Pfizer and Valneva Report Positive Phase 3 VALOR Results Showing High Efficacy for Lyme Disease Vaccine Candidate
Pfizer Inc. and Valneva SE have announced encouraging topline findings from the pivotal Phase 3 VALOR clinical trial evaluating their investigational Lyme disease vaccine candidate, PF-07307405 (also known as LB6V and formerly VLA15). The results mark a significant milestone in the long-standing effort to develop a preventive solution for Lyme disease, a growing public health concern with no currently approved human vaccine available.
The Phase 3 VALOR trial, formally titled “Vaccine Against Lyme for Outdoor Recreationists,” was designed to assess the efficacy, safety, tolerability, immunogenicity, and manufacturing consistency of the 6-valent OspA-based vaccine candidate. Conducted under the clinical trial identifier NCT05477524, the study focused on individuals at higher risk of exposure to Lyme disease, particularly those who frequently engage in outdoor activities in endemic regions.
According to the topline data, the vaccine demonstrated strong efficacy in reducing confirmed cases of Lyme disease. In one of the pre-specified analyses, vaccine efficacy reached 73.2% beginning 28 days after the fourth dose during the second Lyme disease season, compared to placebo. A second pre-specified analysis showed an efficacy of 74.8% starting just one day after the fourth dose, also during the second season. These findings indicate that the vaccine provides substantial protection against infection caused by Borrelia bacteria transmitted through tick bites.
Despite these promising efficacy rates, the study encountered a statistical limitation. The number of Lyme disease cases observed during the trial period was lower than initially expected, which affected the statistical power of the primary endpoint analysis. Specifically, the lower bound of the 95% confidence interval in the first pre-specified analysis did not exceed the predefined threshold of 20, meaning the primary endpoint was not formally met. However, in the second analysis, the lower bound of the confidence interval did surpass this threshold, reinforcing confidence in the vaccine’s protective benefit.
Executives from both companies emphasized the clinical relevance of the findings and their implications for future regulatory submissions. Annaliesa Anderson, Senior Vice President and Chief Vaccines Officer at Pfizer, highlighted the urgent need for a Lyme disease vaccine, noting that the condition can lead to serious and sometimes long-term health complications if left untreated. She stated that the observed efficacy exceeding 70% is highly encouraging and supports continued development and regulatory engagement.
Echoing this sentiment, Thomas Lingelbach, Chief Executive Officer of Valneva, described the results as a critical step forward in achieving the shared goal of delivering a much-needed preventive solution. He also acknowledged Pfizer’s commitment to advancing the program rapidly, underscoring the strength of the collaboration between the two companies.
The investigational vaccine targets the outer surface protein A (OspA) of Borrelia species, which are responsible for Lyme disease. By focusing on six different serotypes of OspA, the vaccine is designed to provide broad protection against the most prevalent strains found in North America and Europe. This multivalent approach is considered essential given the geographic variability of Borrelia species and their role in disease transmission.
The collaboration between Pfizer and Valneva began in April 2020, when the companies entered into a strategic agreement for the co-development of the vaccine candidate. Under the terms of the partnership, Pfizer leads late-stage development and, pending regulatory approval, will be responsible for manufacturing and global commercialization. Valneva contributes its specialized expertise in vaccine research and development, particularly in the field of infectious diseases.
The VALOR study represents one of the most advanced clinical programs targeting Lyme disease prevention. Lyme disease remains a significant and growing concern, particularly in North America and parts of Europe, where incidence rates have been rising due to factors such as climate change, expanding tick habitats, and increased human interaction with natural environments. Symptoms can range from mild flu-like illness to severe complications affecting the joints, heart, and nervous system if not diagnosed and treated early.
Currently, prevention strategies rely heavily on personal protective measures, such as avoiding tick-infested areas, using insect repellents, and performing regular tick checks. The absence of a licensed vaccine has left a critical gap in public health preparedness, making the development of an effective immunization strategy a high priority.
Given the clinically meaningful efficacy demonstrated in the Phase 3 trial and supportive secondary analyses, Pfizer has indicated plans to proceed with regulatory submissions. These submissions will likely be directed to major health authorities, including the U.S. Food and Drug Administration and the European Medicines Agency, with the goal of obtaining approval for widespread use.
If approved, PF-07307405 could become the first vaccine available for Lyme disease in humans, representing a major advancement in infectious disease prevention. It would not only address an unmet medical need but also potentially reduce the burden on healthcare systems and improve quality of life for individuals at risk.
In conclusion, the Phase 3 VALOR trial results underscore the promise of Pfizer and Valneva’s Lyme disease vaccine candidate. While statistical nuances affected the primary endpoint, the overall efficacy data and supportive analyses point to a meaningful protective effect. With regulatory submissions on the horizon, the program is entering a critical phase that could ultimately lead to the introduction of the first human vaccine against Lyme disease, offering hope to millions at risk worldwide.
About VALOR
The VALOR trial is a multicenter, placebo-controlled, randomized, observer-blinded trial conducted at sites in areas of high incidence of Lyme disease across the U.S., Canada, and Europe.1 Pfizer Trial participants aged 5 years and older were randomized 1:1 into two trial groups and received four doses of either PF-07307405 or a saline placebo – one dose administered at months 0, 2, 5-9 followed by a fourth dose one year later, shortly before the start of the following Lyme disease season (season 2).1
About PF-07307405 (LB6V)
There are currently no approved human vaccines for Lyme disease, and PF-07307405 is the Lyme disease vaccine candidate which has currently advanced the furthest along the clinical development timeline, with two pivotal Phase 3 trials completed. This investigational multivalent protein subunit vaccine uses an established mechanism of action for a Lyme disease vaccine that targets the outer surface protein A (OspA) of Borrelia burgdorferi, the bacteria that cause Lyme disease.
When a person is immunized with PF-07307405, their body creates antibodies against six Borrelia OspA serotypes. As the tick feeds on the vaccinated person, these antibodies are ingested by the tick as part of its blood meal. Binding of vaccine-induced antibodies to OspA on Borrelia inside the tick inhibits the bacterium’s ability to leave the tick, preventing it from being transmitted to the human host. The vaccine candidate covers the six most prevalent OspA serotypes expressed by the Borrelia burgdorferi sensu lato species in North America and Europe.
About Lyme Disease
Lyme disease is a systemic infection caused by Borrelia burgdorferi sensu lato bacteria that are transmitted to humans by the bite of infected Ixodes ticks.3 It is considered the most common vector-borne illness in the Northern Hemisphere.4,5 Pfizer The Centers for Disease Control and Prevention (CDC) has estimated that approximately 476,000 people in the U.S. are diagnosed and treated each year and 132,000 cases are reported annually in Europe from countries with surveillance systems.6
Early symptoms of Lyme disease (such as a gradually expanding erythematous rash called erythema migrans or other nonspecific symptoms like fatigue, fever, headache, mild stiff neck, muscle and joint pains) are often overlooked or misinterpreted. Left untreated, the disease can disseminate and cause more serious chronic complications affecting the skin, joints (arthritis), the heart (carditis) or the nervous system.6,7 The medical need for vaccination against Lyme disease is steadily increasing as the geographic footprint of the disease widens.8
About Pfizer: Breakthroughs That Change Patients’ Lives
At Pfizer, we apply science and our global resources to bring therapies to people that extend and significantly improve their lives. We strive to set the standard for quality, safety and value in the discovery, development, and manufacture of health care products, including innovative medicines and vaccines. Every day, Pfizer colleagues work across developed and emerging markets to advance wellness, prevention, treatments and cures that challenge the most feared diseases of our time.
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