Role of Tumor-informed Personalized Circulating Tumor DNA Assay in Informing Recurrence in Patients With Peritoneal Metastases From Colorectal and High-grade Appendix Cancer Undergoing Curative-intent Surgery.

OBJECTIVE: To investigate the role of a personalized, tumor-informed circulating tumor DNA (ctDNA) assay in informing recurrence in patients with peritoneal metastases (PM) from colorectal (CRC) and high-grade appendix (HGA) cancer after curative cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). BACKGROUND: Over 50% of patients with CRC/HGA-PM recur after optimal CRS-HIPEC. The limited sensitivity of axial imaging and diagnostic biomarkers is a significant cause of delay in the detection of recurrence and initiation of further therapies. Plasma ctDNA has a promising role in monitoring response to treatment and/or recurrence after primary cancer resection. METHODS: Patients with CRC/HGA-PM who underwent curative CRS-HIPEC and serial postresection ctDNA assessments were included. Patients with rising postoperative ctDNA levels were compared with those with stable, undetectable ctDNA levels. Primary outcomes were the percentage of patients with recurrence and disease-free survival (DFS). Secondary outcomes were overall survival, ctDNA sensitivity, lead time, and performance of ctDNA compared with carcinoembryonic antigen. RESULTS: One hundred thirty serial postresection ctDNA assessments [median 4, interquartile range (IQR), 3 to 5] were performed in 33 patients (n = 13 CRC, n = 20 HGA) who underwent completeness of cytoreduction-0/1 CRS with a median follow-up of 13 months. Of the 19 patients with rising ctDNA levels, 90% recurred versus 21% in the stable ctDNA group (n = 14, < 0.001). Median DFS in the rising ctDNA cohort was 11 months (IQR, 6 to 12) and not reached in the stable ( P = 0.01). A rising ctDNA level was the most significant factor associated with DFS (hazard ratio: 3.67, 95% CI: 1.06-12.66, P = 0.03). The sensitivity and specificity of rising ctDNA levels in predicting recurrence were 85% and 84.6%, respectively. The median ctDNA lead time was 3 months (IQR, 1 to 4). Carcinoembryonic antigen was less sensitive (50%) than ctDNA. CONCLUSIONS: This study supports the clinical validity of serial ctDNA assessment as a strong prognostic biomarker in informing recurrence in patients with CRC/HGA-PM undergoing curative resection. It also holds promises for informing future clinical trial designs and further research.

Mutational profiles and prognostic impact in colorectal and high-grade appendiceal adenocarcinoma with peritoneal metastases.

BACKGROUND: Next-generation sequencing (NGS) personalizes cancer treatments. In this study, we analyze outcomes based on NGS testing for colorectal cancer (CRC) and high-grade appendiceal adenocarcinoma (HGA) with peritoneal metastases. METHODS: Retrospective review of genomic analyses and outcomes in patients with CRC or HGA with peritoneal metastases at a high-volume center from 2012 to 2019. RESULTS: Ninety-two patients (57 CRC, 35 HGA) were identified. Overall survival was longer for CRC (52.8 vs. 30.5 months, p = 0.03), though rates of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) were similar. Multiple genes were more frequently mutated in CRC, including KRAS (51% vs. 29%, p = 0.04), TP53 (47% vs. 20%, p < 0.01), and APC (46% vs. 6%, p < 0.01). For CRC, multivariate regression showed an increased hazard ratio (HR) with increasing peritoneal cancer index (1.06 [1.01-1.11], p = 0.02) and a decreased HR following CRS/HIPEC (0.30 [0.11-0.80], p = 0.02). PIK3CA mutation associated with significantly increased HR (3.62 [1.06-12.41], p = 0.04), though only in non-CRS/HIPEC patients. Multivariate analysis in the HGA group showed a benefit following CRS/HIPEC (0.18 [0.06-0.61], p = 0.01) and for mucinous disease (0.38 [0.15-0.96], p = 0.04), while there was an increased HR with TP53 mutation (6.89 [2.12-22.44], p < 0.01). CONCLUSION: CRC and HGA with peritoneal spread have distinct mutational profiles. PIK3CA and TP53 mutations are associated with survival for CRC or HGA with peritoneal metastases, respectively.

Prognostic Impact of BRAF and KRAS Mutation in Patients with Colorectal and Appendiceal Peritoneal Metastases Scheduled for CRS and HIPEC.

BACKGROUND: KRAS and BRAF mutations are prognostic and predictive tools in metastatic colorectal cancer, but little is known about their prognostic value in patients scheduled for cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Therefore, we analyzed the prognostic impact of KRAS and BRAF mutations in patients with peritoneal metastases scheduled for CRS and HIPEC. PATIENTS AND METHODS: In a consecutive series of 399 patients scheduled for CRS and HIPEC between 2009 and 2017, 111 subjects with peritoneal metastases from primaries of the appendix, colon, or rectum were analyzed for KRAS mutation and 92 for BRAF mutation. RESULTS: Mutation in KRAS was present in 51/111 (46%), and mutated BRAF was found in 10/92 (11%). There was no difference in overall survival between KRAS mutation tumors and KRAS wild type, whereas BRAF mutation was associated with short survival. No subject with BRAF mutation survived 2 years. On multivariate analysis, completeness of cytoreduction score (CCS, p = 0.000001), presence of signet cell differentiation (p = 0.000001), and BRAF mutation (p = 0.0021) were linked with poor prognosis. CONCLUSIONS: BRAF mutation is a marker of poor prognosis in patients with appendiceal and colorectal peritoneal metastases scheduled for CRS and HIPEC, whereas survival outcome in subjects with mutated KRAS does not differ from wild-type KRAS. This finding suggests that those with BRAF mutation should be considered for alternative treatment options.

Discrimination of low- and high-grade appendiceal mucinous neoplasms by targeted sequencing of cancer-related variants.

DNA was obtained from matching micro-dissected, primary tumor cells, paired metastases, and peripheral blood mononuclear cells (germline) from patients with appendiceal mucinous neoplasms. We compared specimens from patient cohorts comprising low-grade adenomucinous neoplasm versus high-grade mucinous adenocarcinoma using a targeted, amplicon sequencing panel of 409 cancer related genes (Ion Torrent Comprehensive Cancer Panel, Thermo-Fisher, Waltham, MA). Copy number variants, single nucleotide variants and small insertions/deletions were identified using a multiplex algorithm pipeline (GATK, VarScan2, MuTect2, SIFT, SIFT-INDEL, PolyPhen-2, Provean). There were significantly more damaging variants in high-grade versus low-grade tumor cohorts. Both cohorts contained damaging, heterozygous germline variants (catenin ß1; notch receptor 1 and 4) in pathways associated with cell-lineage specification (WNT, NOTCH). Damaging, somatic KRAS proto-oncogene, GTPase mutations were present in both cohorts, while somatic GNAS complex locus mutations were confined to low-grade neoplasms. Variants predominantly affected transcription factors, kinases, and stem cell signaling molecules in canonical pathways including epithelial to mesenchymal transition, stem cell pluripotency, p53, PTEN, and NF-қB signaling pathways. High-grade tumors demonstrated MYC proto-oncogene, bHLH transcription factor (MYC) and death domain associated protein (DAXX) amplification and damaging somatic variants in tumor protein p53 (TP53), likely to amplify an aggressive phenotype. Damaging APC, WNT signaling pathway regulator (APC) deletions were identified in metastatic tissue of both cohorts suggesting a role in invasive disease. Our data suggest that germline dysregulation of WNT and/or NOTCH pathways predisposes patients toward a secretory cell phenotype (i.e., goblet-like cells) upon acquisition of somatic KRAS mutations. Additional somatically acquired variants activating oncogenes MYC and DAXX and inhibiting the critical tumor suppressor, tumor protein TP53, were consistent with manifestation of a high-grade phenotype. These additional changes within the epithelial to mesenchymal transition signaling network (WNT, NOTCH, RAS/ERK/PI3K, PTEN, NF-қB), produce aggressive high-grade tumor characteristics by actively driving cells towards dedifferentiation, proliferation, and migration.

An appendix carcinoid tumor in a patient with hereditary nonpolyposis colorectal cancer.

Gastrointestinal carcinoid tumors are often associated with other tumors, particularly colon adenocarcinomas; but the association between carcinoid tumors and hereditary nonpolyposis colorectal cancer (HNPCC) syndrome has not yet been explored. We report an unusual case of a 28-year-old woman with HNPCC who underwent surgery for a transverse colon adenocarcinoma in whom an appendix carcinoid tumor was incidentally found. To assess whether the carcinoid tumor displayed the characteristic molecular features of HNPCC tumors, we investigated the expression of mismatch-repair (MMR) proteins and microsatellite instability (MSI) status in both tumors. Both tumors demonstrated normal expression of the MMR proteins hMLH1, hMSH2, hMSH6, and hPMS2. Interestingly, the adenocarcinoma exhibited an MSI phenotype but the carcinoid tumor did not, indicating that these 2 tumors arose through different molecular pathways.