Patient-reported Symptom Outcomes and Microsatellite Instability in Patients With Metastatic Colorectal Cancer.

BACKGROUND: The survival of patients with metastatic colorectal cancer (mCRC) is influenced by the genetic and epigenetic changes that might influence the patient experience of symptom burden. Understanding the association of molecular changes with the symptom burden could help clinicians gain insight into the molecular basis of symptom burden and improve treatment tolerance. To date, no studies have compared the patient-reported symptom burden with these molecular subsets among patients with mCRC. PATIENTS AND METHODS: We recruited patients with mCRC that was refractory to ≥ 1 line of therapy who had been enrolled in the Assessment of Targeted Therapies Against Colorectal Cancer trial at The University of Texas MD Anderson Cancer Center. All patients completed a baseline gastrointestinal symptom inventory (MD Anderson Symptom Inventory, gastrointestinal). The symptom burden across key demographic variables and molecular changes, including CRC-associated mutations, microsatellite instability (MSI) status, and the CpG island methylator phenotype (CIMP) were compared using χ2 tests. Association of the symptom burden with overall survival was examined using Cox regression models. RESULTS: Patients with an MSI-high (MSI-H) phenotype reported greater pain (odds ratio [OR], 3.06; 95% confidence interval [CI], 1.61-5.84), fatigue (OR, 2.78; 95% CI, 1.41-5.49), sleep (OR, 2.52; 95% CI, 1.32-4.08); and drowsiness (OR, 2.51; 95% CI, 1.32-4.78) compared with microsatellite stable patients. Patients with an MSI-H phenotype also had greater odds of overall symptom burden (OR, 2.48; 95% CI, 1.29-4.74) compared with microsatellite stable patients. The CIMP-high patients experienced greater odds of pain compared with the CIMP-negative patients (OR, 1.72; 95% CI, 1.06-2.80). A greater overall symptom burden was associated with poor overall survival (hazard ratio, 1.42; 95% CI, 0.98-2.06]), although the difference was not significant (P = .06). CONCLUSION: Correlation of MSI-H-associated tumor features with the symptom burden could help provide a better understanding of underlying mechanisms associated with our findings.

Clinical utility of circulating cell-free DNA in advanced colorectal cancer.

BACKGROUND: Circulating cell-free DNA (cfDNA) isolated from the plasma of cancer patients (pts) has been shown to reflect the genomic mutation profile of the tumor. However, physician and patient assessment of clinical utility of these assays in patients with metastatic colorectal cancer (mCRC) has not been previously described. METHODS: Patients were prospectively consented to a prospective genomic matching protocol (Assessment of Targeted Therapies Against Colorectal Cancer [ATTACC]), with collection of blood for cfDNA extraction and sequencing of a 54-gene panel in a CLIA-certified lab. Formalin-fixed, paraffin-embedded (FFPE) tissue from prior resections or biopsies underwent 50-gene sequencing. Results from both assays were returned to the treating physicians for patient care and clinical trial selection. Follow-up surveys of treating physicians and chart reviews assessed clinical utility. RESULTS: 128 mCRC pts were enrolled between 6/2014 and 1/2015. Results were returned in median of 13 and 26 days for cfDNA and FFPE sequencing, respectively. With cfDNA sequencing, 78% (100/128) of samples had a detectable somatic genomic alteration. 50% of cfDNA cases had potentially actionable alterations, and 60% of these could be genomically matched to at least one clinical trial in our institution. 50% (15/30) of these pts enrolled onto an identified matched trial. Physicians reported that the cfDNA testing improved the quality of care they could provide in 73% of the cases, and that 89% of pts reported greater satisfaction with the efforts to personalize experimental therapeutic agents. CONCLUSIONS: cfDNA sequencing can provide timely information on potentially actionable mutations and amplifications, thereby facilitating clinical trial enrollment and improving the perceived quality of care.

Modeling of Patient-Derived Xenografts in Colorectal Cancer.

Developing realistic preclinical models using clinical samples that mirror complex tumor biology and behavior are vital to advancing cancer research. While cell line cultures have been helpful in generating preclinical data, the genetic divergence between these and corresponding primary tumors has limited clinical translation. Conversely, patient-derived xenografts (PDX) in colorectal cancer are highly representative of the genetic and phenotypic heterogeneity in the original tumor. Coupled with high-throughput analyses and bioinformatics, these PDXs represent robust preclinical tools for biomarkers, therapeutic target, and drug discovery. Successful PDX engraftment is hypothesized to be related to a series of anecdotal variables namely, tissue source, cancer stage, tumor grade, acquisition strategy, time to implantation, exposure to prior systemic therapy, and genomic heterogeneity of tumors. Although these factors at large can influence practices and patterns related to xenotransplantation, their relative significance in determining the success of establishing PDXs is uncertain. Accordingly, we systematically examined the predictive ability of these factors in establishing PDXs using 90 colorectal cancer patient specimens that were subcutaneously implanted into immunodeficient mice. Fifty (56%) PDXs were successfully established. Multivariate analyses showed tissue acquisition strategy [surgery 72.0% (95% confidence interval (CI): 58.2-82.6) vs. biopsy 35% (95% CI: 22.1%-50.6%)] to be the key determinant for successful PDX engraftment. These findings contrast with current empiricism in generating PDXs and can serve to simplify or liberalize PDX modeling protocols. Better understanding the relative impact of these factors on efficiency of PDX formation will allow for pervasive integration of these models in care of colorectal cancer patients. Mol Cancer Ther; 16(7); 1435-42. ©2017 AACR.

FBXW7 missense mutation: a novel negative prognostic factor in metastatic colorectal adenocarcinoma.

BACKGROUND: FBXW7 functions as a ubiquitin ligase tagging multiple dominant oncogenic proteins and commonly mutates in colorectal cancer. Data suggest missense mutations lead to greater loss of FBXW7 function than other gene aberrations do. However, the clinicopathologic factors and outcomes associated with FBXW7 missense mutations in metastatic colorectal cancer (mCRC) have not been described. METHODS: Data were obtained from mCRC patients whose tumors were evaluated by next-generation sequencing for hotspot mutations at The University of Texas MD Anderson Cancer Center. Alterations in FBXW7 were identified, and their associations with clinicopathologic features and overall survival (OS) were evaluated. RESULTS: Of 855 mCRC patients, 571 had data on FBXW7 status; 43 (7.5%) had FBXW7 mutations, including 37 with missense mutations. R465C mutations in exon 9 were the most common missense mutations (18.6%). PIK3CA mutations were associated with FBXW7 missense mutations (p=0.012). On univariate analysis, patients with FBXW7 missense mutations had significantly worse OS (median 28.7 mo) than those with wild-type FBXW7 (median 46.6 mo; p=0.003). On multivariate analysis including other known prognostic factors such as BRAF mutations, FBXW7 missense mutations were the strongest negative prognostic factor for OS (hazard ratio 2.0; p=0.003). CONCLUSIONS: In the largest clinical dataset of mCRC to date, FBXW7 missense mutations showed a strong negative prognostic association.

Association of SMAD4 mutation with patient demographics, tumor characteristics, and clinical outcomes in colorectal cancer.

SMAD4 is an essential mediator in the transforming growth factor-ß pathway. Sporadic mutations of SMAD4 are present in 2.1-20.0% of colorectal cancers (CRCs) but data are limited. In this study, we aimed to evaluate clinicopathologic characteristics, prognosis, and clinical outcome associated with this mutation in CRC cases. Data for patients with metastatic or unresectable CRC who underwent genotyping for SMAD4 mutation and received treatment at The University of Texas MD Anderson Cancer Center from 2000 to 2014 were reviewed. Their tumors were sequenced using a hotspot panel predicted to cover 80% of the reported SMAD4 mutations, and further targeted resequencing that included full-length SMAD4 was performed on mutated tumors using a HiSeq sequencing system. Using The Cancer Genome Atlas data on CRC, the characteristics of SMAD4 and transforming growth factor-ß pathway mutations were evaluated according to different consensus molecular subtypes of CRC. Among 734 patients with CRC, 90 (12%) had SMAD4 mutations according to hotspot testing. SMAD4 mutation was associated with colon cancer more so than with rectal cancer (odds ratio 2.85; p<0.001), female sex (odds ratio 1.71; p = 0.02), and shorter overall survival than in wild-type SMAD4 cases (median, 29 months versus 56 months; hazard ratio 2.08; p<0.001 [log-rank test]). SMAD4 mutation was not associated with age, stage at presentation, colonic location, distant metastasis, or tumor grade. A subset of patients with metastatic CRC (n = 44) wild-type for KRAS, NRAS, and BRAF who received anti-epidermal growth factor receptor therapy with mutated SMAD4 (n = 13) had shorter progression-free survival duration than did patients wild-type for SMAD4 (n = 31) (median, 111 days versus 180 days; p = 0.003 [log-rank test]). Full-length sequencing confirmed that missense mutations at R361 and P356 in the MH2 domain were the most common SMAD4 alterations. In The Cancer Genome Atlas data, SMAD4 mutation frequently occurred with KRAS, NRAS, and BRAF mutations and was more common in patients with the consensus molecular subtype 3 of CRC than in those with the other 3 subtypes. This is one of the largest retrospective studies to date characterizing SMAD4 mutations in CRC patients and demonstrates the prognostic role and lack of response of CRC to anti-epidermal growth factor receptor therapy. Further studies are required to validate these findings and the role of SMAD4 mutation in CRC.