Approaches to monitoring clinical trials.

In prospective clinical trials, safety and efficacy results should be monitored periodically. If early data provide convincing evidence of a superior therapeutic index for one of the treatments, then early trial termination would satisfy important ethical requirements and save valuable resources and time. The data obtained in these studies are often analyzed further to determine whether treatment effects differ in various subsets. In this paper we discuss the problems that can arise from frequently used inappropriate approaches to interim and subset analyses. The proper role of such analyses is then discussed, and valid and useful methods are described for deciding on early termination of negative as well as positive studies and for investigating subset effects.

Policies for study monitoring and interim reporting of results.

Interim analyses of comparative trials are necessary in order to monitor for extreme therapeutic results. However, closing studies and reporting results whenever "trends" appear increases the probability of a false conclusion to well over the desired .05 level. Guidelines for early stopping of comparative trials must be carefully defined to avoid this problem. In addition, to avoid inappropriate early closure of studies due to declining accrual (as investigators draw their own conclusions from early unreliable data), it is recommended that access to interim data be limited to a multidisciplinary monitoring committee responsible for (1) performing and reviewing interim analyses, and (2) deciding when early termination should be considered. Accrual and reporting of studies from two clinical trials groups, one with a policy of limited access to interim data and one without, are compared. The group without monitoring committees had a higher incidence of accrual and reporting problems than the group with monitoring committees.

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.

Phase II trial of chlorozotocin and fluorouracil in islet cell carcinoma: a Southwest Oncology Group study.

PURPOSE: A phase II trial that used fluorouracil (5-FU) and chlorozotocin (CTZ) was performed in patients with metastatic islet cell carcinoma to determine the response rate and toxicity. PATIENTS AND METHODS: Patients received four cycles of induction chemotherapy. Good-risk patients received 5-FU 800 mg/m2/d days 1 to 4 as a continuous intravenous (IV) infusion (CIV) and CTZ 175 mg/m2 IV on day 1. Poor-risk patients (previous radiation to > or = 25% bone marrow-bearing areas; serum bilirubin > or = 5 mg/dL; creatinine > 1.0 mg/dL) received 5-FU 600 mg/m2/d and CTZ 75 mg/m2 in a similar manner. In responding or stable patients, reduced doses of 5-FU and CTZ were continued as maintenance therapy (maximum, 18 months). RESULTS: Forty-seven of 51 patients were eligible, and 44 received chemotherapy. Fourteen of 44 patients had partial responses, with 13 of 36 (36%; 95% confidence interval [CI], 21.0% to 54.0%) good-risk patients and one of eight (12%; 95% CI, 0.3 to 52.6%) poor-risk patients responding. Median survival of all patients was 25 months, and the median response duration was 11 months. Side effects were moderate to severe and included myelosuppression and gastrointestinal toxicity. Thirteen patients developed renal toxicity, which was severe or life-threatening in five. This seemed to be related to the administration of cumulative doses of CTZ > or = 1,500 mg. CONCLUSION: These results demonstrate that the combination of 5-FU and CTZ has activity in islet cell carcinoma, but the occurrence of renal toxicity secondary to CTZ may limit the use of this agent.

5-Fluorouracil and folinic acid in the treatment of metastatic colorectal cancer: a randomized comparison. A Southwest Oncology Group Study.

In order to determine the clinical applicability of the in vitro observation of enhanced cytotoxicity of 5-fluorouracil (5-FU) in the presence of excess reduced folates, the Southwest Oncology Group (SWOG) performed a randomized trial evaluating two dose schedules of 5-FU and folinic acid (FA) in 128 patients with metastatic colorectal cancer. Of 125 eligible patients, 62 were randomized to receive bolus FA (200 mg/m2 days 1 through 4) in addition to 5-FU (1,000 mg/m2 days 1 through 4) by continuous four-day infusion (infusion arm), while 63 were randomized to receive bolus FA (200 mg/m2 days 1 through 5) in addition to 5-FU (325 mg/m2 days 1 through 5) by bolus injection (bolus arm). The toxicities of the two schedules differed, with stomatitis being more severe in the infusion arm and leukopenia being more severe in the bolus arm. The response rates and survival data for the two arms are nearly identical. The median survival of patients on the infusion arm is 11.0 months and of patients on the bolus arm, 10.3 months. The infusion arm produced one complete response (CR) and 12 partial responses (PRs), for a major response rate of 21% of eligible patients. The bolus arm produced three CRs and 11 PRs, for a major response rate of 22% of eligible patients. The response rate produced is minimally superior to recent cooperative group studies of colorectal cancer, but the response rate and survival experience are within the range of experience for treatment with 5-FU alone.

Randomized study of systemic chemotherapy following complete excision of nonosseous sarcomas.

Between June 1975 and April 1981, 61 of the 177 eligible patients whose nonosseous sarcomas of extremity or trunk origin had been completely excised primarily or after local recurrences agreed to participate in a randomized study of adjuvant chemotherapy. Dermatofibrosarcoma, lymphomas, myeloma, Kaposi's sarcoma, and embryonal rhabdomyosarcoma were excluded as were patients with significant second primary cancers and those who received either preoperative or postoperative radiation therapy. After stratification by anatomic status of disease, site of origin, and histologic grade, a random one half of the 61 participants began alternating courses of vincristine/cyclophosphamide/dactinomycin, and vincristine/doxorubicin/dacarbazine at six-week intervals for one year. The control group was evaluated at six-week intervals without adjuvant chemotherapy, but these patients were offered this chemotherapy later if they had progressive disease excised. Although 30% of the 61 patients experienced local recurrence of disease within the first five years after randomization, and only 54% were continuously disease free for five or more years, 82% were surviving at five years (Kaplan-Meier calculations) with a median follow-up of 64.3 months. Partial suppression of distant metastasis by adjuvant chemotherapy was apparent in the overall study, in the extremity tumor category, and in the subgroup of patients who had received limb-sparing surgery; however, no survival advantage for chemotherapy-treated patients was demonstrated. The 30 adjuvant chemotherapy-treated patients received a total of three thoracotomies as compared with 17 salvage thoracotomies for the 31 control patients; however, salvage surgery for local recurrences has been similar in the two groups. Recent improvement in the survival of patients with soft-tissue sarcomas is not necessarily a result of adjuvant chemotherapy or radiation therapy.

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.

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.

A controlled evaluation of recent approaches to biochemical modulation or enhancement of 5-fluorouracil therapy in colorectal carcinoma.

Three hundred thirty-five previously untreated patients with advanced colorectal carcinoma were randomly assigned to treatment with 5-fluorouracil (5-FU) alone, 5-FU plus N-(phosphonacetyl)-L-aspartic acid (PALA), 5-FU plus high-dose thymidine, 5-FU plus levamisole, or 5-FU plus methyl CCNU, vincristine, and streptozotocin (MOF-Strept). Dosages were designed to produce definite toxicity in the majority of patients, although the nature of dose-limiting reactions varied considerably among regimens. 5-FU alone and 5-FU plus levamisole produced mucocutaneous reactions, diarrhea, and leukopenia; 5-FU plus PALA produced primarily mucocutaneous reactions and diarrhea; 5-FU plus thymidine produced leukopenia with occasional neurotoxicity and hypotension; and MOF-Strept produced substantial nausea and vomiting with both thrombocytopenia and leukopenia. Objective response rates among patients with measurable disease varied from 12% (5-FU plus PALA) to 34% (MOF-Strept), but none of the regimens were significantly superior to 5-FU alone. Both interval to progression and survival were comparable among the five regimens with no reasonable chance that any combination regimen could produce as much as a 50% improvement when compared with 5-FU alone. Whereas we observed definite modulation of 5-FU dose--toxicity relationships, particularly with the thymidine and PALA combinations, this did not result in a detectable improvement in therapeutic effect. None of the combination regimens, administered in the dosages and schedules we used, can be recommended as standard therapy of advanced colorectal carcinoma.

Surgical adjuvant therapy of large-bowel carcinoma: an evaluation of levamisole and the combination of levamisole and fluorouracil. The North Central Cancer Treatment Group and the Mayo Clinic.

A total of 401 eligible patients with resected stages B and C colorectal carcinoma were randomly assigned to no-further therapy or to adjuvant treatment with either levamisole alone, 150 mg/d for 3 days every 2 weeks for 1 year, or levamisole plus fluorouracil (5-FU), 450 mg/m2/d intravenously (IV) for 5 days and beginning at 28 days, 450 mg/m2 weekly for 1 year. Levamisole plus 5-FU, and to a lesser extent levamisole alone, reduced cancer recurrence in comparison with no adjuvant therapy. These differences, after correction for imbalances in prognostic variables, were only suggestive for levamisole alone (P = .05) but quite significant for levamisole plus 5-FU (P = .003). Whereas both treatment regimens were associated with overall improvements in survival, these improvements reached borderline significance only for stage C patients treated with levamisole plus 5-FU (P = .03). Therapy was clinically tolerable with either regimen and severe toxicity was uncommon. These promising results have led to a large national intergroup confirmatory trial currently in progress.

A controlled evaluation of combined 5-fluorouracil, doxorubicin, and mitomycin C (FAM) for the treatment of advanced non-small-cell lung cancer.

One hundred eighty-six patients with advanced non-small-cell lung cancer were randomly assigned to treatment with combined 5-fluorouracil, doxorubicin, and mitomycin C (FAM) or combined methotrexate, doxorubicin, cyclophosphamide, and lomustine (MACC). Respective objective regression rates were comparable at 20% and 16%. Distribution of intervals to progression (overall median, 2.8 months) and survival times (overall median, 5.0 months) were essentially identical between the two regimens. The comparability of therapeutic effect was also evident within the subset of 81 patients who had adenocarcinoma cell type, although MACC showed a small advantage in survival after covariate analysis. In large-cell carcinoma, MACC showed a higher regression rate than that of FAM as well as a small advantage in survival. In squamous-cell carcinoma, however, FAM was superior to MACC in regression rates (32% v 4%) and also provided somewhat longer survival. With regard to toxicity, MACC produced a higher incidence of nausea and vomiting, whereas FAM produced more frequent and severe thrombocytopenia. From an overall standpoint, the therapeutic accomplishments of both regimens were disappointing. Our study does, however, provide additional evidence that mitomycin C-containing regimens may be selectively effective for squamous-cell carcinoma of the lung.

A simulation study evaluating bio-creep risk in serial non-inferiority clinical trials for preservation of effect.

In non-inferiority trials, acceptable efficacy of an experimental treatment is established by ruling out some defined level of reduced effect relative to an effective active control standard. Serial use of non-inferiority trials may lead to newly approved therapies that provide meaningfully reduced levels of benefit; this phenomenon is called bio-creep. Simulations were designed to facilitate understanding of bio-creep risk when approval of an experimental treatment with efficacy less than some proportion of the effect of the active control treatment would constitute harm, such as when new antibiotics that are meaningfully less effective than the most effective current antibiotic would be used for treatment of Community-Acquired Bacterial Pneumonia. In this setting, risk of approval of insufficiently effective therapies may be great, even when the standard treatment effect satisfies constancy across trials. Modifiable factors contributing to this manifestation of bio-creep included the active control selection method, the non-inferiority margin, and bias in the active control effect estimate. Therefore, when non-inferiority testing is performed, the best available treatment should be used as the standard, and margins should be based on the estimated effect of this control, accounting for the variability and for likely sources of bias in this estimate, and addressing the importance of preservation of some portion of the standard's effect.

Evaluation of active control trials in AIDS.

In settings in which effective standard treatment exists, active control trials provide an ethically appealing approach to evaluating experimental therapies by allowing all patients to be randomized either to a promising new regimen or to the standard as it would be routinely delivered in clinical practice. This paper describes an appropriate statistical approach for analyzing the clinical efficacy of new treatments in such studies. Confidence intervals for the relative efficacy of the new treatment vis-à-vis standard therapy are used to provide information required to determine whether the experimental treatment has an improved therapeutic index. Desirable properties of this approach include the ability to implement standard group sequential guidelines for early trial termination, the ability to use valid surrogates for hard clinical outcomes, and the availability of straightforward formulas for sample size calculations.

Issues in the design of clinical trials: insights from the trastuzumab (Herceptin) experience.

A guiding objective of phase III clinical trials should be to achieve reliable evaluation of safety and efficacy of interventions in a real-world setting, ie, as the interventions would be delivered in clinical practice. This guiding objective motivates several principles of design. The control regimen should truly reflect standard of care; in turn, one should be reluctant to use placebos that might not be inert or that might adversely impact quality of life. The choice of concomitant therapy should be sufficiently flexible as to allow for treatment options that would be widely representative of routine care. Eligibility criteria should be as inclusive as the intended labeling, specifically excluding only those patients expected to be at high risk for toxicity or have a low likelihood of benefit. Study procedures should be simplified to avoid unnecessary inconvenience to patients and investigators and to reduce trial costs. Clinical end points should be chosen that unequivocally reflect tangible benefit to patients. Experiences from the phase III trial of trastuzumab (Herceptin; Genentech, San Francisco, CA) in metastatic breast cancer, a human immunodeficiency virus/acquired immunodeficiency syndrome trial, and a trial in cardiology will be used to provide additional motivation for several of these principles. These trials provide valuable insights into the challenging issues arising in the design and conduct of clinical trials.

Surgical adjuvant therapy of rectal cancer.

Surgery is the preferred method of curative therapy for carcinoma of the rectum. However, in spite of complete gross tumor resection, many patients with locally advanced tumors will experience recurrence of malignant disease in the pelvis and/or distant metastases. This article summarizes the roles of radiotherapy and chemotherapy, administered alone and in combination, as surgical adjuvant treatment for patients with resectable rectal cancer. A biostatistical overview is presented. It is concluded that strong evidence exists supporting the efficacy of combined postoperative radiotherapy and chemotherapy. Further clinical trials are indicated to determine the optimum chemotherapy regimen, sequence, and duration of the therapy.

Adjuvant continuous infusion 5-FU, whole-abdominal radiation, and tumor bed boost in high-risk stage III colon carcinoma: a Southwest Oncology Group Pilot study.

PURPOSE: Results of a combined modality adjuvant pilot program of low-dose continuous-infusion 5-fluorouracil, whole-abdominal radiation, and tumor bed boost in patients with colon cancer with involved nodes and serosal involvement are presented. METHODS AND MATERIALS: Forty-one eligible patients with completely resected T3N1-2M0 colon cancer (modified Astler-Coller C2) were treated with 5-fluorouracil (5-FU) at a dose of 200 mg/m2/day by continuous infusion and 30 Gy of concomitant whole-abdominal radiation in 1 Gy fractions. An additional 16 Gy boost to the tumor bed was administered in 1.6 Gy fractions. After completion of combined modality treatment and a 21-day rest period, patients received 4 days of 5-FU at a dose of 1000 mg/m2 by continuous infusion every 28 days for nine cycles. RESULTS: Five-year disease-free and overall survival estimates were 58 and 67%, respectively, for all T3N1-2 patients. Five-year disease-free and overall survival estimates for the 19 patients with four or fewer nodes were both 61%. Five-year disease-free survival and overall survival estimates for the 20 patients with more than four involved nodes were 55% and 74%, respectively (the exact number of involved nodes were unknown for two patients). Disease-free and overall survival estimates for patients treated with 5-FU and radiation compare favorably to the 5-FU plus levamisole arm of the intergroup adjuvant colon study (Int 0035/SWOG 8591) in patients with more than four positive nodes where the 5-year disease-free and overall survival estimates were 35% and 39%, respectively. Disease-free and overall survival estimates for patients with four or fewer nodes in the 5-FU plus levamisole arm of the intergroup study were 64 and 68%, which is not markedly different from results obtained with radiation and 5-FU in the current study. There were no treatment-related fatalities. Seventeen percent of patients had severe and 7% had life-threatening toxicity of any kind. One patient had an acute partial bowel obstruction and two patients had chronic low grade enteritis. CONCLUSION: Continuous infusion 5-FU and whole-abdominal radiation with tumor bed boost should be further investigated in a larger trial of T3N1-2 colon cancer.

Evaluating the safety of interventions for prevention of perinatal transmission of HIV.

Efficient approaches are needed for obtaining reliable insights into the safety, in developing and developed country settings, of interventions for prevention of mother-to-child transmission (MCT) of HIV. A randomized trial designed with an appropriate sample size and adequate duration of follow-up provides a powerful tool for obtaining causal evidence regarding the safety and efficacy of MTC prevention interventions. Such trials are ideal for detecting adverse effects (AEs) that occur in the short or moderate term and with moderate to high frequency. Passive and active surveillance procedures, where practical, can provide valuable insights regarding long-term or rare AEs. Ideally, surveillance procedures should be carefully planned sufficiently early to allow prospective definition and uniform collection of important classes of AEs, enhancing the sensitivity and specificity of these surveillance data.

Cyclophosphamide plus cis-platinum in combination: treatment program for stage III or IV ovarian carcinoma.

A randomized prospective comparison of treatment with cyclophosphamide and that with cyclophosphamide and cisplatinum, each in 21 patients with advanced ovarian cancer, has shown that the time to progression of tumor and the duration of survival were markedly improved in the patients receiving the combination chemotherapy. Cytoreductive surgery was performed in most of the patients in the study before the chemotherapy regimen was initiated. Second-look surgery was performed after a year of chemotherapy. The chemotherapy was administered on an outpatient basis, without excessive toxicity. At 2 years, 52.4% of the patients receiving combination therapy had no progression of tumor, whereas 9.5% had no progression of tumor inthe group of patients receiving a single alkylating agent. Survival at 2 years was 61.9% for the combination chemotherapy group and 19.0% for those treated with cyclophosphamide alone. The study demonstrates a striking superiority of combination chemotherapy over single-agent chemotherapy in patients with advanced ovarian cancer.

Interim analyses in clinical trials.

Clinical trials of new cancer treatments often involve multiple analyses of the data to address concerns related to medical ethics and the costs and efficiency of medical research. Failure to account for such interim analyses can introduce significant bias into the results of a study. The authors discuss the role of interim analyses in clinical trials and describe the factors that need to be considered in the planning, monitoring, and reporting of a study involving group sequential hypothesis tests.

VP-16, cyclophosphamide, adriamycin and cis-platinum (V:CAP-I) in patients with metastatic adenocarcinoma of the lung.

In an attempt to improve upon the 42% regression rate of the CAP-I regimen in patients with advanced adenocarcinoma of the lung, VP-16 was added to that regimen. VP-16, as a single agent, had a response rate of 12.5% (3/24) In a similar group of patients. The new regimen, V:CAP-I, had a tumor regression rate of 35% (7/20) and an estimated median survival of 171 days. Hence, we were unable to conclude that the addition of VP-16 to the CAP-I regimen statistically improved the regression rate of the CAP-I regimen.