[Principles and indications of methods of irradiation in oncology].
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Antineoplastic Agents↗
Biomedical subjects
P Bey
Publications and source records attributed to P Bey.
17 beta-(cyclopropylamino)-androst-5-en-3 beta-ol, a selective mechanism-based inhibitor of cytochrome P450(17 alpha) (steroid 17 alpha-hydroxylase/C17-20 lyase).
A new compound, 17 beta-(cyclopropylamino)-androst-5-en-3 beta-ol, MDL 27,302, has been designed and synthesized as a mechanism-based inhibitor of cytochrome P450(17 alpha). The time-dependent inactivation of human testicular P450(17 alpha) is irreversible by dialysis and requires the cofactor, NADPH; Kiapp. 90 nM (determined on cynomolgous monkey testis enzyme). Inactivation was not affected by the nucleophile DTT, suggesting retention of the inhibitor in the enzyme active site during the inactivation process. Inhibition is specific to the cyclopropylamino compound, since the isopropylamino- and cyclobutylamino-analogs were not inhibitory. Enzymatic specificity of MDL 27,302 for P450(17 alpha) was demonstrated by its failure to inhibit steroid 21-hydroxylase and the cholesterol side chain cleavage enzyme (P450scc). Both the 17 alpha-hydroxylase and C17-20 lyase activities of cytochrome P450(17 alpha) of human testis microsomes were inhibited by MDL 27,302.
Androstenols↗
The specificity of two proteinases that cleave adjacent to arginine, C1 esterase and acrosin, for peptide p-nitroanilide substrates.
Relative values of Vmax/Km for hydrolysis of 40 peptide p-nitroanilides catalyzed by human Cl-s and human acrosin are reported. For Cl-s, Ac-Lys(gamma Cbz)-Gly-Arg is the optimum sequence, but 25% of the substrates have (Vmax/Km)rel greater than 0.25 compared to this sequence. The best acrosin substrate tested has the sequence Tos-Gly-Pro-Arg, although (Vmax/Km)rel greater than 0.15 for more than half of the substrates. Proline at P2 is preferred by acrosin. Both enzymes prefer arginine at P1 greater than or equal to 3-fold over lysine and will not accept citrulline. In addition, occupancy of site S3 may yield an increase in Vmax/Km of greater than or equal to 10-fold with either enzyme, but many residues are accepted at S2, S3 and S4. Thus, an acrosin assay using Tos-Gly-Pro-Arg p-nitroanilide as a substrate is more than 20-times as sensitive as existing assays with blocked arginine derivatives.
Acrosin↗
MDL 72,974: a potent and selective enzyme-activated irreversible inhibitor of monoamine oxidase type B with potential for use in Parkinson's disease.
MDL 72,974, (E)-2-(4-fluorophenethyl)-3-fluoroallylamine, was designed to be a selective inhibitor of monoamine oxidase type B (MAO-B). In vitro, the compound inhibits rat brain mitochondrial MAO in a concentration and time-dependent fashion and shows marked selectivity for the B form (IC50 = 680 and 3.6 nM for MAO-A and MAO-B, respectively). After oral administration to rats, the compound shows preferential inhibition of brain MAO-B with ED50 values of 8 and 0.18 mg/kg p.o. for the A and B forms, respectively. Selectivity is retained on repeat dosing. MDL 72,974 did not significantly potentiate the cardiovascular effects of intraduodenually-administered tyramine in anaesthetized rats and had only minor indirect sympathomimatic effects in the pithed rat. At MAO-B selective doses the neurotoxic effect of MPTP in mice was blocked.
Administration, Oral↗
Synthesis of acyclonucleoside hydroxamic acids as inhibitors of ribonucleotide reductase.
N-Hydroxy-alpha-(2-hydroxyethoxy)-1(2H)-pyrimidineacetamides 1-3 were synthesized as potential antitumor agents whose mechanism of action would involve inhibition of ribonucleoside diphosphate reductase (RDPR, EC 1.17.4.1). Acyclonucleoside esters 6-8 were prepared by the stannic chloride catalyzed reaction of methyl chloro[2-(phenylmethoxy)ethoxy]acetate (5) with various silylated pyrimidines, generated in situ from the bases and bis(trimethylsilyl)acetamide. Catalytic didebenzylation of hydroxamate 11 gave 1, while 2 and 3 were synthesized by the reaction of lactones 14 and 22, respectively, with hydroxylamine. In vitro acyclonucleoside hydroxamic acids 1-3 were 3-10-fold less potent than hydroxyurea against calf thymus cytidine diphosphate reductase. 5-Fluorouracil derivative 2 is nearly equipotent with hydroxyurea in inhibiting the growth of HeLa cells, while 1 is a much weaker inhibitor and cytidine derivative 3 is devoid of activity at 200 micrograms/mL.
Antineoplastic Agents↗
[Immediate hematological toxicity during combination chemotherapy-radiotherapy of Hodgkin's disease].
The hematologic immediate toxicity during radiotherapy for Hodgkin's disease was studied from a series of 72 patients with stage IIB or III who received 3 courses or more of chemotherapy before radiotherapy. The toxicity in the group of 36 of them who received total nodal irradiation (TNI) was the most important. Sixteen of the 28 TNI had irradiation interrupted, 12 of them began with inverted Y type. The blood cells count at the beginning of the treatment was crucial; only 16% of the patients had interruption of irradiation when the blood cells count was normal; on the other side, 63% had interruption when the blood cells count was abnormal (P less than 0.05). Toxicity was due to the daily destruction of the dividing bone marrow stem cells located in the irradiated area, from the first day of treatment; there was a progressive decrease in the pool of these stem cells within a late resaturation. The absence of resaturation of this pool after initial chemotherapy and after the first part of irradiation explained the immediate and durable toxicity; in the same way, inverted Y irradiation destroyed a great part of active bone marrow (40%) and the pool of remaining stem cells with high mitotic index would be located in areas irradiated subsequently. So, waiting for the absolute normalisation of blood cells count before beginning irradiation and start irradiation by mantle field (rather than inverted Y) seem to be the 2 measures able to reduce the number of interruptions of irradiation due to hematotoxicity.
Adolescent↗
[Conservative treatment of breast cancer. Carcinologic and cosmetic results of combination quadrantectomy and irradiation at the Centre Alexis-Vautrin].
We studied the association of quadrantectomy and irradiation in 238 patients with a breast carcinoma treated from 1974 to 1984 in the Alexis-Vautrin Center. Five and ten year survival rate are respectively 89 and 77%. Local relapse rate at five and ten year are 2, and 9%. Local relapse rate is correlated with a young age, a high tumor grade and an internal site of tumor. We studied the cosmetic and functional results and compared objective results according to subjective self-evaluation by the patients.
Adenocarcinoma↗
Inhibition of the proteolysis of rat erythrocyte membrane proteins by a synthetic inhibitor of calpain.
A synthetic inhibitor of calpain protects rat erythrocyte membrane-associated cytoskeletal proteins from proteolytic degradation (IC50 = 1 microM) which occurs when the cells are rendered permeable to Ca++. Leupeptin, a naturally occurring inhibitor of the enzyme, does not afford any protection at concentrations up to 100 microM.
Animals↗
Design and early clinical evaluation of selective inhibitors of monoamine oxidase.
1. Selective inhibitors of the monoamine oxidase (MAO) isoenzymes, types A and B, are of potential therapeutic utility. Brain selectivity would overcome the risk of tyramine interactions which have been shown to occur with selective MAO-A but not MAO-B inhibitors. 2. (E)-3-Fluoroallylamines of general structure, FHC = C(R)CH2NH2 have been designed as enzyme-activated, irreversible inhibitors of these enzymes. Two compounds, MDL 72145 (R = 3,4 dimethoxyphenyl) and MDL 72974 (R = 4-fluorophenethyl), are selective and irreversible inhibitors of MAO type B which in vivo show high inhibitory potency against the rat brain enzyme (ED50 0.35 and 0.18 mg/kg p.o., respectively). In animals, these inhibitors do not potentiate the cardiovascular effects of tyramine and have no amphetamine-like effects. However, they do potentiate the central effects of L-Dopa and prevent the neurotoxic effects of MPTP in both mice and monkeys. 3. In early clinical studies, MDL 72145 has been shown to be a potent, long-acting inhibitor of MAO type B. Doses of 16 mg per patient totally inhibit platelet enzyme without potentiating the cardiovascular effects of oral tyramine. Compounds of this type should prove useful in Parkinson's disease. 4. Selective inhibition of brain MAO-A can be achieved by using the bioprecursor amino acid MDL 72394 (E-beta-fluoromethylene-m-tyrosine). This amino acid is decarboxylated by aromatic L-amino acid decarboxylase (AADC) to liberate MDL 72392 (R = 3-hydroxyphenyl), a potent irreversible inhibitor of MAO-A. Combination of MDL 72394 with a peripherally selective inhibitor of AADC (e.g., carbidopa) restricts MAO inhibition to the brain. Consequently, under these conditions, there is a greatly reduced propensity to potentiate the cardiovascular effects of tyramine. 5. This has been confirmed in human volunteers; MDL 72394 (8 mg), combined with carbidopa, substantially decreased urinary MHPG and plasma DHPG concentrations with minimal potentiation of the cardiovascular effects of i.v. tyramine. These results predict that such therapy has potential in the treatment of affective disorders.
1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
Radiation therapy alone for medically inoperable patients with adenocarcinoma of the endometrium.
Surgery with adjuvant radiation is the definitive method for treating patients with Stage I and II FIGO endometrial carcinoma. However, radiation therapy alone becomes the only curative alternative for patients who presented with severe, acute, and chronic medical illnesses which prevented surgical management. We report on 104 such patients treated at Centre Alexis Vautrin in Nancy (FRANCE) between 1975 and 1984. The minimum follow-up was 2 years, the maximum was 11 years. Fifty-two patients were treated by association of external irradiation (RT) and curietherapy (CUR), and 52 by curietherapy alone. The median age of the patients was 68.8 years with a minimum of 43 and maximum of 89 years old. Ninety-six patients (92.3%) were obese. Forty-nine (47.1%) were hypertensive. Forty-one (39.4%) had cardiovascular diseases, 25 (24%) had diabetes mellitus, and 13 (12.5%) had history of phlebitis. Seventy-nine patients (75.9%) were Stage I FIGO, 15 (14.4%) were Stage II, 4 patients (3.8%) were Stage III, and 6 patients (5.7%) were Stage IV. The 5- and 10-year overall absolute survival was 51.6% and 35.9% respectively. The 5- and 10-year determinate survival was 65.9% and 58.6% respectively. The 5- and 10-year absolute survival of patients treated by combination RT + CUR was 59.6 and 49.8% respectively. The 5- and 10-year survival of patients treated by CUR alone was 42.3% and 27% significantly worse (p = 0.025). The 5- and 10-year determinate survival for Stage Ia was 82.1%, 71.4% and for Stage Ib 64.6% and 64.6% respectively. The difference was not significant (p = 0.18). While the 5- and 10-year determinate survival for Stage II was 56.2% and 56.3%, significantly worse than Stage I patients (p = 0.043). Tumor differentiation (G) was found to be a significant prognostic factor in survival (p less than 0.05). Local failure was seen in 9 patients (8.6%) 5 in association with distant metastasis (DM). The 5- and 10-year actuarial local control were 87.6% and 85.1% respectively. Severe complications occurred in 18 patients (17.3%). Five of these patients are still alive with a mean follow-up of 8.8 years (minimum 6 years and maximum 11 years). The rate of complications had considerably diminished after 1980, as techniques improved and computerized dosimetry was used.
Adenocarcinoma↗
Initial chemotherapy and low-dose radiation in limited fields in childhood Hodgkin's disease: results of a joint cooperative study by the French Society of Pediatric Oncology (SFOP) and Hôpital Saint-Louis, Paris.
To minimize the drawbacks of treatment we had shown in a previous study that it was possible after chemotherapy to limit the radiation fields to the involved areas only. Pursuing our policy of deescalation, we started in January 1982 a study in 29 French pediatric and hematologic centers, with two aims: (1) To compare the efficacy of 4 cycles of two different chemotherapeutic regimens (4 ABVD vs 2 MOPP + ABVD) in early stages (CSIA and II A) while other stages would receive 6 cycles of the same regimen (3 MOPP + 3 ABVD); (2) To evaluate the efficacy of irradiation given at a low dose (20 Gy) in the patients who had a minimum 70% reduction of the size of their nodes (good responders). From January 1982 to March 1987, 174 patients were entered in this study, of whom 157 completed their treatment program at the time of analysis. On completion of chemotherapy, 94% were considered as good responders and were irradiated to 20 Gy. Only 6 patients received a mediastinal boost (up to 40 Gy). Of the 6% (10/157) poor responders a complete remission was obtained in 6 after 40 Gy. Among the good responders, 5 patients relapsed, with only 3 within an area irradiated to 20 Gy. So that 4 nodal relapses occurred among 364 involved lymph areas. The actuarial survival at 42 months (median 30 months) is 95% (IA + IIA = 100%, IB + IIB + III = 94% and IV = 80%) and the disease-free survival 88% (respectively 94, 93 and 54). Until now there is no statistically significant difference between the 2 randomized arms. This study shows that it is possible to achieve a durable remission in most children treated with a less toxic protocol eliminating or reducing Nitrogen Mustard and reducing the dose of irradiation. Less late complications and sequelae are expected with a longer follow-up.
Adolescent↗
Non-Hodgkin's lymphomas in 137 patients aged 70 years or older: a retrospective European Organization for Research and Treatment of Cancer Lymphoma Group Study.
The results of a European Organization for Research and Treatment of Cancer (EORTC) retrospective study on non-Hodgkin's lymphoma (NHL) in elderly patients (greater than or equal to 70 years of age) seen in Europe in 1984 are reported. A precodified form was sent to 55 European institutes in order to evaluate the incidence of NHL in the elderly with regard to natural history, treatment-related toxicity, response, and survival. Thirteen institutes participated in the study. One hundred thirty-seven cases of NHL were observed in the elderly during 1984, making up 28% of the total number of NHL seen in those institutes. The median age was 77 years; 21% of the patients had favorable (low-grade) and 73% unfavorable (intermediate- and high-grade) histology, according to the Working Formulation. Stage at presentation was localized (I and II) in 60% and advanced in 37% of the patients. Most of the physicians used standard therapy regimens at reduced doses, from the beginning of the treatment. Sixty patients (44%) underwent a "conservative" treatment (one or two antineoplastic drugs or local field radiotherapy) and 77 (56%) an "aggressive" treatment (polychemotherapy regimens or extended field radiotherapy). Response was similar between the two treatment groups, but severe and lethal toxicity was significantly higher among patients treated with aggressive therapy. Prospective randomized studies are clearly needed to define the optimal treatment in elderly patients with advanced unfavorable NHL.
Aged↗
Inhibition of rat aorta semicarbazide-sensitive amine oxidase by 2-phenyl-3-haloallylamines and related compounds.
The inhibition of semicarbazide-sensitive amine oxidase (SSAO) in rat aorta homogenates by some 2-phenyl-3-haloallylamines has been studied. Derivatives containing a fluorine atom were approximately three times more potent than the corresponding 3-chloroallylamines. These halogen-containing compounds were irreversible inhibitors of SSAO after preincubation with aorta homogenates; kinetic evidence for an initial competitive, reversible interaction (Ki around 0.4-0.6 microM) was found with two compounds (MDL 72145 and 72274). A similar Ki (approx. 0.7 microM) was obtained with 2-phenylallylamine (MDL 72200). However, this compound which lacks a halogen atom was a reversible inhibitor, even after preincubation. The use of a spectrophotometric assay to measure H2O2 production from amine metabolism demonstrated that MDL 72200 was a substrate (Km = 1.4 microM) for SSAO, with a Vmax approximately five times smaller than that of benzylamine (Km = 8.1 microM). Of particular interest in this study is the finding that (E)-2-phenyl-3-chloroallylamine (MDL 72274) is highly selective as an inhibitor of SSAO, compared with MAO-A or B activities, and may be a useful compound for investigating the importance of SSAO in animal tissues.
Allyl Compounds↗
Catalytic irreversible inhibition of bacterial and plant arginine decarboxylase activities by novel substrate and product analogues.
Arginine decarboxylase (ADC) activity from Escherichia coli and two plant species (oats and barley) was inhibited by five new substrate (arginine) and product (agmatine) analogues. The five compounds, (E)-alpha-monofluoromethyldehydroarginine (delta-MFMA), alpha-monofluoromethylarginine (MFMA), alpha-monofluoromethylagatine (FMA), alpha-ethynylagmatine (EA) and alpha-allenylagmatine (AA), were all more potent inhibitors of ADC activity than was alpha-difluoromethylarginine (DFMA), the only irreversible inhibitor of this enzyme described previously. The inhibition caused by the five compounds was apparently enzyme-activated and irreversible, since the loss of enzyme activity followed pseudo-first-order kinetics, was time-dependent, the natural substrate of ADC (arginine) blocked the effects of the inhibitors, and the inhibition remained after chromatography of inhibited ADC on Sephadex G-25 or on overnight dialysis of the enzyme. DFMA, FMA, delta-MFMA and MFMA were effective at very low concentrations (10 nM-10 microM) at inhibiting ADC activity in growing E. coli. FMA was also shown to deplete putrescine effectively in E. coli, particularly when combined with an inhibitor of ornithine decarboxylase, alpha-monofluoromethyl-putrescine. The potential uses of the compounds for the study of the role of polyamine biosynthesis in bacteria and plants is discussed.
Agmatine↗
Enzyme-activated/mechanism-based inhibitors.
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Animals↗
Marked and prolonged inhibition of mammalian ornithine decarboxylase in vivo by esters of (E)-2-(fluoromethyl)dehydroornithine.
(E)-2-(fluoromethyl)dehydroornithine, a new enzyme-activated irreversible inhibitor of ornithine decarboxylase (ODC) is no more effective than alpha-difluoromethylornithine (DFMO) at inhibiting polyamine biosynthesis in rat hepatoma tissue culture (HTC) cells and in rat organs even though its potency is over 15 times higher than that of DFMO in vitro. The methyl, ethyl, octyl and benzyl esters of (E)-2-(fluoromethyl)dehydroornithine were synthesized as potential prodrugs of the amino acid. When tested at concentration equivalent to the Ki value of the amino acid, they are devoid of ODC-inhibitory property. When measured 6 hr after its addition to the HTC cell culture medium, the absorption of methyl ester was 20 times higher than that of the parent amino acid or that of DFMO, and was accompanied by a more marked intracellular accumulation of (E)-2-(fluoromethyl)dehydroornithine than that achieved by the addition of the parent amino acid. The methyl ester used at 10 times lower concentrations is as effective as its parent amino acid or as DFMO at inhibiting polyamine biosynthesis in HTC cells. Similarly, the methyl and the ethyl esters of (E)-2-(fluoromethyl)dehydroornithine used at 10 times lower doses are as effective as the parent amino acid and as DFMO at inhibiting ODC in the ventral prostate of rat, 6 hr after oral administration. All the esters of (E)-2-(fluoromethyl)dehydroornithine produce a particularly long duration of ODC inhibition in the ventral prostate and in the testes. Repeated administration (25 mg/kg given once a day by gavage) of the methyl ester of (E)-2-(fluoromethyl)dehydroornithine for 8 days to rats results in a constant 80% inhibition of ODC over a 24-hr period, accompanied by a 90% decrease of putrescine and spermidine concentrations in the ventral prostate.
Adenosylmethionine Decarboxylase↗