Biochemical Modulation and Pathophysiology of Migraine

PURPOSE N-(phosphonacetyl)-L-aspartic acid (PALA) is a pyrimidine synthesis inhibitor that modulates fluorouracil (FU) cytotoxicity. Two previous studies of patients with colorectal carcinoma documented complete response (CR) and partial response (PR) rates of 40% and 43% using weekly low-dose PALA followed by a 24-hour FU infusion. We investigated whether comparable results could be obtained with biochemical modulation by low-dose PALA using bolus instead of infusional FU. PATIENTS AND METHODS Forty-five patients without prior chemotherapy who had advanced colorectal carcinoma were treated with PALA 250 mg/m2 followed 24 hours later by bolus FU at three dose levels, 600, 700, 800 mg/m2, repeated weekly for 6 weeks followed by a 2-week break. RESULTS The CR and PR rate was 15 of 43 patients or 35% (95% confidence interval [CI], 21% to 49%), with an overall median survival of 18 months. Grade 3 or 4 diarrhea was the major toxicity observed in 24% of patients receiving FU at 700 mg/m2 and in 43% of patients receiving 800 mg/m2. Hematologic toxicity was observed only with an FU dose of 800 mg/m2, and 29% (four of 14) of patients developed grade 4 leukopenia. We also noted the development of ascites in six patients, mild hyperbilirubinemia in 16 patients, and a decreased albumin level in 22 patients; these abnormalities occurred more frequently in responding patients. CONCLUSIONS The observed response rate, median survival, and toxicity in this study are similar to those obtained with PALA plus infusional FU and with other methods of FU modulation. Larger phase III studies are needed to compare bolus FU/PALA regimens with other PALA and non-PALA-containing combinations. Our future focus will be attenuate this regimen's toxicity while maintaining or improving its response rates and survival.

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Fluorouracil plus racemic leucovorin versus fluorouracil combined with the pure l-isomer of leucovorin for the treatment of advanced colorectal cancer: a randomized phase III study.

Journal of Clinical Oncology ◽

10.1200/jco.1997.15.3.908 ◽

1997 ◽

Vol 15 (3) ◽

pp. 908-914 ◽

Cited By ~ 23

Author(s):

W Scheithauer ◽

G Kornek ◽

A Marczell ◽

G Salem ◽

J Karner ◽

...

Keyword(s):

Colorectal Cancer ◽

Advanced Colorectal Cancer ◽

Gastrointestinal Symptoms ◽

Dose Schedule ◽

Phase Iii ◽

Biochemical Modulation ◽

Survival Times ◽

Significant Difference ◽

Duration Of Response ◽

Phase Iii Study

PURPOSE To compare the efficacy and toxicity of fluorouracil (FU) and racemic leucovorin (d,l-LV) versus FU combined with the l-isomer of leucovorin (l-LV) in the treatment of advanced colorectal cancer. PATIENTS AND METHODS A total of 248 patients with advanced measurable colorectal cancer previously unexposed to chemotherapy were randomly assigned to treatment with either FU (400 mg/m2/d by intravenous [I.V.] infusion for 2 hours) and racemic LV (100 mg/m2/d by I.V. bolus injection) given for 5 consecutive days, or the combination of FU and the pure l-isomer of LV using the same dose schedule. In both treatment arms, courses were administered every 28 days if toxicity allowed for a total of 6 months, unless evidence of tumor progression was documented earlier. RESULTS There were no significant differences between the FU/racemic LV and the FU/l-LV arm in the overall response rate (25% v 32%), duration of response (7.2 v 8.0 months), median time to progression or death (6.25 v 8.0 months), or median overall survival time (14.5 v 15.0 months). Except for minor myeloid toxic effects associated with FU/l-LV, there was also no significant difference in terms of adverse reactions. Gastrointestinal symptoms, specifically mucasitis and diarrhea, were less frequent and less severe in both treatment arms compared with other trials with FU/racemic LV reported in the literature, which might be because of the prolonged administration of FU used in both arms. CONCLUSION The combination of FU/l-LV produced response rates, response durations, and survival times similar to those with FU/d,l-LV. Biochemical modulation of FU by either pure l-LV or racemic LV thus appears to result in equivalent clinical efficacy.

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New therapeutic strategies for patients with gastrointestinal malignancies using biochemical modulation of fluorouracil

JAMA ◽

10.1001/jama.273.3.236 ◽

1995 ◽

Vol 273 (3) ◽

pp. 236-239 ◽

Cited By ~ 1

Author(s):

C. J. Allegra

Keyword(s):

Therapeutic Strategies ◽

Biochemical Modulation ◽

Gastrointestinal Malignancies

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Modulation of nitrosourea resistance in myeloid leukemias

Blood ◽

10.1182/blood.v71.5.1487.1487 ◽

1988 ◽

Vol 71 (5) ◽

pp. 1487-1494 ◽

Cited By ~ 22

Author(s):

SL Gerson ◽

JE Trey

Keyword(s):

Dna Repair ◽

Therapeutic Index ◽

Myelogenous Leukemia ◽

Leukemic Cells ◽

Biochemical Modulation ◽

Repair Protein ◽

Myeloid Leukemias ◽

Dna Repair Protein ◽

Dna Alkyltransferase

Abstract Drug resistance in myeloid leukemias may be mediated by an increased capacity to repair chemotherapy-induced DNA damage. Some tumor cell lines that are resistant to nitrosoureas contain the DNA repair protein O6-alkylguanine-DNA alkyltransferase (alkyltransferase). This protects cells by removing cytotoxic, nitrosourea-induced O6-alkylguanine adducts. We measured the level of alkyltransferase activity in myeloid leukemic cells freshly obtained from patients to determine whether the alkyltransferase was an important factor in nitrosourea resistance in these cells and whether inactivation of this protein could sensitize leukemic cells to nitrosoureas. Myeloid leukemic cells from patients with acute nonlymphocytic leukemia and chronic myelogenous leukemia had higher levels of alkyltransferase than did myeloid precursors from normal donors (P less than .01). This difference did not appear to be due to the state of differentiation of the leukemic or normal cells. To show that this repair protein mediated nitrosourea resistance in leukemic cells, cells were treated with the modified base O6- methylguanine to selectively and irreversibly inactivate the alkyltransferase and then exposed to 1,3-bis (2-chloroethyl)-1- nitrosourea (BCNU). An 18-hour incubation in 0.5 mmol/L O6- methylguanine caused an 87% +/- 3.6% decrease in alkyltransferase activity in leukemic cells and a 73% +/- 8.6% decrease in normal myeloid precursors. After treatment with O6-methylguanine, clonogenic leukemic cells from ten different donors became much more sensitive to BCNU, with a decrease in the dose needed to reduce colony survival by 50% (LD50) of 6.3 +/- 1.4-fold. A lesser effect was seen on CFU-GM, BFU- E, and CFU-GEM where the LD50 decreased two- to threefold. These studies show that nitrosourea resistance in myeloid leukemic cells can be abrogated by inactivation of the DNA repair protein O6-alkylguanine- DNA alkyltransferase. This method of biochemical modulation of DNA repair will sensitize leukemic cells to nitrosoureas in vitro and has the potential of increasing the therapeutic index of nitrosoureas in this disease.

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