PFIZER LAUNCHES A PHASE III CLINICAL TRIAL FOR A NEW LYME DISEASE VACCINE

Lyme disease is caused by bacteria that spread to humans through tick bites. If left untreated, the illness can spread and cause serious complications affecting the joints, the heart, or the nervous system.

The need for vaccination against Lyme disease is steadily increasing as the disease is becoming widespread. According to a recent analysis, Lyme disease diagnosis in the U.S. increased by 375% in rural areas and 65% in urban areas from 2007 to 2021.

In December 2022, Pfizer announced the beginning of a Phase III clinical trial to confirm the efficacy and safety of a new vaccine that could protect children and adults against Lyme disease. The Lyme vaccine, VLA15, was developed by Valneva in collaboration with Pfizer.

Read on to learn more about the tick-borne disease, its symptoms, and the first vaccine in the past two decades that can help prevent it.

What Is Lyme Disease?

Borrelia Burgdorferi, and very infrequently Borrelia Mayonii, are the bacteria that cause Lyme disease. It is a vector-borne disease - humans usually catch Lyme disease after being bitten by a tick carrying the Borrelia Burgdorferi or Mayonii bacteria. 

In humans, these bacteria cause an infection that can spread to the joints, heart, and nervous system if left untreated.

Lyme disease bacteria are not present in all ticks.Ticks that can carry Borrelia bacteria are:

• The black-legged deer ticks (most common around the northeastern, mid-Atlantic, and North-Central U.S.)
• The Western black-legged ticks (most common around Pacific coastal U.S.)

In the United States, each year, there are at least 400,000 new cases of Lyme disease, and at least 200,000 more occur in Europe.

There is no evidence that Lyme disease is contagious – it cannot be transmitted from one person to another.

The 3 Stages Of Lyme Disease

Lyme disease occurs in the following three stages:

• Stage 1: This is the early localized Lyme disease stage or stage 1. During stage 1, the body is infected, but the bacteria have not spread yet.
• Stage 2: During the early disseminated Lyme disease stage or stage 2, the bacteria starts to spread throughout the body. 
• Stage 3: During the late Lyme disease stage, the bacteria have spread to distant body sites, such as the joints and the heart. 

Lyme Disease Symptoms

The symptoms of Lyme disease vary from person to person depending on the following:

• Whether the person became infected with the Borrelia Burgdorferi or Borrelia Mayonii bacteria
• The stage of the disease
• The body part affected by the disease

A red, ring-like rash at the site of a recent tick bite is one of the first indicators of Lyme disease. It may appear several days after infection and last several weeks. The rash might also disappear and return several weeks later. On the other hand, some people do not get any rash at all.

During the earlier stages of Lyme disease, patients may also experience flu-like symptoms, such as:

• A headache
• Fever and chills
• Fatigue
• Muscle aches and pain (myalgia)
• Joint pain and stiffness (arthralgia)
• Loss of appetite
• Swollen lymph nodes
• Eye diseases and disorders
• Neurological symptoms, such as meningitis (inflammation in the nervous system)
• Heart problems, such as myocarditis (inflammation of the heart muscle) or pericarditis (swelling of the sac-like tissue surrounding the heart)

People infected with Borrelia Mayonii, and not Borrelia Burgdorferi, may also experience nausea, vomiting, and widespread rashes.

During the late stage of Lyme disease, patients may develop the following symptoms:

• Arthritis (inflammation of the joints)
• Other neurological symptoms, such as speech difficulties and memory problems, in addition to numbness, tingling, and pain in the extremities

How Is Lyme Disease Treated?

The standard treatment for Lyme disease in the earliest stages is usually antibiotics given as pills or by IV for 10-14 days. Treatment may take longer, depending on symptoms.

After three to four weeks of antibiotic therapy, the majority of cases of Lyme disease are curable.

However, some patients may experience persistent symptoms, such as musculoskeletal pain and cognitive dysfunction, for over six months after undergoing Lyme disease treatment. This is also known as ”Post-Treatment Lyme Disease Syndrome” (PTLDS).

New Vaccine May Help Prevent Lyme Disease

People can not develop immunity against Lyme disease after they have had it – even if you had Lyme disease, you can still get it again. So far, there is no vaccine available to prevent this disease. 

Back in 1998, the FDA approved a recombinant Lyme vaccine called LYMErix. However, only three years later, LYMErix was withdrawn from the market because it was less than 80% effective, and there were concerns about its side effects.

More recently, in 2020, the biopharmaceutical company “Pfizer” collaborated with the French specialty vaccine company “Valneva” to develop a new Lyme disease vaccine.

Valneva’s Lyme disease vaccine, named VLA15, is the only active Lyme disease candidate in clinical development today.

How Does The New Lyme Disease Vaccine Work?

The VLA15 vaccine is a protein subunit vaccine. That means it contains protein fragments from the disease-causing pathogen, the Borrelia Burgdorferi bacterium, to trigger protective immunity against it. Because these protein fragments alone cannot cause disease, subunit vaccines are considered very safe. 

Pfizer and Valneva’s vaccine contains OspA protein, one of the most dominant surface proteins expressed by the Borrelia Burgdorferi bacterium when present in a tick. This outer surface protein allows the bacterium to leave the tick and enter the human body.

After receiving the VLA15 vaccine, the patient’s body creates antibodies against the OpsA surface protein. If vaccinated patients become bitten by an infected tick, their antibodies can block the OpsA protein and prevent the bacteria from infecting their bodies.

According to the drug makers, the vaccine requires three doses and covers six Borrelia Burgdorferi bacterium serotypes prevalent in North America and Europe.

The New Lyme Disease Vaccine Facts

The Food and Drug Administration (FDA) granted Fast Track designation to Valneva's Lyme Disease vaccine candidate VLA15 in 2017.

In 2018, data from a Phase I study showed that VLA15 demonstrated strong immunogenicity and safety.

The study enrolled 179 healthy adults from Europe and the U.S. who were not infected with Borrelia Burgdorferi previously. The patients received three shots of the vaccine one month apart.

All treated patients developed antibodies against the OspA surface protein. Moreover, there were very few severe VLA15 side effects in all treatment groups and no associated safety concerns.

In 2020, Pfizer announced their collaboration with Valneva to co-develop and commercialize the VLA15 Lyme Disease Vaccine. 

In 2021, data from the phase II study showed that VLA15 elicited a strong immune response in adults (18-65 years old) with acceptable safety and tolerability profiles.

In February 2022, Pfizer and Valneva reported positive data from the Phase 2 trial for their Lyme disease vaccine candidate. The vaccine was both safe and effective in adults and children.

The study included individuals between the ages of 5 and 11, 12 and 17, and 18 and 65. Patients who received three doses of the vaccine were more protected against Lyme disease than those who received only two doses.

On August 8th, 2022, Valneva and Pfizer initiated a large Phase III Study of their VLA15 Lyme vaccine. The study is done on around 6,000 children and adults, five years and older, from over 50 regions in Europe and the U.S. where Lyme disease is most frequently found, including Finland, Germany, the Netherlands, Poland, and Sweden. All participants will receive three doses of either the VLA15 vaccine or a saline placebo.

In December 2022, the drug makers reported that antibodies against Lyme disease were still present in vaccinated children and adults even 6 months after receiving the third dose of the VLA15 vaccine. It was the first time data showed that the new vaccine could protect children against Lyme disease up to six months after vaccination.

What is Next For Pfizer and Valneva’s Lyme Disease Vaccine?

In 2025, Pfizer may submit a marketing authorization application (MAA) to the European Medicines Agency (EMA) and a biologics license application (BLA) to the U.S. FDA, depending on the outcomes of the Phase III trial. After that, the new vaccine for Lyme disease may become available for people across the United States and Europe.

If the trial succeeds, we will be one step closer to having the first human vaccine against this tick-borne disease in 20 years. 

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Sources:

• Lyme Disease | CDC
• Lyme Disease - StatPearls - NCBI Bookshelf
• Post-Lyme disease syndrome - PMC
• The Lyme vaccine: a cautionary tale - PMC
• Outer surface protein A (OspA) from the Lyme disease spirochete, Borrelia burgdorferi: high-level expression and purification of a soluble recombinant form of OspA

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