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T R Fleming

Publications and source records attributed to T R Fleming.

At least 37 records · Page 2Linked to original sources
PubMed1995

The data and safety monitoring board and acquired immune deficiency syndrome (AIDS) clinical trials.

The urgency of the Acquired immune deficiency syndrome (AIDS) epidemic has mandated that multiple therapeutic approaches be developed and that these approaches be evaluated through clinical trials. To oversee these trials, the National Institute of Allergy and Infectious Diseases (NIAID) has created three large clinical trial programs monitored by a Data and Safety Monitoring Board (DSMB). For each clinical trial, this Board uses a standardized approach employing contemporary biostatistical, medical, and ethical principles. The DSMB is responsible for reviewing interim data on clinical trial performance, treatment safety and efficacy, and overall study progress. If interim results provide convincing evidence of either excessive adverse effects or significant treatment benefit, the DSMB may recommend early termination of the trial to the NIAID and the study investigators. The responsibility, organization, and operating procedures of this DSMB are presented and illustrated through three clinical trials sponsored by NIAID and monitored by the Board. The rationale and operational model for the DSMB may be a useful example for the development of similar review processes in other HIV clinical trial settings.

Advisory Committees↗
PubMed1995

A randomized trial of two schedules of trimetrexate versus 5-fluorouracil in advanced colorectal cancer: a Southwest Oncology Group study.

Trimetrexate (TMQ), a non-classical folate antagonist, was studied in a randomized controlled trial in patients with advanced colorectal cancer and without prior chemotherapy. Patients were randomly assigned to one of three treatments: TMQ at 200 mg/m2 i.v. q 2 weeks, TMQ at 12 mg/m2 i.v. daily x 5 or 5-fluorouracil (5-FU) at 15 mg/kg i.v. weekly. Overall response rates were: 6% (four partial responses in 71 patients, 95% CI of 2-14%) for q 2 week TMQ, 0% (zero of 29, 95% CI of 0-29%) for daily x 5 TMQ and 18% (two complete and nine partial responses in 62 patients, 95% CI of 9-30%) for 5-FU. Median survival estimates were 10.3 months for the q 2 week TMQ schedule, 8.7 months for the daily x 5 TMQ schedule and 13.6 months for the 5-FU schedule. Grade < or = 3 toxicities were significantly more common with TMQ. TMQ does not appear to have significant antitumor activity against colorectal cancer.

Aged↗
PubMed1995

Statistical issues in the design of HIV vaccine trials.

HIV vaccine trials present significant challenges related to trial endpoints, vaccine efficacy measurement, and the role of nonvaccine interventions. Infection is a valid endpoint for detecting sterilizing immunity. But if the vaccine prevents AIDS without preventing infection, infection may be a misleading surrogate. Appropriate endpoints must be defined for other mechanisms of vaccine action. Direct, indirect, behavioral, and biological effects all determine vaccine efficacy. False security among HIV-vaccine recipients may make negative behavioral effects an important component of vaccine performance. Both biological potency and a more comprehensive program effectiveness should be measured. These goals may require unblinded designs or community randomization. Nonvaccine interventions are currently the only HIV-prevention strategy. Support for larger scale implementation requires more rigorous evaluation that is less dependent on self-reported behavioral changes. The vaccine trial cohorts provide a unique opportunity to cost-effectively evaluate behavioral interventions.

AIDS Vaccines↗
PubMed1995

Intergroup study of fluorouracil plus levamisole as adjuvant therapy for stage II/Dukes' B2 colon cancer.

PURPOSE: To determine the effectiveness of fluorouracil plus levamisole administered postoperatively to patients with resected stage II (Dukes' B2) colon cancer. PATIENTS AND METHODS: This randomized controlled clinical trial (INT-0035) was performed by National Cancer Institute-sponsored cancer clinical trials cooperative groups. Patients were assigned to observation only or to fluorouracil (450 mg/m2 intravenously [IV] daily for 5 days and, beginning at 28 days, weekly for 48 weeks) plus levamisole (50 mg orally three times daily for 3 days repeated every 2 weeks for 1 year). Cancer recurrence, survival, and treatment side effects were assessed. RESULTS: Three hundred eighteen eligible patients were analyzed with a median follow-up time of 7 years. Fluorouracil plus levamisole reduced the recurrence rate by 31%, although this trend was not statistically significant (P = .10). A total of 87 patients died: 43 on observation and 44 on fluorouracil plus levamisole. Disparity between effects on recurrence rate and overall survival is partially explained by a higher rate of non-colon cancer-related deaths on fluorouracil plus levamisole (15 v seven) and by the effects of salvage surgery with curative intent. Of seven patients with recurrence who were rendered disease-free by salvage surgery, six were on the observation arm. As was observed in patients treated with fluorouracil plus levamisole for stage III disease, toxicity was acceptable and compliance was excellent. CONCLUSION: Fluorouracil plus levamisole is tolerable and accepted as standard surgical adjuvant therapy for patients with stage III colon cancer, but the data from this study in stage II patients suggest a decreased relapse rate without a significant improvement in survival.

Adenocarcinoma↗
PubMed1995

Phase II study of fluorouracil and its modulation in advanced colorectal cancer: a Southwest Oncology Group study.

PURPOSE: A variety of fluorinated pyrimidine-based regimens for the treatment of disseminated colorectal cancer have been presented in the medical literature. The Southwest Oncology Group designed a screening trial of seven regimens of fluorouracil (5-FU) to assess efficacy and toxicity afforded by biochemical modulation or schedule variations. PATIENTS AND METHODS: Six hundred twenty patients were entered into this trial between August 1989 and January 1993. Eligible patients were classified as having recurrent or disseminated disease that was measurable or nonmeasurable. All eligible patients were evaluated for toxicity and survival; patients with measurable disease were evaluated for response according to standard criteria. RESULTS: No regimen achieved a higher response rate than single-agent bolus 5-FU. Eighty-four percent of patients have been monitored until death. The median survival time for the entire cohort is 14 months. Survival hazards ratios showed a positive trend in favor of the unmodulated infusion regimens, while high-grade toxicities occurred more frequently in the 5-FU bolus arms. The major high-grade toxicities were granulocytopenia and diarrhea. CONCLUSION: In this trial, no regimen provided substantial improvement relative to 5-FU bolus or single-agent therapy for either response or survival in the treatment of disseminated colorectal cancer. The single-agent infusion regimens demonstrated the most encouraging results with a favorable toxicity profile and a 2-month longer survival duration than 5-FU bolus therapy.

Adult↗
PubMed1995

Insights from monitoring the CPCRA didanosine/zalcitabine trial. Terry Beirn Community Programs for Clinical Research on AIDS.

The design, conduct, and analysis of clinical trials that evaluate the safety and efficacy of treatment interventions in patients with HIV infection provide many scientific challenges. A recently completed randomized trial of didanosine (ddI) and zalcitabine (ddC), sponsored by the Terry Beirn Community Programs for Clinical Research on AIDS (CPCRA), is an especially valuable resource for illustrating these challenging issues and for providing insights into how they might be properly addressed. Establishing equivalence of treatment effects on clinical efficacy end points is illustrated through the use of the confidence interval approach. The striking changes in treatment efficacy results that occurred during the course of the CPCRA trial provide important insights into how a data and safety monitoring board can reduce the risk of inappropriate early study termination. The trial also provides valuable insights into how treatment effects should be assessed, revealing inconsistencies between effects on the CD4 surrogate end point and effects on primary clinical efficacy end points and showing the incompleteness of the standardly employed definition of AIDS progression. Finally, the results of this ddI/ddC trial are used to examine the role of covariate adjustment.

Antiviral Agents↗
PubMed1995

Diagnostic plots to reveal functional form for covariates in multiplicative intensity models.

We show how plots based on the residuals from a proportional hazards model may be used to reveal the correct functional form for covariates in the model. A smoothed plot of the martingale residues was suggested for this purpose by Therneau, Grambsch, and Fleming (1990, Biometrika 77, 147-160); however, its consistency required that the covariates be independent. They also noted that the plot could be biased for large covariate effects. We introduce two refinements which overcome these difficulties. The first is based on a ratio of scatter plot smooths, where the numerator is the smooth of the observed count plotted against the covariate, and the denominator is a smooth of the expected count. This is related to the Arjas goodness-of-fit plot (1988, Journal of the American Statistical Association 83, 204-212). The second technique smooths the martingale residuals divided by the expected count, using expected count as a weight. This latter approach is related to a GLM partial residual plot, as well as to the iterative methods of Hastie and Tibshirani (1990, Biometrics 46, 1005-1016) and Gentleman and Crowley (1991, Biometrics 47, 1283-1296). Applications to survival data sets are given.

Analysis of Variance↗
PubMed1994

Surrogate and auxiliary endpoints in clinical trials, with potential applications in cancer and AIDS research.

Surrogate endpoints have been defined by Prentice as response variables that can substitute for a 'true' endpoint for the purpose of comparing specific interventions or treatments in a clinical trial. The applicability of this definition, and of related surrogate endpoint criteria, is discussed, with emphasis on cancer and AIDS research settings. Auxiliary endpoints are defined as response variables, or covariates, that can strengthen true endpoint analyses. Specifically, such response variables provide some additional information on true endpoint occurrence times for study subjects having censored values for such times. Auxiliary variables will very frequently be available, and they may be able to be used without making additional strong assumptions. Approaches to the use of auxiliary variables using ideas based on augmented score and augmented likelihood methods are described.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Phase II trial of dimethyltriazenoimidazole carboxamide in patients with metastatic carcinoid. A Southwest Oncology Group study.

BACKGROUND: The use of chemotherapy in patients with metastatic carcinoid tumors has been of limited value, and investigation of new agents is necessary. Previous reports have suggested that dimethyltriazenoimidazole carboxamide (DTIC) may have antitumor activity. METHODS: A Phase II trial to investigate the clinical response rate to DTIC in patients with metastatic carcinoid tumors was performed. DTIC was administered at low (650 mg/m2) or high (850 mg/m2) doses every 28 days. RESULTS: Sixty-three patients were entered into the study, and 56 were evaluable for toxicity and response. Toxicity was moderate, with the most common side effect being nausea and vomiting (88%). Nine patients (16%; 95% confidence interval, 8-28%) had partial responses, 5 of 25 receiving 850 mg/m2 and 4 of 31 receiving 650 mg/m2 of DTIC. Median survival time of all patients was 20 months. CONCLUSIONS: DTIC has minimal activity in patients with metastatic carcinoid tumors.

Adult↗
PubMed1993

An evaluation of the carcinoembryonic antigen (CEA) test for monitoring patients with resected colon cancer.

OBJECTIVE: To determine the effectiveness of carcinoembryonic antigen (CEA) monitoring in detecting surgically curable recurrence of colon cancer. DESIGN: Clinical data were collected from a national surgical adjuvant trial in which CEA monitoring was elective. SETTING: Cancer centers, universities, and community clinics. PATIENTS: A total of 1216 patients with resected colon cancer, 1017 (84%) of whom had CEA monitoring. MAIN OUTCOME MEASURES: Sensitivity and specificity of CEA testing for cancer recurrence and CEA-motivated diagnostic and surgical interventions and their end results. RESULTS: Among 417 monitored patients with recurrence, 59% had a preceding elevation of CEA concentration. Sixteen percent of 600 patients without recurrence showed a false-positive test result. Carcinoembryonic antigen testing was most sensitive for hepatic or retroperitoneal metastasis and relatively insensitive for local, pulmonary, or peritoneal involvement. Surgical explorations were performed in 115 patients with CEA elevations, and 47 recurrences, usually hepatic, were resected with curative intent. On the other hand, 38 patients with normal CEA concentrations and 23 patients not monitored also underwent such resections--usually for pulmonary or local recurrence. Of all CEA-monitored patients, 2.3% are alive and disease free more than 1 year after salvage surgery (2.9% of those with CEA elevations and 1.9% of those with no elevations). Of patients with no CEA monitoring, 2.0% are also alive and disease free more than 1 year after salvage surgery. CONCLUSIONS: Cancer cures attributable to CEA monitoring are, at best, infrequent. It is questionable whether this small gain justifies the substantial cost in dollars and physical and emotional stress that this intervention may cause for patients.

Biomarkers, Tumor↗
PubMed1993

Evaluation of combination chemotherapy and phase II agents in pancreatic adenocarcinoma. A Southwest Oncology Group study.

BACKGROUND: Pancreatic carcinoma responds poorly to conventional chemotherapy. To identify potentially useful agents, a sequence of clinical trials were done. METHODS: A series of Phase II randomized trials were done by the Southwest Oncology Group in which patients with metastatic or advanced pancreatic cancer were randomized to receive single agents (methylglyoxal-bis-guanylhydrazone [MGBG], dihydroxyanthracenedione [DHAD], and aziridinylbenzoquinone [AZQ]) or a combined regimen of 5-fluorouracil, doxorubicin, mitomycin C, and streptozotocin (FAM-S). Toxicity, response, and survival were determined. RESULTS: Seventy-one patients received FAM-S and 82, the Phase II single agents. Response rates (95% confidence intervals) for the various treatments were: FAM-S, 11% (0%, 21%); MGBG, 6% (0.8%, 21%); DHAD, 0% (0%, 12%); and AZQ, 0% (0%, 16%). The median survival times were: FAM-S Group, 4.8 months and Phase II agent Group, 3.4 months. CONCLUSIONS: The FAM-S regimen and the Phase II agents tested did not have substantial antitumor activity in pancreatic cancer. The use of new agents as initial therapy is reasonable.

Adenocarcinoma↗
PubMed1993

Data monitoring committees and capturing relevant information of high quality.

The integrity and credibility of randomized clinical trials, designed to provide a definitive evaluation of therapeutic interventions, can be substantially enhanced if periodic review of results on the relative efficacy of treatments is conducted by a data monitoring committee (DMC). The role of the DMC can include some important activities which promote obtaining relevant information of high quality. In the final stage of study development, these include review of protocol-specified study objectives and design, and review of procedures planned for capturing high-quality data and for reporting to the DMC. At analyses during the trial, these include careful review of data completeness and accuracy to assist in early detection and resolution of evolving problems.

Clinical Trials as Topic↗
PubMed1993

Monitoring of clinical trials: issues and recommendations.

Interim analyses of randomized trials enable investigators to make more efficient use of limited research resources and to satisfy ethical requirements that a regimen be discontinued as soon as it has been established to have an inferior efficacy/toxicity profile. Unfortunately, the integrity and credibility of these trials can be compromised if inappropriate procedures are used in monitoring interim data. In this paper we discuss how group sequential designs provide useful guidelines that enable one to satisfy the valid objectives of interim monitoring while avoiding undesirable consequences, and we consider how flexible one can be in the way such designs are implemented. We also provide motivation for the role of data-monitoring committees in preserving study integrity and credibility in either government- or industry-sponsored trials. In our view, these committees should have multidisciplinary representation and membership limited to individuals free of apparent significant conflict of interest, and ideally should be the only individuals to whom the data analysis center provides interim results on relative efficacy of treatment regimens. Finally, we discuss some important practical issues such as estimation following group sequential testing, analysis of secondary outcomes after using a group sequential design applied to a primary outcome, early stopping of negative trials, and the role of administrative analyses.

Clinical Trials as Topic↗
PubMed1993

Hepatic toxicity associated with fluorouracil plus levamisole adjuvant therapy.

PURPOSE: To determine the frequency and nature of hepatic toxicity associated with fluorouracil (5-FU) plus levamisole adjuvant therapy. PATIENTS AND METHODS: All patients had resection of stage II or stage III colon cancer and were randomized to receive observation only, levamisole alone, or 5-FU plus levamisole. Serial liver function studies were documented in 1,025 patients who did not develop recurrence during the year of therapy. RESULTS: One hundred forty-nine (39.6%) of 376 patients treated with 5-FU plus levamisole showed laboratory abnormalities consistent with hepatic toxicity, compared with 16.3% of 251 patients treated with levamisole alone and 16.1% of 398 untreated controls. Most common was elevation of alkaline phosphatase, frequently accompanied by elevations of transaminase or serum bilirubin. Characteristically, these changes were mild, not associated with symptoms, and resolved when therapy was stopped. In some instances, they were associated with elevated carcinoembryonic antigen (CEA) tests or with fatty liver seen on computed tomographic (CT) scan or liver biopsy. CONCLUSION: Mild and reversible hepatotoxicity is a common consequence of 5-FU plus levamisole adjuvant therapy, but this is only rarely symptomatic. However, the oncologist should be alert to this phenomenon, since the associated laboratory and imaging findings may simulate those associated with hepatic metastasis.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Primary sclerosing cholangitis: refinement and validation of survival models.

The natural history of primary sclerosing cholangitis was studied in 426 patients from five medical centers. The median follow-up time was 3.0 years (range, 0.01-16.6 years); 100 patients had died by the time of last follow-up. Survival analysis (Cox proportional-hazards regression) was used to identify the variables most useful in predicting survival of patients with primary sclerosing cholangitis. Serum bilirubin concentration, histological stage on liver biopsy, age, and the presence of splenomegaly were independent predictors of a high risk of dying. A mathematical model to predict survival of patients with primary sclerosing cholangitis (based on referral values of those predictors) was statistically validated using two methods. Confidence intervals for predicting patient-specific survival probabilities are also presented. This model to predict survival could be used to stratify participants in therapeutic trials, counsel patients and their families, decide on candidacy for and timing of liver transplantation, and provide mathematical controls for evaluating the efficacy of therapies for primary sclerosing cholangitis, including transplantation.

Adult↗
PubMed1992

High incidence of coagualopathy in phase II studies of recombinant tumor necrosis factor in advanced pancreatic and gastric cancers.

This multi-center trial was carried out to assess the therapeutic potential of recombinant tumor necrosis factor (rTNF) as the first form of systemic therapy for advanced carcinomas of gastric and pancreatic origin. To be eligible patients were required to have no overt sign of coagulopathy and hepatic function studies with enzymes less than two times beyond the normal range. Twenty nine patients with gastric cancer and 26 with pancreatic cancer were entered from various institutions in the Southwest Oncology Group with 27 and 22, respectively, meeting eligibility criteria. Drug treatment consisted of rTNF (Genentech) given at a dose of 150 micrograms intravenously for five consecutive days every 3 weeks; 50% dose reduction was made for acute intolerance such as hypotension or severe fever and chills. Although eight patients with gastric cancer and five patients with pancreatic cancer received four or more courses of treatment, no objective antitumor responses were recorded. As in other trials common toxicities of rTNF included nausea and vomiting, chills and fever, hypotension, headache, myalgias, fatigue and malaise. However, in this trial, other toxicities became prominent: four episodes of symptomatic disseminated intravascular clotting occurred among patients with pancreatic cancer. Eleven with this disease and five with gastric cancer manifested laboratory findings of abnormal amounts of fibrin split products, and/or hypofibrinogenemia, and/or thrombocytopenia after treatment began. Other laboratory abnormalities that were commonly encountered included hyperglycemia, hypertriglyceridemia, anemia, neutropenia and an elevation in liver enzymes. We conclude that rTNF does not demonstrate antitumor efficacy against adenocarcinomas of the stomach and the pancreas.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗