Characterization of KRAS Mutational Regression in Oligometastatic Patients
Alessandro Ottaiano1, Roberta Penta de Vera d'Aragona2, Anna Maria Trotta1
1Istituto Nazionale Tumori di Napoli, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) "G. Pascale", Naples, Italy.
Background:
We previously reported rare regressive genetic trajectories of KRAS pathogenic mutations as a specific hallmark of the genuine oligometastatic status in colorectal cancer (CRC).
Methods:
Survival 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.
Results:
The 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).
Conclusions:
We 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.
Insights
Oligometastatic colorectal cancer (CRC) patients show immune cell cytotoxicity against KRAS-mutated cells. This finding supports monitoring disease and developing new immunotherapies for CRC.
Area of Science:
- Oncology
- Immunology
- Genetics
Background:
- Colorectal cancer (CRC) patients with oligometastatic status exhibit unique KRAS mutation patterns.
- KRAS mutations are key drivers in CRC progression and treatment resistance.
Purpose of the Study:
- To investigate the immune cell cytotoxicity in oligometastatic CRC patients with KRAS mutations.
- To explore the correlation between genetic regression of KRAS mutations and immune responses.
Main Methods:
- Analysis of 140 metastatic CRC patients, including KRAS mutation assessment (Illumina NovaSeq 6000, TruSight™ Oncology 500 kit).
- HLA typing and measurement of lymphocyte densities (NKs, CD8+ T cells) within tumors.
- Flow cytometry to evaluate CD107a externalization as a measure of cytotoxicity against KRAS-mutated colon cancer cells.
Main Results:
- Oligometastatic status significantly improved survival in CRC patients.
- Three patients showed genetic regression of KRAS mutations, correlating with high lymphocyte densities and CD8+ T cell cytotoxicity.
- Patients with HLA-C7 expression demonstrated enhanced CD3+/CD8+ cytotoxicity against KRAS-mutated cancer cells.
Conclusions:
- CD3+/CD8+ lymphocytes in oligometastatic CRC patients exhibit specific cytotoxicity against KRAS-mutated colon cancer cells.
- This immune response may serve as a biomarker for monitoring oligometastatic disease.
- Findings suggest potential for developing novel adoptive immunotherapies for CRC.
