ViiV Healthcare’s investigational broadly neutralising antibody - N6LS - successfully maintains viral suppression in long-acting treatment of HIV

Rhea-AI Summary

ViiV Healthcare announced positive results from its phase IIb EMBRACE study evaluating N6LS (VH3810109), a broadly neutralising antibody for HIV treatment. When administered every four months in combination with monthly cabotegravir long-acting (CAB LA), N6LS effectively maintained viral suppression in HIV patients stable on treatment.

Key findings at the six-month endpoint showed that 96% of participants receiving N6LS 60mg/kg intravenously and 88% receiving 3000mg subcutaneously maintained HIV-1 RNA levels below 50 copies/mL, compared to 96% in the standard-of-care group. The treatment was generally well-tolerated, though subcutaneous administration showed more frequent infusion site reactions (14%) compared to none with IV administration.

Based on these favorable results, ViiV Healthcare will advance development of a six-month IV formulation of N6LS in combination with CAB LA in an EMBRACE part two trial.

Positive

• High efficacy rates: 96% IV and 88% subcutaneous success in viral suppression
• Generally well-tolerated IV administration with no grade 3-4 adverse events
• Potential for extended dosing intervals (every 4 months)
• Advancement to next development phase with 6-month formulation

Negative

• Confirmed virologic failure in two participants from each treatment group
• Higher adverse events in subcutaneous administration (14% infusion site reactions)
• 16% of subcutaneous group experienced grade 3-4 adverse events

Insights

Financial Analyst

The positive Phase IIb EMBRACE study results for ViiV Healthcare's N6LS (VH109) represent incrementally positive news for Pfizer as a minority shareholder in this HIV-focused joint venture. The data shows N6LS administered every four months combined with monthly cabotegravir long-acting successfully maintained viral suppression in 96% of IV-dosed patients and 88% of subcutaneously-dosed patients.

This advancement builds upon ViiV's existing Cabenuva product, potentially extending the dosing interval for HIV treatment from monthly to every four months, with plans to evaluate a six-month formulation. For patients, this represents meaningful improvement in treatment burden and potentially better adherence.

While promising, these are interim Phase IIb results that will require additional clinical validation before regulatory submissions. The actual financial impact for Pfizer remains modest given its minority stake in ViiV (GSK maintains majority ownership). The long-acting HIV treatment market represents a growing segment of the $30+ billion global HIV therapeutics market, though ViiV faces competition from Gilead and other players developing long-acting options.

For Pfizer specifically, this positive clinical advancement strengthens one segment of its diverse portfolio but isn't likely to significantly move the needle on near-term financials given the development timeline and ownership structure.

Pharmaceutical R&D Expert

The EMBRACE study results demonstrate that ViiV's broadly neutralizing antibody N6LS shows strong clinical potential as a component of a less-frequent HIV treatment regimen. The mechanism—targeting the CD4 binding site on HIV—represents an important approach in the HIV treatment landscape.

The 96% efficacy rate for IV administration is particularly noteworthy, matching the standard of care group while significantly reducing dosing frequency. The subcutaneous formulation's 88% efficacy rate is somewhat lower but still clinically meaningful, though the higher rate of injection site reactions (14% vs. none in IV group) presents a potential tolerability challenge.

The confirmed virologic failures in two participants from each N6LS group warrant monitoring as the development progresses. Resistance development remains a key consideration in HIV therapies, though the data suggests this isn't a widespread concern with the current regimen.

ViiV's decision to advance a six-month IV formulation represents a logical progression based on these positive results, potentially doubling the current four-month interval. If successful, this would position the N6LS/cabotegravir combination as one of the longest-acting HIV treatments available, significantly improving the treatment paradigm for patients requiring lifelong therapy. The continuing pursuit of "ultra long-acting regimens" aligns with the broader industry trend toward reducing treatment burden for chronic conditions.

• Results from the phase IIb study, EMBRACE, demonstrate that N6LS, a bNAb administered every four months, effectively maintained undetectable viral load when combined with cabotegravir long-acting (CAB LA)
• Results add to the growing body of evidence that N6LS is a potent antiviral that can function as a component of a complete antiretroviral regimen
• EMBRACE study to continue investigating a combination of N6LS dosed at six months with CAB LA

LONDON--(BUSINESS WIRE)-- ViiV Healthcare, the global specialist HIV company majority owned by GSK, with Pfizer and Shionogi as shareholders, today announced positive findings from the company’s EMBRACE phase IIb study.¹ The study found that N6LS (VH3810109 or VH109), given every four months in combination with monthly cabotegravir long-acting (CAB LA), successfully kept viral levels suppressed in adults living with HIV who were already stable on treatment. It was also well tolerated by participants.

These results were presented today at the Conference on Retroviruses and Opportunistic Infections (CROI 2025) in San Francisco, U.S.

Kimberly Smith, M.D., MPH, Head of Research & Development at ViiV Healthcare, said: "As leaders in long-acting injectable innovation, we are building on the positive patient and physician experience we have with Cabenuva and pioneering the next generation of long-acting treatment options. The EMBRACE study demonstrated that VH109, a CD4-binding broadly neutralising antibody, administered every four months with cabotegravir, achieved high efficacy and was well tolerated through six months. We’re looking forward to continuing the development of VH109 as a component of our future ultra long-acting regimens.”

Results from the EMBRACE study at the six-month primary endpoint showed that 96% of participants receiving VH109 60mg/kg intravenously (IV) and 88% receiving VH109 3000mg subcutaneously (SC) with rHuPH20 maintained HIV-1 RNA levels below 50 copies/mL, compared to 96% in the standard-of-care group. VH109 was administered in both arms every four months, combined with monthly CAB LA. Confirmed virologic failure was observed in two participants from each VH109 group.

Overall, 4% of the IV group and 6% of the SC group had HIV-1 RNA levels of 50 copies/mL or higher, compared to none in the standard-of-care group when measured at month six.

VH109 was generally well tolerated, though infusion site reactions were more frequent with SC administration, occurring in 14% compared to none with IV administration. Adverse events specific to the use of study medication were reported in 64% of the IV group and 65% of the SC group, with 16% of participants in the SC group experiencing grade 3-4 adverse events (erythema). No participants in the IV group experienced a grade 3-4 adverse event.

Based on the favourable results seen in the trial, ViiV Healthcare will be progressing a six-month IV formulation of VH109 in combination with CAB LA for further evaluation in an EMBRACE part two trial.

About Cabenuva (cabotegravir + rilpivirine)
Cabenuva is indicated as a complete regimen for the treatment of HIV-1 infection in adults and adolescents 12 years and older and weighing at least 35kg to replace the current antiretroviral regimen in those who are virologically suppressed (HIV-1 RNA <50 c/ml) on a stable antiretroviral regimen with no history of treatment failure and with no known or suspected resistance to either cabotegravir or rilpivirine.

The complete regimen combines the integrase strand transfer inhibitor (INSTI) cabotegravir, developed by ViiV Healthcare, with rilpivirine, a non-nucleoside reverse transcriptase inhibitor (NNRTI) developed by Janssen Sciences Ireland Unlimited Company. Rilpivirine tablets are approved in the U.S. and when used with cabotegravir is indicated for short-term treatment of HIV-1 infection in adults and adolescents 12 years and older and weighing at least 35kg who are virologically suppressed (HIV-1 RNA less than 50 copies/mL) on a stable regimen with no history of treatment failure and with no known or suspected resistance to either cabotegravir or rilpivirine.

INSTIs inhibit HIV replication by preventing the viral DNA from integrating into the genetic material of human immune cells (T-cells). This step is essential in the HIV replication cycle and is also responsible for establishing chronic disease. Rilpivirine is an NNRTI that works by interfering with an enzyme called reverse transcriptase, which stops the virus from multiplying.

Please consult the full Prescribing Information.

Trademarks are owned by or licensed to the ViiV Healthcare group of companies.

About ViiV Healthcare
ViiV Healthcare is a global specialist HIV company established in November 2009 by GSK (LSE: GSK) and Pfizer (NYSE: PFE) dedicated to delivering advances in treatment and care for people living with HIV and for people who could benefit from HIV prevention. Shionogi became a ViiV shareholder in October 2012. The company’s aims are to take a deeper and broader interest in HIV and AIDS than any company has done before and take a new approach to deliver effective and innovative medicines for HIV treatment and prevention, as well as support communities affected by HIV. For more information on the company, its management, portfolio, pipeline, and commitment, please visit viivhealthcare.com.

About GSK
GSK is a global biopharma company with a purpose to unite science, technology, and talent to get ahead of disease together. Find out more at gsk.com.

Cautionary statement regarding forward-looking statements
GSK cautions investors that any forward-looking statements or projections made by GSK, including those made in this announcement, are subject to risks and uncertainties that may cause actual results to differ materially from those projected. Such factors include, but are not limited to, those described under Item 3.D “Risk factors” in GSK’s Annual Report on Form 20-F for 2024.

Registered in England & Wales:
GSK plc
No. 3888792

ViiV Healthcare Limited
No. 06876960

Registered Office:
79 New Oxford Street
London
WC1A 1DG

ViiV Healthcare Limited
GSK Medicines Research Centre
Gunnels Wood Road, Stevenage
SG1 2NY

References

^{___________________________________
1} Taiwo, B et al. VH3810109 (N6LS) Efficacy and Safety in Adults Who Are Virologically Suppressed: The EMBRACE Study. Presented at the Conference on Retroviruses and Opportunistic Infections (CROI 2025), 9-12 March, San Francisco, CA

View source version on businesswire.com: https://www.businesswire.com/news/home/20250312440906/en/

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FAQ

What are the success rates of N6LS in the EMBRACE phase IIb HIV trial?

96% of IV recipients and 88% of subcutaneous recipients maintained HIV-1 RNA levels below 50 copies/mL at 6 months.

How often is N6LS administered in the HIV treatment regimen?

N6LS is administered every four months, combined with monthly cabotegravir long-acting (CAB LA).

What are the main side effects reported in the N6LS EMBRACE trial?

Main side effects included infusion site reactions in 14% of subcutaneous recipients, with 16% experiencing grade 3-4 adverse events (erythema). IV administration showed better tolerance.

What are ViiV Healthcare's next steps for N6LS development?

ViiV Healthcare will progress a six-month IV formulation of N6LS combined with CAB LA for evaluation in EMBRACE part two trial.