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Human Papillomavirus Type 33 L1 Protein

This article summarizes several clinical trials investigating the use of Human Papillomavirus Type 33 L1 Protein as part of the 9-valent HPV vaccine (Gardasil 9) for preventing HPV infection and treating HPV-related conditions. The trials evaluate the vaccine’s safety, efficacy, and immunogenicity in various populations and clinical scenarios, including extended dosing schedules, use in immunocompromised patients, and treatment of HPV-related lesions.

Table of Contents

What is Human Papillomavirus Type 33?

Human Papillomavirus Type 33 (HPV 33) is one of several types of HPV that can cause health problems in humans. HPV is a very common virus that spreads through sexual contact. While most HPV infections clear up on their own, some types like HPV 33 can persist and lead to serious conditions.[1]

HPV 33 is considered a high-risk type because it can cause changes in cells that may develop into cancer over time. It is associated with an increased risk of cervical cancer as well as other genital and anal cancers.[1]

About the HPV Type 33 L1 Protein Vaccine

The HPV Type 33 L1 protein vaccine is part of a broader vaccine called Gardasil 9, which protects against 9 types of HPV, including type 33. Gardasil 9 is what’s known as a 9-valent HPV vaccine, meaning it targets 9 different HPV types.[1]

This vaccine contains proteins that mimic the outer shell (capsid) of the HPV virus. Specifically, it contains the L1 protein from HPV type 33. The L1 protein is the major component of the virus’s outer surface.[1]

How the Vaccine Works

The vaccine works by stimulating the body’s immune system to produce antibodies against the L1 protein of HPV type 33. Here’s a simple breakdown of how it functions:

  1. The vaccine introduces harmless proteins that look like parts of the HPV 33 virus to your immune system.
  2. Your immune system recognizes these proteins as foreign and produces antibodies against them.
  3. If you’re later exposed to the real HPV 33 virus, your body already has antibodies ready to fight it off before it can establish an infection.

This process, called immunization, helps prevent infection with HPV 33 and reduces the risk of developing HPV 33-related diseases like cervical cancer.[1]

Who Should Get Vaccinated

The HPV vaccine is recommended for the following groups:

  • All children aged 11-12 years (can start as early as age 9)
  • Teens and young adults up to age 26 who weren’t vaccinated earlier
  • Some adults aged 27-45 years who weren’t previously vaccinated (discuss with your doctor)

The vaccine is most effective when given before any exposure to HPV, which is why it’s recommended for preteens.[1]

Dosing and Administration

The typical dosing schedule for the HPV vaccine is:

  • 2 doses for those starting vaccination before age 15
  • 3 doses for those starting at age 15 or older

The vaccine is given as an injection in the upper arm or thigh. It’s important to complete the full series of shots for the best protection.[1]

Effectiveness

Clinical trials have shown that the 9-valent HPV vaccine, which includes protection against HPV type 33, is highly effective. It can prevent over 90% of cancers caused by the HPV types included in the vaccine when given before exposure to the virus.[2]

Ongoing studies are evaluating the long-term effectiveness of the vaccine. One study is looking at the vaccine’s ability to prevent oral persistent HPV infection in adult males.[2]

Safety and Side Effects

The HPV vaccine has been extensively tested and is considered very safe. Like all vaccines, it can cause some mild side effects, which may include:

  • Pain, redness, or swelling at the injection site
  • Fever
  • Headache or feeling tired
  • Nausea
  • Muscle or joint pain

Serious side effects are rare. As with any medical treatment, it’s important to discuss potential risks and benefits with your healthcare provider.[1]

Ongoing Research

Several clinical trials are currently underway to further study the HPV vaccine, including its use in specific populations:

  • A study evaluating the vaccine’s effectiveness in immunocompromised children and adolescents[3]
  • Research on the optimal timing of vaccination for patients who have undergone stem cell transplantation[4]
  • A trial investigating the use of the vaccine to prevent recurrence of high-grade vulvar lesions in women[5]
  • A study on HPV vaccination after treatment for high-grade cervical lesions in women over 45[6]

These ongoing studies aim to expand our understanding of the vaccine’s benefits and optimize its use in various patient groups.

Trial Focus Key Population Main Objectives Dosing Schedule
Extended dosing intervals 9-14 year olds, 16-26 year old women Compare 2-dose vs 3-dose regimens, evaluate safety and immunogenicity Various 2-dose and 3-dose schedules
Immunocompromised patients Children and adolescents after stem cell transplant Evaluate immunogenicity of early vs late vaccination post-transplant 3-dose schedule starting at 9 or 15 months post-transplant
Oral HPV prevention Adult males 20-45 years old Assess efficacy in preventing oral HPV infection 3-dose regimen
Treatment of vulvar HSIL Women with vulvar high-grade squamous intraepithelial lesions Evaluate efficacy as adjuvant therapy after HSIL treatment 3-dose schedule
Cervical lesion treatment Women over 45 with high-grade cervical lesions Assess efficacy in clearing HPV after lesion treatment 3-dose schedule
Wart treatment Patients with difficult-to-treat palmar or plantar warts Evaluate efficacy in treating resistant warts 3-dose schedule

FAQ

  • What is the 9-valent HPV vaccine? The 9-valent HPV vaccine (Gardasil 9) is a vaccine that protects against nine types of human papillomavirus (HPV), including types 6, 11, 16, 18, 31, 33, 45, 52, and 58. It contains virus-like particles of the L1 protein from each of these HPV types.
  • Who are the target populations for these clinical trials? The trials target various populations, including children and adolescents aged 9-14, young adults aged 16-26, immunocompromised patients, women with vulvar high-grade squamous intraepithelial lesions (vHSIL), and patients with difficult-to-treat palmar or plantar warts.
  • What are the main objectives of these clinical trials? The main objectives include evaluating the vaccine's safety, immunogenicity, and efficacy in preventing HPV infection, assessing extended dosing schedules, studying its use in immunocompromised patients, and investigating its potential in treating HPV-related conditions like vHSIL and warts.
  • How is the vaccine administered in these trials? The vaccine is typically administered as a series of intramuscular injections. The number of doses and timing varies between trials, with some studies comparing 2-dose regimens to 3-dose regimens or evaluating extended interval dosing.
  • What are some of the key outcomes being measured? Key outcomes include antibody levels against HPV types, seroconversion rates, incidence of HPV-related infections or lesions, safety and tolerability of the vaccine, and in some trials, quality of life measures and treatment efficacy for existing HPV-related conditions.

Ongoing Clinical Trials on Human Papillomavirus Type 33 L1 Protein

  • Study on HPV Vaccine Timing for Patients After Stem Cell Transplantation Using Gardasil 9

    Recruiting

    2 1 1 1
    Investigated diseases:
    Investigated drugs:
    Sweden

Glossary

  • Human Papillomavirus (HPV): A group of viruses that can cause various types of cancer and genital warts. There are many different types of HPV, some of which are targeted by vaccines.
  • 9-valent HPV vaccine: A vaccine that protects against nine types of HPV (6, 11, 16, 18, 31, 33, 45, 52, and 58), providing broader protection than earlier HPV vaccines.
  • L1 Protein: The major capsid protein of HPV, which self-assembles into virus-like particles used in HPV vaccines to stimulate an immune response.
  • Immunogenicity: The ability of a substance, such as a vaccine, to provoke an immune response in the body.
  • Seroconversion: The development of detectable antibodies in the blood directed against an infectious agent, indicating an immune response to vaccination or infection.
  • Geometric Mean Titer (GMT): A measure of the average antibody level in a group of subjects, calculated using the geometric mean of individual antibody titers.
  • High-grade Squamous Intraepithelial Lesion (HSIL): Abnormal, precancerous changes in the cells of the cervix, vulva, or other areas that may progress to cancer if left untreated.
  • Allogeneic Stem Cell Transplantation: A procedure where a patient receives blood-forming stem cells from a genetically similar, but not identical, donor to treat certain blood cancers and disorders.
  • Immunocompromised: Having a weakened immune system, which can be due to certain diseases, medications, or medical treatments.
  • Competitive Luminex Immunoassay (cLIA): A laboratory test used to measure antibody levels against specific HPV types in blood samples.

References

  1. http://clinicaltrials.eu/trial-id/2022-500256-37-00
  2. http://clinicaltrials.eu/trial-id/2022-501974-21-00
  3. http://clinicaltrials.eu/trial-id/2022-501413-31-00
  4. http://clinicaltrials.eu/trial/study-on-hpv-vaccine-timing-for-patients-after-stem-cell-transplantation-using-gardasil-9/
  5. http://clinicaltrials.eu/trial/study-on-hpv-vaccine-for-women-with-vulvar-hsil-evaluating-the-effectiveness-of-nonavalent-hpv-vaccine-in-preventing-recurrence-of-vulvar-high-grade-lesions/
  6. http://clinicaltrials.eu/trial/study-on-hpv-vaccine-after-treatment-for-high-grade-cervical-lesions-in-women-over-45/