Prognostic and predictive roles of high-degree microsatellite instability in colon cancer: A National Cancer Institute-national surgical adjuvant breast and bowel project collaborative study

Purpose: The role of high-degree microsatellite instability (MSI-H) as a marker to predict benefit from adjuvant chemotherapy remains unclear. Patients and Methods: To help define its impact, we conducted an analysis of National Surgical Adjuvant Breast and Bowel Project (NSABP) patients who were randomly assigned to a surgery-alone group (untreated cohort) and patients assigned to an adjuvant fluorouracil (FU) -treated group (treated cohort). MSI-H and other potential markers were assessed (TGF-BRII, p53, thymidylate synthase, and Ki67). Results: In all, 98 (18.1%) of 542 patients exhibited MSI-H, and there was a strong inverse relationship between MSI-H and mutant p53 status (P \u3c .001). The prognostic analyses showed increased recurrence-free survival (RFS) for MSI-H patients versus MSS/MSI-L patients (P = .10), but showed no difference in overall survival (OS; P \u3c .67). There was a potential interaction between MSI-H and mutant p53 in terms of improved RFS (P = .03). In the predictive marker analysis, we observed no interaction between MSI status and treatment for either RFS (P = .68) or OS (P = .62). Hazard ratios (HR) for RFS for MSI-H versus MSS/MSI-L patients were 0.77 (95% CI, 0.40 to 1.48) in the untreated-patients group and 0.60 (95% CI, 0.30 to 1.19) in the treated-patients group. HRs for OS were 0.82 (95% CI, 0.44 to 1.51) and 1.02 (95% CI, 0.56 to 1.85) for the respective groups. There was a trend toward improved RFS in patients with MSI-H and mutant p53. Conclusion: These results do not support the use of MSI-H as a predictive marker of chemotherapy benefit. © 2007 by American Society of Clinical Oncology

Pemetrexed/oxaliplatin for first-line treatment of patients with advanced colorectal cancer: a phase II trial of the National Surgical Adjuvant Breast and Bowel Project Foundation Research Program.

BACKGROUND: Pemetrexed and oxaliplatin have clinical activity as single agents in colorectal cancer (response rates, 10%-17%). In this study, these drugs were used in combination as first-line therapy in a group of patients with metastatic colorectal cancer. PATIENTS AND METHODS: Fifty-four evaluable patients were to receive pemetrexed (500 mg/m2) with folic acid and vitamin B12 supplementation and oxaliplatin (120 mg/m2) every 21 days for 6 cycles or until disease progression occurred. Patients with stable or responding disease could continue therapy beyond 6 cycles at the discretion of the investigator. Eligibility criteria included a diagnosis of untreated metastatic adenocarcinoma of the colon or rectum, measurable disease, Zubrod performance status or=12 weeks life expectancy. RESULTS: The confirmed clinical response rate (primary endpoint) was 29.6% (95% confidence interval [CI], 18%-48.6%), with 1 complete response and 15 partial responses. Median time to progression was 5.3 months (95% CI, 3.9-6.3 months), and median survival was 12.3 months (95% CI, 8.6-17 months). Grade 3/4 nadir neutropenia occurred in 33.3% of patients, and 3 patients experienced grade 3 febrile neutropenia or infection associated with grade 3/4 neutropenia. Grade 3/4 nadir thrombocytopenia was seen in 11.1% of patients. Only 4% of the patients developed grade 3/4 neurotoxicity. CONCLUSION: This regimen of pemetrexed and oxaliplatin has activity in advanced colorectal cancer, and the toxicity profile suggests that escalation of the dose of pemetrexed in this combination may be possible