Breakthrough in cancer research could spawn new treatments

This is about Immunotherapy.
One of the approaches is to use customized vaccines that target the Antigens and/or NeoAntigens that cancer cells express.
A existing problem with this approach is that it currently takes a couple months to develop a custom vaccine. By the time it's administered, the cancer may have mutated and the vaccine is unable to deal with the new antigens and/or neoantigens, UNLESS, the vaccine is targeting the "trunk" mutations.
Can science / researchers parse the "trunk" mutations (which are responsible for spread) from the "passenger" mutations (which are along for the ride, but don't contribute to the spread)?
If so, great.
If not, these vaccine approaches may be best for slow growing cancers which mutate slower. Since Lobular is often a lazy cancer (and probably has less mutations than aggressive breast cancer), it's worth speculating if these Immunotherapy vaccines that target Antigens / Neoantigens warrant consideration for ILC.