Intergroup Randomized Phase III Study of Postoperative Oxaliplatin, 5-Fluorouracil, and Leucovorin Versus Oxaliplatin, 5-Fluorouracil, Leucovorin, and Bevacizumab for Patients with Stage II or III Rectal Cancer Receiving Preoperative Chemoradiation: A Trial of the ECOG-ACRIN Research Group (E5204).

BACKGROUND: The addition of bevacizumab to chemotherapy improved outcomes for patients with metastatic colon cancer. E5204 was designed to test whether the addition of bevacizumab to mFOLFOX6, following neoadjuvant chemoradiation and definitive surgery, could improve overall survival (OS) in patients with stage II/III adenocarcinoma of the rectum. SUBJECTS, MATERIALS, AND METHODS: Patients with stage II/III rectal cancer who had completed neoadjuvant 5-fluorouracil-based chemoradiation and had undergone complete resection were enrolled. Patients were randomized to mFOLFOX6 (Arm A) or mFOLFOX6 with bevacizumab (Arm B) administered every 2 weeks for 12 cycles. RESULTS: E5204 registered only 355 patients (17% of planned accrual goal) as it was terminated prematurely owing to poor accrual. At a median follow-up of 72 months, there was no difference in 5-year overall survival (88.3% vs. 83.7%) or 5-year disease-free survival (71.2% vs. 76.5%) between the two arms. The rate of treatment-related grade ≥ 3 adverse events (AEs) was 68.8% on Arm A and 70.7% on Arm B. Arm B had a higher proportion of patients who discontinued therapy early as a result of AEs and patient withdrawal than did Arm A (32.4% vs. 21.5%, p = .029).The most common grade 3-4 treatment-related AEs were neutropenia, leukopenia, neuropathy, diarrhea (without prior colostomy), and fatigue. CONCLUSION: At 17% of its planned accrual, E5204 did not meet its primary endpoint. The addition of bevacizumab to FOLFOX6 in the adjuvant setting did not significantly improve OS in patients with stage II/III rectal cancer. IMPLICATIONS FOR PRACTICE: At 17% of its planned accrual, E5204 was terminated early owing to poor accrual. At a median follow-up of 72 months, there was no significant difference in 5-year overall survival (88.3% vs. 83.7%) or in 5-year disease-free survival (71.2% vs. 76.5%) between the two arms. Despite significant advances in the treatment of rectal cancer, especially in improving local control rates, the risk of distant metastases and the need to further improve quality of life remain a challenge. Strategies combining novel agents with chemoradiation to improve both distant and local control are needed.

Phase II Study of Olaparib (AZD-2281) After Standard Systemic Therapies for Disseminated Colorectal Cancer.

BACKGROUND: Effective new agents for patients with colorectal cancer (CRC) with disease progression during standard therapy regimens are needed. We hypothesized that poly ADP ribose polymerase (PARP) inhibitor therapy in patients with CRC and inefficient tumor DNA repair mechanisms, such as those with high-level microsatellite instability (MSI-H), would result in synthetic lethality. METHODS: This was an open-label phase II trial testing olaparib 400 mg p.o. b.i.d. for patients with disseminated, measurable CRC failing standard therapies with centrally confirmed tumor MSI status. The primary endpoint was the tumor response, assessed by RECIST, version 1.0. The secondary endpoints were safety/toxicity, progression-free survival (PFS), and overall survival (OS). RESULTS: Thirty-three patients (20 microsatellite stable [MSS], 13 MSI-H) were enrolled. The median age for all patients was 57 years and for MSS and MSI-H patients was 51 and 61 years, respectively. All patients received at least one 28-day cycle of olaparib. No patient had a complete or partial response. Nausea (48%), fatigue (36%), and vomiting (33%) were the most commonly reported treatment-related adverse events. The median PFS for all patients was 1.84 months. No statistically significant differences were found in the median PFS or OS for the MSS group compared with the MSI-H group. CONCLUSION: Single-agent olaparib delivered after failure of standard systemic therapy did not demonstrate activity for CRC patients, regardless of microsatellite status. Future trials, testing PARP inhibitors in patients with CRC should focus on the use of DNA-damaging chemotherapy and/or radiation therapy, combined with PARP inhibitors, remembering the toxicity reported in the present study. IMPLICATIONS FOR PRACTICE: Microsatellite instability (MSI-H) colorectal tumors exhibit hypermethylation in tumor mismatch repair genes, or have mutations in one or more of these genes resulting from a germ-line defect (Lynch syndrome). PARP inhibitors such as olaparib are most effective in tumors associated with inability to repair DNA damage. However, in this trial, single agent olaparib failed to elicit responses in patients with MSI-H colorectal tumors, and in those with microsatellite-stable tumors. It is possible that by adding olaparib to radiation therapy, or to a systemic DNA damaging agent, tumor lethality could be obtained. However, the price would be increased toxicity.

HIV Infection Is Associated With Poor Outcomes for Patients With Anal Cancer in the Highly Active Antiretroviral Therapy Era.

BACKGROUND: HIV status may affect outcomes after definitive chemoradiotherapy for anal cancer. OBJECTIVE: Here, we report a large series in the highly active antiretroviral therapy era comparing outcomes between HIV-positive and HIV-negative patients with anal cancer. DESIGN: This was a retrospective chart review. SETTINGS: The study was conducted at an outpatient oncology clinic at large academic center. PATIENTS: A total of 107 patients were reviewed, 39 HIV positive and 68 HIV negative. All of the patients underwent definitive chemoradiation for anal cancer. MAIN OUTCOME MEASURES: Data on patient characteristics, treatment, toxicity, and outcomes were collected. Overall survival, colostomy-free survival, local recurrence-free survival, and distant metastasis-free survival were analyzed. RESULTS: Median follow-up was 15 months. HIV-positive patients were younger (median, 52 vs 64 years; p < 0.001) and predominantly men (82% men vs 49% men; p = 0.001). There were no significant differences in T, N, or stage groups. HIV-positive patients had a significantly longer duration from biopsy to start of chemoradiation (mean number of days, 82 vs 54; p = 0.042). There were no differences in rates of acute toxicities including diarrhea, fatigue, or dermatitis. HIV-positive patients had significantly higher rates of hospitalization (33% vs 15%; p = 0.024). The 3-year overall survival rate was 42% in HIV-positive and 76% in HIV-negative patients (p = 0.037; HR, 2.335 (95% CI, 1.032-5.283)). Three-year colostomy-free survival was 67% in HIV-positive and 88% in HIV-negative patients (p = 0.036; HR, 3.231 (95% CI, 1.014-10.299)). Differences in overall survival rates were not significant on multivariate analysis. LIMITATIONS: This study was limited by its retrospective design and small patient numbers. CONCLUSIONS: In this cohort, HIV-positive patients had significantly worse overall and colostomy-free survival rates than HIV-negative patients. However, differences in survival were not significant on multivariate analysis. Additional studies are necessary to establish the etiology of this difference.

Comparison of anal cancer outcomes in public and private hospital patients treated at a single radiation oncology center.

OBJECTIVE: To compare clinical and treatment characteristics and outcomes in locally advanced anal cancer, a potentially curable disease, in patients referred from a public or private hospital. METHODS: We retrospectively reviewed 112 anal cancer patients from a public and a private hospital who received definitive chemoradiotherapy at the same cancer center between 2004 and 2013. Tumor stage, radiotherapy delay, radiotherapy duration, and unplanned treatment breaks ≥10 days were compared using t-test and χ(2) test. Overall survival (OS), disease free survival (DFS), and colostomy free survival (CFS) were examined using the Kaplan-Meier method and compared with the log-rank test. Cox proportional hazard models for OS and DFS were developed. RESULTS: The follow-up was 14.9 months (range, 0.7-94.8 months). Public hospital patients presented with significantly higher clinical T stage (P<0.05) and clinical stage group (P<0.05), had significantly longer radiotherapy delays (P<0.05) and radiotherapy duration (P<0.05), and had more frequent radiation therapy (RT) breaks ≥10 days (P<0.05). Three-year OS showed a marked trend in favor of private hospital patients for 3-year OS (72.8% vs. 48.9%; P=0.171), 3-year DFS (66.3% vs. 42.7%, P=0.352), and 3-year CFS (86.4% vs. 68.9%, P=0.299). Referral hospital was not predictive of OS or DFS on multivariate analysis. CONCLUSIONS: Public hospital patients presented at later stage and experienced more delays in initiating and completing radiotherapy, which may contribute to the trend in poorer DFS and OS. These findings emphasize the need for identifying clinical and treatment factors that contribute to decreased survival in low socioeconomic status (SES) populations.

Radiation therapy improves survival in rectal small cell cancer - Analysis of Surveillance Epidemiology and End Results (SEER) data.

BACKGROUND: Small cell carcinoma of the rectum is a rare neoplasm with scant literature to guide treatment. We used the Surveillance Epidemiology and End Results (SEER) database to investigate the role of radiation therapy in the treatment of this cancer. METHODS: The SEER database (National Cancer Institute) was queried for locoregional cases of small cell rectal cancer. Years of diagnosis were limited to 1988-2010 (most recent available) to reduce variability in staging criteria or longitudinal changes in surgery and radiation techniques. Two month conditional survival was applied to minimize bias by excluding patients who did not survive long enough to receive cancer-directed therapy. Patient demographics between the RT and No_RT groups were compared using Pearson Chi-Square tests. Overall survival was compared between patients who received radiotherapy (RT, n = 43) and those who did not (No_RT, n = 28) using the Kaplan-Meier method. Multivariate Cox proportional hazards model was used to evaluate important covariates. RESULTS: Median survival was significantly longer for patients who received radiation compared to those who were not treated with radiation; 26 mo vs. 8 mo, respectively (log-rank P = 0.009). We also noted a higher 1-year overall survival rate for those who received radiation (71.1% vs. 37.8%). Unadjusted hazard ratio for death (HR) was 0.495 with the use of radiation (95% CI 0.286-0.858). Among surgery, radiotherapy, sex and age at diagnosis, radiation therapy was the only significant factor for overall survival with a multivariate HR for death of 0.393 (95% CI 0.206-0.750, P = 0.005). CONCLUSIONS: Using SEER data, we have identified a significant survival advantage with the use of radiation therapy in the setting of rectal small cell carcinoma. Limitations of the SEER data apply to this study, particularly the lack of information on chemotherapy usage. Our findings strongly support the use of radiation therapy for patients with locoregional small cell rectal cancer.

Neoadjuvant doxorubicin/cyclophosphamide followed by ixabepilone or paclitaxel in early stage breast cancer and evaluation of ßIII-tubulin expression as a predictive marker.

BACKGROUND: This randomized phase II trial was designed to compare the rate of pathologic complete response (pCR) induced by neoadjuvant cyclophosphamide plus doxorubicin (AC) followed by ixabepilone or paclitaxel in women with early stage breast cancer (BC). Expression of ßIII-tubulin as a predictive marker was also evaluated. PATIENTS AND METHODS: Women with untreated, histologically confirmed primary invasive breast adenocarcinoma received four cycles of AC followed by 1:1 randomization to either ixabepilone 40 mg/m2 (3-hour infusion) every 3 weeks for four cycles (n = 148) or weekly paclitaxel 80 mg/m2 (1-hour infusion) for 12 weeks (n = 147). All patients underwent a core needle biopsy of the primary cancer for molecular marker analysis prior to chemotherapy. ßIII-Tubulin expression was assessed using immunohistochemistry. RESULTS: There was no significant difference in the rate of pCR in the ixabepilone treatment arm (24.3%; 90% confidence interval [CI], 18.6-30.8) and the paclitaxel treatment arm (25.2%; 90% CI, 19.4-31.7). ßIII-Tubulin-positive patients obtained higher pCR rates compared with ßIII-tubulin-negative patients in both treatment arms; however, ßIII-tubulin expression was not significantly associated with a differential response to ixabepilone or paclitaxel. The safety profiles of both regimens were generally similar, although neutropenia occurred more frequently in the ixabepilone arm (grade 3/4: 41.3% vs. 8.4%). The most common nonhematologic toxicity was peripheral neuropathy. CONCLUSIONS: Neoadjuvant treatment of early stage BC with AC followed by ixabepilone every 3 weeks or weekly paclitaxel was well tolerated with no significant difference in efficacy. Higher response rates were observed among ßIII-tubulin-positive patients.

Multicenter, randomized phase II trial of bevacizumab plus folinic acid, fluorouracil, gemcitabine (FFG) versus bevacizumab plus folinic acid, fluorouracil, oxaliplatin (FOLFOX4) as first-line therapy for patients with advanced colorectal cancer.

PURPOSE: To assess safety and efficacy of folinic acid, 5-fluorouracil, gemcitabine (FFG) and folinic acid, fluorouracil, oxaliplatin (FOLFOX4) regimens with added bevacizumab as first-line treatment in patients with advanced colorectal cancer (CRC). PATIENTS AND METHODS: Patients with Stage III unresectable or Stage IV adenocarcinoma of the colon or rectum were randomly assigned to either FFG weekly for 6 weeks of an 8-week cycle or FOLFOX4 every 2 weeks. After FDA approval, bevacizumab 5 mg/kg was added every 2 weeks. Treatment continued until disease progression. Planned enrollment was 190 patients. Primary endpoint was overall response rate (ORR); secondary endpoints included evaluation of adverse events, time to progression (TTP), and overall survival (OS). Disease Control Rate (DCR; % of patients with complete or partial responses or stable disease) was a post hoc analysis. RESULTS: The trial was stopped prematurely due to low enrollment. Of 84 enrolled patients (42 to each arm), 36 patients (18 in each arm) received bevacizumab. ORR was greater (P = .002) for FOLFOX4 (17/42; 40.5%) than for FFG (4/42; 9.5%); however, TTP, OS, and DCR results were not statistically different comparing FOLFOX4 and FFG. Peripheral neuropathy was more frequent (P = <.001) with FOLFOX4 (18/42; 42.9%) than with FFG (1/42; 2.4%). CONCLUSIONS: FFG and FOLFOX4 were generally well tolerated. Based on ORR, FOLFOX4 was superior to FFG. However, differences in TTP and OS comparing regimens were inconclusive. General use of gemcitabine as a biomodulator of 5-fluorouracil in CRC cannot be recommended at this time and the regimen remains investigational.

Phase III trial of fluorouracil-based chemotherapy regimens plus radiotherapy in postoperative adjuvant rectal cancer: GI INT 0144.

PURPOSE: Adjuvant chemoradiotherapy after or before resection of high-risk rectal cancer improves overall survival (OS) and pelvic control. We studied three postoperative fluorouracil (FU) radiochemotherapy regimens. PATIENTS AND METHODS: After resection of T3-4, N0, M0 or T1-4, N1, 2M0 rectal adenocarcinoma, 1,917 patients were randomly assigned to arm 1, with bolus FU in two 5-day cycles every 28 days before and after radiotherapy (XRT) plus FU via protracted venous infusion (PVI) 225 mg/m2/d during XRT; arm 2 (PVI-only arm), with PVI 42 days before and 56 days after XRT + PVI; or arm 3 (bolus-only arm), with bolus FU + leucovorin (LV) in two 5-day cycles before and after XRT, plus bolus FU + LV (levamisole was administered each cycle before and after XRT). Patients were stratified by operation type, T and N stage, and time from surgery. RESULTS: Median follow-up was 5.7 years. Lethal toxicity was less than 1%, with grade 3 to 4 hematologic toxicity in 49% to 55% of the bolus arms versus 4% in the PVI arm. No disease-free survival (DFS) or OS difference was detected (3-year DFS, 67% to 69% and 3-year OS, 81% to 83% in all arms). Locoregional failure (LRF) at first relapse was 8% in arm 1, 4.6% in arm 2, and 7% in arm 3. LRF in T1-2, N1-2, and T3, N0-2 primaries who received low anterior resection (those most suitable for primary resection) was 5% in arm 1, 3% in arm 2, and 5% in arm 3. CONCLUSION: All arms provide similar relapse-free survival and OS, with different toxicity profiles and central catheter requirements. LRF with postoperative therapy is low, justifying initial resection for T1-2, N0-2 and T3, and N0-2 anterior resection candidates.

Assessment of infusional 5-fluorouracil schedule and dose intensity: a Southwest Oncology Group and Eastern Cooperative Oncology Group study.

BACKGROUND: Building on results from Southwest Oncology Group trial 8905, this trial was designed to compare low-dose continuous infusion (LDCI) of 5-fluorouracil (5-FU) versus intermittent high-dose infusion (HDI) of 5-FU in disseminated colorectal cancer (CRC) for evidence of survival advantage based on dose intensity. A companion trial was funded to assess molecular parameters associated with fluoropyrimidine response or resistance and toxicity from these treatments. PATIENTS AND METHODS: Eligibility included histologic diagnosis of disseminated CRC, measurable or evaluable disease, no previous therapy for metastatic disease, performance status of 0-2, and adequate renal, hepatic, cardiac, and hematologic function. Stratification factors were measurable versus evaluable disease, performance status of 0/1 versus 2, presence versus absence of adjuvant therapy, and presence versus absence of previous surgery and enrollment on the companion trial. Patients were randomized to receive (1) LDCI 5-FU 300 mg/m(2) per day for 28 days every 5 weeks or (2) HDI 5-FU 2,600 mg/m(2) for 24 hours each week. RESULTS: Between April 1995 and May 1999, 730 patients were accrued (LDCI arm, n = 360; HDI arm, n = 370). Of these, 708 eligible patients were assessable for survival and 690 for toxicity. Median survival for both groups was 13 months. Toxicity was mild; < 10% of patients in both arms had grade > 4 events. There were 8 study-related deaths (1%). Less than 10% of patients were enrolled in the companion trial. CONCLUSIONS: Increasing 5-FU dose intensity yields no survival advantage beyond that achieved with LDCI 5-FU. This study confirms the favorable toxicity profile of infusional 5-FU. Because no preferential benefit was observed for either infusion schedule, the more convenient weekly schedule should be considered for 5-FU-based combination regimens for disseminated CRC.

Hypersensitivity Reactions to oxaliplatin: incidence and management.

Oxaliplatin (Eloxatin) is a novel platinum compound that has activity in a wide variety of tumors. Several hypersensitivity reactions distinct from laryngopharyngeal dysesthesia have been described. We retrospectively analyzed 169 consecutive patients who received oxaliplatin for esophageal or colorectal cancer between 1/1/00 and 7/31/02 and reviewed any significant adverse reactions labeled as hypersensitivity reactions. Thirty-two patients (19%) reportedly experienced hypersensitivity. Skin rash was the most common event (22 patients), occurring after a median of three infusions. Fever was seen in five patients after a median of two infusions. Five patients experienced respiratory symptoms at median infusion number 6. Ocular symptoms of lacrimation and blurring of vision were seen in two patients. Five patients experienced more than one type of reaction. Treatments prescribed for hypersensitivity were antihistamines, steroids, and topical emollients. One patient developed grade 4 hypersensitivity during cycle 6, characterized by laryngeal edema, tongue swelling, and labored breathing. This patient underwent a desensitization procedure, adapted from guidelines for carboplatin (Paraplatin) allergy. Subsequently, three cycles were administered over 6 hours and were well tolerated. However, during the fourth infusion postdesensitization, the patient developed recurrent signs of hypersensitivity. In conclusion, hypersensitivity is frequently seen with oxaliplatin, but most reactions are mild.

Phase II clinical trial of 5-fluorouracil, trimetrexate, and leucovorin (NFL) in patients with advanced pancreatic cancer.

BACKGROUND: Advanced pancreatic cancer has limited treatment options. 5-fluorouracil (5-FU) is frequently used in the treatment of pancreatic cancer. Preclinical studies suggest synergism between trimetrexate (TMTX),5-FU, and leucovorin (NFL). AIM: We conducted a phase II trial to evaluate the activity and safety of NFL in pancreatic cancer. METHOD: Eligible patients (n = 21) with untreated advanced pancreatic cancer were treated with 110 mg/m2 intravenous (IV) THTX on day 1 and 200 mg/m2 IV leucovorin prior to 500 mg/m2 IV 5-FU on day 2. Oral leucovorin (15 mg every 6 h for seven doses) started intravenous 24 h later. RESULTS: Treatment was administered for 6 wk followed by a 2-wk rest period. Response was evaluated every 8 wk. All patients were evaluable for response and toxicity. Most patients (80%) had distant metastases. Forty-five cycles of chemotherapy were administered. The most common serious toxicities were Grade 3 diarrhea (23.8%) and nausea and vomiting (14.2%). The response rate was 4.1% (95% CI, 0-23%), median survival was 6.8 mo, and 1-yr survival was 19%. CONCLUSION: Treatment with NFL is well-tolerated in patients with advanced pancreatic cancer. The median survival and 1-yr survival in these patients with poor prognosis compares favorably with other treatment options.

Effect of concurrent radiation therapy and chemotherapy on pulmonary function in patients with esophageal cancer: dose-volume histogram analysis.

PURPOSE: The pulmonary effects of concurrent radiation therapy and chemotherapy were studied in patients enrolled in a phase I trial for esophageal cancer. MATERIALS AND METHODS: Pulmonary function tests were performed prospectively before and after combined-modality therapy (oxaliplatin, 5-fluorouracil, and radiation therapy) in 20 patients with esophageal cancer. Cumulative and differential lung DVH analysis from 0 to 5400 cGy in 25-cGy intervals was performed for the last 15 patients. Correlation between radiation exposure in various dose ranges and percent reduction in pulmonary function tests was calculated as an exploratory analysis. RESULTS: Significant reductions in carbon monoxide diffusion capacity corrected for hemoglobin (12.3%) and total lung capacity (2.5%) were evident at a median of 15.5 days after radiation therapy. DVH analysis revealed that the single dose of maximum correlation between lung volume radiation exposure and lung function reduction was less than 1000 cGy for all pulmonary functions. The percent lung volume that received a total dose between 700 and 1000 cGy maximally correlated with the percent reductions in total lung capacity and vital capacity, and the absolute lung volume that received a total dose between 700 and 1000 cGy maximally correlated with the percent reductions in total lung capacity, vital capacity, and carbon monoxide diffusion capacity. DISCUSSION: Significant declines in carbon monoxide diffusion capacity and total lung capacity are evident immediately after the administration of conformal radiation therapy, oxaliplatin, and 5-fluorouracil for esophageal cancer. Other lung functions remain statistically unchanged. The percent or absolute lung volume that received a total dose between 700 and 1000 cGy may be significantly correlated with the percent decline of carbon monoxide diffusion capacity, total lung capacity, and vital capacity. These associations will be evaluated further in a follow-up study.

Biochemical modulation of 5-fluorouacil through dihydropyrimidine dehydrogenase inhibition: a Southwest Oncology Group phase II trial of eniluracil and 5-fluorouracil in advanced resistant colorectal cancer.

PURPOSE: To investigate the hypothesis that a systemic agent designed to inhibit dihydropyrimidine dehydrogenase (DPD), the first enzyme in the fluoropyrimidine degradative pathway, could improve the effective amount of 5-fluorouracil (5-FU) delivered to a tumor resulting in enhanced response. PATIENTS AND METHODS: Eligibility included cytologically or pathologically verified diagnosis of colorectal cancer that recurred during or within 12 months of completion of adjuvant therapy, representing patients generally considered resistant to fluorinated pyrimidine therapy. Stratification was into two cohorts: recurrence while receiving adjuvant therapy, and relapse within 12 months of completing adjuvant therapy. Treatment consisted of 28 days of oral therapy every five weeks with eniluracil and 5-FU administered in a 10:1 ratio. The daily dose of eniluracil was 10 mg/m2 with 5-FU 1 mg/m2, divided into two doses. RESULTS: Twenty-five patients are evaluable for response: 9 relapsed during therapy and 16 relapsed within one year of adjuvant therapy. In the first group, there was one partial response (9%; 95% CI 0-41%); in the second cohort there was one confirmed complete response (5%; 95% CI 0-23%) and one unconfirmed partial response, for an overall response rate of 10%. CONCLUSIONS: This regimen lacks significant activity in this target population. Pre-treatment intratumoral DPD expression was not assessed, therefore the mechanism of fluorinated pyrimidine resistance cannot be specifically attributed to elevated DPD levels. Attempting restoration of chemotherapy sensitivity through blockade of enzymes or signal transduction molecules responsible for resistance is rational, provided that tumor target expression is the basis for trial entry.

Phase I and pharmacokinetic study of once daily oral administration of S-1 in patients with advanced cancer.

PURPOSE: To determine the maximum tolerated dose, dose-limiting toxicities(DLTs), and pharmacokinetics of S-1, a combination of tegafur, 5-chloro-2,4-dihydroxypyridine (CDHP), and oxonic acid, administered once daily in patients with advanced cancer. EXPERIMENTAL DESIGN: Eighteen patients with refractory malignancies were treated with S-1 administered once daily for 21 consecutive days, followed by a 1-week break. Of 16 evaluable patients, 6 were treated at a dose of 50 mg/m(2)/day, and 10 were treated at 60 mg/m(2)/day. RESULTS: DLTs were observed in 1 of 6 evaluable patients treated with 50 mg/m(2)/day and in 4 of 10 evaluable patients treated with 60 mg/m(2)/day. DLTs included diarrhea, nausea/vomiting, fatigue, and hyperbilirubinemia. The maximum tolerated dose was 50 mg/m(2)/day. Pharmacokinetic data are consistent with potent modulation of 5-fluorouracil (5-FU) by CDHP, with prolonged half-life and 5-FU AUC at least 10-fold higher than reported in previous studies of equitoxic doses of tegafur modulated by uracil. Pharmacodynamic analysis demonstrated a correlation between diarrhea grade and both 5-FU C(max) (r = 0.57, P < 0.05) and 5-FU area under the curve (r = 0.74, P < 0.01). CONCLUSIONS: The recommended Phase II dose of S-1 administered once daily for 21 consecutive days of 28 is 50 mg/m(2). The pharmacokinetic data presented provide evidence of 5-FU modulation by CDHP. Pharmacodynamic analyses suggest that the utility of pharmacology-based dosing of S-1 should be explored in future trials. Evaluation of once-daily dosing of S-1 in malignancies for which fluoropyrimidines have known antitumor activity is warranted.