It’s been a while, but as I recall the side effects were fairly minimal and transient. Certainly less than chemo, and roughly the same as hormonal treatments. A few days of flu like symptoms resulting from the immune system being supercharged with prostate specific antigens.
It’s expensive and an involved process. There is no practical reason it couldn’t be given earlier, except that with the label for late stage cancer, insurance won’t pay for it. But it stands to reason as a immunotherapy that it would work better if given earlier, and the evidence shows that it works better when given to patients with low Gleason scores.
FDA took a long time to approve it, which is the main reason I thought of it here, contrasting with how they rushed the Covid mRNA shots. I am not a fan of calling those “vaccines”. It seems they have changed the definition of vaccine and I wish they didn’t. Just call them therapies. It would be great if they could generate patient specific treatments. NantHealth, which is owned by Patrick Soon-Shiong (biotech billionaire and owner of the LA Times and San Diego Tribune) has been developing genetic sequencing databases of cancer tumors with the idea that those specific sequences could be treated with targeted therapies. They may not need to be patient specific but rather gene sequence specific. I wonder if there is some connection there between NantHealth to these mRNA cancer gene therapies.
Unfortunately, the term "cancer vaccine" misdirects attention from important details that distinguishes immunotherapy from the classic meaning of vaccine as provoking a protective immune response by presenting an antigen that is unique to an infectious disease.
As I understand the NantHealth technology, their approach is to develop lines of universal natural killer cells that are combined with antigens aimed at tumor types and patient specific tumors. This seems to me not so much a vaccine as providing as therapy a key part of the immune response that a vaccine aims to generate. The use of mRNA is apparently part of the NantHealth production process.
I have to confess that I am far beyond my education. I have a clear memory of my college biology professor explaining in class in 1973 that as remarkable as the discovery of DNA was, he did not see how we would ever be able to read the secrets hidden in the massive length of its four letter code.
Only a decade later though, an odd, brilliant chemist named Kary Mullis figured out a practical way of how to do it using PCR amplification. He eventually got the Nobel Prize.