Human papillomavirus (“HPV”) is a group of viruses that is extremely common worldwide. HPV infection can cause normal cells to turn abnormal. Different types of HPV have different effects. For some “high-risk” HPV types, this change can lead to malignancy in the host. However, out of the more than 150 HPV types, only 13 are known to be cancer causing. The other “low-risk” HPV types lead to skin warts. Some HPV types, such as 6 and 11, have a tendency to target anal and genital areas, while others target the skin in other parts of the body.
Anogenital warts, or condyloma acuminata, are warts affecting either the anus or genitals. They most commonly present as solitary or clustered lesions on the penile shaft, scrotum, and on the vaginal labia majora, although they may also be found on internal body surfaces of the anogenital region.
Although usually asymptomatic, patients with anogenital warts may experience bleeding, burning, tenderness, or pain associated with their warts. Patients with anogenital warts have significantly higher rates of reported anxiety and depression and lower overall satisfaction with life. Sexual and romantic relationships are especially impacted by the physical and psychological burden of anogenital warts.
HPV, the cause of anogenital warts, is typically transmitted by sexual contact, although non-sexual transmission is possible. The number of new and total sexual partners is the greatest known risk factor for infection with HPV types 6 and 11 and development of anogenital warts. HIV positive and immunocompromised individuals present more frequently with anogenital warts than the general population. Rarely, infection with HPV types 6 and 11 can be passed from mother to child during pregnancy, which can lead to warts or tumors in the child’s respiratory tract and subsequent breathing problems due to airway obstruction.
HPV type 6
Anogenital warts are the most common viral sexually transmitted disease. Visible anogenital warts are present in approximately 1% of sexually active U.S. adults and approximately 15% have evidence of subclinical infection, as detected by HPV DNA assays. Peak incidence occurs in patients 20 to 24 years old, and the vast majority of those with anogenital warts are between the ages of 17 and 33. Up to 1.4 million Americans are newly affected each year.
Over 90% of warts contain HPV types 6 or 11. Unlike the predominant HPV types in anal and cervical cancer, HPV types 6 and 11 have low malignant potential, since these types do not integrate into the host’s DNA, a process that predisposes cells to uncontrolled proliferation. Nonetheless, individuals with warts remain at a greater risk of developing anogenital and head and neck cancers.
Standard of Care
Diagnosis of anogenital warts can usually be made by visual examination. If the lesion is large or atypical upon inspection, anoscopy, colposcopy, or vaginal speculum examination may be required. In rare cases, lesion biopsy can aid in diagnosis.
Spontaneous regression of anogenital warts only occurs in 20-30% of cases. Therefore, treatment is important to reduce physical and psychological symptoms, prevent transmission, and lower the risk of anogenital cancers.
Intervention strategies include topical chemical agents that stop the wart’s growth, acids that physically destroy the lesion, or immune modulators that upregulate the body’s immune response to the infection. Excisional removal is considered as a last resort. Despite the range in different therapeutic options, current treatment strategies are suboptimal – cumulative recurrence rates range between 30-70% within six months of initial treatment.
Inability to eradicate the causative HPV infection is the common problem underlying treatment failure. HPV vaccination has been effective at reducing the incidence of anogenital warts, specifically in girls below 26 years of age; however, the vaccine’s ability to prevent recurrence requires further investigation.
Considering the high disease prevalence worldwide, the immense psychosocial burden, and the high recurrence rates using current therapies, there is an unmet need for disease-modifying therapies that specifically target the underlying HPV infection in persons with anogenital warts.