Trimodality treatment versus surgery alone for esophageal cancer. A stratified analysis with minimally invasive pretreatment staging

BACKGROUND

Accurate pretreatment staging of esophageal cancer (EC) is important in the evaluation and comparison of results of different treatment modalities. Few studies using minimally invasive staging techniques for this purpose have been reported. We previously demonstrated the usefulness of the thoracoscopic/laparoscopic (Ts/Ls) technique in pretreatment staging of EC. This study was conducted to evaluate the impact of trimodality based on pretreatment Ts/Ls staging diagnosis on EC.

METHODS

A retrospective study was performed on 2 groups of EC patients. Group A (44 patients) underwent pretreatment Ts/Ls staging and had trimodality treatment. Preoperative therapy consisted of concurrent chemotherapy (5-FU + cisplatinum) and radiotherapy. Group B (33 patients) underwent surgery alone. The study focused on stratified comparison of patterns of recurrence and survival in different pretreatment surgical T, N, and TNM stage categories.

RESULTS

The 3-year disease free survival of Group A was 40.8% with a median survival of 32.0 months, it was 43.6% with a median survival of 23.6 months in Group B. The difference was not significant (p=0.87). There was no difference in recurrence pattern between the 2 groups. Patients with squamous cell carcinoma in Group A had no local recurrence during the follow-up period while those in Group B had a high local recurrence rate of 40% (p<0.005). When stratified by T factor, patients with locally advanced T stage (T3-4) in Group A had a lower distant recurrence rate than their counterpart patients in Group B (9.1 vs 38.5%, p=0.03), they had a better survival but the difference was not significant (3-year disease free survival: 41.7 vs 17.9%, p=0.14). There were no significant differences in recurrence pattern and survival in different N categories and TNM stages between 2 groups. Multivariate analysis showed that only pretreatment surgical N status was an independent prognostic factor for the whole group (p=0.02).

CONCLUSIONS

Pretreatment Ts/Ls staging can provide accurate staging information for EC patients. Trimodality treatment was successful in local control for patients with squamous cell carcinoma. It was effective in reducing distant recurrence and might prolong survival in patients with advanced T stages. Pretreatment lymph node status was the most important prognosticator regardless of treatment modality. Pretreatment pathological staging should be included in the future clinical trials on multimodality treatments in EC patients.

Transcriptional control of intestinal cytochrome P-4503A by 1alpha,25-dihydroxy vitamin D3

It was previously shown that CYP3A4 is induced in the human intestinal Caco-2 cell model by treatment with 1alpha,25-dihydroxy vitamin D3 (1,25-D3). We demonstrate the vitamin D analog, 19-nor-1alpha,25-dihydroxy vitamin D2, is also an effective inducer of CYP3A4 in Caco-2 cells, but with half the potency of 1,25-D3. We report that treatment of LS180 cells, a human intestinal cell line, with 1 to 10 nM 1,25-D3 dose dependently increased CYP3A4 protein and CYP3A4 mRNA expression. CYP3A4- and CYP3A23-promoter-Luciferase reporter constructs transiently transfected into LS180 cells were transcriptionally activated in a dose-dependent manner by 1,25-D3, whereas mutation of the nuclear hormone receptor binding motif (ER6) in the CYP3A4 promoter abrogated 1,25-D3 activation of CYP3A4. Although the CYP3A4 ER6 promoter element has been shown to bind the pregnane X receptor (PXR), this receptor does not mediate 1,25-D3 induction of CYP3A4 because a) PXR is not expressed in Caco-2 cells; b) PXR mRNA expression is not induced by 1,25-D3 treatment of LS180 cells; and c) the ligand binding domain of human PXR was not activated by 1,25-D3. 1,25-D3 uses the vitamin D receptor to induce CYP3A4 because a) the vitamin D receptor (VDR)-retinoid X receptor (RXR) heterodimer binds specifically to the CYP3A4 ER6; b) selective mutation of the CYP3A4 ER6 disrupted the binding of VDR-RXR; and c) reporter constructs containing only three copies of the CYP3A4 ER6 linked to a TK-CAT reporter were activated by 1,25-D3 only in cells cotransfected with a human VDR expression plasmid. These data support the hypothesis that 1,25-D3 and VDR induce expression of intestinal CYP3A by binding of the activated VDR-RXR heterodimer to the CYP3A PXR response element and promoting gene transcription.

Accurate lymph node assessment prior to trimodality therapy for esophageal carcinoma

PURPOSE

The diagnosis of esophageal carcinoma has historically been associated with a poor prognosis. Recently, investigators have reported improved outcomes for this patient population with the use of trimodality therapy. These results have fueled the debate regarding which patients may benefit from this aggressive treatment course. This retrospective analysis was conducted in order to evaluate the importance of regional lymph node involvement, determined by surgical staging before the initiation of therapy.

PATIENTS AND MATERIALS

Between July 1991 and June 1999, 45 patients underwent surgical staging with thoracoscopy and/or laparoscopy followed by induction chemoradiation and surgical resection. All patients underwent consultation in our thoracic multidisciplinary clinic. Thoracoscopy included nodal sampling from American Thoracic Society levels 5, 6, 8, and 9 within the mediastinum. Laparoscopy included inspection of the liver and nodal sampling from the lesser curvature and the celiac axis. Preoperative chemoradiation consisted of two cycles of 5-fluorouracil (1000 mg/M2) and cisplatin (100 mg/M2) weeks 1 and 4 with 50.4 Gy. Radiotherapy was delivered at 1.8 Gy/fraction with 39.6 Gy being delivered to the large-field and 10.8 Gy to a small-field boost. The routine surgical procedure was an Ivor-Lewis esophagectomy performed 4 to 6 weeks after completion of induction therapy.

RESULTS

The median follow up was 24 months for all patients. The median overall survival was 23 months, with 1-, 2-, and 3-year survivals of 64%, 42%, and 34%, respectively. Thirty patients had pathological evidence of lymph node disease before therapy. The pathological complete response rate for the entire group was 51%. Node-positive patients had a path complete response rate of 14%, as compared with 59% for those who were NO. The median survival for these two groups was 15 months versus 35 months. Patients whose nodes were cleared by chemoradiation had a 3-year survival of 40%, whereas all patients with persistent nodal disease were dead by 2 years. Twenty-one patients have experienced recurrence of their disease. Thirteen patients had evidence of distant metastasis only, three local only, and five with both.

CONCLUSION

Trimodality therapy offers patients with esophageal cancer an opportunity for long-term survival. Our experience has shown that minimally invasive pretreatment surgical staging provides useful information that can predict complete response and can help in the selection of appropriate patients for aggressive therapy.

Sequence diversity in CYP3A promoters and characterization of the genetic basis of polymorphic CYP3A5 expression

Variation in the CYP3A enzymes, which act in drug metabolism, influences circulating steroid levels and responses to half of all oxidatively metabolized drugs. CYP3A activity is the sum activity of the family of CYP3A genes, including CYP3A5, which is polymorphically expressed at high levels in a minority of Americans of European descent and Europeans (hereafter collectively referred to as 'Caucasians'). Only people with at least one CYP3A5*1 allele express large amounts of CYP3A5. Our findings show that single-nucleotide polymorphisms (SNPs) in CYP3A5*3 and CYP3A5*6 that cause alternative splicing and protein truncation result in the absence of CYP3A5 from tissues of some people. CYP3A5 was more frequently expressed in livers of African Americans (60%) than in those of Caucasians (33%). Because CYP3A5 represents at least 50% of the total hepatic CYP3A content in people polymorphically expressing CYP3A5, CYP3A5 may be the most important genetic contributor to interindividual and interracial differences in CYP3A-dependent drug clearance and in responses to many medicines.

The use of concurrent chemotherapy with high-dose radiation before surgical resection in patients presenting with apical sulcus tumors

PURPOSE

Patients presenting with apical sulcus tumors have historically been treated with preoperative radiotherapy followed by surgical resection. Since 1991, we have delivered an induction regimen consisting of combination chemotherapy and high-dose radiation in an attempt to improve tumor responses and increase survival for this patient population.

PATIENTS AND MATERIALS

This retrospective analysis consisted of 23 (13 men and 10 women) consecutive patients who completed trimodality therapy. The median age was 53 years. Histologies included adenocarcinoma (nine patients), squamous cell (five patients), large cell (three patients), and undifferentiated non-small cell lung carcinoma (six patients). Pretreatment stages were T3NO (14 patients), T3N2 (two patients), T3N3 (one patient), T4NO (five patients), and T4N2 (one patient). Preoperative therapy consisted of daily radiotherapy (median dose, 59.4 Gy) delivered at 1.8 Gy/day and concurrent combination chemotherapy consisting of either two cycles of cisplatin and etoposide or weekly carboplatin and paclitaxel. Surgical resection typically included lobectomy with chest wall resection.

RESULTS

All 23 patients were available for analysis of response and survival. The median follow-up was 53 months. The median number of days between completion of induction therapy and surgery was 56 days. Postoperative complications included prolonged atelectasis (two patients), pulmonary embolism (one patient), subarachnoid-pleural fistula (one patient), and deep vein thrombosis in the subclavian vein (one patient). The pathological complete response rate to induction therapy was 46% for the entire group. An additional 38% had evidence of tumor regression at the time of surgery. The 5-year disease-free and overall survivals were 36% and 49%, respectively. The median overall survival was 33 months. The median overall survival for those who achieved a pathological complete response has not been reached. Analysis of factors including age, sex, histology, differentiation, stage of disease, and radiation dose failed to identify any predictors of response or survival. CONCLUSION Concurrent chemotherapy and high-dose radiation can be safely delivered before surgery in patients presentingwith apical sulcus tumors. Our results compare favorably to other institutional series and support the further investigation of this approach in prospective trials.

Structural and spectroscopic studies of the native hemocyanin from Maia squinado and its structural subunits

The dodecameric hemocyanin of the crab Maia squinado contains five major electrophoretically separable polypeptide chains (structural subunits) which have been purified by FPLC ion exchange chromatography. The various proteins have been characterized by fluorescence spectroscopy, combined with fluorescence quenching studies, using acrylamide, caesium chloride and potassium iodide as tryptophan quenchers. The results show that the tryptophyl side chains of dodecameric Hc are deeply buried in hydrophobic regions of the hemocyanin aggregates and the quenching efficiency values for the native Hc in comparison with those from the constituent subunits are two to four times less. The conformational stabilities of the native dodecameric aggregate and its isolated structural subunits towards various denaturants (pH, temperature, guanidinium hydrochloride) indicate that the quaternary structure is stabilized by hydrophilic and polar forces, whereby, both, the oxy- and apo-forms of the protein have been considered. The critical temperatures for the structural subunits, Tc, determined by fluorescence spectroscopy, are in the region of 50-60 degrees C, coinciding with the melting temperatures, Tm, determined by CD spectroscopy. The free energy of stabilization in water, deltaG(D)H2O, toward guanidinium hydrochloride is about two times higher for the dodecamer as compared to the isolated subunits. These studies reveal that oligomerization between functional subunits has a stabilizing effect on the whole molecule and differences in the primary structures result in different stabilities of the subunits.

Creation of polarized cells coexpressing CYP3A4, NADPH cytochrome P450 reductase and MDR1/P-glycoprotein

PURPOSE

To develop model polarized cell systems expressing cytochrome P4503A4. NADPH P450 reductase, and P-glycoprotein (Pgp).

METHODS

LLC-PK1 and derivative L-MDR1 cells stably expressing Pgp, the product of the multidrug resistance gene (MDR1), were transfected stably using either a mammalian neomycin selectable expression vector (CYP3A4-Neo) or an episomal vector based on Epstein-Barr virus (CYP3A4-Hygro). These CYP3A4 expressing cells were compared with LLC-PK1, L-MDR1, or Caco-2 cells transduced with Adenovirus-3A4 vector (Ad3A4) with or without simultaneous Adenovirus-P450 Reductase (AdRed) transduction. Cells were characterized for expression of CYP3A4 protein and CYP3A4 mediated metabolism towards midazolam and testosterone. Analysis of membrane integrity and drug transport assays were performed to determine whether infection with recombinant Ad3A4 +/- AdRed affected Pgp function.

RESULTS

The rank order of optimal CYP3A4 expression and activities in LLC-PKI and L-MDR1 cells from highest to lowest was cells cotransduced with Ad3A4 plus AdRed >> Ad3A4 >>> CYP3A4-Hygro > CYP3A4-Neo. Similarly, coexpression of Ad3A4 plus AdRed led to enhanced CYP3A4 mediated metabolism in Caco-2 cells over cells with Ad3A4 alone. Incubation of transwell cultured cells expressing Ad3A4/AdRed with midazolam led to readily detectable metabolite in the medium. In microsomes from Caco-2 and LLC-PK1 cells, each co-transduced with Ad3A4/AdRed, Vmax values for testosterone 6beta-hydroxylase activity ranged from 414 to 1350 pmoles/min/mg, respectively. For either Caco-2 or LLC-MDR1 cells, TEER values and the rate of apical to basal and basal to apical transport of vinblastine or digoxin were similar in cells with and without Ad3A4/Red transduction.

CONCLUSIONS

Polarized cellular systems coexpressing Ad3A4, AdRed, and the MDR1/Pgp transporter were developed and characterized. The results document the utility of these polarized model systems for simultaneous drug transport/drug metabolism studies. Since the experimental approach can be adapted to study the interplay of multiple enzyme/ transporting systems, it may find significant application as a screening tool for the pharmaceutical industry and as a more basic research tool to study the kinetics of intestinal drug bioavailability.

Safe pulmonary resection after chemotherapy and high-dose thoracic radiation

BACKGROUND

Pulmonary resection after high-dose thoracic irradiation is reported to be associated with a high morbidity and mortality, and has been considered to be prohibitive.

METHODS

We report safe pulmonary resection in 19 consecutive patients receiving neoadjuvant therapy that included greater than 59 Gy thoracic radiation. The mean thoracic radiation dose was 61.8 Gy (range 59.5-66.5) and mean age was 52 years (range 36-72 years). Cell type was adenocarcinoma (6), squamous (7), and other non-small cell lung cancer (NSCLC) (6). Sixteen of 19 patients received concurrent chemotherapy. Median time from end of treatment to surgical resection was 89 days (range 22-258 days). Surgical resection included 13 lobectomies and six pneumonectomies (four right, two left).

RESULTS

A complete pathologic response was seen in 8 of 19 (42%) patients. Three patients required intraoperative transfusion of blood. Mean intensive care unit stay was 2.0 days (range 1-8 days), and mean length of stay (LOS) was 8.0 days (range 3-18 days). There were four postoperative complications; one bronchopulmonary fistula, one subarachnoid-pleural fistula, and 2 patients with prolonged atelectasis. There was no incidence of acute respiratory distress syndrome (ARDS) or operative mortality.

CONCLUSIONS

Pulmonary resection, including pneumonectomy, after chemotherapy and high-dose thoracic radiation may be performed safely with a low rate of intraoperative and postoperative complications.

The MYND motif is required for repression of basal transcription from the multidrug resistance 1 promoter by the t(8;21) fusion protein

Chromosomal translocations in acute leukemia that affect the AML-1/CBFbeta transcription factor complex create dominant inhibitory proteins. However, the mechanisms by which these proteins act remain obscure. Here we demonstrate that the multidrug resistance 1 (MDR-1) promoter is a target for AML/ETO transcriptional repression. This repression is of basal, not activated, expression from the MDR-1 promoter and thus represents a new mechanism for AML/ETO function. We have defined two domains in AML/ETO that are required for repression of basal transcription from the MDR-1 promoter: a hydrophobic heptad repeat (HHR) motif and a conserved zinc finger (ZnF) domain termed the MYND domain. The HHR mediates formation of AML/ETO homodimers and AML/ETO-ETO heterodimers. Single serine substitutions at conserved cysteine residues within the predicted ZnFs also abrogate transcriptional repression. Finally, we observe that AML/ETO can also inhibit Ets-1 activation of the MDR-1 promoter, indicating that AML/ETO can disrupt both basal and Ets-1-dependent transcription. The fortuitous inhibition of MDR-1 expression in t(8;21)-containing leukemias may contribute to the favorable response of these patients to chemotherapeutic drugs.

Renal and hepatic family 3A cytochromes P450 (CYP3A) in spontaneously hypertensive rats

Troleandomycin (TAO), a selective family 3A cytochromes P450 (CYP3A) inhibitor, decreases enhanced in vivo corticosterone 6 beta-hydroxylation and blood pressure in spontaneously hypertensive rats (SHR). Corticosterone 6 beta-hydroxylation was measured in liver and kidney microsomes, to determine ontogeny and the effect of TAO on CYP3A activity at the organ level. SHR kidney CYP3A activity increased from 4 to 8 weeks, stabilized at 11 and 16 weeks, and was much higher than in control (Wistar-Kyoto, WKY) rats at all ages. Hepatic activity showed less consistency in strain difference. TAO produced a relatively large decrease in renal CYP3A activity compared with liver. Although renal CYP3A mRNA was not present in sufficient quantity for detection by northern blot analysis of total RNA, its presence was demonstrated in SHR by reverse transcriptase-polymerase chain reaction amplification. Correlations between renal CYP3A activity and systolic blood pressure in SHR and WKY rats with variations in age, strain and drug treatment are consistent with the role of the enzyme in the pathogenesis of blood pressure elevation in SHR.

Heterogeneity of cytochrome P450IIIA expression in rat gut epithelia

The P450IIIA (CYP3A) cytochromes are a major family of enzymes that play an important role in the metabolism of many medications, including cyclosporine A, as well as some dietary xenobiotics, including aflatoxin B1. The purpose of the studies was to detect, localize, and characterize P450IIIA enzymes present throughout the digestive tract. To this end, P450IIIA-specific antibodies were used to examine gut epithelial microsomes and histological tissue sections obtained from the digestive tract of both male and female rats. P450IIIA-related proteins were detected in epithelia throughout the gut; however, the specific proteins expressed appeared to differ among digestive organs and between male and female rats. RNA obtained from the gut epithelia was also analyzed using P450IIIA-specific synthetic oligonucleotides as probes on Northern blots and as primers for the polymerase chain reaction. P450IIIA1, which is a dexamethasone inducible enzyme in liver, was also found to be induced by dexamethasone treatment in epithelia from stomach and jejunum, but not from colon or esophagus. It was concluded that P450IIIA enzymes are present in mature epithelia throughout the gastrointestinal tract. However, expression of the P450IIIA enzymes is influenced by anatomic location and gender.