Tailor-made cancer vaccines that target unique genetic errors in a patient's tumour have been developed in the US. Safety tests on 3 people showed the immune system could be trained to fight skin cancers. Scientists say the early results mark a "significant step" towards personalised cancer vaccines

To begin, many people have naturally arising T cells against melanoma antigens that can be found within extracted tumors. The reason why some people still develop melanoma isn't due to them not having T cells that are antigen specific, it is because the T cells become tolerant (due to some of the checkpoints mechanisms I mention in my comment above as well as tumor microenvironment conditions such as cytokines (IL-10), metabolites, hypoxic conditions, T reg influence, MDSC presence etc) at the site of the tumor or in the lymphatic system. From this immunological framework, DC vaccine technology will have difficulties for a variety of reasons. If a patient already has cancer and they are vaccinated with tumor antigen + GMCSF + adjuvant such as CpG or MPL, they will likely develop T cells that are specific to that tumor antigen as well as type 1 macrophages that promote anti-tumor immune activity. However, the reason that makes it so difficult for a prolonged anti-cancer response is due to the inhibitory compensatory mechanisms that, under normal circumstances, prevent host-tissue damage. I agree with you completely from that stand point. Your last statement kind of recapitulates the difficulty of formulating an effective vaccine with a clonally conserved antigen, "hopefully oncoadditcted." Unfortunately cancer cells mutate and the few cells that do not present MART-1 (due to slight MHC mutation that prevents MART-1 binding for example) will survive. Thus it becomes important to attack a cancer cell with TCRs with more than one affinity. I think the technology that has huge potential in the future is that which identifies neo-antigens that can be used to generate multiple TCRs with different antigen specificity and affinity for every patient.(ie. increase the antigenic repertoire of the T cells its call something else but I cant think of it off the top of my head). Adoptive T cell therapy with multiple TCRs plus immunoinhibitory eliminating preparative regiments combined with the addition of checkpoint blockade therapies several weeks to months to years after ACT might be the most effective way to eradicate metastatic melanoma. This would easily be a million dollar treatment in today's medicine. Hopefully this answers something.

/r/science Thread Parent Link - bbc.com