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This study was aimed at investigating the mutations in colorectal cancer (CRC) for recurrent neoantigen identification. A total of 1779 samples with whole exome sequencing (WES) data were obtained from 7 published CRC cohorts. Common HLA genotypes were used to predict the probability of neoantigens at high-frequency mutants in the dataset. Based on the WES data, we not only obtained the most comprehensive CRC mutation landscape so far but also found 1550 mutations which could be identified in at least 5 patients, including KRAS G12D (8%), KRAS G12V (5.8%), PIK3CA E545K (3.5%), PIK3CA H1047R (2.5%), and BMPR2 N583Tfs∗44 (2.8%). These mutations can also be recognized by multiple common HLA molecules in Chinese and TCGA cohort as potential “public” neoantigens. Many of these mutations also have high mutation rates in metastatic pan-cancers, suggesting their value as therapeutic targets in different cancer types. Overall, our analysis provides recurrent neoantigens as potential cancer immunotherapy targets.

T cell receptor-engineered T cells (TCR-Ts) have emerged as potent cancer immunotherapies. While most research focused on classical cytotoxic CD8+ T cells, the application of CD4+ T cells in adoptive T cell therapy has gained much interest recently. However, the cytotoxic mechanisms of CD4+ TCR-Ts have not been fully revealed. In this study, we obtained an MHC class I-restricted MART-127-35-specific TCR sequence based on the single-cell V(D)J sequencing technology, and constructed MART-127-35-specific CD4+ TCR-Ts and CD8+ TCR-Ts. The antitumor effects of CD4+ TCR-Ts were comparable to those of CD8+ TCR-Ts in vitro and in vivo. To delineate the killing mechanisms of cytotoxic CD4+ TCR-Ts, we performed single-cell RNA sequencing and found that classical granule-dependent and independent cytolytic pathways were commonly used in CD4+ and CD8+ TCR-Ts, while high expression of LTA and various costimulatory receptors were unique features for cytotoxic CD4+ TCR-Ts. Further signaling pathway analysis revealed that transcription factors Runx3 and Blimp1/Tbx21 were crucial for the development and killing function of cytotoxic CD4+ T cells. Taken together, we report the antitumor effects and multifaceted killing mechanisms of CD4+ TCR-Ts, and also indicate that MHC class I-restricted CD4+ TCR-Ts could serve as potential adoptive T cell therapies.

Neoantigens are mutated antigens specifically generated by cancer cells but absent in normal cells. With high specificity and immunogenicity, neoantigens are considered as an ideal target for immunotherapy. This study was aimed to investigate the signature of neoantigens in breast cancer. Somatic mutations, including SNVs and indels, were obtained from cBioPortal of 5991 breast cancer patients. 738 non-silent somatic variants present in at least 3 patients for neoantigen prediction were selected. PIK3CA (38%), the highly mutated gene in breast cancer, could produce the highest number of neoantigens per gene. Some pan-cancer hotspot mutations, such as PIK3CA E545K (6.93%), could be recognized by at least one HLA molecule. Since there are more SNVs than indels in breast cancer, SNVs are the major source of neoantigens. Patients with hormone receptor-positive or HER2 negative are more competent to produce neoantigens. Age, but not the clinical stage, is a significant contributory factor of neoantigen production. We believe a detailed description of breast cancer neoantigen signatures could contribute to neoantigen-based immunotherapy development.

This study was aimed to investigate the mutations in colorectal cancer (CRC) for recurrent neoantigen identification. A total of 1,779 samples with whole exome sequencing (WES) data were obtained from 7 published CRC cohorts. Common HLA genotypes were used to predict the probability of neoantigens at high frequency mutants in the dataset. Based on the WES data, we not only obtained the most comprehensive CRC mutation landscape so far, but also found 1550 mutation sites which could be identified in at least 5 or more patients, including KRAS G12D (8%), KRAS G12V (5.8%), PIK3CA E545K (3.5%), PIK3CA H1047R (2.5%) and BMPR2 N583Tfs*44 (2.8%). These mutations can also be recognized by multiple common HLA molecules as potential 'public' neoantigens. Many of these mutations also have high mutation rates in metastatic pan-cancers, suggesting their value as therapeutic targets in different cancer types. Overall, our analysis provides recurrent neoantigens as potential cancer immunotherapy targets.

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