AUTHOR=Ottaiano Alessandro , de Vera d’Aragona Roberta Penta , Trotta Anna Maria , Santorsola Mariachiara , Napolitano Maria , Scognamiglio Giosuè , Tatangelo Fabiana , Grieco Paolo , Zappavigna Silvia , Granata Vincenza , Perri Francesco , Luce Amalia , Savarese Giovanni , Ianniello Monica , Casillo Marika , Petrillo Nadia , Belli Andrea , Izzo Francesco , Nasti Guglielmo , Caraglia Michele , Scala Stefania 

TITLE=Characterization of KRAS Mutational Regression in Oligometastatic Patients

JOURNAL=Frontiers in Immunology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.898561

DOI=10.3389/fimmu.2022.898561

ISSN=1664-3224

ABSTRACT=<sec><title>Background</title><p>We previously reported rare regressive genetic trajectories of <italic>KRAS</italic> pathogenic mutations as a specific hallmark of the genuine oligometastatic status in colorectal cancer (CRC).</p></sec><sec><title>Methods</title><p>Survival and prognostic impact of disease extent in 140 metastatic CRC patients were evaluated through the Kaplan–Meyer curves and the Log-Rank test. <italic>KRAS</italic> mutations were assessed through the Illumina NovaSeq 6000 platform and TruSight™ Oncology 500 kit. HLA typing was carried out by PCR with sequence-specific oligonucleotides. Lymphocyte densities in tumors were expressed as cells per square millimeter. NKs isolated and CD8<sup>+</sup> from NK-depleted PBMCs were characterized through flow cytometry. CD107a externalization was evaluated as NKs/CD8 cytotoxicity toward human colon cancer cells HT29, SW620, HCT116, and LS174T carrying different <italic>KRAS</italic> mutations.</p></sec><sec><title>Results</title><p>The oligometastatic status was a strong and independent variable for survival (HR: 0.08 vs. polymetastatic disease; 95% CI: 0.02–0.26; <italic>p</italic> &lt; 0.001). Eighteen oligometastatic patients were selected. Twelve were alive at the last follow-up, and 9 were characterized. Genetic regression of <italic>KRAS</italic> was observed in 3 patients: patient (PAT)2, PAT5, and PAT8. PAT2 and PAT5 presented the highest levels of GrzB<sup>+</sup> lymphocytes in the tumor cores of the metastases (120 ± 11.2 and 132 ± 12.2 cells/mm<sup>2</sup>, respectively). Six out of 9 patients (67%), including PAT2 and PAT5, expressed HLA-C7. Twopatients (PAT2 and PAT5) presented high CD3<sup>+</sup>/CD8<sup>+</sup>-dependent cytotoxicity against HLA-C7+ SW620 cells (p.G12V-mutated cells), which was consistent with their observed mutational regression (p.G12V/p.G13D in primary→p.G13D in metastatic tumor).</p></sec><sec><title>Conclusions</title><p>We provide evidence that CD3<sup>+</sup>/CD8<sup>+</sup> lymphocytes from oligometastatic CRC patients display differential cytotoxicity against human colon cancer cells carrying <italic>KRAS</italic> mutations. This could provide an interesting basis for monitoring oligometastatic disease and developing future adoptive immunotherapies.</p></sec>