Direct evidence for the formation of deoxyribonucleotide adducts from carcinogenic N-nitroso-N-methylaniline revealed by the 32P-postlabeling technique

N-Nitroso-N-methylaniline (NMA) is an esophageal carcinogen in the rat. NMA forms a benzenediazonium ion (BDI) during microsomal cytochrome P-450 2B1 (CYP2B1) catalyzed metabolism. Using the nuclease P1-enhanced version of the 32P-postlabeling assay we investigated the formation of adducts by NMA with deoxyadenosine 3'-monophosphate (dAp) and deoxyguanosine 3'-monophosphate (dGp). 32P-postlabeling analysis of dAp and dGp, which were modified by NMA activated with microsomes of rats pretreated with phenobarbital (PB), and directly labeled resulted in each case in the appearance of one single adduct spot. Quantitative analysis of adducts revealed that the extent of dGp modification by activated NMA was more than 23 times greater than the extent of modification of dAp. The results suggest strongly that BDI, derived from NMA by CYP2B1 present in PB microsomes, participates in the formation of dAp and dGp adducts.

The profile of urinary metabolites of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone in rats is determined by its pulmonary metabolism

Metabolism of the tobacco specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in rats was compared to metabolism in primary lung and liver cells. Untreated rats and rats pretreated with phenobarbital, acetone or phenethyl isothiocyanate (PEITC) were used for all experiments. Also the influence of [-]-1-methyl-2-[3-pyridyl]-pyrrolidine (nicotine) administered concomitantly with NNK, or incubated with isolated cells, upon NNK metabolism was investigated and found to be only marginal upon alpha-hydroxylation and pyridine N-oxidation in vivo. In hepatocytes nicotine inhibited NNK pyridine N-oxidation, alpha-hydroxylation and glucuronidation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), whereas in lung cells the influence of nicotine was not as pronounced. In vivo phenobarbital induced alpha-hydroxylation and pyridine N-oxidation. In vitro the effects of the modulators were most pronounced upon hepatocytes, where phenobarbital greatly induced pyridine N-oxidation and PEITC inhibited alpha-hydroxylation. NNAL was conjugated to its beta-glucuronide in lung cells at four times higher rates than in hepatocytes. The ratios of the sum of N-oxides to the sum of alpha-hydroxylation products in vivo were similar to those in lung cells, especially at low NNK concentrations (1 microM), while in hepatocytes alpha-hydroxylation was more pronounced. The same correlation of metabolism in isolated lung cells with whole rats was observed if oxidative NNAL metabolism was related to oxidative NNK metabolism. Here hepatocytes showed a much higher formation of NNAL oxidation products than either lung cells formed, or rats excreted in urine. This was true despite a lower rate of metabolism in the lung than in liver if based on cell number, the rate based on mg protein was four times higher in lung than liver. Only after phenobarbital treatment was the contribution of hepatic metabolism to excreted metabolites important. In conclusion the lung which is also the target of NNK carcinogenesis, and not the liver, is the organ with the most important contribution to NNK and NNAL metabolism at concentrations relevant to human exposure.

Phase I trial of methotrexate-albumin in a weekly intravenous bolus regimen in cancer patients. Phase I Study Group of the Association for Medical Oncology of the German Cancer Society

Methotrexate-albumin conjugate (MTX-HSA) is a novel human albumin-based prodrug conjugate of methotrexate (MTX). A low MTX loading rate provided optimal tumor targeting and therapeutic efficacy during preclinical testing. The objectives of this first Phase I study of MTX-HSA were to determine dose-limiting toxicity (DLT) and maximum tolerated dose (MTD) in a weekly regimen. Seventeen cancer patients who were no longer amenable to standard treatment were enrolled and were evaluable for DLT. Up to eight injections were performed in weekly intervals. Dose escalation was as follows: 20, 40, 50, and then 60 mg/m2 MTX-HSA (based on the amount of MTX bound to albumin). Additional MTX-HSA courses were feasible in case of tumor response. DLT (mainly stomatitis, Common Toxicity Criteria grade 3) occurred, beginning at the 50 mg/m2 dose level after repeated administrations; in one case, thrombocytopenia was dose-limiting. Two events of DLT occurred at the 60 mg/m2 dose level within the first two administrations. Mild anemia, transaminitis, and one case of skin toxicity were found. No significant leukopenia, nausea, renal toxicity, or other toxicities were observed. MTX-HSA was well tolerated. Drug accumulation occurred on the weekly schedule. The half-life of the drug was estimated to be up to 3 weeks. Tumor responses were seen in three patients: (a) a partial response was seen in one patient with renal cell carcinoma (response duration, 30 months, ongoing); (b) a minor response was seen in one patient with pleural mesothelioma (response duration, 31 months, ongoing); and (c) a minor response was seen in one patient with renal cell carcinoma (response duration, 14 months until progression). Poststudy treatment was administered at 2-4-week intervals. No signs of toxicity or drug accumulation were seen. Altered pharmacological properties of MTX-HSA such as plasma half-life, tumor targeting, or intracellular metabolism might have contributed to these responses. The MTD for weekly administration was 4 x 50 mg/m2 MTX-HSA during short-term treatment. A regimen with MTX-HSA injections of 50 mg/m2 every 2 weeks was recommended for a further clinical Phase I study.

One step isolation of bovine asialoglycoprotein receptor and its characterization by sequence analysis and MALDI mass spectrometry

The asialoglycoprotein receptor (ASGP-R), which is responsible for the uptake of partially deglycosylated serum glycoproteins was isolated from bovine liver. The receptor was purified in one step from solubilized plasma membranes by affinity chromatography on 6-(beta-D-lactosyl)-n-hexylamine coupled to N-hydroxysuccinimide activated Sepharose with a coupling degree of 7.6 micromol/ml gel. The preparation yielded two distinct polypeptides with apparent molecular weights of 48 and 43 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A polyclonal antibody raised against the human ASGP-R recognized the bovine 43 kDa protein in Western blot analysis. The 48 and 43 kDa polypeptides were digested by trypsin and the digests were subsequently analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Sequence analysis of four tryptic fragments, two each of the 48 kDa and of the 43 kDa polypeptides revealed that these were highly homologous to ASGP-R subunits from man, mouse and rat.

Dose-intensive therapy for limited-stage small-cell lung cancer: long-term outcome

PURPOSE

To determine progression-free survival (PFS) and overall long-term survival for limited-stage small-cell lung cancer (SCLC) patients aged 60 years or younger who respond to first-line chemotherapy followed by high-dose combination alkylating agents (cyclophosphamide 5,625 mg/m(2), cisplatin 165 mg/m(2), and carmustine 480 mg/m(2)) with hematologic stem-cell support and chest and prophylactic cranial radiotherapy.

PATIENTS AND METHODS

Patients were selected on the basis of their continued response to first-line therapy, their relative lack of significant comorbidity, and their ability to obtain financial clearance.

RESULTS

Of 36 patients with stage III SCLC, nine patients (25%) had achieved a complete response (CR), 20 had achieved a near-CR, and seven had achieved a partial response before undergoing high-dose therapy. Toxicity included three deaths (8%). For all patients, the median PFS was 21 months. The 2- and 5-year survival rates after dose intensification were 53% (95% confidence interval [CI], 39% to 72%), and 41% (95% CI, 28% to 61%). Of the 29 patients who were in or near CR before undergoing high-dose therapy, 14 remain continuously progression-free a median of 61 months (range, 40 to 139 months) after high-dose therapy. Actuarial 2- and 5-year PFS rates were 57% (95% CI, 41% to 79%) and 53% (95% CI, 38% to 76%). By multivariate analysis, short intensive induction chemotherapy was associated with favorable outcome (P <.05).

CONCLUSION

Use of high-dose systemic therapy with intensive local-regional radiotherapy was associated with manageable treatment-related morbidity and mortality. Patients who were in or near CR before intensification are enjoying an unmaintained 5-year PFS rate of 53%. Late complications were infrequent, and most patients returned to full-time work and activity. A randomized comparison of this approach and conventional-dose therapy should define the use of dose intensification with hematopoietic support in patients with responding limited-stage SCLC.

Analysis of the inhibition of N-nitroso-dimethylamine activation in the liver by N-nitro-dimethylamine using a new non-linear statistical method

N-nitro-dimethylamine (NTDMA) is carcinogenic to rats: it induces nasal cavity tumours. It can be demethylated to N-nitromethylamine and formaldehyde and reduced to N-nitroso-dimethylamine (NDMA): a potent liver carcinogen and also of the nasal cavity if activation in the liver is blocked. To explain the mechanism of NTDMA carcinogenicity we compared its demethylation with that of NDMA in liver microsomes from female and male rats, untreated, fasted or treated with ethanol to induce cytochrome P450 2E1 (CYP2E1). Kinetic parameters were analysed by nonlinear statistical methods, which yielded unbiased parameter estimates for the calculated Km and Vmax values. Km for both compounds was very similar in females (24-47 microM) whereas Vmax for NTDMA was consistently higher than for NDMA as substrate: 1.07-4.70 nmol formaldehyde/mg microsomal protein x min and 0.52-2.76 nmol, respectively. In liver microsomes from induced male rats NTDMA was found to be a much more effective inhibitor of NDMA activation (KEI 39.6-73.6 microM) than NDMA of NTDMA demethylation (KEI 224-286 microM). Nasal microsomes can demethylate both NDMA and NTDMA but the kinetics are vastly different. NTDMA is demethylated at a linear rate and approximately 10-fold more effectively than NDMA. The mechanism of carcinogenicity of ingested NTDMA, we propose, is a partial reduction to NDMA in the liver and inhibition of NDMA activation in the liver by residual NTDMA, which enables NDMA to reach the nasal mucosa where it is activated to DNA-alkylating species and the observed tumours are formed.

Complications of laparoscopic cholecystectomy in Switzerland. A prospective 3-year study of 10,174 patients. Swiss Association of Laparoscopic and Thoracoscopic Surgery

BACKGROUND

We set out to analyze the technical aspects, intraoperative complications, morbidity, and mortality of laparoscopic cholecystectomy in a multi-institutional study representative of Switzerland.

METHODS

Data were collected from 10,174 patients from 82 surgical services. A total of 353 different parameters per patient were included.

RESULTS

We found intraoperative complications in 34.4% of patients and had a conversion rate of 8.2%. This rate was significantly increased in patients with complicated cholelithiasis and in those with previous upper-but not lower-abdominal surgery. In most cases, conversions to open procedures were required because of technical difficulties due to inflammatory changes and/or unclear anatomical findings at the time of operation. Bleeding was a common intraoperative complication, that significantly increased the risk of conversion. Patients with loss of gallstones in the peritoneal cavity had increased rates of abscesses. The rate of common bile duct injuries was 0.31%, but it decreased significantly as the laparoscopic experience of the surgeon increased. The rate of common bile duct injuries was not increased in patients with acute cholecystitis or in the 1.32% of patients undergoing laparoscopic common bile duct exploration. Intraoperative cholangiography did not reduce the risk of common bile duct injuries, but it allowed them to be diagnosed intraoperatively in 75% of patients. Local complications were recorded in 4.79% of patients, and systemic complications were seen in 5.59%. The mortality rate was 0.2%.

CONCLUSIONS

Although laparoscopic cholecystectomy is a safe procedure, the rate of conversion to open cholecystectomy is still substantial. The conversion rate depends both on the indication and intraoperative complications. There is still a 10.38% morbidity associated with the procedure; however, the incidence of common bile duct injuries, which decreases with growing laparoscopic experience, was relatively low.

The relationship between high-dose treatment and combination chemotherapy: the concept of summation dose intensity

The most important variables for the clinical use of antitumor agents (AAs) are dose and combination chemotherapy. The objectives of this study were to analyze the relationship between these two variables and to propose a unified conceptual framework for the construct and interpretation of clinical trials. Definitions and variables with respect to dose include potency, therapeutic index, standard dose, efficacy, relative efficacy, dose-limiting toxicity (DLT), dose rate, dose density, dose intensity, and fractional dose intensity. Our overarching concept, that is, summation dose intensity (SDI), was calculated in several ways, depending upon the nature of the data, and included the relative efficacy method, the unit regimen method, and the high dose method. The SDI concept was then applied to disease categories and strategies to determine its usefulness and effectiveness in integrating dose and combinations. The tumors and settings were: mustargen-vincristine-procarbazine-prednisone in Hodgkin's disease, combination chemotherapy for acute lymphocytic leukemia in children, metastatic breast cancer including dose and combinations, selected other solid tumors, alternating chemotherapy, and high dose studies in the leukemias and lymphomas. SDI was effective in integrating and quantifying dose and combination chemotherapy. For classical AAs, the implication of SDI for the construct and analysis of clinical trials was emphasized. In addition to new drug development, emphasis should be given to reducing or eliminating DLTs, such as those of the marrow, now and, in the future, those of the gastrointestinal tract toxicity and other DLTs. The above was derived from and applies to the classical AAs. Whether they will apply to, with appropriate adjustment, agents with significantly different dose-response curves, such as biotherapeutics and hormonal agents, remains to be determined.

A single scale for comparing dose-intensity of all chemotherapy regimens in breast cancer: summation dose-intensity

PURPOSE

To construct a single scale for comparing the dose-intensity of all chemotherapy regimens in breast cancer.

MATERIALS AND METHODS

First-line single-agent trials in metastatic disease were reviewed. The unit dose-intensity (UDI) that was required to produce a 30% complete response plus partial response (CR + PR) rate was determined for each drug. Randomized trials were then analyzed that prospectively tested dose-intensity. The dose-intensities of the drugs in each arm were expressed as fractions of their UDIs and added together. This yielded each arm's summation dose-intensity (SDI), which was then correlated with treatment outcomes.

RESULTS

In the single-agent trials, dose-response relationships were linear when the studies covered a range of dose-intensities. In the randomized trials that tested dose-intensity in metastatic disease, response rates and median survival correlated linearly with the SDIs of the treatment arms. An increment of one SDI unit increased CR + PR rate by approximately 30%, CR rate by 10%, and median survival by 3.75 months. Metastatic disease trials were negative if the difference between the arms was less than 0.54 SDI units. Adjuvant trials that tested a dose-intensity difference of less than 0.65 SDI units were also negative.

CONCLUSION

A single-agent dose-response database can be derived from historic literature that enables comparison of the dose-intensity of all combination regimens on one scale. The dose-intensity increase required to improve outcome can then be identified in earlier trials that tested that variable. SDI methodology should be tested prospectively in contemporary patients, and may be useful in guiding dosage increases beyond the conventional range.

Dose and dose intensity as determinants of outcome in the adjuvant treatment of breast cancer. The Cancer and Leukemia Group B

BACKGROUND

Both total dose and dose intensity of adjuvant chemotherapy are postulated to be important variables in the outcome for patients with operable breast cancer. The Cancer and Leukemia Group B study 8541 examined the effects of adjuvant treatment using conventional-range dose and dose intensity in female patients with stage II (axillary lymph node-positive) breast cancer.

METHODS

Within 6 weeks of surgery (radical mastectomy, modified radical mastectomy, or lumpectomy), 1550 patients with unilateral breast cancer were randomly assigned to one of three treatment arms: high-, moderate-, or low-dose intensity. The patients received cyclophosphamide, doxorubicin, and 5-fluorouracil on day 1 of each chemotherapy cycle, with 5-fluorouracil administration repeated on day 8. The high-dose arm had twice the dose intensity and twice the drug dose as the low-dose arm. The moderate-dose arm had two thirds the dose intensity as the high-dose arm but the same total drug dose. Disease-free survival and overall survival were primary end points of the study.

RESULTS

At a median follow-up of 9 years, disease-free survival and overall survival for patients on the moderate- and high-dose arms are superior to the corresponding survival measures for patients on the low-dose arm (two-sided P<.0001 and two-sided P = .004, respectively), with no difference in disease-free or overall survival between the moderate- and the high-dose arms. At 5 years, overall survival (average +/- standard error) is 79% +/- 2% for patients on the high-dose arm, 77% +/- 2% for the patients on the moderate-dose arm, and 72% +/- 2% for patients on the low-dose arm; disease-free survival is 66% +/- 2%, 61% +/- 2%, and 56% +/- 2%, respectively.

CONCLUSION

Within the conventional dose range for this chemotherapy regimen, a higher dose is associated with better disease-free survival and overall survival.

shaven and sparkling are mutations in separate enhancers of the Drosophila Pax2 homolog

We have previously shown that the sparkling gene, which like mammalian Pax2 plays an important role in eye development, is encoded by the Drosophila homolog of Pax2. Here we demonstrate that D-Pax2 also encodes the shaven function, which is crucial during bristle development. Both sv and spa alleles, previously thought to represent different genes, are mutations in two widely separated enhancers of D-Pax2. The sv function of D-Pax2 acts in at least two distinct steps of mechanosensory bristle development: the specification of the alternative fate of shaft as opposed to socket cell, and later the differentiation of the shaft cell.

Biochemical characterization of in vivo alkylating agent resistance of a murine EMT-6 mammary carcinoma. Implication for systemic involvement in the resistance phenotype

While cancer drug resistance has been extensively studied in cell culture, little is known about more clinically relevant in vivo resistance. The in vivo resistance of a murine mammary carcinoma EMT-6 to alkylating agents was demonstrated in the present study to be associated with multiple biochemical changes. These included an up to 1.5-fold increase in activity of phase II drug metabolizing enzymes (DMEs), such as glutathione (GSH), glutathione reductase (GR), glutathione S-transferase (GST), glutathione peroxidase (GPX) and aldehyde dehydrogenase (ALDH), and an up to 88% decrease of phase I DME activity [7-ethoxycumarin O-deethylase (ECOD), P450 reductase (PR)] in the resistant tumors compared with the parental tumor. Transplant of either parental or resistant tumors to mice was accompanied by a decrease of both phase I and phase II DME activity in the livers of female Balb/C mice compared with the non-tumor mice. Moreover, at the protein level, while cytochrome P450 (CYP) IIB1/2 in the liver of mouse bearing both the sensitive and the resistant tumor was significantly diminished compared to that in the liver of non-tumor control mouse in Western analysis, there was actually an increase of this protein in the liver of the host bearing either of the two resistant tumors compared to that of the sensitive tumor-bearing animal. Although this in vivo resistance phenotype is not expressed in cell culture, the profile of most of the enzyme changes in the resistant tumors remained similar in in vitro culture of the isolated tumor cells. Collectively, these results demonstrate that this in vivo alkylating agent resistance is associated with multiple changes of both phase I and phase II DMEs in the resistant tumors, and some of these, such as CYP IIB1/2 protein are further altered in the resistant tumor-bearing mouse liver, suggesting a potential role of systemic factors in this resistance phenotype.

Dose escalation of the hypoxic cell sensitizer etanidazole combined with ifosfamide, carboplatin, etoposide, and autologous hematopoietic stem cell support

Multiple mechanisms of drug resistance contribute to treatment failure. Although high-dose therapy attempts to overwhelm these defenses pharmacologically, this approach is only successful in a fraction of treated patients. Many drug resistance mechanisms are shared between malignant and normal cells, but the expression of various drug resistance mechanisms associated with hypoxia is largely confined to tumor tissue. Thus, reversal of this mechanism is likely to provide a therapeutic advantage to the host. This study was designed to define the dose-limiting toxicities and maximum tolerated dose of etanidazole when it is given concurrently with high-dose ifosfamide, carboplatin, and etoposide (ICE), with hematopoietic stem cell support. The maximum tolerated doses of high-dose ICE were administered concurrently with dose escalations of etanidazole, a hypoxic cell sensitizer. All agents were given by 96-h continuous i.v. infusion beginning on day -7. Mesna uroprotection was provided. Autologous marrow and cytokine mobilized peripheral blood progenitor cells were reinfused on day 0. Granulocyte colony-stimulating factor was administered following reinfusion until the granulocytes recovered to > 1000/microliter. Fifty-five adults with advanced malignancies were enrolled in cohorts of five to nine patients. Four dose levels of etanidazole between 3 and 5.5 g/m2/day (12, 16, 20, and 22 g/m2 total doses) and two doses of carboplatin (1600 and 1800 mg/m2 total doses) were evaluated. Seven patients died of organ toxicity (13%); two each from veno-occlusive disease of liver and sepsis; and one each from sudden death, renal failure, and refractory thrombocytopenic hemorrhage. Five deaths occurred at the top dose level. One additional patient suffered a witnessed cardiorespiratory arrest from ventricular fibrillation and was resuscitated. Dose-dependent and largely reversible peripheral neuropathy was observed consisting of two syndromes: severe cramping myalgic/neuralgic pain, predominantly in stocking glove distribution, occurring between day -3 and day 0, and a sensory peripheral neuropathy with similar distribution peaking around day +60. The maximal achievable dose of etanidazole (16 g/m2 dose level) resulted in a mean serum level of 38 micrograms/ml (25-55 micrograms/ml). Etanidazole significantly enhanced host toxicity of high-dose ICE. Effective modulatory doses of etanidazole could not be given with acceptable toxicity using this schedule.

Chemopreventive effects of dithiocarbamates on aflatoxin B1 metabolism and formation of AFB1 adducts with glutathione

Several agents with anticarcinogenic potential such as diethyldithiocarbamate (DDTC), lactose-DDTC, proline-dithiocarbamate (PDTC), its dimer proline-thiuramdisulfide (PTDS) and 4-carboxy-piperazine-TDS (4-pip-TDS) were investigated for their influence on the metabolism and the detoxication of aflatoxin B1 (AFB1) in vitro and in vivo. Aflatoxins are a group of mycotoxins produced by aspergillus species and are among the most important risk factors for hepatocellular carcinoma in certain areas of the world. AFB1 metabolism measured by the formation of tris-diol adducts showed that the thiuramdisulfides 4-carboxy-piperazine-TDS and PTDS were better inhibitors in vitro than the corresponding dithiocarbamates. Ex vivo studies in rats showed that dithiocarbamates (DTCs) including sugar linked lactose-DDTC decreased the formation of tris-diol adducts. Among the dithiocarbamates administered, DDTC showed a 40% inhibition whereas the other compounds showed only marginal effects. In vivo experiments on the formation of glutathione-adducts derived from AFB1-endo- and exo-epoxides showed that lactose-DDTC enhanced the formation of AFB1-GSH adducts, whereas PDTC, 4-pip-TDS, PTDS and DDTC displayed inhibitory effects. We conclude that DTCs may be promising agents in the chemoprevention of liver carcinogenesis caused by AFB1.

Spilled gallstones after laparoscopic cholecystectomy. A relevant problem? A retrospective analysis of 10,174 laparoscopic cholecystectomies

BACKGROUND

Spilled gallstones after laparoscopic cholecystectomy may cause abscess formation, but the exact extent of this problem remains unclear.

METHOD

The data (collected by the Swiss Association of Laparoscopic and Thoracoscopic Surgery) on 10,174 patients undergoing laparoscopic cholecystectomy at 82 surgical institutions in Switzerland between January 1992 and April 1995 were retrospectively analyzed with special interest in spilled gallstones and their complications.

RESULTS

In 581 cases (5.7%) spillage of gallstones occurred; 34 of these cases were primarily converted to an open procedure for stone retrieval. Of the remaining 547 cases only eight patients (0.08%) developed postoperatively abscess formation requiring reoperation.

CONCLUSIONS

Spillage of gallstones after laparoscopic cholecystectomy is fairly common and occurs in about 6% of patients. However, abscess formation with subsequent surgical therapy remains a minor problem. Removal of spilled gallstones is therefore not recommended for all patients, but an attempt at removal should be performed whenever possible.

High-dose multimodality therapy with autologous stem-cell support for stage IIIB breast carcinoma

PURPOSE

Women with locally unresectable and inflammatory breast carcinoma (IBC) have an approximately 30% 5-year disease-free survival (DFS) rate with conventional multimodality therapy. A short but dose-intensive multimodality phase II trial was designed in an attempt to improve outcome in stage IIIB disease. Mastectomy was performed after high-dose therapy to evaluate pathologic response to treatment.

METHODS

Women with newly diagnosed disease received four 2-week cycles of doxorubicin 90 mg/m2 with granulocyte colony-stimulating factor (G-CSF), followed by cyclophosphamide 6,000 mg/m2, thiotepa 500 mg/m2, and carboplatin 800 mg/m2 (CTCb) with marrow and peripheral-blood progenitor cell (PBPC) support. Local therapy consisted of mastectomy and radiotherapy. Tamoxifen (5 years) was begun if the patient was estrogen receptor-positive (ER+).

RESULTS

Fifty women (46 stage IIIB [91% IBC], four stage IIIA) entered the study and 47 are assessable. Ten had mastectomy before any systemic therapy (seven with pathologic IBC, three with residual tumor after mastectomy). Eighty percent received full-dose doxorubicin with 60% on schedule. Clinical response rates to induction were 15% complete response (CR), 5% very good partial response (VGPR), 59% partial response (PR), and 21% minor response (MR)/stable disease (SD). Mastectomy after CTCb in 37 patients showed a 14% pathologic CR rate, 29% microscopic foci in breast and/or axilla, and 57% gross tumor. Fifteen (32%) patients have relapsed (median, 17 months post-CTCb). The 30-month DFS is estimated at 64%. For those in pathologic CR, with microscopic, or with gross disease remaining after CTCb, the 30-month DFS is estimated at 100%, 70%, and 38%, respectively. Those with zero, one to three, or > or = four positive nodes at axillary dissection had a median DFS of 31, 18, and 13 months, respectively.

CONCLUSION

This short but dose-intensive multimodality approach for stage IIIB breast carcinoma is feasible with encouraging results to date.

Acute in vivo resistance in high-dose therapy

In the design of sequential high-dose chemotherapy regimens, the selection of antitumor alkylating agents to be included in each intensification and the interval between the intensifications are critical to the design of the therapy. The tumor cell survival assay and tumor growth delay assay using the murine EMT-6 mammary carcinoma were used as a solid tumor model in which to address these issues. Tumor-bearing mice were treated with high-dose melphalan or cyclophosphamide followed 7 or 12 days later by melphalan, cyclophosphamide, thiotepa, or carboplatin. After treatment with melphalan both 7 and 12 days later, the tumor was resistant to each of the four drugs studied. After treatment with cyclophosphamide both 7 and 12 days later, the tumor was resistant to melphalan and thiotepa but was not resistant to cyclophosphamide or carboplatin. To extend the interval between high-dose treatments to 14 and 21 days, after the first intensification the tumor was transferred to second hosts that were either drug-treated or not drug treated. When high-dose melphalan-treated tumors were treated with a second high dose of melphalan, the tumors were very resistant with the 14-day interval and less resistant with the 21-day interval. This small effect was evident in the bone marrow colony-forming unit, granulocyte-macrophage (CFU-GM), except in the hosts pretreated with melphalan. When high-dose cyclophosphamide-treated tumors were treated with a second high dose of cyclophosphamide, drug resistance was observed both with the 14-day and 21-day interval if the host was non-pretreated or was pretreated with melphalan, but not if the host was pretreated with cyclophosphamide. The same was true in the bone marrow CFU-GM. Tumor growth delay studies supported these findings in that treatment with high-dose cyclophosphamide, melphalan, thiotepa, and carboplatin resulted in less than additive tumor growth delay, whereas treatment with high-dose cyclophosphamide prior to treatment with high-dose melphalan, cyclophosphamide, thiotepa, or carboplatin resulted in additivity to greater-than-additive tumor growth delay. High-dose combination regimens required dose reduction of the drugs, which resulted in decreased tumor growth delays.

Preoperative Nyhus classification of inguinal hernias and type-related individual hernia repair. A case for diagnostic laparoscopy

The goal of this prospective study was to determine the clinical value (sensitivity and specificity) of preoperative hernia classification (Nyhus classification) using three distinct methods: clinical examination, Doppler ultrasonography, and diagnostic laparoscopy. Thirty patients with 35 suspected groin hernias were included. Definitive hernia classification was achieved by laparoscopic peritoneal incision and dissection of the inguinal floor. Twenty-eight laparoscopic hernia repairs followed. Sensitivity and specificity were calculated for each preoperative evaluation method. Clinical examination was found to be more accurate than Doppler ultrasonography. The highest scores for sensitivity (0.93) and specificity (1.00) were achieved, however, by diagnostic laparoscopy. Therefore, the authors consider diagnostic laparoscopy to be a valuable preoperative tool for assessing hernia type. An accurate preoperative hernia classification will allow an individualized type-related hernia repair (open: anterior, posterior approach, or laparoscopic: transabdominal preperitoneal, total preperitoneal, inner-ring closure, mesh insertion).

Non-small cell lung cancer: novel treatment strategies

Prevention of cigarette smoking and early lung cancer detection remain important in our approach to the control of non-small cell lung cancer (NSCLC). In recent years, chemotherapy has emerged as a viable option in the treatment of NSCLC. The most impressive and widely confirmed evidence for this is the fact that chemotherapy can eradicate NSCLC micrometastases. Indeed, in some studies employing neoadjuvant chemotherapy followed by local surgery, pathology-confirmed complete remission rates as high as 20% have been reported. New agents showing preliminary activity in NSCLC include paclitaxel, vinorelbine, gemcitabine, and irinotecan (CPT-11). Certainly, however, there remains a need for novel, effective single-agent and combination chemotherapies. The seed/soil tumor concept, in which the seed consists of the tumor cells per se and the soil is the stroma containing the seeds, has proven helpful in devising new treatment strategies. Such strategies may include the use of antisoil agents, including antiangiogenesis, anti-invasion, and antimetastasis agents, both separately and particularly in conjunction with established antitumor agents. New therapeutic targets and methods of antitumor agent development based on modern molecular biology and pharmacology will provide a greater opportunity to improve the treatment of NSCLC.

Pharmacokinetics of methotrexate-albumin conjugates in tumor-bearing rats

Linking chemotherapeutic drugs to a macromolecular carrier system may enhance tumor targeting, reduce toxicity and overcome drug resistance mechanisms. As an elementary model to evaluate the pharmacological properties of macromolecular drug carrier systems we chose rat serum albumin (RSA) for carrier and methotrexate (MTX) as antineoplastic drug. The conjugation procedure yielded conjugates with an approximate 1:1 molar loading rate (MTX(1)-RSA). In the first part of the study a residualizing [111In]DTPA protein label was used for mapping in vivo the catabolic sites of the native carrier protein and of the MTX(1)-RSA drug conjugate in Walker 256 carcinosarcoma bearing rats. The tumor accumulation was about 14% of the injected dose for the RSA and MTX(1)-RSA tracers after 24 h. Tracer entrapment by organs with an active mononuclear phagocyte system was low (liver below 7% and spleen below 1.5% of the injected dose after 24 h). The 1:1 conjugation of MTX to RSA did not decisively alter the pharmacokinetic properties nor the tumor or tissue distribution of the native carrier protein RSA. In the second part of the study the different properties of the MTX(1)-RSA conjugate were compared with MTX in vivo. About 2 mg MTX/kg body weight either of the drug conjugate or of the original drug were injected after being additionally spiked with radiolabeled tracers. Plasma concentrations were simultaneously determined by immunological and radioactive means. After 24 h about 12% MTX(1)-RSA was found in circulation compared to 0.03% MTX. Favorable tumor accumulation rates of about 14% were achieved for MTX(1)-RSA versus 0.04% for MTX. About 45-fold more of the injected dose of [3H]MTX accumulated in the liver as compared to the tumor (1.5 versus 0.03%) after 24 h. Conjugation of MTX to RSA reversed this ratio in favor of the tumor to 1:1.4 (13.6 versus 9.6%). In conclusion, the potential therapeutic benefit of the MTX(1)-RSA conjugate lies in its very long tumor exposure time and its improved tumor accumulation rate compared to conventional MTX. In addition the conjugation to albumin might enhance the therapeutic effects over those achieved by long-term continuous infusion of MTX, as MTX(1)-RSA enters the cells by a different uptake mechanism. This might also help to circumvent MTX resistance mechanisms, such as a reduction in folate receptor numbers or impaired MTX polyglutamylation.

An investigation of the metabolism of N-nitrosodimethylamine and N-nitrosomethylaniline by horseradish peroxidase in vitro

The demethylation of carcinogenic N-nitrosodimethylamine (NDMA) and N-nitrosomethylaniline (NMA) is catalyzed by horseradish peroxidase in the presence of hydrogen peroxide. NMA is a better substrate for peroxidase than NDMA. The Km values are 0.74 and 3.12 mmol/l for NMA and NDMA, respectively. The oxidation of NDMA and NMA is inhibited by radical trapping agents (nitrosobenzene, glutathione, ascorbate, NADH). This indicates the radical mechanism for the peroxidase-mediated oxidation of both N-nitrosamines. The in vitro metabolism of NMA using peroxidase was investigated in detail. Beside formaldehyde, the metabolites formed from NMA by peroxidase include aniline, p-aminophenol and phenol. Phenol formation presumably arose from N-demethylation of NMA via a benzenediazonium ion (BDI) intermediate while aniline and p-aminophenol from denitrosation of this carcinogen. The results are discussed from the point of view of the role of peroxidases in the metabolism of N-nitrosamines.