A preventive vaccine (e.g. Gardasil) that blocks cancer-causing HPV infection before it starts — the opposite end of the spectrum from a personalized neoantigen vaccine, and the bulk of today's cancer-vaccine market.
Not all “cancer vaccines” are alike. The HPV vaccine (Gardasil, Cervarix) is prophylactic: given to healthy people, it primes immunity against the human papillomavirus, whose chronic infection causes most cervical and several other cancers. By blocking the virus, it prevents those cancers from ever forming. The hepatitis B vaccine works the same way against a share of liver cancers.
This is fundamentally different from a personalized neoantigen vaccine, which is therapeutic — given to someone who already has cancer, and built from that tumor's own mutations to direct an immune attack. Preventive vaccines target a shared viral antigen present in everyone; neoantigen vaccines target mutations unique to one patient.
The distinction matters when reading market figures. Prophylactic shots like HPV generate essentially all of the revenue in today's multi-billion-dollar “cancer vaccine” market, so a headline number for that whole category badly overstates the still-pre-commercial neoantigen-vaccine opportunity.