Gardasil 9 for the Prevention of Some Head and Neck Cancers: Measuring the Benefit

The US Food and Drug Administration (FDA) has approved Merck Sharp & Dohme Corp.’s human papillomavirus (HPV) vaccine Gardasil 9 (human papillomavirus 9-valent vaccine, recombinant) for the prevention of oropharyngeal cancers and other head and neck cancers caused by 9 different HPV strains.¹ The accelerated approval was granted based on evidence that the vaccine can prevent HPV-related anogenital infections and a clinical trial (ClinicalTrials.gov Identifier: NCT04199689) to evaluate its ability to prevent HPV-related throat infections in men is ongoing.

“More and more in the US, we are moving away from seeing cancers epidemiologically. We are seeing less cancers of, for example, the tonsils, base of tongue and larynx due to tobacco and alcohol risk, but an increase in prevalence of HPV-driven cancers,” said Glenn Hanna, MD, head and neck oncologist at Dana-Farber Cancer Institute in Boston, Massachusetts.

Although direct evidence for the prevention of oral and head and neck cancers from the vaccine is not currently available, many are fairly convinced that the vaccine is likely to work based on evidence of the prevention of genital warts, precancerous cervical lesions, and now, anogenital infections.

“There isn’t much question that this vaccine is a prophylactic against oral cancer — I haven’t seen any skepticism in this regard,” said Noel Brewer, professor in the department of health behavior at the University of North Carolina at Chapel Hill and chair of the National HPV Vaccination Roundtable. “The question is whether this enthusiasm for the vaccine passes whatever tests the FDA require [for the agency] to formally approve [it]. They have an excellent vaccine safety testing system,” added Dr Brewer.

The original Gardasil (human papillomavirus quadrivalent [types 6, 11, 16, and 18] vaccine, recombinant) vaccine was originally approved in 2006 in girls and women for the prevention of cervical cancer and is currently indicated for males and females aged 9 to 45 years, after a 2018 label expansion increased the recommended upper age from 26 years to 45 years.²

“HPV subtypes drive carcinogenesis in many mucosal tissues. It would make sense that if the vaccine prevents against high-risk cervical carcinoma subtypes, it will help with head and neck. It’s not a question for me if it’s beneficial — I always felt it should be — but it was a bit of time before the comfort level or evidence happened to support its use,” said Dr Hanna.

The American Cancer Society also recently revised their guidelines on HPV vaccination,³ encouraging earlier vaccination starting in individuals aged 9 to 12 years in males and females, but does not recommend HPV vaccination in people older than 26 years, due to concerns about benefit.

Some are hoping that the new approval for head and neck cancer prevention may prompt an increased uptake in males, who represent around 80% of cases of HPV-related head and neck cancers. 

“I see around a 4:1 ratio of males [to] females, in my busy head and neck academic practice. It’s the majority of our new patient population,” said Dr Hanna.

Previously, the only approved indication for men to get Gardasil for cancer prevention was anogenital cancer, which may have caused some providers to be hesitant about recommending the vaccine due to stigma.

“Our research with both straight men and gay men suggests prevention against any cancer is motivating. But the stigma associated with anogenital cancer may be important for the provider, and oral cancer is less stigmatized. The men themselves seem to not care much which cancer is being prevented,” Dr Brewer noted.

This article originally appeared on Cancer Therapy Advisor