J Immunother Cancer 2024;12:e008817. doi:10.1136/jitc-2024-008817Open access immunogenicity, feasibility, and efficacy and includes three escalating dose levels. We found the EVX- 01- CAF09b vaccine to be safe at all dose levels with primarily local side effects. Two patients experienced grade 3 systemic immune- related side effects. These did not deviate from what is observed with anti- PD- 1 treatment alone and were judged must likely ICI related even though this trial was not designed so that contribution from the vaccine can be ruled out.28 The level of side effect in this vaccine trial is in contrast to the known high risk of severe toxicity of other ICI combination treatments, for example, anti- PD- 1/anti- CTLA- 4 (>50% grade 3–4 AEs).29 Eight of the Figure 5 Correlation between clinical responses, neoepeptide immunogenicity and quality scores. Patient clinical BOR was grouped in responders. Immune responses detected before vaccination (Pre), during and after vaccination (Post) and in follow- up samples are grouped and compared with the clinical outcomes of the patients. (A) The number of EVX- 01 peptides with T cell responses detected by Elispot was compared with the patients BOR. (B) The fraction of EVX- 01 peptides with T cell responses detected by Elispot was compared with the patients BOR. (C) The number of de- novo responses per patient compared with the patients BOR. (D, F) PIONEER quality score for EVX- 01 peptides inducing functional responses detected by Elispot (immunogenic) compared with non- immunogenic EVX- 01 peptides. Prediction scored for both PIONEER2 and PIONEER4 is shown. EVX- 01 responses detected by the pMHC- I multimers in ex vivo PBMCs are marked in red. A t- test was used to test the difference between immunogenic and non- immunogenic EVX- 01 peptides’ prediction scores (*p<0.05, **p<0.01). (E, G) The PIONEER quality scores for EVX- 01 peptides (both from PIONEER2 and PIONEER4) was compared between patients BOR. Means were compared between response groups using t- test.