Final Results of 9-Valent HPV Vaccine Show Extended Cancer Protection

Final results of the trial that led to FDA approval show that a new 9-valent HPV vaccine can reduce cases of HPV and cervical cancer.

A new type of vaccine that targets nine different strains of the human papillomavirus (HPV) was approved by the US Food and Drug Administration in December. Now, the final results of a phase IIb/III study showed the good results that led to this approval. The other main HPV vaccine targets only four HPV types, and the new vaccine has the potential to increase protection against cervical cancer-causing strains of the virus.

“Current HPV vaccines address approximately 70% of cervical cancers through protection from HPV-16 and HPV-18,” wrote study authors led by Elmar A. Joura, MD, of the Medical University of Vienna in Austria. “The 9vHPV vaccine offers the potential to increase overall prevention of cervical cancer from approximately 70% to approximately 90%.”

The 9vHPV vaccine adds protection against the oncogenic subtypes 31, 33, 45, 52, and 58; in the new study, it was tested against the quadrivalent vaccine (qHPV) that protects against HPV types 6, 11, 16, and 18. Results of the trial were published on Februrary 19 in the New England Journal of Medicine.

The study included 14,215 women, randomized to receive either the 9vHPV vaccine or the qHPV vaccine. All participants were between the ages of 16 and 26. Follow-up included swabs of labial, vulvar, perineal, perianal, endocervical, and ectocervical tissue at a number of points through 54 months.

In an intention-to-treat analysis, the incidence of any high-grade cervical, vulvar, and vaginal disease was 14 per 1,000 person-years in both of the vaccine groups. Among only those who were not HPV-infected on day 1, the rates were 2.4 per 1,000 person-years in the 9vHPV group and 4.2 per 1,000 person-years in the qHPV group, for a risk reduction of 42.5%.

In the per-protocol analysis, there was only one case out of 6,016 individuals of high-grade disease related to the five new HPV types covered with the 9vHPV vaccine, for a rate of 0.1 per 1,000 person-years. There were 30 such cases out of 6,017 individuals with the qHPV vaccine, for a rate of 1.6 per 1,000 person-years. This gave a risk reduction of 96.7%. Both vaccines offered very good protection against disease related to HPV-6, 11, 16, and 18. Serologic analysis showed that antibody responses to those four types in the 9vHPV group were noninferior to those in the qHPV group.

There were more adverse events related to the injection site with the 9vHPV vaccine; these occurred in 90.7% of participants, compared with 84.9% of those in the qHPV group. More than 90% of these events were mild to moderate in intensity.

“In conclusion, the results of this study showed that the prophylactic administration of 9vHPV vaccine prevented infection and disease associated with the vaccine HPV types,” the authors wrote. “The effect of vaccination on the burden of cancer remains to be determined.”