Characterization of KRAS Mutational Regression in Oligometastatic Patients

Abstract

BackgroundWe previously reported rare regressive genetic trajectories of KRAS pathogenic mutations as a specific hallmark of the genuine oligometastatic status in colorectal cancer (CRC).MethodsSurvival and prognostic impact of disease extent in 140 metastatic CRC patients were evaluated through the Kaplan–Meyer curves and the Log-Rank test. KRAS 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+ 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 KRAS mutations.ResultsThe oligometastatic status was a strong and independent variable for survival (HR: 0.08 vs. polymetastatic disease; 95% CI: 0.02–0.26; p < 0.001). Eighteen oligometastatic patients were selected. Twelve were alive at the last follow-up, and 9 were characterized. Genetic regression of KRAS was observed in 3 patients: patient (PAT)2, PAT5, and PAT8. PAT2 and PAT5 presented the highest levels of GrzB+ lymphocytes in the tumor cores of the metastases (120 ± 11.2 and 132 ± 12.2 cells/mm2, respectively). Six out of 9 patients (67%), including PAT2 and PAT5, expressed HLA-C7. Twopatients (PAT2 and PAT5) presented high CD3+/CD8+-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).ConclusionsWe provide evidence that CD3+/CD8+ lymphocytes from oligometastatic CRC patients display differential cytotoxicity against human colon cancer cells carrying KRAS mutations. This could provide an interesting basis for monitoring oligometastatic disease and developing future adoptive immunotherapies.

Oligo-Metastatic Disease in Oncology: Exploring the Limits and the Potential of Genetic Assessment

“…Finally, we previously observed a higher prevalence of the HLA-C7 allele in OMD from CRC patients. This data could support the enhanced presentation of specific tumor antigens and align with specific immunological phenomena underlying the oligo-metastatic status [60].…”

Oligo-Metastatic Cancers: Putative Biomarkers, Emerging Challenges and New Perspectives

“…Furthermore, as already reported in other settings, in contrast with the common knowledge suggesting that gene mutations constantly prompt cell transformation and metastases, some driver gene mutations ( PBRM1 and SETD2 ) were associated with attenuated progression and OMD. More studies have been reported in colorectal cancer (CRC) where molecular subtyping (“canonical” and “immune” subtypes) [ 90 ], regression of key-driver gene mutations ( KRAS , PIK3CA ) [ 91 ], high level of T-cell infiltration into metastases [ 92 ], high level of peripheral cytotoxic T-cells [ 93 ], specific gene mutations ( ERBB2 ) [ 92 ] correlates with the OMD phenotype. In particular, in our previous reports [ 91 , 92 ], we provided an evolutionary and dynamic analytic perspective, highlighting that comparing primary and metastatic lesions could assist in identifying the true de novo oligo-metastatic behavior.…”

“… The patients with these characteristics develop poly-metastatic widely diffusive disease. Ottaiano, 2022 [ 93 ] Colorectal cancer. KRAS regression from primary to metastatic lesions.…”

Optimizing Treatment Strategy for Oligometastases/Oligo-Recurrence of Colorectal Cancer

“…The extended studies regarding distinctive molecular profile of oligometastatic CRC have demonstrated that oligometastatic CRC is a specific disease having a potential of cure and not simply an evolutionary step towards polymetastatic disease, which has more aggressive biological behavior [ 207 , 208 , 209 , 210 , 211 , 212 ]. Loss of KRAS and SMAD4 mutations characterizes the oligometastatic disease while a progressive mutational evolution (gain in KRAS, PI3KCA, BRAF, and SMAD4) is observed in polymetastatic evolving disease.…”