Nathan R. Foster

Defective Mismatch Repair As a Predictive Marker for Lack of Efficacy of Fluorouracil-Based Adjuvant Therapy in Colon Cancer

PURPOSE Prior reports have indicated that patients with colon cancer who demonstrate high-level microsatellite instability (MSI-H) or defective DNA mismatch repair (dMMR) have improved survival and receive no benefit from fluorouracil (FU) -based adjuvant therapy compared with patients who have microsatellite-stable or proficient mismatch repair (pMMR) tumors. We examined MMR status as a predictor of adjuvant therapy benefit in patients with stages II and III colon cancer. METHODS MSI assay or immunohistochemistry for MMR proteins were performed on 457 patients who were previously randomly assigned to FU-based therapy (either FU + levamisole or FU + leucovorin; n = 229) versus no postsurgical treatment (n = 228). Data were subsequently pooled with data from a previous analysis. The primary end point was disease-free survival (DFS). RESULTS Overall, 70 (15%) of 457 patients exhibited dMMR. Adjuvant therapy significantly improved DFS (hazard ratio [HR], 0.67; 95% CI, 0.48 to 0.93; P = .02) in patients with pMMR tumors. Patients with dMMR tumors receiving FU had no improvement in DFS (HR, 1.10; 95% CI, 0.42 to 2.91; P = .85) compared with those randomly assigned to surgery alone. In the pooled data set of 1,027 patients (n = 165 with dMMR), these findings were maintained; in patients with stage II disease and with dMMR tumors, treatment was associated with reduced overall survival (HR, 2.95; 95% CI, 1.02 to 8.54; P = .04). CONCLUSION Patient stratification by MMR status may provide a more tailored approach to colon cancer adjuvant therapy. These data support MMR status assessment for patients being considered for FU therapy alone and consideration of MMR status in treatment decision making.

DNA Mismatch Repair Status and Colon Cancer Recurrence and Survival in Clinical Trials of 5-Fluorouracil-Based Adjuvant Therapy

BACKGROUND Approximately 15% of colorectal cancers develop because of defective function of the DNA mismatch repair (MMR) system. We determined the association of MMR status with colon cancer recurrence and examined the impact of 5-fluorouracil (FU)-based adjuvant therapy on recurrence variables. METHODS We included stage II and III colon carcinoma patients (n = 2141) who were treated in randomized trials of 5-FU-based adjuvant therapy. Tumors were analyzed for microsatellite instability by polymerase chain reaction and/or for MMR protein expression by immunohistochemistry to determine deficient MMR (dMMR) or proficient MMR (pMMR) status. Associations of MMR status and/or 5-FU-based treatment with clinicopathologic and recurrence covariates were determined using χ(2) or Fisher Exact or Wilcoxon rank-sum tests. Time to recurrence (TTR), disease-free survival (DFS), and overall survival (OS) were analyzed using univariate and multivariable Cox models, with the latter adjusted for covariates. Tumors showing dMMR were categorized by presumed germline vs sporadic origin and were assessed for their prognostic and predictive impact. All statistical tests were two-sided. RESULTS In this study population, dMMR was detected in 344 of 2141 (16.1%) tumors. Compared with pMMR tumors, dMMR was associated with reduced 5-year recurrence rates (33% vs 22%; P < .001), delayed TTR (P < .001), and fewer distant recurrences (22% vs 12%; P < .001). In multivariable models, dMMR was independently associated with delayed TTR (hazard ratio = 0.72, 95% confidence interval = 0.56 to 0.91, P = .005) and improved DFS (P = .035) and OS (P = .031). In stage III cancers, 5-FU-based treatment vs surgery alone or no 5-FU was associated with reduced distant recurrence for dMMR tumors (11% vs 29%; P = .011) and reduced recurrence to all sites for pMMR tumors (P < .001). The dMMR tumors with suspected germline mutations were associated with improved DFS after 5-FU-based treatment compared with sporadic tumors where no benefit was observed (P = .006). CONCLUSIONS Patients with dMMR colon cancers have reduced rates of tumor recurrence, delayed TTR, and improved survival rates, compared with pMMR colon cancers. Distant recurrences were reduced by 5-FU-based adjuvant treatment in dMMR stage III tumors, and a subset analysis suggested that any treatment benefit was restricted to suspected germline vs sporadic tumors.

Intraepithelial Effector (CD3+)/Regulatory (FoxP3+) T-Cell Ratio Predicts a Clinical Outcome of Human Colon Carcinoma

BACKGROUND & AIMS Regulatory T cells (Tregs) express the forkhead box transcription factor (FoxP3) and suppress the antitumor immune response. We investigated whether the intratumoral densities of FoxP3(+) and effector CD3(+) lymphocytes are associated with prognosis of patients with colon cancer. METHODS FoxP3 and CD3 expression and location were determined in stage II and III colon carcinomas (n = 160) and normal mucosa (n = 25) by immunohistochemistry; CD4 and FoxP3 were localized by dual immunofluorescence microscopy. T-cell markers were compared with pathological variables, DNA mismatch repair status, and patient survival using Cox proportional hazards models. RESULTS FoxP3(+) and CD3(+) T-cell densities were increased in carcinomas compared with autologous normal mucosa (P < .0001). An increase in intraepithelial FoxP3(+) cells was associated with poor tumor differentiation (P = .038), female sex (P = .028), and advanced patient age (P = .042). FoxP3(+) cell density was not prognostic, yet patients with tumors with reduced intraepithelial CD3(+) T-cell densities had reduced disease-free survival (DFS) rates (hazard ratio [HR], 1.87 [95% confidence interval, 1.10-3.16]; P = .018). A low intraepithelial CD3(+)/FoxP3(+) cell ratio predicted reduced DFS (46.2% vs 66.7% survival at 5 years; HR, 2.17 [95% confidence interval, 1.11-4.23]; P = .0205). The prognostic impact of these markers was maintained when tumors were stratified by mismatch repair status. By multivariate analysis, a low CD3(+)/FoxP3(+) cell ratio (P= .0318) and low numbers of CD3(+) T cells (P = .0397) predicted shorter DFS times and were stronger prognostic variables than tumor stage or number of lymph node metastases. CONCLUSIONS A low intraepithelial CD3(+)/FoxP3(+) cell ratio and reduced numbers of CD3(+) T cells were associated with shorter patient survival time, indicating the importance of an effector to Treg cell ratio in colon cancer prognosis.

Prognostic Significance of Defective Mismatch Repair and BRAF V600E in Patients with Colon Cancer

Purpose: Colon tumors with defective DNA mismatch repair (dMMR) have a well-characterized phenotype and accounts for ∼15% to 20% of sporadic colon cancer as well as those colon cancer patients with Lynch syndrome. Although the presence of dMMR seems to be a favorable prognostic marker, data suggest that these patients do not respond as well to adjuvant chemotherapy. Experimental Design: In this study, we examined the prognostic significance of tumor MMR deficiency and the presence of a specific mutation in BRAF (V600E) in a group of patients (n = 533) who participated in a randomized prospective clinical trial through the North Central Cancer Treatment Group. Results: Tumors with dMMR were found to be associated with higher tumor grade (P = 0.001), proximal location (P < 0.0001), and improved overall and disease-free survival (P = 0.05 and 0.04, respectively). Among all cases examined, evaluation of the BRAF V600E mutation status revealed no statistically significant differences in either disease-free or overall survival. Patients were then grouped into four categories for further analysis: dMMR/BRAF(−), dMMR/BRAF(+), pMMR/BRAF(−), and pMMR/BRAF(+). The dMMR/BRAF(−) group had a significantly improved overall survival (5-year overall survival of 100% versus 73%, P = 0.002) compared with all others. The remaining three groups had very similar survival outcomes. An additional cohort of tumors previously classified as having dMMR were also tested for the BRAF V600E alteration. Results remained significant (P = 0.006) when the two groups were combined for analysis. Conclusions: Overall, these data suggest that the underlying molecular etiology of those tumors having dMMR may influence the disease outcome in these patients.

Obesity Is an Independent Prognostic Variable in Colon Cancer Survivors

Purpose: Obesity is associated with an increased risk of colon cancer. However, the influence of body mass index (BMI) on the prognosis of colon cancer survivors and its relationship to gender remains unknown. Experimental Design: BMI (kg/m2) was categorized in patients with tumor-node-metastasis stage II and III colon carcinomas (n = 4,381) enrolled in seven randomized trials of 5-fluorouracil–based adjuvant chemotherapy. Cox proportional hazards models were used to determine the association of BMI with disease-free survival (DFS) and overall survival (OS). Results: Among colon cancer patients, 868 (20%) were obese (BMI, ≥30 kg/m2), of which 606 were class 1 (BMI, 30-34 kg/m2) and 262 were class 2,3 (BMI, ≥35 kg/m2). Obese versus normal-weight patients were more likely to be younger, have distal tumors, show intact DNA mismatch repair, and have more lymph node metastases (P < 0.017). In a multivariate analysis, BMI was significantly associated with both DFS (P = 0.030) and OS (P = 0.0017). Men with class 2,3 obesity showed reduced OS compared with normal-weight men [hazard ratio, 1.35; 95% confidence interval, 1.02-1.79; P = 0.039]. Women with class I obesity had reduced OS [hazard ratio, 1.24; 95% confidence interval, 1.01-1.53; P = 0.045] compared with normal-weight women. Overweight status was associated with improved OS in men (P = 0.006), and underweight women had significantly worse OS (P = 0.019). BMI was not predictive of therapeutic benefit. Conclusions: Obesity is an independent prognostic variable in colon cancer survivors and shows gender-related differences. These data suggest that obesity-related biological factors can influence clinical outcome. Clin Cancer Res; 16(6); 1884–93

Gemcitabine and ISIS-2503 for Patients With Locally Advanced or Metastatic Pancreatic Adenocarcinoma: A North Central Cancer Treatment Group Phase II Trial

PURPOSE Gemcitabine remains the standard therapy for metastatic pancreatic adenocarcinoma (ACA), but has limited activity. ISIS-2503 is an antisense compound directed against H-ras with preclinical activity against pancreatic ACA in tumor models. The combination of ISIS-2503 and gemcitabine has been evaluated in a prior phase I study. METHODS Patients with metastatic or locally advanced pancreatic ACA not amenable to surgery or local radiation received gemcitabine 1,000 mg/m(2) intravenously over 30 minutes on days 1 and 8 and ISIS-2503 6 mg/kg/d as a continuous intravenous infusion over 14 days of an every-3-weeks cycle. Responses were monitored by radiologic imaging every 6 weeks. RESULTS Forty-eight eligible patients were enrolled, 43 with metastatic disease. Median follow-up was 12.6 months (range, 2.2 to 16.8 months) for living patients. A median of four cycles of treatment was given (range, 1 to 18 cycles). All patients were assessable for response and toxicity. The 6-month survival percentage was 57.5% (95% CI, 44.9% to 73.5%) and the median survival was 6.6 months. The response rate was 10.4% (one complete response, four partial responses). Clinically significant toxicity was limited except for one fatal pulmonary embolism. CONCLUSION This study shows a promising response rate to the combination of gemcitabine and ISIS-2503 in patients with pancreatic ACA. The observed 6-month survival rate in these patients met our protocol-defined criteria for success. This regimen is tolerable, but is of unclear benefit. Additional studies evaluating the role of gemcitabine and ISIS-2503 in the treatment of pancreatic ACA should be considered.

Gemcitabine, Cisplatin, and Radiotherapy for Patients With Locally Advanced Pancreatic Adenocarcinoma: Results of the North Central Cancer Treatment Group Phase II Study N9942

PURPOSE A phase II study was conducted to determine the efficacy and toxicity of radiotherapy with concomitant gemcitabine and cisplatin for patients with locally advanced pancreatic adenocarcinoma. PATIENTS AND METHODS Forty-eight patients with locally advanced pancreatic adenocarcinoma received gemcitabine (30 mg/m2) and cisplatin (10 mg/m2) twice weekly during the first 3 weeks of radiotherapy. The radiation dose to the primary tumor and regional nodes was 45 Gy in 25 fractions, and the gross tumor volume received an additional 5.4 Gy in three fractions. Four weeks after radiotherapy, patients received gemcitabine (1,000 mg/m2) once weekly every 3 of 4 weeks for a 12-week period. The primary end point was survival at 12 months. Secondary end points were time to progression, toxicity, and quality of life. RESULTS Survival at 1 year was 40% for 47 eligible patients. The median survival was 10.2 months. Confirmed responses were observed for 8.5% (two partial, two complete), and median time to progression was 7.3 months. Grade 4 or higher toxicity was observed for 31% and consisted primarily of hematologic and GI toxicity. There was a trend toward improved overall quality of life, measured by the Symptom Distress Scale (P = .06), with significant improvements in domains of insomnia, pain, and outlook. CONCLUSION The combination of radiotherapy, gemcitabine, and cisplatin was well tolerated. Survival results were similar to those achieved with other treatment regimens for patients with locally advanced pancreatic cancer but did not meet our predefined criteria for additional evaluation of this regimen.

Body mass index at diagnosis and survival among colon cancer patients enrolled in clinical trials of adjuvant chemotherapy.

Although obesity is an established risk factor for developing colon cancer, its prognostic impact and relation to patient sex in colon cancer survivors remains unclear.

Comparison of Error Rates in Single-Arm Versus Randomized Phase II Cancer Clinical Trials

PURPOSE To improve the understanding of the appropriate design of phase II oncology clinical trials, we compared error rates in single-arm, historically controlled and randomized, concurrently controlled designs. PATIENTS AND METHODS We simulated error rates of both designs separately from individual patient data from a large colorectal cancer phase III trials and statistical models, which take into account random and systematic variation in historical control data. RESULTS In single-arm trials, false-positive error rates (type I error) were 2 to 4 times those projected when modest drift or patient selection effects (eg, 5% absolute shift in control response rate) were included in statistical models. The power of single-arm designs simulated using actual data was highly sensitive to the fraction of patients from treatment centers with high versus low patient volumes, the presence of patient selection effects or temporal drift in response rates, and random small-sample variation in historical controls. Increasing sample size did not correct the over optimism of single-arm studies. Randomized two-arm design conformed to planned error rates. CONCLUSION Variability in historical control success rates, outcome drifts in patient populations over time, and/or patient selection effects can result in inaccurate false-positive and false-negative error rates in single-arm designs, but leave performance of the randomized two-arm design largely unaffected at the cost of 2 to 4 times the sample size compared with single-arm designs. Given a large enough patient pool, the randomized phase II designs provide a more accurate decision for screening agents before phase III testing.

Prognostic Impact of Bim, Puma, and Noxa Expression in Human Colon Carcinomas

Purpose: Proapoptotic BH3-only proteins (Bim, Bad, Bid, Puma, and Noxa) initiate apoptosis by binding to regulatory sites on antiapoptotic Bcl-2 proteins, directly neutralizing their cytoprotective function. Expression of these proteins in colon cancer patients may account for differences in recurrence and survival rates. Experimental Design: Archival tumor-node-metastasis stage II and III primary colon carcinomas from patients treated in 5-fluorouracil–based adjuvant therapy trials were studied. Immunohistochemical analysis of Bim, Puma, and Noxa proteins was done using tissue microarrays (n = 431). Immunoscores were determined and correlated with clinicopathologic variables and disease-free survival (DFS) and overall survival (OS) rates. Results: Elevated expression of proapoptotic Bim (hazard ratio, 0.65; 95% confidence interval, 0.44-0.97; P = 0.033) and Puma (hazard ratio, 0.59; 95% confidence interval, 0.37-0.93; P = 0.022), but not Noxa, proteins in the tumor cytoplasm was significantly associated with more favorable OS in a univariate analysis, and elevated Bim expression was also associated with better DFS (P = 0.023). Patient age, tumor stage, and histologic grade were also prognostic. Multivariate Cox analysis showed that Bim (DFS, P = 0.030; OS, P = 0.045) and Puma (OS, P = 0.037) expression were independent predictors of OS after adjustment for histologic grade, tumor stage, age, and treatment. Furthermore, the combined variable of Bim and Puma was highly discriminant for both DFS (P = 0.0034) and OS (P = 0.0011). Conclusions: The proapoptotic BH3-only proteins Bim and Puma can provide prognostic information for stage II and III colon cancer patients receiving 5-fluorouracil–based adjuvant chemotherapy. Furthermore, our results support BH3-only proteins as molecular targets of novel anticancer drugs.