Clover Biopharmaceuticals receives FDA clearance for RSV vaccine trial, expands respiratory disease research

Clover Biopharmaceuticals has taken a critical step in advancing respiratory syncytial virus (RSV) prevention with the U.S. Food and Drug Administration (FDA) granting clearance for its Investigational New Drug (IND) application for SCB-1019. The approval allows the company to move forward with a Phase I clinical trial assessing SCB-1019 as a revaccination option for older adults who have previously received GSK’s RSV vaccine, Arexvy.

Enrollment for the trial has already begun in the United States, with up to 160 participants aged 60 to 85 years expected to take part. This study aims to evaluate SCB-1019’s safety, reactogenicity, and immunogenicity in a real-world revaccination setting, comparing its effectiveness to Arexvy and a placebo. The trial’s outcome could position Clover Biopharmaceuticals as a key player in the competitive RSV vaccine market, where demand for effective long-term protection remains high.

Why Is SCB-1019 Positioned as a Potential Best-in-Class RSV Vaccine?

Clover Biopharmaceuticals has emphasized SCB-1019’s potential to provide robust immune protection without the need for an adjuvant. The vaccine candidate is based on the company’s proprietary Trimer-Tag technology, designed to stabilize trimeric antigens that mimic natural viral structures, enhancing the body’s immune response. This approach allows SCB-1019 to achieve high immunogenicity levels while maintaining a favorable tolerability profile.

In previous clinical studies, Clover Biopharmaceuticals compared SCB-1019 head-to-head against GSK’s Arexvy in a cohort of 70 RSV vaccine-naïve older adults. The results demonstrated that SCB-1019 generated geometric mean titers (GMTs) of RSV-A neutralizing antibodies reaching approximately 30,500 IU/mL, comparable to the 26,700 IU/mL achieved by Arexvy. However, SCB-1019 showed a significant advantage in tolerability, with only 16.7% of participants experiencing local adverse reactions, compared to 76.7% in the Arexvy group. These findings suggest SCB-1019 may offer a safer alternative for revaccination, addressing one of the key limitations of existing protein-based RSV vaccines.

What Are the Challenges of RSV Revaccination?

While first-generation RSV vaccines have provided effective protection, concerns remain over their long-term durability and suitability for revaccination. Current RSV vaccines, including Arexvy and Pfizer‘s Abrysvo, have been approved primarily for single-dose administration in older adults. However, as protection wanes over time, the need for a reliable booster option has become a focal point for researchers and vaccine manufacturers.

Clover Biopharmaceuticals aims to fill this gap with SCB-1019, offering a vaccine formulation that maintains strong immune protection without the need for additional adjuvants. The company believes that SCB-1019’s non-adjuvanted design could improve immune memory responses while reducing the risk of adverse events associated with repeated administration of adjuvanted vaccines.

Beyond its use as an RSV booster, Clover Biopharmaceuticals is also evaluating SCB-1019 as part of a combination respiratory vaccine. This candidate, incorporating RSV, human metapneumovirus (hMPV), and potentially parainfluenza virus type 3 (PIV3), is expected to enter clinical trials in 2025. If successful, the combination vaccine could provide broader protection against multiple respiratory pathogens, reducing the burden of seasonal outbreaks in vulnerable populations.

How Is Clover Competing in the Global RSV Vaccine Market?

The global RSV vaccine market is rapidly expanding, with pharmaceutical giants like GSK, Pfizer, and Moderna investing heavily in vaccine development. Market analysts predict that RSV vaccine sales could exceed $2.2 billion by 2032, driven by increased awareness of RSV’s impact on infants and older adults.

However, the market has also experienced turbulence. GSK’s Arexvy, despite its strong initial launch, saw a 72% decline in revenue during the third quarter of 2024, leading to concerns over its long-term commercial viability. The company has since focused on optimizing its vaccine portfolio while addressing challenges in sustaining RSV immunization uptake.

Similarly, Pfizer has faced setbacks with Abrysvo, as the company has had to rework its sales strategies to counter declining vaccine demand. This has included reallocating sales representatives and focusing on physician education to drive awareness of RSV revaccination needs.

Clover Biopharmaceuticals enters this competitive environment with an alternative approach, leveraging its proprietary Trimer-Tag technology to develop differentiated vaccine candidates. If SCB-1019 successfully navigates clinical trials, the company could carve out a niche in the revaccination and combination vaccine segments, areas that remain underserved by existing players.

What Could SCB-1019 Mean for the Future of RSV Prevention?

As Clover Biopharmaceuticals progresses with its SCB-1019 clinical trial, the broader implications for RSV prevention could be significant. A successful revaccination candidate would provide a much-needed option for older adults at risk of severe RSV infections, particularly those with underlying health conditions. Furthermore, the potential integration of SCB-1019 into a combination vaccine could streamline immunization efforts, reducing the number of shots required for comprehensive respiratory protection.

Industry experts will closely monitor Clover Biopharmaceuticals’ clinical trial results, as they could reshape expectations for RSV vaccine durability and boostability. Given the setbacks experienced by leading vaccine manufacturers in maintaining RSV vaccine sales, a next-generation revaccination candidate like SCB-1019 could reinvigorate interest in the market.

As the RSV vaccine landscape continues to evolve, Clover Biopharmaceuticals is positioning itself as a contender capable of addressing key gaps in long-term protection and combination immunization. If the company’s technology delivers on its promise, SCB-1019 could emerge as a transformative solution in the fight against respiratory infections, reinforcing the importance of continued innovation in vaccine development.