External control arms in oncology: current use and future directions.

Although randomized control trials allow for a comparison of treatment arms with minimal concern for confounding by known and unknown factors, a randomized study is not feasible in certain disease settings. When a randomized design is not possible, incorporating external control data into the study design can be an effective way to expand the interpretability of the results of an experimental arm by introducing the ability to carry out a formal or an informal comparative analysis. This paper provides an introduction to the concepts of external controls in oncology trials, followed by a review of relevant and current research on this topic. The paper also focuses on general considerations for designing a trial that may incorporate external control data, followed by case studies of the marketing applications submitted to the Food and Drug Administration that included external control data.

A Food and Drug Administration analysis of survival outcomes comparing the Adjuvant Paclitaxel and Trastuzumab trial with an external control from historical clinical trials.

BACKGROUND: Although the Adjuvant Paclitaxel and Trastuzumab (APT) trial has been adopted clinically, single-arm trials have limitations, and interest remains whether these patients with small node-negative human epidermal growth factor receptor 2 (HER2)-positive early breast cancer (EBC) would benefit from more intensive chemotherapy. This analysis explored whether external controls can contextualize single-arm studies to add to clinical decision making in the use of de-escalated therapy in patients with low-risk HER2-positive EBC. PATIENTS AND METHODS: Patient-level data from five randomized trials supporting drug approval in adjuvant HER2-positive EBC were pooled, and patients with low-risk EBC were selected (n = 1770). Patients treated concurrently with trastuzumab and either anthracycline/cyclophosphamide/taxane/trastuzumab (ACTH) or taxane/carboplatin/trastuzumab (TCH; n = 1366) were matched (1:1) to patients treated with paclitaxel and trastuzumab (TH) in the APT trial (n = 406) using propensity scores. Patients treated with anthracycline/cyclophosphamide/taxane (ACT; n = 374) were also matched (1:1) to those treated with TH. Propensity scores were estimated using covariates of age, tumor stage, estrogen receptor status, progesterone receptor status, and histological grade. RESULTS: After matching, the estimated probabilities of invasive disease-free survival (iDFS) at 3 and 5 years were 98.6% and 96.5% in the TH arm, and 96.6% and 92.9% in the ACTH/TCH arm, respectively. The estimated probabilities of overall survival (OS) at 3 and 5 years were 99.7% and 99.3% in the TH arm, and 99.0% and 97.4% in the ACTH/TCH arm, respectively. Comparing the TH arm with the ACT arm in the matched sample, the estimated difference in iDFS was 7.5% (TH 98.8% and ACT 91.3%) at 3 years and 12.6% (TH 96.1% and ACT 83.5%) at 5 years. The estimated difference in OS was 2.6% (TH 100% and ACT 97.4%) at 3 years, and 5.3% (TH 99.3% and ACT 94.0%) at 5 years. CONCLUSIONS: Our analyses suggest that patients' outcomes in both arms were in general similar, thus providing additional reassurance regarding de-escalation of therapy.

Analysis of time-to-treatment discontinuation of targeted therapy, immunotherapy, and chemotherapy in clinical trials of patients with non-small-cell lung cancer.

BACKGROUND: Pragmatic end points, such as time-to-treatment discontinuation (TTD), defined as the date of starting a medication to the date of treatment discontinuation or death has been proposed as a potential efficacy end point for real-world evidence (RWE) trials, where imaging evaluation is less structured and standardized. PATIENTS AND METHODS: We studied 18 randomized clinical trials of patients with metastatic non-small-cell lung cancer (mNSCLC), initiated after 2007 and submitted to U.S. Food and Drug Administration. TTD was calculated as date of randomization to date of discontinuation or death and compared to progression-free survival (PFS) and overall survival (OS) across all patients, as well as in treatment-defined subgroups [EGFR mutation-positive treated with tyrosine kinase inhibitor (TKI), EGFR wild-type treated with TKI, ALK-positive treated with TKI, immune checkpoint inhibitor (ICI), chemotherapy doublet with maintenance, chemotherapy monotherapy]. RESULTS: Overall across 8947 patients, TTD was more closely associated with PFS (r = 0.87, 95% CI 0.86-0.87) than with OS (0.68, 95% CI 0.67-0.69). Early TTD (PFS-TTD ≥ 3 months) occurred in 7.7% of patients overall, and was more common with chemo monotherapy (15.0%) while late TTD (TTD-PFS ≥ 3 months) occurred in 6.0% of patients overall, and was more common in EGFR-positive and ALK-positive patients (12.4% and 22.9%). In oncogene-targeted subgroups (EGFR positive and ALK positive), median TTDs (13.4 and 14.1 months) exceeded median PFS (11.4 and 11.3 months). CONCLUSIONS: At the patient level, TTD is associated with PFS across therapeutic classes. Median TTD exceeds median PFS for biomarker-selected patients receiving oncogene-targeted therapies. TTD should be prospectively studied further as an end point for pragmatic randomized RWE trials only for continuously administered therapies.

Exploratory analysis of the association of depth of response and survival in patients with metastatic non-small-cell lung cancer treated with a targeted therapy or immunotherapy.

BACKGROUND: Response Evaluation Criteria in Solid Tumors (RECIST) permits rapid evaluation of new therapeutic strategies in cancer. However, RECIST does not capture the heterogeneity of response in highly active therapies. Depth of tumor response may provide a more granular view of response. We explored the association between, depth of response (DepOR), with overall survival (OS) and progression-free survival (PFS) for patients with NSCLC being treated with an ALK inhibitor (ALKi) or an anti-PD-1 antibody (Ab). METHODS: Experimental arms from two randomized controlled trials (RCTs) of an ALKi and two RCTs of an anti-PD-1 Ab were separately pooled. Patient responses were grouped into DepOR 'quartiles' by percentage of maximal tumor shrinkage (Q1 = 1%-25%, Q2 = 26%-50%, Q3 = 51%-75%, and Q4 = 76%-100%), Q0 had no shrinkage. We carried out a retrospective exploratory responder analysis to evaluate the association between DepOR and OS or PFS using hazard ratios (HR) generated by the Cox proportional hazards model. RESULTS: In the pooled ALK analysis there were 12, 39, 70, 144, and 40 patients in quartiles 0-4, respectively. The DepOR versus PFS/OS analyses HR were: 0.19/0.94 for Q1 0.11/0.56 for Q2, 0.05/0.28 for Q3, and 0.03/0.05 for Q4. In the PD-1 trials within quartiles 0-4 there were 168, 70, 44, 45, and 28 patients, respectively. The DepOR versus PFS/OS analyses HR were 0.3/0.52 for Q1, 0.22/0.47 for Q2, 0.09/0.07 for Q3, and 0.07/0.14 for Q4. CONCLUSIONS: Our analysis suggests a greater DepOR is associated with longer PFS and OS for patients receiving ALKi or anti-PD1 Ab. Overall, this suggests that DepOR may provide an additional outcome measure for clinical trials, and may allow better comparisons of treatment activity.

Drug Development, Trial Design, and Endpoints in Oncology: Adapting to Rapidly Changing Science.

As a result of enhanced understanding of genetic and immunologic underpinnings of cancer, there has been progress in development of targeted and immunotherapies in oncology. The traditional linear sequential model of drug development has evolved. Early clinical trials of breakthrough therapies often include expansion cohorts, termed "seamless drug development." The US Food and Drug Administration (FDA) uses expedited programs, such as breakthrough designation and accelerated approval ensuring that transformative therapies are available to patients earlier in the cycle of evidence generation.

Activity of taxol in patients with squamous cell carcinoma and adenocarcinoma of the esophagus.

BACKGROUND: Carcinomas of the esophagus and gastroesophageal junction are uncommon and account for approximately 1% of all malignancies in the United States. Advanced squamous cell carcinoma or adenocarcinoma of these sites remains incurable. The median survival of patients is between 4 and 8 months, and their prognosis has not changed in the past several decades. Undoubtedly, there is an urgent need to develop new effective drugs for patients with carcinoma of the esophagus or the gastroesophageal junction. PURPOSE: Our purpose was to evaluate the response rate, duration of response, and toxic effects in previously untreated patients with unresectable local-regional or metastatic carcinoma of the esophagus who were enrolled in a phase II study of paclitaxel (Taxol). METHODS: Fifty-two patients with either metastatic or local-regional unresectable carcinoma of the esophagus were eligible for this study. All patients were premedicated with dexamethasone, cimetidine, and diphenhydramine hydrochloride to prevent allergic reaction. The starting dose of paclitaxel was 250 mg/m2 repeated every 21 days. Patients received 5 micrograms/kg granulocyte-colony stimulating factor (G-CSF) subcutaneously daily 24 hours after the completion of paclitaxel to reduce the duration and severity of granulocytopenia. RESULTS: Of the 52 patients who were initially enrolled, 50 (44 men and six women) were evaluated for toxic effects and response. Thirty-two had adenocarcinoma, and 18 had squamous cell carcinoma. The median age was 58 years (range, 36-77 years). The median Zubrod performance status was 1 (range, 0-1). The median number of courses was four, and the total number of courses administered was 227. The median dose of paclitaxel was 250 mg/m2 (range, 150-280 mg/m2). Paclitaxel dosage was reduced in 52 (23%) of 227 courses and increased in 15 (7%) of 227 courses. Sixteen (32%) patients achieved either a complete or partial response, and 11 (22%) achieved a minor response. Among 32 patients with adenocarcinoma, 11 (34%; 95% confidence interval [CI] = 18%-50%) had either a complete or partial response and six had a minor response. Five (28%; 95% CI = 7%-49%) of 18 patients with squamous cell carcinoma had a partial response, and five (28%) had a minor response. The median duration of partial response was 17 weeks (range, 7 to > or = 58 weeks). At a median follow-up of 9 months, 32 patients remain alive, with an actuarial median survival duration of 13.2 months (range, 2 to > or = 17.5 months). Paclitaxel followed by G-CSF was very well tolerated. CONCLUSIONS: These data indicate that paclitaxel is an active agent against adenocarcinoma and squamous cell carcinoma of the esophagus.

Phase I trial of Taxotere: five-day schedule.

BACKGROUND: Taxotere, a semisynthetic compound structurally related to taxol, has a broad spectrum of activity in murine transplantable tumors; in the B16 melanoma model, it caused a total log cell kill 2.5 times greater than that caused by taxol at equitoxic doses. PURPOSE: We conducted a phase I study of Taxotere (a) to determine its qualitative and quantitative toxic effects and a starting dose for phase II trials, (b) to investigate its clinical pharmacology, and (c) to document its antitumor activity. METHODS: Taxotere was given as a 1-hour infusion at a starting dose of 1 mg/m2 per day for 5 consecutive days. The 5-day course of therapy was repeated every 21 days. Thirty-nine cancer patients with advanced disease were entered in the study; at least three patients were entered at each dose level. Initial dose escalations were planned at 100% increments until biologic activity was observed; subsequent escalations were planned at 50% increments until grade 2 toxicity (the National Cancer Institute's Common Toxicity Criteria) occurred and then at 25% increments until the maximum tolerated dose was established. RESULTS: Thirty-nine patients were entered in the study. Successive dose levels used were 1, 4, 8, 16, 12, and 14 mg/m2 per day. The dose-limiting toxic effects were granulocytopenia and concurrent mucositis. Grade 4 granulocytopenia associated with grade 3 mucositis developed in six of 12 patients treated at a dose of 16 mg/m2 per day, two of 10 treated at 12 mg/m2 per day, and two of eight treated at 14 mg/m2 per day. Because these toxic effects occurred concurrently, all patients so affected developed neutropenic fevers and required hospitalization. Neither cardiac nor neurologic toxic effects were noted. Anti-tumor activity was observed in six patients with ovarian cancer and in one with breast carcinoma. Although pharmacokinetic parameters were consistent between day 1 and day 5 for individual patients, considerable variation existed among those treated at the same dose level. A relationship was observed between the area under the curve for plasma concentration of drug x time (AUC) on day 1 and the percentage decrease in absolute granulocyte counts. CONCLUSION: Granulocytopenia associated with oral mucositis is the dose-limiting toxicity of this schedule. We recommended a starting dose of 14 mg/m2 per day for phase II studies of this 5-day schedule. Dose modifications on days 2-5 based on the day-1 AUC may allow individualized dosing.

Phase I trial of spiromustine (NSC 172112) and evaluation of toxicity and schedule in a murine model.

Phase I evaluation of spiromustine was performed using an every-3-week schedule and a weekly X 3 schedule. Neurotoxicity was the dose-limiting toxicity presenting as alterations in cortical integrative functions (orientation, language, coordination), leading to a decrease in the level of consciousness. Traditional criteria for grading neurotoxicity poorly characterized these toxicities. The maximum tolerated dose was 6 mg/m2 every 3 weeks and 3 mg/m2 weekly X 3. Concurrent murine studies confirmed spiromustine as a schedule independent drug with toxicity correlating with peak plasma levels. Physostigmine had little effect on decreasing neurotoxicity in the murine model. The solvating agent used was not responsible for the neurotoxicity. Injection of spiromustine on a split-dose schedule decreased the acute neurological toxicity in mice and allowed a larger total dosage to be delivered (compared to single bolus dosage). Based on these results a split-dose schedule is suggested for future clinical trials.

Acodazole hydrochloride: phase I trial, pharmacokinetics, and evaluation of cardiotoxicity in dogs.

Acodazole (NSC 305884) was examined in a Phase I trial evaluating a 1-h infusion repeated every 21 days in 37 patients with advanced carcinomas. Cardiac toxicity was dose-limiting at 1370 mg/m2, manifested as multiple premature ventricular contractions, QTc interval prolongation, and decreasing heart rate. Other toxicities included mild to moderate nausea and vomiting and local reaction near the i.v. injection site requiring the use of central venous catheters. Antineoplastic activity was not observed. Acodazole levels assayed by high-performance liquid chromatography disclosed a peak plasma level of 19 +/- 4 (SEM) micrograms/ml for 1370 mg/m2. Acodazole plasma levels decreased in a triphasic manner over a 100-fold range. The volume of distribution at steady state was 238 +/- 18 liter/m2 suggesting extensive tissue binding. The total body clearance was 13.6 +/- 0.9 liter/h/m2; the percentage of urinary excretion was 29 +/- 2% for 48 h. To evaluate cardiac toxicity, acodazole was administered to five dogs at 2262 mg/m2 (1-h infusion) which provided plasma concentrations similar to those achieved at 1370 mg/m2 in humans. Consistent findings in dogs were drug-related prolongation of QTc intervals, and reduction in heart rate, left ventricular dP/dt, and mean blood pressures. Clinical development of acodazole requires studies to further elucidate and alleviate this cardiac toxicity.

A Benefit-Risk Analysis Approach to Capture Regulatory Decision-Making: Non-Small Cell Lung Cancer.

Drug regulators around the world make decisions about drug approvability based on qualitative benefit-risk analyses. There is much interest in quantifying regulatory approaches to benefit and risk. In this work the use of a quantitative benefit-risk analysis was applied to regulatory decision-making about new drugs to treat advanced non-small cell lung cancer (NSCLC). Benefits and risks associated with 20 US Food and Drug Administration (FDA) decisions associated with a set of candidate treatments submitted between 2003 and 2015 were analyzed. For benefit analysis, the median overall survival (OS) was used where available. When not available, OS was estimated based on overall response rate (ORR) or progression-free survival (PFS). Risks were analyzed based on magnitude (or severity) of harm and likelihood of occurrence. Additionally, a sensitivity analysis was explored to demonstrate analysis of systematic uncertainty. FDA approval decision outcomes considered were found to be consistent with the benefit-risk logic.

Docetaxel.

PURPOSE: We reviewed the preclinical and clinical profiles of the antineoplastic taxoid docetaxel (Taxotere, Rhône-Poulenc Rorer, Collegeville, PA). DESIGN: From the literature and manufacturer's data, we detail docetaxel's activity, tolerability, and pharmacokinetics in preclinical and phase I studies and its activity and side effects in phase II trials in various neoplasms. RESULTS: Docetaxel promotes the assembly of and stabilizes microtubules, preventing their depolymerization. In phase I studies in patients with solid tumors refractory to standard chemotherapy, docetaxel's major dose-limiting toxicity (DLT) was dose- but not schedule-dependent neutropenia; another major side effect was schedule-dependent grade 3 mucositis. Other, generally less severe effects included hypersensitivity reactions (HSRs), neurotoxicities, cutaneous reactions, alopecia, and asthenia. Responses were observed in breast, bronchial, and ovarian carcinomas. The recommended dose for phase II studies was 100 mg/m2 as a 1-hour intravenous (i.v.) infusion every 3 weeks. Preliminary phase II results confirmed docetaxel's activity against breast, non-small-cell and small-cell lung, ovarian, head and neck, and gastric cancers; melanoma; and soft tissue sarcomas. Neutropenia again was the principal dose-limiting side effect. Nonhematologic effects, usually grade 1 or 2, including HSRs, were common. HSRs were manageable with premedication. Corticosteroid premedication partially alleviated fluid retention seen after repeated docetaxel courses. Studies are evaluating docetaxel in various combination regimens in advanced breast cancer, non-small-cell lung cancer, and other solid tumors. CONCLUSION: Multicenter and single-institution studies have demonstrated docetaxel's consistent significant activity in various cancers. Phase III and combination therapy trials are ongoing. Work is in progress to understand and prevent/resolve some of this drug's side effects.

Effect of initial resection of small-cell carcinoma of the lung: a review of Southwest Oncology Group Study 7628.

The role of surgery in small-cell carcinoma of the lung (SCCL) has been recently re-evaluated. We reviewed the records of 262 patients with limited SCCL on Southwest Oncology Group (SWOG) protocol 7628. Fifteen patients were identified who presented after surgical resection (12 lobectomy, three pneumonectomy). All patients were subsequently treated with chemotherapy, radiotherapy +/- immunotherapy (BCG). Median survival time was 10.5 months. Median survival time of patients with initial surgical resection was 25 months (P = .004). Forty-five percent of the surgical patients were alive at two years v 13.7% of the nonsurgical patients (P less than .05). A second subgroup of 33 patients was identified with small primary tumors who did not undergo surgical resection. Median survival time in this group was ten months (P = .03). Site of initial relapse was clearly documented in 142 patients. Fifty-six percent of patients not receiving surgery had initial relapse within the chest compared to 13% of patients undergoing surgery (P = .002). Whether the survival benefit identified was caused by or was incidental to surgical resection of the primary lesion remains to be determined in randomized prospective trials of operable candidates.

Phase II study of fluorouracil and recombinant interferon alfa-2a in previously untreated advanced colorectal carcinoma.

We conducted a phase II clinical trial of fluorouracil (5FU) and recombinant interferon alfa-2a (rIFN alpha-2a) in 52 previously untreated patients with bidimensionally measurable metastatic colorectal cancer. During week 1, 5FU was administered as a continuous intravenous infusion, 750 mg/m2/d for 5 consecutive days. Intravenous bolus administration of 5FU 750 mg/m2 was given weekly for 7 weeks starting on day 12. rIFN alpha-2a (Roferon; Hoffman-LaRoche, Nutley, NJ), 9 x 10(6) U, was administered subcutaneously three times weekly during weeks 1 to 8. Patients were evaluated for response on week 9. Of 52 patients enrolled in the study, 51 were assessable for toxicity, and 45 were assessable for response. Fifteen patients experienced partial response, and one patient achieved a clinical complete response for an overall response rate of 35% (95% confidence interval [CI], 22%, 50%). Median duration of response is 7.5 months (range, 4 to 11 months). Seventy percent of patients entered on the study are alive with a median follow-up duration of 7 months. Twenty-five percent of patients developed grade 4 toxicity, and 82% developed grade 3 toxicity. One drug-related death in the presence of sepsis was reported, and two treatment-related seizures occurred. Our experience with this schedule produced a lower response rate with greater toxicity than previously reported. Current randomized trials comparing this schedule of 5FU with rIFN alpha-2a to 5FU plus folinic acid (leucovorin) or single-agent 5FU may determine its role in the treatment of advanced colorectal carcinomas.

Phase II trial of uracil and tegafur plus oral leucovorin: an effective oral regimen in the treatment of metastatic colorectal carcinoma.

PURPOSE: To determine the activity and evaluate the toxicity of uracil and tegafur in a 4:1 molar concentration (UFT; Taiho Pharmaceutical Ltd, Tokyo, Japan) plus oral calcium leucovorin in the treatment of patients with advanced colorectal carcinoma. PATIENTS AND METHODS: Forty-five patients with advanced, bidimensionally measurable metastatic colorectal carcinoma were enrolled onto the trial. None of the patients had received prior chemotherapy or biologic therapy for advanced disease. Patients received either 350 or 300 mg/m2/d UFT plus 150 mg/d leucovorin administered orally in divided daily doses every 8 hours for 28 days followed by a 7-day rest period. Response was evaluated after two courses of therapy. RESULTS: Eighteen patients (three treated at 350 mg/m2/d and 15 at 300 mg/m2/d) had partial responses, and one patient had a complete response (response rate, 42.2%; 95% confidence interval, 28% to 58%). Responses were observed in sites that included liver (n = 18), lung (n = 6), and bone (n = 1). Of seven patients who received 350 mg/m2 UFT, prolonged grade 3 diarrhea developed in five; this resulted in a reduction in the UFT starting dose to 300 mg/m2/d in the remaining 38 patients. Grade 1 or 2 toxic effects included diarrhea, nausea, vomiting, abdominal cramping, anorexia, fatigue, oral mucositis, excessive lacrimation, and rash. Among 38 patients who received the 300-mg/m2/d dose, grade 3 toxic reactions included diarrhea (n = 4), vomiting (n = 2), abdominal cramping (n = 1), and fatigue (n = 2). CONCLUSION: UFT 300 mg/m2/d plus oral leucovorin 150 mg/d administered for 28 days demonstrated significant activity against metastatic colorectal carcinoma. This oral regimen was well tolerated and devoid of the neutropenia or significant oral mucositis that complicates intravenous schedules of fluorouracil (5-FU) plus leucovorin. The results of this clinical trial will serve as the basis for a randomized phase III study to compare this oral schedule of UFT plus leucovorin with intravenous 5-FU plus leucovorin to determine the relative efficacy, impact on quality of life, and cost of the two regimens.

Phase I and pharmacokinetic study of exatecan mesylate (DX-8951f): a novel camptothecin analog.

PURPOSE: To determine the maximum-tolerated dose (MTD), dose-limiting toxicity (DLT), pharmacokinetic (PK) profile, and recommended phase II dose of Exatecan mesylate (DX-8951f) when administered as a 24-hour continuous infusion every 3 weeks to patients with solid tumors. PATIENTS AND METHODS: Twenty-two patients with advanced solid tumors, all previously treated, and with performance status < or = 2, were entered. The starting dose of DX-8951f was 0.15 mg/m(2); the dose was escalated according to the modified continual reassessment method. The drug was administered until disease progression or until unacceptable toxic effects occurred. RESULTS: Seven dose escalations were completed, and a total of 53 courses were delivered (median, two courses; range, one to eight courses) during the study. At doses 1.2 mg/m(2) and lower, toxicities were mostly grade 1, primarily hematologic. In the initial cohort of three patients treated at 2.4 mg/m(2), grade 2 hematologic toxicity was observed. Of the six additional patients entered at 2.4 mg/m(2), three had grade 3 or 4 granulocytopenia. At doses higher than 2.4 mg/m(2), DLT granulocytopenia was observed. Nonhematologic toxicities, including nausea, vomiting, diarrhea, fatigue, and alopecia, were mild to moderate. Neither complete nor partial responses were observed, but four patients had stable disease. The PK profile of DX-8951f seemed linear at the doses administered. The plasma clearance, total volume of distribution, and terminal elimination half-life were approximately 3 L/h, 40 L, and 14 hours, respectively. CONCLUSION: The DLT of this DX-8951f schedule was granulocytopenia for minimally pretreated patients, and both granulocytopenia and thrombocytopenia for heavily pretreated patients. The MTD for both minimally and heavily pretreated patients was 2.4 mg/m(2). DX-8951f seems to have a linear PK profile on the basis of single-dose administration. The recommended phase II dose with this schedule is 2.4 mg/m(2) for minimally pretreated patients. A lower dose should be used for heavily pretreated patients.

Phase I assessment of the pharmacokinetics, metabolism, and safety of emitefur in patients with refractory solid tumors.

PURPOSE: To determine the toxicities, dose-limiting toxicities (DLT), maximum-tolerated dose, and pharmacokinetic profile of emitefur (BOF-A2) in patients with advanced solid tumors. METHODS: This was a phase I dose-escalating trial in which cohorts of patients received BOF-A2 (cohort 1, 300 mg/m(2) orally [PO] tid; cohort 2, 200 mg/m(2) PO tid; cohort 3, 200 mg/m(2) bid; and cohort 4, 250 mg/m(2) bid) for 14 consecutive days followed by 1 week of rest (cycle 1). Pharmacokinetics, toxicity, and tumor response were monitored. RESULTS: Nineteen patients received 110 cycles (three patients in cohort 1, three patients in cohort 2, 10 patients in cohort 3, and three patients in cohort 4). DLT (grade 3 stomatitis, diarrhea, leukopenia) was observed in cohorts 1, 2, and 4. Pharmacokinetics indicated that prolonged systemic expression of fluorouracil (5-FU) is maintained after administration of BOF-A2 at a dose of 200 mg bid for 14 days. The mean steady-state concentration of plasma 5-FU was > or = 24 ng/mL, which was 184-fold greater than the minimum effective cytotoxic concentration in vitro. Lack of variation of 5-FU trough levels within a day at steady-state indicates suppression of circadian variation. One patient in cohort 3 achieved a partial response and five patients maintained stable disease in excess of 6 months. CONCLUSION: BOF-A2 at a dose of 200 mg PO bid for 14 days followed by 7 days of rest is well tolerated. Prolonged exposure to 5-FU above the predicted preclinical minimum effective concentration is maintained, without evidence of circadian variation. Furthermore, evidence of antitumor activity is suggested.

Phase I study of preoperative oral uracil and tegafur plus leucovorin and radiation therapy in rectal cancer.

PURPOSE: Preoperative combined-modality therapy for rectal cancer may allow for sphincter preservation, while decreasing recurrence rates and improving the overall prognosis. Oral chemotherapy with uracil and tegafur (UFT) plus leucovorin (LV) may reduce costs and complications associated with protracted infusions of fluorouracil. Our goal was to evaluate the safety of UFT plus LV combined with preoperative radiation and determine the maximum-tolerated dose (MTD) and dose-limiting toxicity (DLT) of UFT plus LV in this setting. PATIENTS AND METHODS: Patients with tumor-node-metastasis stage II or III rectal cancer received escalating doses of UFT (starting at 250mg/m(2)/d, with 50-mg/m(2)/d increments between consecutive cohorts) and fixed doses of LV (90 mg/d). The UFT and LV combination was given 5 days per week concurrently with a 5-week course of preoperative radiation totaling 45 Gy (1.8 Gy/fraction). Surgery was performed 4 to 6 weeks after radiation and was followed by four 35-day cycles of fixed doses of UFT and LV (28 days of therapy each cycle). RESULTS: Fifteen patients were treated, and 13 received the full preoperative chemotherapy. All planned radiation was delivered successfully. The MTD of UFT with radiation was 350 mg/m(2)/d with 90 mg/d of LV. Diarrhea was the DLT. Sphincter-preserving surgery was performed in 12 of 14 patients. One patient had progressive disease before surgery. Pathologic evaluation of 14 resected specimens showed a complete response in three cases. CONCLUSION: Preoperative chemoradiation with oral UFT plus LV is feasible and well tolerated and should be further investigated.