achieving durable HBsAg loss. For patients with low baseline antigen levels, the regimen offers hope. Yet, the 8-10% functional cure rate in broader populations falls short of transformative benchmarks, and the reliance on an unsecured partner clouds the path to market.

Financially, Vir’s $1.0 billion cash balance buys time, but its stock’s decline and analyst pessimism reflect investor doubts about execution. The company’s survival hinges on securing a CHB partner, advancing CHD programs, and managing costs without sacrificing research momentum.

For investors, the calculus is grim: Vir’s shares now trade at a $1.8 billion market cap, down from $10 billion in 2021. While the science holds promise, the odds of overcoming financial and operational hurdles remain low. Until Vir secures partnerships or demonstrates stronger efficacy, the stock may remain a high-risk gamble for all but the most speculative investors.