Addition of rituximab to chemotherapy overcomes the negative prognostic impact of cyclin E expression in diffuse large B-cell lymphoma

BACKGROUND

High levels of cyclin E (CCNE) are accompanied by shorter survival in cyclophosphamide, hydroxydaunorubicin, oncovin and prednisone (CHOP)-treated diffuse large B-cell lymphomas (DLBCL), independent of the international prognostic index (IPI). Data on the prognostic role of CCNE in the 'rituximab (R)-era' are lacking.

METHODS

To test reproducibility and applicability of observations from the 'pre-R era' to the 'R era', we examined the prognostic role of CCNE expression by immunohistochemistry in 1579 DLBCL on tissue microarrays (TMA); 339 patients were treated by CHOP and 635 by R-CHOP.

RESULTS

1209 samples (77%) were evaluable; failures were due to missing TMA punches and fixation artefacts. Mean expression of CCNE was 13% (0-85%); applying a cut-off of >16%, 382 DLBCL (31%) were positive. CCNE did not correlate with any of the known variables (IPI, primary site, cell of origin, proliferation, and BCL2- or C-MYC rearrangements). We were able to reproduce data suggesting an IPI- and response to therapy independent, negative prognostic impact of CCNE in CHOP-treated DLBCL patients: CCNE-positive cases had a median survival of 16 months compared with 57 months in negative ones (p=0.012). In R-CHOP-treated patients the prognostic impact of CCNE was abrogated and only IPI, cell of origin and response to therapy had a prognostic significance.

CONCLUSIONS

Addition of R to CHOP overcomes the negative prognostic impact of CCNE in DLBCL. Thus, R not only prolongs survival in DLBCL but also serves a cautionary note that prognostic factors should not be transferred into the 'R era' without proper scientific studies.

Tumor oxygenation and radiosensitization by pentoxifylline and a perflubron emulsion carbogen breathing

Oxygen tension measurements were made in three tumors: (i) the murine FSaII fibrosarcoma, (ii) the rat 9L gliosarcoma and (iii) the rat 13672 mammary adenocarcinoma using a pO2 histograph. Tumor oxygenation measurements were made while the animals breathed air or breathed carbogen (95% oxygen/5% carbon dioxide). Pentoxifylline or a perflubron emulsion was administered to the animals and tumor oxygen measurements were repeated under both breathing conditions. Both pentoxifylline and the perflubron emulsion improved the oxygenation of the FSaII fibrosarcoma under air breathing conditions but did not alter the oxygen profiles of either rat tumor compared with air breathing alone. Carbogen breathing increased the oxygenation of all tumors. Pentoxifylline administration did not change the oxygen profiles of the tumors under carbogen breathing conditions but administration of the perflubron emulsion increased the oxygenation of all three tumors under carbogen breathing conditions compared with carbogen breathing alone. Co-administration of pentoxifylline and the perflubron emulsion enhanced the radiation response of the Lewis lung tumor to daily fractionated radiation under air breathing conditions with a dose modifying factor of 1.65 and under carbogen breathing conditions with a dose modifying factor of 2.25. Over a range of perflubron emulsion doses, pentoxifylline increased the growth delay of the Lewis lung tumor in a constant manner. These results indicate that pentoxifylline and the perflubron emulsion have the largest impact on the oxygenation of more hypoxic tumors and that administration of the perflubron emulsion/carbogen breathing is the most effective means of increasing tumor oxygenation and radiation response.

Decreased tumor oxygenation after cyclophosphamide, reoxygenation and therapeutic enhancement with a perflubron emulsion carbogen breathing

Oxygen profiles of the rat mammary 13672 carcinoma were determined using a pO2 histograph prior to treatment and 24 h and 48 h after i.p. administration of a single dose of cyclophosphamide (300 mg/kg). The tumors were severely hypoxic at 24 h post the administration of cyclophosphamide. There was little increase in oxygenation of the tumors at 48 h post therapy compared with 24 h post therapy indicating that reoxygenation after cyclophosphamide was occurring very slowly in this tumor. Carbogen breathing improved the oxygenation of the tumors under each of the conditions studied. Administration of the perflubron emulsion (8 ml/kg) produced little or no change in the oxygenation of the tumors under normal air breathing conditions. However, the addition of carbogen breathing to administration of the perflubron emulsion increased the oxygenation of the tumors to levels equal to or greater than carbogen breathing at the mean/median pO2's. Perhaps most significantly, administration of the perflubron emulsion with carbogen breathing increased the oxygenation of the most hypoxic regions of the tumors but carbogen breathing alone did not. The growth delay of the Lewis lung carcinoma increased with increasing dose.of the perflubron emulsion along with cyclophosphamide (3 x 150 mg/kg) and carbogen breathing (6 h). This combination treatment was most effective when the cyclophosphamide was prepared in the perflubron emulsion. The number of lung metastases decreased in a manner parallel with increased efficacy of the treatment toward the primary tumor.

Prolonged survival of renal allograft in rats by methotrexate-albumin conjugates as immunosuppressive therapy

Methothrexate (MTX) causes unwanted adverse events by affecting gastrointestinal and bone marrow cells when used as an immunosuppressant. Our aim was to reduce those side effects by covalent binding of methothrexate to human serum albumin (HSA) targeting rapidly proliferating lymphocytes, which are known to ingest albumin as an energy source. Twenty-one rats received a kidney transplant. Group A (n = 5) received standard immunosupression (free MTX); group B (n = 9), albumin-MTX conjugates; and group C (n = 7) albumin control. The primary endpoint of this animal study was transplant survival, which was evaluated as death due to uremia. The study was terminated on day 100. Placebo-treated rat recipients (group C) rejected their grafts at a median of 8 days, which was prolonged to 17 days in standard immunosuppressed rats (group A), resulting in doubling transplant survival compared to nonimmunosuppressed animals. However, the same dose given as HSA-conjugated MTX prolonged the median survival time to 43 days. (group B). Hence, the administration of conjugated methotrexate appeared to result in a doubling of transplant survival compared with standard immunosuppression. Moreover, two animals receiving MTX-HSA became long-term survivors without additional immunosuppression. Further studies should be performed to evaluate the significance of these findings in larger animals and possibly in clinical studies.

Clinical studies with tumour necrosis factor

The mechanism of tumour necrosis factor (TNF) cytotoxicity remains unknown. The in vivo antitumour effects of TNF may be related to direct cytotoxicity, immunomodulatory effects or endothelial effects on tumour vasculature. Phase I and early Phase II clinical trials of human recombinant TNF are under way in Japan, the USA, the UK and Germany. The maximum Phase II dose for TNF has not been established. The clinical toxicity of TNF is generally similar to that of other biological agents. Systemic toxicity, including fever, chills, anorexia and nausea, has been seen in most patients treated with TNF and has not been clearly related to dose. Other toxicities have included liver function abnormalities, hypotension, transient neurological changes and haematological abnormalities. Few clinical responses have been reported but organized Phase II testing remains to be completed. Combination trials with interferons have recently been initiated. Phase II efficacy studies of TNF as a single agent and in combination are needed for an assessment of the value of this agent in cancer therapy.

Post-surgical follow-up (by ELISA and immunoblotting) of cured versus non-cured cystic echinococcosis in young patients

The study was designed to determine comparatively the prognostic value of immunoblotting and ELISA in the serological follow-up of young cystic echinococcosis (CE) patients exhibiting either a cured or a progredient (non-cured) course of disease after treatment. A total of 54 patients (mean age 9 years, range from 3 to 15 years) with surgically, radiologically and/or histologically proven CE were studied for a period up to 60 months after surgery. Additionally, some of the patients underwent chemotherapy. Based on the clinical course and outcome, as well as on imaging findings, patients were clustered into 2 groups of either cured (CCE), or non-cured (NCCE) CE patients. ELISA showed a high rate of seropositivity 4 to 5 years post-surgery for both CCE (57.1%) and NCCE (100%) patients, the difference found between the two groups was statistically not significant. Immunoblotting based upon recognition of AgB subcomponents (8 and 16 kDa bands) showed a decrease of respective antibody reactivities after 4 years post-surgery. Only sera from 14.3% of CCE patients recognized the subcomponents of AgB after 4 years, while none (0%) of these sera was still reactive at 5 years post-surgery. At variance, immunoblotting remained positive for AgB subcomponents in 100% of the NCCE cases as tested between 4 and 5 years after surgical treatment. Immunoblotting therefore proved to be a useful approach for monitoring post-surgical follow-ups of human CCE and NCCE in young patients when based upon the recognition of AgB subcomponents.

Improved serodiagnosis of alveolar echinococcosis of humans using an in vitro-produced Echinococcus multilocularis antigen

Serology is an important tool for the diagnosis of alveolar echinococcosis (AE) in humans. In order to improve serodiagnostic performance, we have developed an in vitro-produced Echinococcus mulilocularis metacestode vesicle fluid (EmVF) antigen for application in an immunoblot assay. Immunoblot analysis of EmVF revealed an abundant immunoreactive band triplet of 20-22 kDa, achieving a sensitivity of 100% based on the testing of sera from 62 pre-operative and pre-treatment cases of active and inactive AE. Thus, the EmVF-immunoblotting allowed the specific detection of cases seronegative by the Em2- and/or EmII/3-10-ELISA, usually attributable to abortive, inactive cases of AE. The specificity of the EmVF-immunoblotting did not allow discrimination between AE and cystic echinococcosis (CE) but was 100% with respect to non-Echinococcus parasitic infections or cancer malignancies. Based on the findings of this study, it is recommended that the current ELISA test combination (Em2- and II/3-10-ELISA) be complemented with EmVF-immunoblotting, allowing an improved diagnosis of both clinical and subclinical forms of AE, including those associated with E. multilocularis-specific antibody reactivities not detectable by ELISA.

Oxidation pattern of the anticancer drug ellipticine by hepatic microsomes - similarity between human and rat systems

Ellipticine is an antineoplastic agent, whose mode of action is based mainly on DNA intercalation, inhibition of topoisomerase II and formation of DNA adducts mediated by cytochrome P450 (CYP). We investigated the ability of CYP enzymes in rat, rabbit and human hepatic microsomes to oxidize ellipticine and evaluated suitable animal models mimicking its oxidation in humans. Ellipticine is oxidized by microsomes of all species to 7-hydroxy-, 9-hydroxy-, 12-hydroxy-, 13-hydroxyellipticine and ellipticine N(2)-oxide. However, only rat microsomes generated the pattern of ellipticine metabolites reproducing that formed by human microsomes. While rabbit microsomes favored the production of ellipticine N(2)-oxide, human and rat microsomes predominantly formed 13-hydroxyellipticine. The species difference in expression and catalytic activities of individual CYPs in livers are the cause of these metabolic differences. Formation of 7-hydroxy- and 9-hydroxyellipticine was attributable to CYP1A in microsomes of all species. However, production of 13-hydroxy-, 12-hydroxyellipticine and ellipticine N(2)-oxide, the metabolites generating DNA adducts, was attributable to the orthologous CYPs only in rats and humans. CYP3A predominantly generates these metabolites in rat and human microsomes, while CYP2C3 activity prevails in microsomes of rabbits. The results underline the suitability of rat species as a model to evaluate human susceptibility to ellipticine.

The impact of induction duration and the number of high-dose cycles on the long-term survival of women with metastatic breast cancer treated with high-dose chemotherapy with stem cell rescue: an analysis of sequential phase I/II trials from the Dana-Farber/Beth Israel STAMP program

Although high-dose chemotherapy (HDC) with stem cell rescue for the treatment of women with metastatic breast cancer (MBC) is currently a controversial strategy, we report the long-term outcomes of women undergoing high-dose therapy for MBC over the past 12 years while participating in a sequence of research studies transitioning between a single to a double intensification approach. Univariate and multivariate analyses provide a framework to understand the prognostic factors important for event-free and overall survival. Between May 1988 and April 1998, we enrolled 188 women with MBC into 3 trials of previously reported sequential transplantation strategies. Trial I (long induction/single transplantation) accepted 62 women in partial or complete response to an unspecified induction therapy and treated them with high-dose CTCb (cyclophosphamide, thiotepa, and carboplatin) supported by marrow or peripheral blood progenitor cells (PBPC). Trial II (long induction/double transplantation) accepted 68 women in partial or complete response to an unspecified induction therapy, and mobilized stem cells with 2 cycles of AF (doxorubicin and 5-fluorouracil) with granulocyte colony-stimulating factor (G-CSF). These women then received 1 cycle of high-dose single-agent melphalan followed 3 to 5 weeks later by CTCb, each with marrow or PBPC support. Trial III (short induction/double transplantation) enrolled 58 women prior to chemotherapy treatment for metastatic disease. Induction/mobilization consisted of 2 cycles given 14 days apart of doxorubicin and G-CSF. In contrast to trials I and II, patients with stable disease or better response to induction were eligible to proceed ahead with 2 cycles of HDC, 1 being CTCb and the other being dose escalated paclitaxel together with high-dose melphalan (TxM). These 2 HDC regimens were administered 5 weeks apart. TxM was given first in 32 patients and CTCb was given first in 26 patients. The median follow-up periods for trials I, II, and III were 98, 62, and 39 months from the initiation of induction chemotherapy and 92, 55, and 36 months from last high-dose therapy, respectively. The patient characteristics upon entry into these trials were similar. Important differences were that only those patients achieving a partial response or better to induction therapy were enrolled and analyzed for trials I and II, but all patients were analyzed on an intent-to-treat basis for trial III, including those who did not receive intensification. The median event-free survival (EFS) times from induction chemotherapy were 13, 19, and 27 months for trials I, II, and III, respectively (III versus I + II, P = .0004; III versus I, P = .0005; III versus II, P = .005; II versus I, P = .25). The median overall survival (OS) times from induction chemotherapy were 30, 29, and 57 months for trials I, II, and III, respectively (III versus I + II, P = .002; III versus I, P = .003; III versus II, P = .009; II versus I, P = .47). By multivariate Cox regression, participation in the short induction/double transplantation trial III and having no prior adjuvant chemotherapy remained favorable prognostic factors for both EFS and OS. The presence of visceral disease shortened EFS, and hormone sensitivity was of borderline significance. No substantive differences in the characteristics of the patient populations between the 3 trials appeared to interact with outcomes. In conclusion, we found that single transplantation in responding patients after long induction achieves a small cohort of long-term survivors, similar to the results reported by other transplantation centers. Adding a cycle of single-agent high-dose melphalan in this context delayed median time to relapse but did not affect long-term EFS or OS. The double transplantation approach using CTCb and TxM early in the course of treatment was associated with the best EFS and overall survival and was safe, feasible, and tolerable. Treatment duration was only 14 weeks, and this treatment option eliminated lengthy induction chemotherapy. Although selection biases may have in part contributed to this effect, a randomized comparison of standard therapy versus short induction/double transplantation is warranted.

The anticancer agent ellipticine on activation by cytochrome P450 forms covalent DNA adducts

Ellipticine is a potent antitumor agent whose mechanism of action is considered to be based mainly on DNA intercalation and/or inhibition of topoisomerase II. Using [3H]-labeled ellipticine, we observed substantial microsome (cytochrome P450)-dependent binding of ellipticine to DNA. In rat, rabbit, minipig, and human microsomes, in reconstituted systems with isolated cytochromes P450 and in Supersomes containing recombinantly expressed human cytochromes P450, we could show that ellipticine forms a covalent DNA adduct detected by [32P]-postlabeling. The most potent human enzyme is CYP3A4, followed by CYP1A1, CYP1A2, CYP1B1, and CYP2C9. Another minor adduct is formed independent of enzymatic activation. The [32P]-postlabeling analysis of DNA modified by activated ellipticine confirms the covalent binding to DNA as an important type of DNA modification. The DNA adduct formation we describe is a novel mechanism for the ellipticine action and might in part explain its tumor specificity.

Carcinogenic and nephrotoxic alkaloids aristolochic acids upon activation by NADPH : cytochrome P450 reductase form adducts found in DNA of patients with Chinese herbs nephropathy

Aristolochic acid (AA), a naturally occurring nephrotoxin and carcinogen, has been found to be implicated in an unique type of renal fibrosis, designated Chinese herbs nephropathy (CHN), and associated with the development of urothelial cancer in CHN patients. Understanding, which enzymes are involved in AA activation and/or detoxication is important in the assessment of individual susceptibility of humans to this natural carcinogen. Using the nuclease P1 version of the 32P-postlabeling assay we examined the ability of microsomal NADPH: CYP reductase to activate AA to metabolites forming DNA adducts. Renal and hepatic microsomes, containing NADPH:CYP reductase, generated AA-DNA adduct patterns reproducing those found in renal tissues in patients suffering from a renal fibrosis CHN and urothelial cancer. 7-(Deoxyadenosin-N6-yl)aristolactam I, 7-(deoxyguanosin-N2-yl)aristolactam I and 7-(deoxyadenosin-N6-yl)aristolactam II were identified as AA-DNA adducts formed by AAI. Two AA-DNA adducts, 7-(deoxyguanosin-N2-yl) aristolactam II and 7- (deoxyadenosin-N6-yl) aristolactam II, were generated from AAII. According to the structures of the DNA adducts identified, nitroreduction is the crucial pathway in the metabolic activation of AA. The identity of NADPH: CYP reductase as activating enzyme in microsomes has been proved with different cofactors and an enzyme inhibitor. Alpha-lipoic acid, a selective inhibitor of NADPH: CYP reductase, significantly decreased the amount of the adducts formed by microsomes. Likewise, only a cofactor of the enzyme, NADPH, supported the DNA adduct formation of AAI and AAII, while NADH was ineffective. These results demonstrate an involvement of NADPH: CYP reductase in the activation pathway of AAI and AAII in the microsomal system. Moreover, using the purified enzyme, the participation of this enzyme in the formation of AA-DNA adducts was confirmed. The results presented here are the first report demonstrating a reductive activation of natural nitroaromatic compounds, AA, by NADPH: CYP reductase.

Human cervical tumor cell (SiHa) surface alphavbeta3 integrin receptor has associated matrix metalloproteinase (MMP-2) activity

PURPOSE

Integrins are transmembrane heterodimeric molecules that mediate cellular adhesion and are involved in different biological processes, such as tumor development and invasion of tumor cells. Matrixmetalloproteases (MMP) are a family of secreted or membrane proteins capable of digesting extracellular matrix. It has been shown that MMP-2 binds to alphavbeta3 integrin. Recent evidence suggests that a complex of membrane-type MMP (MT1-MMP) and tissue inhibitor of metalloptroteinase-2 (TIMP-2) participate in the activation of alphavbeta3-associated MMP-2. We investigated whether alphavbeta3 and MMP-2 are associated on the membranes of a human cell line, SiHa, and the possible involvement of MT1-MMP and TIMP-2 in the modulation of MMP-2 activity.

METHODS

Immunoprecipitation of SiHa membrane extracts with monoclonal antibodies against alphav or MMP-2, and western blots of immunoprecipitates and serum-free conditioned media were performed. TIMP-2 in conditioned medium and MT1-MMP in the membrane fraction was assayed by western blot. Zymography of anti-alphav antibody immunoprecipitates and conditioned media were used to show gelatinolytic activity.

RESULTS

The coprecipitation of MMP-2 with alphavbeta3 by anti-alphav antibody is a strong indication that SiHa cell surface alphavbeta3 integrin is a receptor for MMP-2. Immunoblot assays show the expression of MT1-MMP on SiHa cell membranes and secreted TIMP-2 and pro-MMP-2 in the medium.

CONCLUSIONS

SiHa cells express all the molecules which are reported to form a complex to activate pro-MMP-2. Active MMP-2 associated with alphavbeta3 may regulate matrix degradation and thereby modulate directed motility of SiHa cells.

Randomized controlled trial of laparoscopic transabdominal preperitoneal hernioplasty vs Shouldice repair

BACKGROUND

There is a scarcity of data on long-term results after laparoscopic hernia repair. Herein we report on the outcome of a group of patients who were followed up for 5 years in a multicenter study on hernia repair.

METHODS

A total of 100 patients with 127 hernias were randomized to undergo either transabdominal preperitoneal (TAPP) or Shouldice hernia repair. Follow-up was by clinical examination and standardized questionnaire.

RESULTS

Of the 100 patients who underwent surgery, 84 were available for follow-up at 5 years. The TAPP procedure was less painful than the Shouldice repair, with fewer patients receiving narcotic analgesics. The median time to return to 100% activity was shorter in the laparoscopic group (21 days) than in the Shouldice group (40 days). Up to 60 months after the operation, the complication rate was lower in laparoscopically repaired hernias (19/66) than in the open group (25/61). There were two recurrences (3.9%) in the TAPP group and five in the Shouldice group (10.2%).

CONCLUSION

The TAPP hernia repair yields comparable or better results than Shouldice herniorrhaphy in terms of postoperative pain, recovery, and recurrence rate.

AIF-1 expression defines a proliferating and alert microglial/macrophage phenotype following spinal cord injury in rats

Microglial cells are among the first and dominant cell types to respond to CNS injury. Following calcium influx, microglial activation leads to a variety of cellular responses, such as proliferation and release of cytotoxic and neurotrophic mediators. Allograft inflammatory factor-1, AIF-1 is a highly conserved EF-handed, putative calcium binding peptide, associated with microglia activation in the brain. Here, we have analyzed the expression of AIF-1 following spinal cord injury at the lesion site and at remote brain regions. Following spinal cord injury, AIF-1+ cells accumulated in parenchymal pan-necrotic areas and perivascular Virchow-Robin spaces. Subsequent to culmination at day 3--a situation characterized by infiltrating blood borne macrophages and microglia activation--AIF-1+ cell numbers decreased until day 7. In remote areas of Wallerian degeneration and delayed neuronal death, a more discrete and delayed activation pattern of AIF-1+ microglia/macrophages reaching maximum levels at day 14 was observed. There was a considerable match between AIF-1+ cells and PCNA (proliferating cell nuclear antigen) or Ki-67+ labeled cells. AIF-1 expression preceded the expression of ED1, thus indicating a pre-phagocytic role. It appears that AIF-1+ microglia/macrophages are among the earliest cells to respond to spinal cord injury. Our results suggest a role of AIF-1 in the initiation of the early microglial response leading to activation and proliferation essential for the acute response to CNS injury. AIF-1 might modulate microgliosis influencing the efficacy of tissue debris removal, myelin degradation, recruitment of oligodendrocytes and re-organisation of the CNS architecture.

N-nitrososdimethylamine is activated in microsomes from hepatocytes to reactive metabolites which damage DNA of non-parenchymal cells in rat liver

The liver carcinogen N-nitrosodimethylamine (NDMA) has to be metabolically activated by specific cytochromes before it can react with cellular macromolecules (e.g. proteins or DNA). Although hepatocytes are believed to be responsible for this activation, the liver tumours originate mainly from non-parenchymal cells (NPC). To investigate their activation capacity we determined NDMA-demethylase activity in isolated microsomes from both liver cell types. The results demonstrate that only hepatocytes have activation capacity. Additional experiments were performed with hepatocytes and NPC using the single cell microgel electrophoresis assay (MGE). DNA damage appears in both cell types following in vivo exposure. Tested in vitro, however, the carcinogens induce DNA damages only in hepatocytes (the cells which activate these compounds). N-nitroso-hydroxymethyl-methylamine could be the responsible metabolite as it is stable enough to be transported from hepatocytes to NPC in an intact liver.

A short course of induction chemotherapy followed by two cycles of high-dose chemotherapy with stem cell rescue for chemotherapy naive metastatic breast cancer: sequential phase I/II studies

Two cycles of high-dose chemotherapy with stem cell support (HDC) may increase the total dose delivered and dose intensity. A brief induction phase and different non-cross-resistant agents for each HDC cycle were used to avoid drug resistance. Twenty-six women with metastatic BC had induction and stem cell mobilization with two cycles of doxorubicin/G-CSF given every 14 days. Patients with stable disease or better after induction received HD CTCb followed by HD melphalan and dose-escalated paclitaxel. At 475 mg/m(2) of paclitaxel by 24-h infusion, dose-limiting transient peripheral sensory neuropathy was encountered. No toxic deaths occurred. Complete and near complete response after completion of therapy was achieved in 22 (85%) of 26 patients. The median EFS was 38 months. The median OS has not yet been reached. At a median follow-up of 33 (25-43) months, actuarial EFS and OS were 54% (95% confidence interval (CI), 39-69%) and 69% (95% CI, 56-79%), respectively. This double transplant approach lasts only 14 weeks and is feasible, safe, and tolerable. Whilst selection biases may in part contribute to favorable EFS and OS, a randomized comparison of standard therapy vs double transplant in both metastatic and locally advanced breast cancer is warranted.

Headless flies generated by developmental pathway interference

Ectopic expression of transcription factors in eye-antennal discs of Drosophila strongly interferes with their developmental program. Early ectopic expression in embryonic discs interferes with the developmental pathway primed by Eyeless and generates headless flies, which suggests that Eyeless is necessary for initiating cell proliferation and development of both the eye and antennal disc. Interference occurs through a block in the cell cycle that for some ectopic transcription factors is overcome by D-CycE or D-Myc. Late ectopic expression in cone cell precursors interferes with their differentiation. We propose that this developmental pathway interference is a general surveillance mechanism that eliminates most aberrations in the genetic program during development and evolution, and thus seriously restricts the pathways that evolution may take.

Evidence for activation of carcinogenic o-anisidine by prostaglandin H synthase: 32P-postlabelling analysis of DNA adduct formation

2-Methoxyaniline (o-anisidine) is a urinary bladder carcinogen in both mice and rats. Since the urinary bladder contains substantial peroxidase activity, we examined the ability of prostaglandin H synthase (PHS), a prominent enzyme in the urinary bladder, to activate this carcinogen to metabolites binding to macromolecules. Using [14C]-labeled o-anisidine, we observed substantial PHS-dependent binding of o-anisidine to protein, DNA and polydeoxyribonucleotides [poly(dX)]. This binding is inhibited by radical scavengers glutathione, ascorbate and NADH. The nuclease P1 and 1-butanol extraction enrichment procedure of the 32P-postlabeling analysis of DNA modified by activated o-anisidine provide evidence that covalent binding to DNA is the principal type of DNA modification. Deoxyguanosine is determined to be the major target for binding of o-anisidine in DNA. The possibility that o-anisidine is carcinogenic to the rodent urinary bladder via its activation by bladder PHS is suggested. The results presented here are the first report demonstrating a PHS-mediated activation of o-anisidine to reactive species forming covalent DNA adducts.

Mode of action of methotrexate-albumin in a human T-cell leukemia line and activity against an MTX-resistant clone

Limitations of low mol. wt anticancer drugs are short tumor exposure times and toxicity to normal tissue. Methotrexate (MTX) covalently linked to human serum albumin (HSA) as a macromolecular carrier caused tumor regressions concomitant with a favorable toxicity profile in a clinical phase I trial (Hartung et aL, Clin. Cancer Res., 1999, 5, 753). We examined the uptake, intracellular degradation, metabolism and thymidylate synthase (TS) inhibition of MTX-HSA in the T-cell leukemia line CCRF-CEM and the MTX transport resistant clone CCRF-CEM/MTX. The number of MTX molecules per albumin molecule was determined by electrospray mass spectrometry. A loading ratio (LR) of approximately 1.4 mol MTX/albumin revealed intact complexes with one and two MTX molecules/albumin. In the complex with an LR of 5.7, albumin with up to 16 MTX molecules was seen. MTX-HSA was taken up by CCRF-CEM cells via endocytosis and cleaved by lysosomal enzymes. Liberated MTX was a poor substrate of folylpolyglutamate synthetase and was exported into the medium. TS was inhibited and cell survival was impaired by MTX-HSA in a time- and concentration-dependent manner. CCRF-CEM/MTX cells exhibited a growth inhibition of 30-40% after MTX-HSA treatment, but no TS inhibition. The alternative uptake route via endocytosis enables MTX-HSA to overcome transport resistance to MTX.

Human enzymes involved in the metabolic activation of carcinogenic aristolochic acids: evidence for reductive activation by cytochromes P450 1A1 and 1A2

Aristolochic acid (AA), a naturally occurring nephrotoxin and rodent carcinogen, has recently been associated with the development of urothelial cancer in humans. Determining the capability of humans to metabolize AA and understanding, which human enzymes are involved in AA activation is important in the assessment of individual susceptibility. Using the nuclease P1-enhanced version of the (32)P-postlabeling assay, we compared the ability of human, minipig and rat hepatic microsomal samples to activate AA to metabolites forming DNA adducts. Human microsomes generated AA-DNA adduct profiles reproducing those found in renal tissues from humans exposed to AA. Identical patterns of AA-DNA adducts were also observed when AA was activated by minipig and rat microsomes. Therefore, microsomes of both animals are suitable in vitro systems mimicking the enzymatic activation of AA in humans. To define the role of specific P450 enzymes and NADPH:P450 reductase in the activation of AA by human microsomes we investigated the modulation of AA-DNA adduct formation by specific inducers or selective inhibitors of P450s and cofactors or inhibitors of NADPH:P450 reductase. The inducer of P450 1A1/2, beta-naphthoflavone, significantly stimulated the levels of AA-DNA adducts formed by rat microsomes, but inducers of P450 2B1/2 and 2E1 had no such effect. Furthermore, only inhibitors of the P450 1A subfamily (alpha-naphthoflavone, furafylline) significantly decreased the amount of adducts formed by microsomes from humans, minipigs and rats. alpha-Lipoic acid, an inhibitor of NADPH:P450 reductase, inhibited adduct formation too, but to a lower extent. On the basis of these results, we attribute most of the microsomal activation of AA to P450 1A1 and 1A2, although a role of NADPH:P450 reductase cannot be ruled out. With purified enzymes (recombinant P450 1A1/2 and NADPH:P450 reductase) and microsomes from baculovirus transfected insect cells expressing recombinant human P450 1A1/2 and NADPH:P450 reductase, the participation of these enzymes in the formation of AA-DNA adducts was confirmed. These results are the first report on the activation of AA by human enzymes and clearly demonstrate the role of P450 1A1, 1A2, and NADPH:P450 reductase in catalyzing the reductive activation of AA.

Cyclophosphamide, doxorubicin, vincristine, prednisone, and etoposide (CHOPE) for advanced-stage Hodgkin's disease: CALGB 8856

Successful treatment of advanced-stage Hodgkin's disease (HD) may critically depend on dose intensity. Because mechlorethamine, Oncovin, procarbazine, and prednisone (MOPP), and Adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD) are not suitable for major dose escalation, we evaluated the activity and toxicity of combined cyclophosphamide, doxorubicin, vincristine, prednisone, and etoposide (CHOPE) in advanced HD, here used at conventional dose intensity, as a preparatory study prior to using this regimen at higher dose intensity. Ninety-two patients were treated with CHOPE (cyclophosphamide, 750 mg/m2, day 1; doxorubicin, 50 mg/m2, day 1; vincristine, 1.4 mg/m2, days 1 and 8; prednisone, 100 mg/day, days 1-5; and etoposide, 80 mg/m2, days 1, 2, and 3) every 21 days. All had advanced HD with no prior chemotherapy with 46% stage IV, 63% with B symptoms, and 57% with bulky disease (> 5 cm). Radiation and growth factor support were not permitted. Full-dose vincristine (not capped at maximum 2 mg/dose) was used in the first 33 patients. An initial cohort of 41 patients was treated with four cycles of CHOPE to evaluate safety and efficacy followed by four cycles of ABVD. A second cohort of 51 patients was treated with 6-8 cycles of CHOPE alone. Toxicity was generally acceptable and primarily hematologic, with neutrophils < 500 in 63% of cohort I and 90% of cohort II, and platelets < 25,000 in 7% of cohort I and 8% of cohort II. The long-term neurotoxicity of full-dose, high-intensity vincristine was acceptable and largely reversible. In cohort I, 92% of patients achieved a complete response (CR) or partial response (PR) with four cycles of CHOPE and 85% were in CR after four additional cycles of ABVD. In cohort II, 77% achieved a CR with 6-8 cycles of CHOPE alone. FFS was 76% in cohort I and 59% in cohort II, with a median follow-up of 8.2 and 5.7 years, respectively. CHOPE, at conventional dose intensity as used here, is an effective first-line regimen for the treatment of advanced-stage HD and may warrant evaluation using higher doses of cyclophosphamide and etoposide with granulocyte colony stimulating factor (G-CSF) support.

Evidence for reductive activation of carcinogenic aristolochic acids by prostaglandin H synthase -- (32)P-postlabeling analysis of DNA adduct formation

Aristolochic acid (AA), a naturally occurring nephrotoxin and carcinogen, is implicated in an unique type of renal fibrosis, designated Chinese herbs nephropathy (CHN), which can develop to urothelial cancer. Understanding which enzymes are involved in AA activation and/or detoxication is important in the assessment of an individual susceptibility to this natural carcinogen. We examined the ability of prostaglandin H synthase (PHS) to activate AA to metabolites forming DNA adducts with the nuclease P1 and 1-butanol extraction enrichment procedure of the (32)P-postlabeling assay. PHS is a prominent enzyme in the kidney and urothelial tissues. Ram seminal vesicle (RSV) microsomes, which contain high levels of PHS, generated AA-DNA adduct patterns reproducing those found in renal tissues in CHN patients. 7-(Deoxyadenosin-N(6)-yl)aristolactam I, 7-(deoxyguanosin-N(2)-yl)aristolactam I and 7-(deoxyadenosin-N(6)-yl)aristolactam II were identified as AA-DNA adducts formed by AAI. Two adducts, 7-(deoxyguanosin-N(2)-yl)aristolactam II and 7-(deoxyadenosin-N(6)-yl)aristolactam II, were generated from AAII. According to the structures of the DNA adducts identified, nitroreduction is the crucial pathway in the metabolic activation of AA. The identity of PHS as the activating enzyme in RSV microsomes was proven with different cofactors and inhibitors. Only indomethacin, a selective inhibitor of PHS, significantly decreased the amount of adducts formed by RSV microsomes. The inhibitor of NADPH:CYP reductase (alpha-lipoic acid) and some selective inhibitors of cytochromes P450 (CYP) were not effective. Likewise, only cofactors of PHS, arachidonic acid and hydrogen peroxide, supported the DNA adduct formation of AAI and AAII, while NADPH and NADH were ineffective. These results demonstrate a key role of PHS in the activation pathway of AAI and AAII in the RSV microsomal system and were corroborated with the purified enzyme, namely ovine PHS-1. The results presented here are the first report demonstrating a reductive activation of nitroaromatic compounds by PHS-1.

Laparoscopic appendectomy in Switzerland: a prospective audit of 2, 179 cases

BACKGROUND/AIMS

Since its introduction in 1983, laparoscopic appendectomy (LA) has not replaced the conventional open procedure. The patient benefit seems limited to a decreased wound infection rate, and the overall morbidity and mortality rates remain equal to those of open appendectomy.

METHODS

The data (collected by the Swiss Association of Laparoscopic and Thoracoscopic Surgery) from 2, 179 patients undergoing LA at 84 surgical institutions in Switzerland between January 1995 and December 1997 were retrospectively analyzed.

RESULTS

More than 90% of all patients had no intra- or postoperative complications. However, perforated appendicitis was associated with more complications, in particular a threefold increased wound infection rate (9.2 vs 3.5%). Furthermore, the conversion and reoperation rates of perforated appendicitis were significantly increased compared to 'simple' acute appendicitis (25. 5 and 10.4% vs 4.8 and 2.1%, respectively). LA performed with a stapling device is superior to LA performed with loops, although the difference is not significant.

CONCLUSION

Therefore, LA is a safe and effective procedure. The postoperative morbidity and mortality rates are comparable to those of open appendectomy, which is still the most commonly used procedure in Switzerland. The question of whether perforated appendicitis is better treated laparoscopically or by the open procedure cannot be answered with our data.

A short course of induction chemotherapy followed by two cycles of high-dose chemotherapy with stem cell rescue for chemotherapy naive metastatic breast cancer

A single cycle of high-dose chemotherapy with stem cell support (HDC) in women with responsive metastatic breast cancer (BC) consistently achieves over 50% complete and near complete response (CR/nCR). This significant cytoreduction results in a median event-free survival (EFS) of 8 months, and approximately 20% 3-year and 16% 5-year EFS in selected patients. To improve long-term outcomes, new strategies to treat minimal residual tumor burden are needed. Increased total dose delivered can be achieved with two cycles of HDC. Critical design issues include shortening induction chemotherapy to avoid development of drug resistance and the use of different agents for each HDC cycle. We have determined the maximum tolerated dose (MTD) for paclitaxel combined with high-dose melphalan in the context of a double transplant and explored the impact of a short induction phase. Between June 1994 and August 1996, we enrolled 32 women with metastatic BC on to this phase I double transplant trial. Induction consisted of doxorubicin 30 mg/m2/day days 1-3 given for 2 cycles every 14 days with G-CSF 5 microg/kg s.c. days 4-12. Stem cell collection was performed by leukapheresis in each cycle when the WBC recovered to above 1000/microl. Patients with stable disease or better response to induction were eligible to proceed with HDC. HDC regimen I (TxM) included paclitaxel with dose escalation from 0 to 300 mg/m2 given on day 1 and melphalan 180 mg/m2 in two divided doses given on day 3. HDC regimen II was CTCb (cyclophosphamide 6 g/m2, thiotepa 500 mg/m2, and carboplatin 800 mg/m2 total doses) delivered by 96-h continuous infusion. At the first dose level of 150 mg/m2 paclitaxel by 3 h infusion, four of five patients developed dose-limiting toxicity consisting of diffuse skin erythema and capillary leak syndrome. Only two of these five completed the second transplant. Subsequently, paclitaxel was delivered by 24-h continuous infusion together with 96 h of dexamethasone and histamine receptor blockade. This particular toxicity was not observed again. No toxic deaths occurred and dose-limiting toxicity was not encountered. Three patients were removed from study prior to transplant: one for insurance refusal and two for disease progression. All others completed both cycles of transplant. Complete and near complete response (CR/nCR) after completion of therapy was achieved in 23 (72%) of 32 patients. The median EFS is 26 months. The median overall survival has not yet been reached. At a median follow-up of 58 months, EFS and overall survival are 41% and 53%, respectively. This double transplant approach is feasible, safe, and tolerable. Treatment duration is only 14 weeks and eliminates lengthy induction chemotherapy. The observed event-free and overall survivals are promising and are better than expected following a single transplant. Whilst selection biases may in part contribute to this effect, a much larger phase II double transplant trial is warranted in preparation for a potential randomized comparison of standard therapy vs single vs double transplant.

Comparative analysis of methotrexate polyglutamates in lymphoblast preparations from bone marrow and blood, and the contribution of residual red blood cells

PURPOSE

Blasts isolated from bone marrow aspirates or blood samples of patients with acute lymphoblastic leukemia (ALL) or acute myelogenous leukemia (AML) were compared for uptake of methotrexate (MTX) and formation of MTX polyglutamates (MTX-Glu(n)). Red blood cells (RBC) from the same patient samples were also analyzed.

METHODS

Blasts were isolated by standard density centrifugation. RBC were prepared from the pellet of the same centrifugation. MTX-Glu(n) were analyzed by means of HPLC and radiochemical quantification.

RESULTS

In lymphoblasts isolated from blood, the distribution patterns of MTX-Glu(n) were the same as in bone marrow lymphoblasts, but the total amount of MTX-Glu(n) accumulated in blood lymphoblasts was reduced by 41% 51% when compared to the same number of bone marrow lymphoblasts of the same patient. RBC accumulated MTX but no formation of MTX-Glu(n) occurred.

CONCLUSIONS

The determination of MTX and MTX-Glu(n) in lymphoblasts isolated from blood samples of patients with common ALL provides qualitative information on the capacity of the blasts to form MTX-Glu(n) since distribution patterns of MTX and MTX-Glu(n) parallel that of bone marrow lymphoblasts. The amounts of MTX-Glu(n) accumulated, however, were much lower in blood lymphoblasts. Blood lymphoblasts are therefore not useful for a quantitative analysis of MTX-Glu(n). The contribution of RBC to MTX and MTX-Glu(n) in vitro is only marginal and residual RBC in lymphoblast preparations from bone marrow can therefore be ignored.

Reactions of oligodendrocytes to spinal cord injury: cell survival and myelin repair

The aim of this study was to elucidate whether oligodendrocytes die in fiber tracts that are spared by a spinal cord injury but are in close vicinity of inflammatory cells. Adult rat spinal cords were studied histologically 1 day to 2 weeks after a contusion lesion that left the ventral white matter largely intact. Massive oligodendrocyte death occurred in the lesion center, along with the death of neurons, microglia, and astrocytes. Oligodendrocytes, specifically positive for proteolipid protein (PLP) mRNA, were counted in the ventral white matter where axons at the rostral and caudal edges of the lesion were histologically intact. Although these regions contained many macrophages and neutrophils hypothesized to contribute to secondary tissue loss, there was no significant loss of oligodendrocytes. In the ventral funiculus, 3 and 6 mm rostral and caudal to the lesion, oligodendrocyte numbers were also unchanged, in spite of the presence of many activated microglial cells. From day 7 on, oligodendrocytes in close vicinity to the lesion increased their expression of PLP mRNA. We conclude that, at least within the first 2 weeks after a spinal cord contusion lesion, there is no major devastating influence of inflammatory cells or their mediators on oligodendrocytes. When death occurs, it may be due to mechanical trauma, ischemia, or excitotoxicity within the lesion or it may occur as a result of axonal degeneration.

Oxidation of xenobiotics by plant microsomes, a reconstituted cytochrome P450 system and peroxidase: a comparative study

The microsomal fraction from tulip bulbs (Tulipa fosteriana, L.) contains cytochrome P450 (CYP3, EC 1.14.14.1) and peroxidase (EC 1.11.1.7.) enzymes catalyzing the NADPH--and hydrogen peroxide--dependent oxidation of the xenobiotic substrates, N-nitrosodimethylamine (NDMA), N-nitrosomethylaniline (NMA), aminopyrine and 1-phenylazo 2-hydroxynaphthalene (Sudan I), respectively. Oxidation of these model xenobiotics has also been assessed in a reconstituted electron-transport chain with a partially purified CYP fraction, phospholipid and isolated tulip NADPH:CYP reductase (EC 1.6.2.4.). Peroxidase isolated from tulip bulbs (isoenzyme C) oxidizes these xenobiotics, too. Values of kinetic parameters (Km, Vmax), requirements for cofactors (NADPH, hydrogen peroxide), the effect of inhibitors and identification of products formed from the xenobiotics by the microsomal fraction, partially purified CYP and peroxidase C were determined. These data were used to estimate the participation of the CYP preparation and peroxidase C in oxidation of two out of the four studied xenobiotics (NMA, Sudan I) in tulip microsomes. Using such detailed study, we found that the CYP-dependent enzyme system is responsible for the oxidation of these xenobiotics in the microsomal fraction of tulip bulbs. The results demonstrate the progress in resolving the role of plant CYP and peroxidase enzymes in oxidation of xenobiotics.

Double high-dose chemotherapy with stem cell rescue (HD-SCR) in patients with breast cancer - effect of sequence

INTRODUCTION

A preliminary analysis of our double high-dose chemotherapy with stem cell rescue (HD-SCR) clinical trial for breast cancer, and preclinical cross-resistant studies, suggested that melphalan (M) adversely affected response to subsequent chemotherapy, i.e., that the sequence of alkylating agents (AAs) might affect response. We, therefore, constructed and examined preclinical models to determine whether prior exposure to M, in fact, adversely affected response to other therapy.

PURPOSE

The purpose of the study was to determine whether the sequence of AAs, specifically the prior use of M, adversely affected response to subsequent treatment.

METHODS

The methods employed were the following: (1) Human tumor cell lines rendered resistant by in vitro sequential exposure to five different AAs were developed. The resistant cell lines were examined for cross-resistance to alkylating and other agents. (2) In vivo studies in the p388 mouse leukemia for resistance and cross-resistance among the AAs. (3) In vivo studies of the effect of sequence of AAs on response in mice bearing EMT6 breast cancer. (4) The double transplant model was developed in the mouse and the sequence of high-dose AAs was studied. (5) Biochemical and reverse transcriptase-polymerase chain reaction (RT-PCR) studies of the various resistant tumor cell lines.

RESULTS

(1) The in vitro human tumor cells resistant to M were cross-resistant in 57% of tests to other AAs. In contrast, resistance for other AAs crossed to other agents in only 10 to 20% of tests. (2) The in vivo studies of p388 indicated that resistance to M commonly crossed to other AAs and many non-AAs. (3) The results for the mouse breast cancer (EMT6) studies of the sequence of AAs again indicated that M employed first markedly reduced responsiveness to subsequent treatment, particularly with AAs. (4) The double transplant model: again, M first markedly reduced response to other agents. (5) The in vitro resistant human tumor cell lines, particularly the breast cancer cell line MCF7, were found to contain high concentrations of glutathione S1 transferase gamma, which is consistent with that mechanism being responsible for resistance.

CONCLUSION

The sequence of alkylating agent treatment may substantially influence response. Melphalan, particularly, produces resistance that commonly crosses to the other AAs. Mechanistic studies indicate significant changes in glutathione S1 transferase, a known mechanism for broadly based resistance to AAs.

Mood state and brain electric activity in ecstasy users

Resting EEG during open and closed eyes and subsequent mood ratings were obtained from 15 Ecstasy users and 14 Ecstasy-naive controls. Absolute spectral power on the scalp, and the three-dimensional, intracerebral distribution of neuroelectric activity using low resolution brain electromagnetic tomography (LORETA) were computed. LORETA revealed global increases of theta, alpha 1 and beta 2/3 power during eyes open in Ecstasy users, and spectral analyses revealed a right-posterior increase of alpha 2 power (confirmed by LORETA) and increased beta band activity during open eyes. Ecstasy users had higher levels of state depressiveness, emotional excitability and a trend-level increase in state anxiety. The observed differences may be related to regular exposure to Ecstasy or other illicit drugs, or may be pre-existing.

double-time is identical to discs overgrown, which is required for cell survival, proliferation and growth arrest in Drosophila imaginal discs

We have isolated the discs overgrown gene of Drosophila and shown that it encodes a homolog of the Casein kinase I(delta)/(epsilon) subfamily and is identical to the double-time gene. However, in contrast to the weak double-time alleles, which appear to affect only the circadian rhythm, discs overgrown alleles, including bona fide null alleles, show strong effects on cell survival and growth control in imaginal discs. Analysis of their phenotypes and molecular lesions suggests that the Discs overgrown protein is a crucial component in the mechanism that links cell survival during proliferation to growth arrest in imaginal discs. This work provides the first analysis in a multicellular organism of Casein kinase I(delta)/(epsilon) functions necessary for survival. Since the amino acid sequences and three-dimensional structures of Casein kinase I(delta)/(epsilon) enzymes are highly conserved, the results suggest that these proteins may also function in controlling cell growth and survival in other organisms.

Prostaglandin H synthase-medicated oxidation and binding to DNA of a detoxication metabolite of carcinogenic Sudan I, 1-(phenylazo)-2,6-dihydroxynaphthalene

The metabolite of the carcinogenic azo dye Sudan I, 1-(phenylazo)-2,6-dihydroxynaphthalene (6-OH-Sudan I), which is considered to be the detoxification product of this dye is metabolized by prostaglandin H synthase (PHS) in the presence of arachidonic acid or H2O2 in vitro. The apparent Michaelis constant value for 6-OH-Sudan I as a substrate is 98.9 microM. 1-(Phenylazo)-2,6-naphthoquinone is a principal product of the 6-OH-Sudan I oxidation. This oxidation is inhibited by radical scavengers nitrosobenzene, ascorbate, glutathione and NADH. This indicates that PHS metabolizes 6-OH-Sudan I through a one-electron oxidation mechanism, giving rise to free radicals. During the PHS-mediated reaction, 6-OH-Sudan I is activated to metabolites binding to protein and DNA. The 32P-postlabeling analysis of DNA modified by activated 6-OH-Sudan I provides evidence that covalent binding to DNA is the principal type of DNA modification. The PHS-mediated binding of 6-OH-Sudan I to DNA presumably proceeds through formation of 1-(phenylazo)-2,6-naphthoquinone. The results suggest strongly that the C-hydroxylated derivative of Sudan I (6-OH-Sudan I) should be evaluated as a proximate carcinogenic metabolite, which may participate in the initiation of Sudan I-carcinogenesis in the urinary bladder.

The interval between courses of high-dose chemotherapy with stem cell rescue: therapeutic hypotheses

The interval between courses of chemotherapy have classically been kept to a minimum in order to maximize dose intensity. Certain clinical observations suggest that longer intervals, particularly in the high-dose setting, may be more effective. This is based in part on the evidence that resistance is reversible over time and that the interval should be sufficient to allow for such a reversal. Clinical evidence for such reversibility include the following. In metastatic breast cancer, double or double high-dose stem cell rescue (HD-SCR) studies involving a minimal interval, have not, at least as yet, been shown to be superior to single HD-SCR. In Hodgkin's disease, response after relapse correlates directly with duration of time to relapse. In a comparative study of metastatic breast cancer, early HD-SCR preceded by daunorubicin induction was inferior to delayed HD-SCR. The latter was not preceded by induction chemotherapy. In a comparative study of childhood ALL, patients randomized to delayed (4 month interval) intensification had a significantly superior survival as compared to patients randomized to immediate (1 month interval) intensification. Taken together, these clinical observations indicate that resistance is reversible and that optimization of the interval must take this into account. Cytokinetic modeling of those clinical studies also found that delayed HD-SCR could result in a superior effect. Cytokinetic models of minimal residual tumor which were also examined included the Skipper exponential model, the Norton-Simon model which emphasizes the Gompertzian effect, the clonal evolution model, and the Retsky-Demisheli model which derives from a bimodal relapse pattern above. Biological and clinical data have resulted in a clinical protocol in the CALGB wherein patients with metastatic breast cancer are randomly allocated to (1) a single HD-SCR arm; (2) a double HD-SCR with a 5-week interval; and (3) a double HD-SCR arm with a 16 week interval.

Mechanisms of resistance to methotrexate in childhood acute lymphoblastic leukemia: circumvention of thymidylate synthase inhibition

PURPOSE

In about 25% of patients suffering from acute lymphoblastic leukemia (ALL) treatment failures occur that are most likely due to development of resistance to methotrexate (MTX). Blasts from patients with ALL were evaluated for MTX uptake, formation of long-chain MTX polyglutamates (MTX-Glu5+6), cytotoxicity and thymidylate synthase inhibition by MTX and compared to blasts from patients with acute myelogenous leukemia (AML).

METHODS

Radioactively labeled MTX-Glu(n) were analyzed by means of HPLC. Thymidylate synthase activity was measured by a tritium-release assay. Cytotoxicity was determined by trypan blue exclusion.

RESULTS

In most ALL blasts (n = 9) large amounts of MTX-Glu5+6 (1.06-7.03 pmol/10(7) cells) and high cytotoxicity (43.5% 92.7%) were found, while in others small amounts of MTX-Glu5+6 (0.0-0.39 pmol/10(7) cells) caused only weak cytotoxicity (6.0% 27.9%) (n = 5, 2 relapsed patients). Resistance to MTX in blasts from AML patients (n = 5) was also caused by reduced synthesis of MTX-Glu5s+6 (0.0-0.42 pmol/10(7) cells). In contrast, some ALL blasts (n = 7, 4 relapsed patients) were able to survive MTX treatment despite large amounts of MTX-Glu5+6 (1.5-5.05 pmol/10(7) cells) and extensive thymidylate synthase inhibition.

CONCLUSIONS

Since the majority of ALL patients were examined at first diagnosis, an inherent mechanism of resistance seems most likely. We propose a mechanism based on the switch of thymidylate synthesis to the salvage pathway.

Aristolactam I a metabolite of aristolochic acid I upon activation forms an adduct found in DNA of patients with Chinese herbs nephropathy

Aristolochic acid (AA) a naturally occuring nephrotoxin and carcinogen is implicated in a unique type of renal fibrosis, designated Chinese herbs nephropathy (CHN). We identified AA-specific DNA adducts in kidneys and in a ureter obtained from CHN patients after renal transplantation. AA is a plant extract of aristolochia species containing AA I as the major component. Aristolactams are the principal detoxication metabolites of AA, which were detected in urine and faeces from animals and humans. They are activated by cytochrome P450 (P450) and peroxidase to form DNA adducts. Using the 32P-postlabelling assay we investigated the formation of DNA adducts by aristolactam I in these two activation systems. A combination of two independent chromatographic systems (ion-exchange chromatography TLC and reversed-phase HPLC) with reference compounds was used for the identification of adducts. Aristolactam I activated by peroxidase led to the formation of several adducts. Two major adducts were identical to adducts previously observed in vivo. 7-(deoxyguanosin-N2-yl)aristolactam I (dG-AAI) and 7-(deoxyadenosin-N6-yl)aristolactam I (dA-AAI) were formed in DNA during the peroxidase-mediated one-electron oxidation of aristolactam I. Aristolactam I activated by P450 led to one major adduct and four minor ones. Beside the principal AA-DNA adducts identified recently in the ureter of one patient with CHN, an additional minor adduct was detected, which was found to have indistinguishable chromatographic properties on TLC and HPLC from the major adduct formed from aristolactam I by P450 activation. Thus, this minor AA-adduct might be evolved from the AAI detoxication metabolite (aristolactam I) by P450 activation. These results indicate a potential carcinogenic effect of aristolactam I in humans.

Safety and efficacy of using a single agent or a phase II agent before instituting standard combination chemotherapy in previously untreated metastatic breast cancer patients: report of a randomized study--Cancer and Leukemia Group B 8642

PURPOSE

We undertook a prospective, randomized phase III trial to evaluate the safety and efficacy of using a phase II agent before initiating therapy with standard combination chemotherapy in metastatic breast cancer patients.

PATIENTS AND METHODS

A total of 365 women with measurable metastatic breast cancer, previously untreated with chemotherapy for their metastatic disease, were randomized to receive either immediate chemotherapy with cyclophosphamide, doxorubicin, and fluorouracil (CAF) or up to four cycles of one of five sequential cohorts of single-agent drugs: trimetrexate, melphalan, amonafide, carboplatin, or elsamitrucin, followed by CAF.

RESULTS

The toxicity of each single agent followed by CAF was comparable to that of CAF alone. The cumulative response rates for the single agent followed by CAF were not statistically different from those of CAF alone (44% v 52%; P = .24). However, in the multivariate analysis, patients with visceral disease had a trend toward lower response rates on the phase II agent plus CAF arm (P = .078). Although survival and response duration also were not statistically significantly different between the two study arms (P = .074 and P = .069, respectively), there was a suggestion of benefit for the CAF-only arm.

CONCLUSION

The brief use of a phase II agent, regardless of its efficacy, followed by CAF resulted in response rates, toxicities, durations of response, and survival statistically equivalent to those seen with the use of CAF alone. These findings support the use of a new paradigm for the evaluation of phase II agents in the treatment of patients with metastatic breast cancer.

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.