The Polycomb-group gene, extra sex combs, encodes a nuclear member of the WD-40 repeat family

We have delimited the extra sex combs (esc) gene to < 4 kb that include a single transcript and are able to rescue both the maternal and zygotic esc phenotypes. Several mutations have been identified within the esc transcript. In agreement with earlier genetic studies, esc is expressed maternally and its product is most abundant during the early embryonic stages. It encodes a protein of the WD-40 repeat family, which localizes predominantly to the nucleus. During germ band extension, it is expressed in a stereotypic pattern of neuroblasts. We propose a model in which Esc is recruited by gap proteins both to act as a corepressor that competes with the TAFII80 coactivator to block transcription and also to mediate the transition to permanent repression by Polycomb-group proteins.

Prognostic factors for prolonged progression-free survival with high-dose chemotherapy with autologous stem-cell support for advanced breast cancer

PURPOSE

With a median observation time of 50 months from transplant, 13 (22%) of 62 women with metastatic breast cancer treated with high-dose chemotherapy at the Dana-Farber Cancer Institute (DFCI)/Beth Israel Hospital (BIH) remain progression-free. This study determined factors prognostic for prolonged progression-free survival (PFS).

METHODS

From June 1988 to January 1992, women who responded to standard chemotherapy received high-dose cyclophosphamide, thiotepa, and carboplatin with autotransplantation. Data encompassing initial breast cancer diagnosis, metastatic presentation, and response to induction treatment were examined for correlations with improved PFS.

RESULTS

The 5-year PFS rate for the entire group is estimated to be 21% (95% confidence interval [CI], 10% to 32%). For those patients who attained a complete response (CR) to induction therapy, the 5-year PFS rate is estimated to be 31% (95% CI, 0% to 63%). In univariate analyses, a single metastatic site, CR to induction therapy, prolonged interval from primary diagnosis to first metastases, estrogen receptor (ER)-negative tumors, and older age (> or = 40 years) were associated with prolonged PFS. In multivariate analyses, single metastatic site (P = .002) and attainment of a CR to induction chemotherapy (P = .04) were the most significant predictors for PFS, with a strong trend observed for an interval from primary diagnosis to onset of metastatic disease of 24+ months (P = .066).

CONCLUSION

We and others have shown that 10% to 25% of women with metastatic breast cancer are progression-free after high-dose chemotherapy with autotransplantation. Those with chemosensitive disease, minimal tumor bulk, and a prolonged disease-free interval appear to benefit most. Emphasis should continue to focus on the development of more effective cytotoxic regimens and biologic approaches to increase the percentage of patients who may benefit from this approach.

[Early results of the initial 100 laparoscopic hernia operations under peridural anesthesia]

From November 1992 to March 1994 we performed 100 transabdominal laparoscopic herniographies in 84 patients. The mean age was 54.6 years. 83% of all hernias were primary, 17% recurrent and 16% bilateral. All hernias were classified according to Nyhus and individually repaired. Except in type 2 hernias, a large polypropylene mesh was inserted (15 x 12 cm) and the peritoneum closed with a running suture. During a mean follow-up time of 14 months no recurrent hernias, infections or bowel adhesions were observed. The mean postoperative hospital stay was 4.1 days and the mean time off work 16.4 days. Intraoperative complications were found in 11.9%, early postoperative complications in 25% and late postoperative complications in 3.6%.

Benzenediazonium ion derived from Sudan I forms an 8-(phenylazo)guanine adduct in DNA

1-(Phenylazo)-2-hydroxynaphthalene (Sudan I, Solvent Yellow 14) is a liver and urinary bladder carcinogen in mammals. Sudan I forms benzenediazonium ion during cytochrome P-450 catalyzed metabolism. Calf thymus DNA was reacted with Sudan I activated by microsomal enzymes or with benzenediazonium ion in vitro, and the adducts formed were analyzed by the 32P-postlabeling technique. Both enrichment procedures (1-butanol extraction and nuclease P1 digestion) of this technique were employed for detection and quantitation of the DNA adducts formed. Cochromatographic analyses of adduct spots obtained by reaction with DNA or homopolydeoxyribonucleotides showed that the major Sudan I-DNA adduct was formed with deoxyguanosine. This adduct was also found in DNA directly reacted with benzenediazonium ion. The major Sudan I-DNA adduct was characterized by UV/vis absorbance spectroscopy as well as by the chromatographic properties of the adduct on cellulose or poly(ethylenimine)--cellulose TLC and HPLC. The characteristics are identical to those of the adduct synthesized from benzenediazonium ion and guanine, identified by mass, UV/vis, and 1H-NMR spectroscopy as 8-(phenylazo)guanine. The results suggest strongly that benzenediazonium ion derived from Sudan I reacts with DNA in vitro to form the stable 8-(phenylazo)guanine adduct.

Molecular basis of intracistronic complementation in the Passover locus of Drosophila

The only demonstrated mechanism for intracistronic genetic complementation requires physical interaction of protein subunits to create a functional molecule. We demonstrate another and perhaps quite general mechanism utilizing proteins with unique and shared domains. The Drosophila neural mutant Passover (Pas) disrupts specific synaptic connections. Alleles of a lethal complementation group exhibit a complex pattern of complementation with Pas alleles. Whereas all heterozygotes between these lethal alleles and Pas are viable, only some alleles complement the neural defect of Pas. Lethal and neural functions are separately encoded by two proteins that have distinct N-terminal domains and a common C-terminal portion. Neural-specific and lethal-specific mutations map to unique exons, while neural-lethal mutations map to shared exons. Combinations of lethal and neural alleles result in production of both proteins and demonstrate intracistronic complementation.

Phase I study of high-dose ifosfamide, carboplatin and etoposide with autologous hematopoietic stem cell support

More effective high-dose combination regimens are needed which have broad cytotoxic activity, steep dose-response relations and non-overlapping non-hematologic toxicities (to allow administration of full doses of each agent). This study was designed to define the dose-limiting toxicities and maximum tolerated doses of ifosfamide, carboplatin and etoposide (ICE) with hematopoietic stem cell support. Ifosfamide and carboplatin were initially fixed at 75% and 80% of the single agent maximum tolerated doses, respectively, and etoposide added to the combination. After the dose-limiting toxicity of etoposide was reached, its dose was fixed and ifosfamide and carboplatin were individually dose escalated as tolerated. All agents were given by 96h continuous infusion (days -7 to -3). Autologous marrow, with or without peripheral blood progenitor cells, was reinfused on day 0. Forty eight adults with advanced malignancies were enrolled in cohorts of three to five patients. At the maximum tolerated doses of ifosfamide 16 g/m2, carboplatin 1.8 g/m2 and etoposide 1.2 g/m2, renal toxicity precluded further dose escalation. Two patients died of organ (renal, CNS) toxicity (4%). Renal toxicity was particularly prominent in patients with prior cisplatin exposure. An early chemotherapy-stopping rule was developed, supported by pharmacologic analysis, which resulted in immediate discontinuation of ifosfamide and carboplatin if the serum creatinine, monitored twice daily during chemotherapy, exceeded 1.5 mg/dl and was > 0.5 mg/dl above baseline. High-dose ICE is well tolerated if serum creatinines are carefully monitored during chemotherapy administration. The early chemotherapy-stopping rule may enhance safety of the regimen but requires validation by addition correlation with pharmacokinetic data for each of the chemotherapeutic agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Noncytotoxic human CD4+ T-cell clones presenting and simultaneously responding to an antigen die of apoptosis

Activated T-cells expressing MHC class II surface antigens are able to present antigen and thus function as peptide-presenting cells (T-APCs). In this study we investigated whether antigen presentation by T-cells induced programmed cell death. As a model we used tetanus p30 peptide (aa 947-967)-specific, noncytotoxic CD4+ T-cell clones (C11 and C31). For experimental purposes these T-cell clones were stimulated (a) with p30 peptide-pulsed and fixed EBV-transformed antigen-presenting cells (B-APCs), (b) with p30-pulsed and fixed activated T-cells as APCs (as T-APCs we used either the T-cell clones themselves or an autologous T-cell clone (CT3) with p30 unrelated specificity), or (c) with soluble p30 peptide. The efficiency of antigen presentation was monitored by measuring proliferation as [3H]thymidine uptake. Apoptosis was measured by quantifying fragmented, cytoplasm DNA with the fluorescent dye 4,6-diamidino-2-phenylindole or by visualizing fragmented DNA by gel electrophoresis. Stimulation with p30-pulsed and fixed B-APCs or T-APCs induced proliferation but no apoptosis of the responding T-cells. However, stimulation of cloned T-cells with soluble peptide induced up-regulation of the FAS surface molecules and apoptosis, which was dependent on the peptide doses. Because cloned T-cells express HLA class II molecules, they can theoretically exert both functions at once: antigen presentation and antigen response when they are stimulated with soluble peptide. Because death by apoptosis is only seen under such circumstances, we suggest that T-cells simultaneously presenting and responding to an antigen die of apoptosis and thus contribute to the down-regulation of the immune response. Such phenomena might occur in HIV infection when activated CD4+ T-cells take up gp120 via their CD4 molecules, present it on their HLA class II surface antigens, and are simultaneously stimulated via their TCR.

Peroxidase-activated carcinogenic azo dye Sudan I (Solvent Yellow 14) binds to guanosine in transfer ribonucleic acid

Peroxidase in the presence of hydrogen peroxide catalyzes in vitro the activation of the carcinogenic azo dye Sudan I (1-phenylazo-2-hydroxynaphthalen) to tRNA-, homopolyribonucleotide- and 5'-monophosphate nucleoside-bound products. tRNA, poly G and guanosine 5'-monophosphate modified by activated Sudan I become colored and have an absorption maximum of approx. 480 nm. Cochromatographic analysis of adducts obtained by a reaction with tRNA and guanosine 5'-monophosphate on a thin layer of cellulose showed that the major Sudan I-tRNA adduct was formed by a reaction of activated Sudan I with guanosine in tRNA. The radical mechanism of the binding of the Sudan I molecule, containing the whole azo aromatic system, to nucleic acids is discussed.

Comparative studies on the pharmacokinetics of hydrophilic prolinedithiocarbamate, sarcosinedithiocarbamate and the less hydrophilic diethyldithiocarbamate

The pharmacokinetics of the antitoxic and anticarcinogenic compounds diethyldithiocarbamate, prolinedithiocarbamate and sarcosinedithiocarbamate were compared in rats. The bioavailability, the distribution in the organism, the oxidation to thiuramdisulfides, the cleavage to CS2 and the excretion in urine and bile were investigated. The results showed different behaviour of the three compounds. The more toxic diethyldithiocarbamate had a short in vivo half-life, was oxidized to tetraethylthiuramdisulfide in blood, and was metabolized to high yields of CS2 in 24 h. In contrast, prolinedithiocarbamate was more stable in vivo, was found predominantly in the urinary tract and was excreted in urine. The differences could not be explained by the presence of the carboxy group in the latter dithiocarbamate, since sarcosinedithiocarbamate, which also contains a carboxy group, behaved like diethyldithiocarbamate.

Analysis of 4-hydroxycyclophosphamide in human blood

Cyclophosphamide is a prodrug activated by cytochrome P450 isozymes in the liver. The product of hepatic activation of cyclophosphamide is 4-hydroxycyclophosphamide. Previously reported methods for determining 4-hydroxycyclophosphamide were either impractical or unreliable for monitoring infusion pharmacokinetics in conjunction with clinical trials. One procedure in which a fluorescent hydroxyquinoline derivative was prepared from 4-hydroxycyclophosphamide and analyzed by HPLC appeared to work at first, but gradually lost its selectivity due to degradation of the column by the strongly acidic mobile phase. An alternative procedure was developed using a weakly acidic eluent and postcolumn treatment with trifluoroacetic acid. This provided for protonation of the hydroxyquinoline, required for sensitive fluorescence detection, but spared the column. The resulting assay was sensitive, selective, reproducible, and accurate. The method was used to monitor 4-hydroxycyclophosphamide pharmacokinetics during and after 4 day infusions of 1.5 g/m2-day of cyclophosphamide given to three patients. It was also used to measure the time-dependent disappearance of acrolein and 4-hydroxycyclophosphamide added to human blood from healthy donors and that of metabolically derived 4-hydroxycyclophosphamide in the blood of a patient treated with cyclophosphamide. Slower decomposition was observed in the latter two cases than in the blood spiked with acrolein. Reliable data were obtained from > 1000 determinations using the same column without significant degradation of its stationary phase.

A preclinical model for sequential high-dose chemotherapy

Dose-intensive chemotherapy regimens have entered clinical trial based on the notion that log-linear tumor-cell killing, especially with antitumor alkylating agents, is maintained at higher drug doses. Several clinical trials employing two intensifications are underway. Using the tumor-cell survival assay, animals bearing the FSaII fibrosarcoma were treated with single doses of various chemotherapeutic agents once or twice with a 3- or 7-day interval between the drugs. Isobologram methodology was used to determine if the sequential treatment regimens resulted in subadditive, additive or greater-than-additive tumor-cell killing. When melphalan was followed 3 or 7 days later by a second dose of melphalan there was evidence of resistance to the second dose of melphalan as indicated by subadditive tumor-cell killing. Melphalan followed 3 days later by cyclophosphamide (300 mg/kg) produced greater-than-additive tumor-cell killing, however, when the interval was 7 days the resulting tumor-cell killing was subadditive. Melphalan followed 3 or 7 days later by thiotepa or carboplatin produced subadditive-to-additive tumor-cell killing. Adriamycin followed 3 days later by melphalan, cyclophosphamide, thiotepa, or carboplatin resulted in subadditive-to-additive tumor-cell killing by the combinations. These results indicate that sequential drug-intensive treatments may not optimize tumor-cell killing in vivo.

Long-term persistence and cytokinetics of human tumor cells in vitro following high-dose alkylating agent exposure

Relapse after high-dose alkylating agent therapy continues to be an important clinical issue. To begin to understand the characteristics of cells surviving alkylating agent exposure human MCF-7 breast carcinoma cells were exposed to a range of concentrations of melphalan or cis-diamminedichloroplatinum(II) and cell survival determined by colony formation over a time course of 4 weeks. When antitumor alkylating agent exposure killed 3-4 logs of cells as determined by surviving fraction after 1 week of colony formation a progressive increase in surviving fraction was evident over the 4-week course of the experiment. Many attached single cells with abnormal morphology were evident in these dishes; however, the colonies which arose over the 4-week observation time were made up of cells morphologically indistinguishable from the control cells. Cell cycle patterns in the cultures exposed to high concentrations of the antitumor alkylating agents indicated a block in G2/M but by 4 weeks post-drug exposure most had returned to a normal exponential growth pattern. When MCF-7 cells or human SW2 small cell lung cancer cells were exposed to a concentration of melphalan or cis-diamminedichloroplatinum(II) that killed 1-2 logs of cells followed by exposure to a concentration range of the same drug for 24 h or 7 days later resistance to the second drug exposure was evident in both cell lines. Using [14C]melphalan the uptake of the drug into MCF-7 cells pre-treated was compared. Decreased drug uptake did not appear to be a factor in resistance to melphalan observed upon re-exposure to the drug. The potential clinical implications of these findings is discussed.

Randomized clinical trials and other approaches in clinical research

Phase III randomized clinical trials have greatly contributed to our understanding of the pathobiology of neoplastic disease and, particularly, to therapeutic progress. However, randomized Phase III studies are no better than or are critically dependent on Phase I and Phase II studies for positive therapeutic leads that are compelling enough to test in the Phase III arena. The variables involved in the series of randomized trials that led to the curative treatment of acute lymphocytic leukemia also resulted in an understanding of the principles of cancer therapy in therapeutic research. These principles, when applied to Hodgkin's disease in non-Hodgkin's lymphoma, testis cancer, childhood solid tumors, and others, resulted in a substantial cure rate for those diseases. However, for the adult epithelial common solid tumors, a second strategy, adjuvant chemotherapy, was required This has resulted in a 20% reduction in mortality in patients with node positive and node negative breast cancer. Tamoxifen has been similarly effective in patients with postmenopausal breast cancer. In colon cancer, adjuvant chemotherapy with fluorouracil plus levamisole has decreased mortality to a comparable degree. New agents, modulations, combination chemotherapy, and biotherapeutics are being addressed to the adjuvant situation which has proven effective in a variety of neoplastic diseases. A third strategy is neoadjuvant chemotherapy. This involves the use of chemotherapy first for patients with solid tumors, designed to down-stage the primary tumor thus making it more susceptible to less radical surgery and to organ- or limb-sparing procedures in osteogenetic sarcoma and in head and neck cancer. For example, neoadjuvant chemotherapy has not resulted in an increased survival as compared with the appropriate control but has allowed for important quality-of-life contributions, such as limb-sparing and radical surgery-sparing procedures. In addition to new agents and combination chemotherapy, dose is a critical variable. This is most evident clinically in the transplantation arena. Comparative studies recently completed, for example, in patients with adjuvant breast cancer and with acute leukemia indicate that dose is a significant factor in tumor control.

Intensive postremission chemotherapy in adults with acute myeloid leukemia. Cancer and Leukemia Group B

BACKGROUND

About 65 percent of previously untreated adults with primary acute myeloid leukemia (AML) enter complete remission when treated with cytarabine and an anthracycline. However, such responses are rarely durable when conventional postremission therapy is administered. Uncontrolled trials have suggested that intensive postremission therapy may prolong these complete remissions.

METHODS

We treated 1088 adults with newly diagnosed AML with three days of daunorubicin and seven days of cytarabine and randomly assigned patients who had a complete remission to receive four courses of cytarabine at one of three doses: 100 mg per square meter of body-surface area per day for five days by continuous infusion, 400 mg per square meter per day for five days by continuous infusion, or 3 g per square meter in a 3-hour infusion every 12 hours (twice daily) on days 1, 3, and 5. All patients then received four courses of monthly maintenance treatment.

RESULTS

Of the 693 patients who had a complete remission, 596 were randomly assigned to receive postremission cytarabine. After a median follow-up of 52 months, the disease-free survival rates in the three treatment groups were significantly different (P = 0.003). Relative to the 100-mg group, the hazard ratios were 0.67 for the 3-g group (95 percent confidence interval, 0.53 to 0.86) and 0.75 for the 400-mg group (95 percent confidence interval, 0.60 to 0.94). The probability of remaining in continuous complete remission after four years for patients 60 years of age or younger was 24 percent in the 100-mg group, 29 percent in the 400-mg group, and 44 percent in the 3-g group (P = 0.002). In contrast, for patients older than 60, the probability of remaining disease-free after four years was 16 percent or less in each of the three postremission cytarabine groups.

CONCLUSIONS

These data support the concept of a dose-response effect for cytarabine in patients with AML who are 60 years of age or younger. The results with the high-dose schedule in this age group are comparable to those reported in similar patients who have undergone allogeneic bone marrow transplantation during a first remission.

High-dose ifosfamide/carboplatin/etoposide with autologous hematopoietic stem cell support: safety and future directions

Agents with broad cytotoxic activity, steep linear log dose-response relationships, relative non-cross-resistance, and nonoverlapping nonhematologic toxicities can be combined to create new high-dose combination regimens. We have previously reported phase I dose-escalation studies of ifosfamide, carboplatin, and the combination of the two. Etoposide has reported synergism with these alkylators and produces mucositis as its dose-limiting toxicity. The current study was designed to define the maximum tolerated doses of high-dose combination ifosfamide/carboplatin/etoposide (ICE), with stem cell support for amelioration of hematologic toxicity. Forty-eight adults with advanced malignancy received ICE chemotherapy by 96-hour continuous infusion. Initially, etoposide was added to fixed-dose ifosfamide and carboplatin, then the maximum tolerated dose of etoposide was fixed while doses of the alkylators were individually escalated. Autologous marrow, with or without peripheral blood progenitor cells, was reinfused 3 days after completing chemotherapy. The maximum tolerated doses of ifosfamide, carboplatin, and etoposide were identified as 16 g/m2, 1.8 g/m2, and 1.2 g/m2, respectively. Mortality was 4%. Patients who had prior cisplatin exposure were at increased risk for renal toxicity. If serum creatinine levels (monitored twice daily) rose sharply during chemotherapy, ifosfamide and carboplatin were immediately stopped. Severe multiorgan toxicity developed in the few patients who experienced early renal toxicity. Early stopping enhanced the safety of this regimen. Interpatient differences in chemotherapy drug metabolism or reduced renal clearance may predispose individuals to severe toxicity by increasing overall drug exposure. It was concluded that the ICE regimen is well tolerated and warrants further exploration as treatment of patients with small cell lung cancer, ovarian and germ cell carcinomas, and lymphomas in phase II trials.

Characterization of DNA adducts formed by aristolochic acids in the target organ (forestomach) of rats by 32P-postlabelling analysis using different chromatographic procedures

We report the analysis of DNA adducts in the target organ (forestomach) of male Sprague-Dawley rats treated orally with two doses (10 mg/kg body wt) per week for 2 weeks of either aristolochic acid I (AAI), aristolochic acid II (AAII) or the plant extract aristolochic acid (AA). DNA adducts were detected and quantitated using the nuclease P1-enhanced version of the 32P-postlabelling assay. For identification of adducts, reference compounds were prepared by reaction of enzymatically activated AAI and AAII with 3'-purine phosphonucleosides and analysed by the n-butanol enrichment procedure. These reference compounds were assigned to the previously characterized DNA adducts of AAI [7-(deoxyguanosin-N2-yl)-aristolactam I = dG-AAI, 7-(deoxyadenosin-N6-yl)-aristolactam I = dA-AAI] and AAII [7-(deoxyadenosin-N6-yl)-aristolactam II = dA-AAII]. Cross referencing of the carcinogen-modified nucleoside bisphosphates obtained from forestomach DNA with the synthetic standard compounds by ion-exchange chromatography and reversed-phase HPLC demonstrated that the major DNA adducts formed by AAI and AA were identical to dG-AAI and dA-AAI. Likewise, forestomach DNA isolated from AAII-treated rats showed two purine-derived adduct spots, the major one being dA-AAII, the minor one being tentatively identified as 7-(deoxyguanosin-N2-yl)-aristolactam II. A minor adduct detected in forestomach DNA of rats treated with AAI was found to be chromatographically indistinguishable from the adduct identified as dA-AAII, indicating a possible demethoxylation reaction of AAI. Quantitation of DNA adducts revealed that in in vitro reactions with 3'-phosphonucleosides the adduct levels were approximately one order higher for both AAI- and AAII-derived adducts than in forestomach DNA modified with AAI or AAII in vivo. In vitro as well as in vivo adduction by AAI was more efficient than adduction by AAII. The pattern of adduct spots obtained from forestomach DNA of rats treated with the plant extract AA reflected the composition of the extract determined by HPLC analysis. Irrespective of the aristolochic acid used to induce DNA adducts, deoxyadenosine is the major target of modification, pointing to the general importance of deoxyadenosine adducts for chemical carcinogenesis of these naturally occurring products. This study shows that the combination of two independent chromatographic systems considerably enhances the fidelity of identification of DNA adducts with the 32P-postlabelling assay.

Caffeine-derived N-nitroso compounds. IV: Kinetics of mononitrosocaffeidine demethylation by rat liver microsomes

The study describes the kinetics of demethylation of mononitrosocaffeidine (MNC), a new asymmetric N-nitrosamine derived from caffeine. The demethylation of its precursor compound caffeidine was also studied. The results presented here suggest (a) that liver microsomes from fasted rats preferentially demethylate the N-methylnitrosamine group in MNC indicating the demethylation by cytochrome P450IIE1, (b) demethylation of MNC shows two apparent Km values, one of 117-166 microM responsible for the demethylation at the N-methylnitrosamino group of MNC, and the other Km of 1.84-2.26 mM for the remaining N-demethylations, (c) in contrast, caffeidine is a low affinity substrate for microsomal demethylation as indicated by a high Km of 14.3-16.3 mM, and (d) the demethylation at amino-N amino-N, and N-1 in both these compounds are mainly catalysed by P450 enzymes induced by Aroclor 1245 in rats.

A method for in situ hybridization in wholemounted lamprey brain: neurofilament expression in larvae and adults

Nonisotopic in situ hybridization (NISH) using both cDNA and cRNA probes is rapidly gaining favor over autoradiographic methods. Typically, either biotinylated or digoxigenin-labeled probes are used to detect mRNAs in sectioned tissue or in cultured cells. With a few exceptions, most applications of NISH in wholemount preparations have been limited to Drosophila embryos. A protocol developed for NISH in whole adult Drosophila CNS was extended to wholemounted larval and adult lamprey brain preparations. Digoxigenin-labeled RNA probes were transcribed from cloned fragments of a lamprey neurofilament (NF180) cDNA. Hybridization with these probes, and comparisons with Nissl-stained wholemounts and wholemounts retrogradely labeled by injections of tracer into the spinal cord, demonstrated that NF180 mRNA was expressed in only a subset of neurons in the lamprey CNS. These included primarily neurons with long axons that project out of the brainstem, e.g., reticulospinal neurons and cranial motor neurons. Metamorphosis from the larval to the adult form was accompanied by an increase in the number of neurons expressing NF180 and in the apparent level of NF expression as judged by the intensity of labeling. For example, in the oculomotor and trochlear nuclei, expression of NF180 was seen in postmetamorphic young adult lampreys but not in larvae. In the trigeminal motor nucleus, both the number of neurons expressing NF180 and the intensity of the hybridization labeling increased with metamorphosis. The ability to do NISH in lamprey brain wholemounts eliminates the need for serial reconstructions and thus facilitates the study of selected gene expression during metamorphosis and regeneration.

Isolation of plant cytochrome P-450 and NADPH: cytochrome P-450 reductase from tulip bulbs (Tulipa fosteriana L.) oxidizing xenobiotics

Cytochrome P-450 and NADPH: cytochrome P-450 reductase were solubilized by detergents from microsomal fraction of tulip bulbs Tulipa fosteriana L. and purified to electrophoretic homogeneity. The purification was achieved by anion-exchange column chromatography, hydroxyapatite-column chromatography and affinity chromatography. The two enzyme showed relative molecular weights of about 54,200 and 77,600 for cytochrome P-450 and NADPH: cytochrome P-450 reductase, respectively. The purified enzymes were characterized by their absorption spectra and by kinetic characteristics. The interaction with endogeneous as well as exogenous substrates was studied by differential spectroscopy. Both enzymes in the presence of dilauroyl phosphatidylcholine and NADPH were able to oxidize xenobiotics (N-nitroso-N-methylaniline and N-nitroso-N-dimethylamine) in the reconstitution experiments.

Continuous-infusion cisplatin, 5-fluorouracil, and leucovorin for advanced non-small cell lung cancer

BACKGROUND

Cisplatin, 5-fluorouracil, and leucovorin (PFL) have demonstrated synergistic activity in preclinical models. Continuous infusion of these agents maximizes the potential for synergistic interaction and forms the basis of the PFL regimen.

METHODS

Sixty-one patients with advanced (Stages IIIB and IV) non-small cell lung cancer were entered into the study. Thirty-one were treated with cisplatin 25 mg/m2/day on days 1-5, 5-fluorouracil 800 mg/m2/day on days 2-6, and calcium leucovorin 500 mg/m2/day on days 1-6. Because of severe mucositis, the final 30 patients were treated with the same dosage of cisplatin but with the deletion on day 6 of leucovorin and 5-fluorouracil. Cycles were repeated every 28 days. Response was assessed after two cycles. Responding patients received an additional two cycles. Patients with Stage IIIB disease received radiation therapy to the mediastinum and sites of involved disease.

RESULTS

PFL had an overall response rate of 41%. Median survival was 8.1 months, and median time to treatment failure was 4.2 months. Importantly, 68% (17 of 25) of responses were maximal after just two cycles of chemotherapy. Notable toxicities included mucositis (43% > or = Grade 3) and myelosuppression. Response, time to failure, or survival did not differ between the two schedules. Mucositis was less severe with 4-day PFL.

CONCLUSIONS

PFL as given in this manner is an active regimen for the treatment of patients with advanced non-small cell lung cancer. The rapidity of response makes it a regimen for incorporation into protocols for Stage IIIA disease. A neoadjuvant study using PFL is underway.

Neoadjuvant treatment of stage IIIA non-small cell lung cancer. Long-term results

The multimodality approach to locally advanced Stage III non-small cell lung cancer is continuing to evolve. In this trial, 54 patients with surgically staged IIIA disease were treated with neoadjuvant chemotherapy, surgical resection, and chest radiotherapy. Response to four cycles of CAP chemotherapy (cyclophosphamide, doxorubicin, cisplatin) was 39% (8% complete responses). One septic death occurred. Thoracotomy was performed on 31 patients, of whom 29 (56%) were resected and 24 (44%) were completely resected. Complete resections were more frequently observed in chemotherapy responders. Extranodal mediastinal extension in nonresponding patients was the most frequent reason not to attempt thoracotomy. The overall median times to progression and survival were 11.6 (.7-66.5) and 17.9 (2.8-71.4) months. Long-term disease-free survival was observed in 11 patients (20%) with a median follow-up of 46.5 (24-71) months. All these patients underwent complete resection and constitute 46% of the patients undergoing complete resection. Median times to progression and survival were 33.4 (5.0-66.5) and 33.5 (10-71.4) months for completely resected patients. Although the ability to perform surgery identified a population that has favorable locoregional control and disease-free survival, distant relapse continues to represent the major obstacle to enhanced survival in resected patients. Unresected patients, however, are likely to relapse in both local and distant sites. Response to chemotherapy may not only enhance systemic control, but may also increase the probability of complete resection. Randomized trials should be conducted to evaluate the role of individual modalities (surgery, chemotherapy, or radiotherapy) while applying the remaining modalities maximally. The temptation to compare different treatment approaches should be resisted.

Phase II study of topotecan in metastatic non-small-cell lung cancer

PURPOSE

Topotecan is an inhibitor of topoisomerase I that has shown preclinical activity against non-small-cell lung cancer (NSCLC). This phase II study was designed to determine the clinical activity and toxicity spectrum of topotecan in untreated patients with metastatic NSCLC.

PATIENTS AND METHODS

Twenty previously untreated patients received topotecan every 21 days at the dose of 2 mg/m2/d intravenously (IV) for 5 days for two cycles, at which point response was assessed. Patients with either clinical response or stable disease (SD) received additional cycles of the drug until toxicity developed or disease progression (PRG) occurred.

RESULTS

This study was designed to enter 30 patients. However, because no clinical responses were seen in the first 20 patients entered onto the study, the early-stopping rule was invoked and patient accrual was halted. Eleven patients (55%) had SD on topotecan, and nine (45%) had PRG. Toxicity included neutropenia and rash. The median survival duration for all patients was 7.6 months.

CONCLUSION

We observed no objective clinical responses despite producing high-grade neutropenia. Phase II trials of topotecan using different schedules or higher doses supported by growth factors may clarify the role of topotecan in the treatment of NSCLC. The combination of topotecan with cisplatin and topoisomerase II inhibitors such as etoposide should be explored. Finally, the median survival duration of 7.6 months for 20 patients treated with an agent that failed to produce any obvious clinical responses compares favorably to the survival obtained with combinations of existing agents. This supports the further study of novel compounds in this clinical setting.

Methotrexate and gamma-tert-butyl methotrexate transport in CEM and CEM/MTX human leukemic lymphoblasts

In a continuing investigation of determinants of their 200-fold methotrexate resistance and their collateral sensitivity to gamma-tert-butyl methotrexate, the ability of CEM/MTX cells to transport the two drugs was analyzed and compared with that of CEM cells. The Km and Vmax values for the influx of methotrexate into CEM cells did not differ significantly from those of CEM/MTX cells, and this was the case for gamma-tert-butyl methotrexate as well. Surface binding and influx rates were proportional to cell surface area, but differences in efflux rates and methotrexate uptake were too large to be explained on this basis. Neither methotrexate nor trimetrexate competed with gamma-tert-butyl methotrexate influx in CEM cells. However, both drugs perturbed the gamma-tert-butyl methotrexate steady state in CEM cells, resulting in slightly less uptake than with gamma-tert-butyl methotrexate alone. However, the major difference between the two cell types was in the methotrexate uptake plateau, which was much greater in the case of the parental cell line. A related observation was the more rapid efflux of methotrexate from CEM/MTX cells than from CEM cells. The poor uptake, the associated meager capacity to polyglutamylate methotrexate and the enhanced methotrexate efflux appear to be responsible for its decreased activity against CEM/MTX cells. Half-lives for gamma-tert-butyl methotrexate efflux were the same in both cell lines, allowing the drug to accumulate to cytotoxic levels despite its inability to form polyglutamates.