A. A. Adjei

Phase I Trial of 17-Allylamino-17-Demethoxygeldanamycin in Patients With Advanced Cancer

PURPOSE We determined the maximum-tolerated dose (MTD) and the dose-limiting toxicities (DLT) of 17-allylamino-17-demethoxygeldanamycin (17-AAG) when infused on days 1, 8, and 15 of a 28-day cycle in advanced solid tumor patients. We also characterized the pharmacokinetics of 17-AAG, its effect on chaperone and client proteins, and whether cytochrome P450 (CYP) 3A5 and NAD(P)H:quinone oxidoreductase 1 (NQO1) polymorphisms affected 17-AAG disposition or toxicity. PATIENTS AND METHODS An accelerated titration design was used. Biomarkers were measured in peripheral-blood mononuclear cells (PBMCs) at baseline and on days 1 and 15, and pharmacokinetic analysis was performed on day 1 of cycle 1. CYP3A5*3 and NQO1*2 genotypes were determined and correlated with pharmacokinetics and toxicity. RESULTS Twenty-one patients received 52 courses at 11 dose levels. DLTs at 431 mg/m(2) were grade 3 bilirubin (n = 1), AST (n = 1), anemia (n = 1), nausea (n = 1), vomiting (n = 1), and myalgias (n = 1). No tumor responses were seen. 17-AAG consistently increased heat shock protein (Hsp) 70 levels in PBMCs. At the MTD, the clearance and half-life (t(1/2)) of 17-AAG were 11.6 L/h/m(2) and 4.15 hours, respectively; whereas the active metabolite 17-aminogeldanamycin had a t(1/2) of 7.63 hours. The CYP3A5*3 and NQO1*2 polymorphisms were not associated with 17-AAG toxicity. The CYP3A5*3 polymorphism was associated with higher 17-AAG clearance. CONCLUSION The MTD of weekly 17-AAG is 308 mg/m(2). 17-AAG induced Hsp70 in PBMCs, indicating that Hsp90 has been affected. Further evaluation of 17-AAG is ongoing using a twice-weekly regimen, and this schedule of 17-AAG is being tested in combination with chemotherapy.

Metaplastic breast cancer: Prognosis and response to systemic therapy

BACKGROUND Metaplastic breast cancer is a rare disease with little information available to guide therapy. The goals of this study were to describe the patient characteristics, systemic therapies and clinical outcomes of all patients with primary metaplastic breast cancer treated at Mayo Clinic between 1976 and 1997. PATIENTS AND METHODS Patients were identified through the medical index of Mayo Clinic. Clinical information was abstracted from the medical record of each patient. A literature search using MEDLINE and CANCERLIT for the years 1966-1997 was performed to identify all previously reported case series in the English language containing 10 or more patients. RESULTS Twenty-seven patients were identified with a median age at diagnosis of 59 years (range 39-90 years). The median tumor size was 3.4 cm (range 0.5-7.0 cm). One patient had metastatic disease at presentation. Twenty-three patients had information available on nodal status, estrogen receptor (ER) and progesterone receptor (PR) status. Twenty patients (87%) were node-negative and three patients (13%) were both ER and PR positive. Disease-free survival (DFS) and overall survival (OS) were assessed for those who presented with local-regional disease. The three-year DFS was 40% (95% CI: 23%-73%) and the three-year OS was 71% (95% CI: 51%-97%). In univariate analysis, those patients 60 years of age or older at diagnosis were found to have an increased DFS (P = 0.011). Among those with prior estrogen use, both DFS (P = 0.022) and OS (P = 0.003) were decreased. Thirteen patients (50%) developed metastases with a median DFS time of 2.4 years. Ten different chemotherapy regimens were utilized for metastatic disease and one partial response was observed. There were no responses to tamoxifen in four patients with metastatic disease. Median survival after the development of metastases was eight months. CONCLUSIONS Despite presenting more commonly as node-negative disease, DFS and OS in metaplastic breast cancer is decreased compared to typical adenocarcinomas. Systemic therapy also appears to be less effective. Patients with metaplastic breast cancer, particularly those with metastatic disease could be appropriate candidates for innovative therapeutic regimens.

Human estrogen sulfotransferase (SULT1E1) pharmacogenomics: gene resequencing and functional genomics

Estrogens are used as drugs and estrogen exposure is a risk factor for hormone‐dependent diseases such as breast cancer. Sulfate conjugation is an important pathway for estrogen metabolism. The sulfotransferase (SULT) enzyme SULT1E1 has the lowest Km values for estrogens and catecholestrogens of the 10 known human SULT isoforms. We previously cloned and characterized the human SULT1E1 cDNA and gene as steps toward pharmacogenetic studies. In the present experiments, we set out to determine whether common, functionally significant genetic polymorphisms might exist for SULT1E1. As a first step, we ‘resequenced’ the eight SULT1E1 exons and exon–intron splice junctions as well as portions of the 5′‐flanking region using DNA from 60 African‐American and 60 Caucasian‐American subjects. In all, 23 polymorphisms, 22 single nucleotide polymorphisms (SNPs) and one insertion deletion were observed. There were three nonsynonymous coding SNPs (cSNPs) that altered the following encoded amino acids: Asp22Tyr, Ala32Val and Pro253His. Among these, 12 pairs of SNPs were tightly linked. In addition, 12 unambiguous SULT1E1 haplotypes were identified, including six that were common to both populations studied. Transient expression in COS‐1 cells of constructs containing the three nonsynonymous cSNPs showed significant decreases in SULT1E1 activity for the Tyr22 and Val32 allozymes, with corresponding decreases in levels of immunoreactive protein. There were no changes in levels of either activity or immunoreactive protein for the His253 allozyme. Apparent Km values of the Val32 allozyme for the two cosubstrates for the reaction, 17β‐estradiol and 3′‐phosphoadenosine 5′‐phosphosulfate, were not significantly different from those of the wild‐type enzyme, but there was a two‐ to three‐fold increase in Km values for the His253 allozyme and a greater than five‐fold increase for the Tyr22 allozyme. These observations raise the possibility that genetically determined variation in SULT1E1‐catalyzed estrogen sulfation might contribute to the pathophysiology of estrogen‐dependent diseases as well as variation in the biotransformation of exogenously administered estrogens.

Phase I study of the matrix metal loproteinase inhibitor, BAY 12–9566

BACKGROUND Matrix metalloproteinases (MMPs) are involved in tumor invasion and metastasis and have been implicated in breast, ovarian, colorectal, and lung cancer growth. We undertook a phase I study of BAY 12-9566, an inhibitor of MMP-2, MMP-9, and MMP-3, in patients with solid tumors to determine its safety, pharmacokinetics, and effects on potential surrogate markers of biologic activity. PATIENTS AND METHODS BAY 12-9566 was orally administered daily at four dose levels; 400 mg daily, 400 mg b.i.d., 400 mg t.i.d., and 800 mg b.i.d. Drug disposition was determined on days 1 and 29 with weekly trough levels measured during the first four weeks. Plasma vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and urinary pyridinoline and deoxypyridinoline crosslinks were determined at baseline, once weekly for four weeks, and then every four weeks. RESULTS Thirteen patients were entered on trial. BAY 12-9566 was well tolerated, with only one grade 3 headache, one grade 3 anemia, one grade 3 thrombocytopenia, and no musculoskeletal effects. The median treatment duration was 57 days (range 7-560). Mean trough levels of BAY 12-9566 on day 28 ranged from 80.5 to 108.6 mg/l. Plasma trough levels were 1500-42,000-fold above the Kis for MMP-2, MMP-3, and MMP-9 at the 800 mg p.o. b.i.d. dose level. There was no significant change in VEGF, bFGF, pyridinoline, and deoxypyridinoline crosslinks with BAY 12-9566 administration. CONCLUSIONS The recommended dose for further testing is 800 mg p.o. b.i.d.

Interindividual variability in acetaminophen sulfation by human fetal liver: Implications for pharmacogenetic investigations of drug-induced birth defects

BACKGROUND Acetaminophen (APAP) use in early pregnancy has been associated with the risk of gastroschisis, a rare but serious congenital defect of the abdominal wall. The purpose of this study was to characterize the variability of APAP sulfation in a panel of human fetal livers and to identify the sulfotransferases (SULT) isoform(s) responsible for catalyzing that activity. METHODS APAP sulfation was determined in a panel of human fetal (n = 73) and postnatal (n = 18) liver cytosol preparations and correlated with the catalytic activity of various SULT isoforms as determined using prototypic substrates and specific antibodies. RESULTS Of 10 heterologously expressed SULT isoforms examined, SULT1A1, SULT1A3/4, SULT1E1, and SULT2A1 all catalyzed the formation of APAP sulfate with K(m) values of 2.4, 1.5, 1.9, and 3.7 mM, respectively. Catalytic activities for these four isoforms were expressed at varying levels in human fetal liver, and APAP sulfation was positively correlated with each of the four prototypic activities. Several regression and clustering approaches revealed that SULT1A3/4 was the primary determinant of prenatal APAP sulfation but that SULT1A1 or SULT1E1 were also major contributors in subsets of samples. CONCLUSIONS The results of this study lead to the hypothesis that genetic variation in SULT1A3/4 represents a risk factor for the development of gastroschisis in the offspring of mothers exposed to APAP early in pregnancy. Interpretation of genetic association studies conducted to test this hypothesis will be complicated by the variable contributions of other SULTs toward APAP-sulfate formation in individual subjects.

Estrogen Bioactivation, Genetic Polymorphisms, and Ovarian Cancer

Recent experimental evidence has shown that catechol estrogens can be activated through metabolism to form depurinating DNA adducts and thereby initiate cancer. Limited data are available regarding this pathway in epithelial ovarian cancer. We conducted a case-control study of 503 incident epithelial ovarian cancer cases at the Mayo Clinic in Rochester, MN, and Jacksonville, FL, and a 48-county region in North Carolina. Six hundred nine cancer-free controls were frequency matched to the cases on age, race, and residence. After an interview to obtain data on risk factors, a sample of blood was collected for DNA isolation. Subjects were genotyped for seven common single nucleotide polymorphisms in four genes involved in catechol estrogen formation (CYP1A1 and CYP1B1) or conjugation (COMT and SULT1A1). Data were analyzed using logistic regression, stratified by race, and with adjustment for design factors and potential confounders. None of the individual genotypes were significantly associated with ovarian cancer risk. However, an oligogenic model that considered the joint effects of the four candidate genes provided evidence for an association between combinations of these genes and ovarian cancer status (P = 0.015). Although preliminary, this study provides some support for the hypothesis that low-penetrance susceptibility alleles may influence risk of epithelial ovarian cancer.

Prophylactic cranial irradiation in small-cell lung cancer: Findings from a North Central Cancer Treatment Group Pooled Analysis

BACKGROUND This pooled analysis evaluated the outcomes of prophylactic cranial irradiation (PCI) in 739 small-cell lung cancer (SCLC patients with stable disease (SD) or better following chemotherapy ± thoracic radiation therapy (TRT) to examine the potential advantage of PCI in a wider spectrum of patients than generally participate in PCI trials. PATIENTS AND METHODS Three hundred eighteen patients with extensive SCLC (ESCLC) and 421 patients with limited SCLC (LSCLC) participated in four phase II or III trials. Four hundred fifty-nine patients received PCI (30 Gy/15 or 25 Gy/10) and 280 did not. Survival and adverse events (AEs) were compared. RESULTS PCI patients survived significantly longer than non-PCI patients {hazard ratio [HR] = 0.61 [95% confidence interval (CI): 0.52-0.72]; P < 0.0001}. The 1- and 3-year survival rates were 56% and 18% for PCI patients versus 32% and 5% for non-PCI patients. PCI was still significant after adjusting for age, performance status, gender, stage, complete response, and number of metastatic sites (HR = 0.82, P = 0.04). PCI patients had significantly more grade 3+ AEs (64%) compared with non-PCI patients (50%) (P = 0.0004). AEs associated with PCI included alopecia and lethargy. Dose fractionation could be compared only for LSCLC patients and 25 Gy/10 was associated with significantly better survival compared with 30 Gy/15 (HR = 0.67, P = 0.018). CONCLUSIONS PCI was associated with a significant survival benefit for both ESCLC and LSCLC patients who had SD or a better response to chemotherapy ± TRT. Dose fractionation appears important. PCI was associated with an increase in overall and specific grade 3+ AE rates.BACKGROUND This pooled analysis evaluated the outcomes of prophylactic cranial irradiation (PCI) in 739 small-cell lung cancer (SCLC patients with stable disease (SD) or better following chemotherapy ± thoracic radiation therapy (TRT) to examine the potential advantage of PCI in a wider spectrum of patients than generally participate in PCI trials. PATIENTS AND METHODS Three hundred eighteen patients with extensive SCLC (ESCLC) and 421 patients with limited SCLC (LSCLC) participated in four phase II or III trials. Four hundred fifty-nine patients received PCI (30 Gy/15 or 25 Gy/10) and 280 did not. Survival and adverse events (AEs) were compared. RESULTS PCI patients survived significantly longer than non-PCI patients {hazard ratio [HR] = 0.61 [95% confidence interval (CI): 0.52-0.72]; P < 0.0001}. The 1- and 3-year survival rates were 56% and 18% for PCI patients versus 32% and 5% for non-PCI patients. PCI was still significant after adjusting for age, performance status, gender, stage, complete response, and number of metastatic sites (HR = 0.82, P = 0.04). PCI patients had significantly more grade 3+ AEs (64%) compared with non-PCI patients (50%) (P = 0.0004). AEs associated with PCI included alopecia and lethargy. Dose fractionation could be compared only for LSCLC patients and 25 Gy/10 was associated with significantly better survival compared with 30 Gy/15 (HR = 0.67, P = 0.018). CONCLUSIONS PCI was associated with a significant survival benefit for both ESCLC and LSCLC patients who had SD or a better response to chemotherapy ± TRT. Dose fractionation appears important. PCI was associated with an increase in overall and specific grade 3+ AE rates.

Human phenylethanolamine N-methyltransferase pharmacogenomics: gene re-sequencing and functional genomics

Phenylethanolamine N‐methyltransferase (PNMT, EC2.1.1.28) catalyzes the N‐methylation of norepinephrine to form epinephrine. As a step toward understanding the possible contribution of inheritance to individual variation in PNMT‐catalyzed epinephrine formation, we ‘re‐sequenced’ the entire human PNMT gene, including the three exons, the introns and approximately 1 kb of the 5′‐flanking region (5′‐FR), using DNA samples from 60 African‐American (AA) and 60 Caucasian‐American (CA) subjects. Within the 3.5 kb re‐sequenced, 18 single nucleotide polymorphisms (SNPs) were observed, including four non‐synonymous coding SNPs (cSNPs) that resulted in the following alterations in encoded amino acid sequence: Asn9Ser, Thr98Ala, Arg112Cys and Ala175Thr. When constructs for the non‐synonymous cSNPs were transiently expressed in COS‐1 cells, the Ala98 allozyme displayed significantly lower levels of both activity and immunoreactive protein (p < 0.002) than did the wild‐type (WT) enzyme due, at least in part, to accelerated protein degradation by a proteasome‐mediated process. Luciferase reporter gene constructs were also created for the six common PNMT 5′‐FR haplotypes observed. Significant differences were observed among haplotypes in their ability to drive transcription. These observations raise the possibility of inherited variation in the ability to form epinephrine from norepinephrine as a result of variant PNMT polymorphisms and haplotypes.

Structural Basis of Substrate Recognition in Thiopurine S-Methyltransferase

Thiopurine S-methyltransferase (TPMT) modulates the cytotoxic effects of thiopurine prodrugs such as 6-mercaptopurine by methylating them in a reaction using S-adenosyl- l-methionine as the donor. Patients with TPMT variant allozymes exhibit diminished levels of protein and/or enzyme activity and are at risk for thiopurine drug-induced toxicity. We have determined two crystal structures of murine TPMT, as a binary complex with the product S-adenosyl- l-homocysteine and as a ternary complex with S-adenosyl- l-homocysteine and the substrate 6-mercaptopurine, to 1.8 and 2.0 A resolution, respectively. Comparison of the structures reveals that an active site loop becomes ordered upon 6-mercaptopurine binding. The positions of the two ligands are consistent with the expected S N2 reaction mechanism. Arg147 and Arg221, the only polar amino acids near 6-mercaptopurine, are highlighted as possible participants in substrate deprotonation. To probe whether these residues are important for catalysis, point mutants were prepared in the human enzyme. Substitution of Arg152 (Arg147 in murine TPMT) with glutamic acid decreases V max and increases K m for 6-mercaptopurine but not K m for S-adenosyl- l-methionine. Substitution at this position with alanine or histidine and similar substitutions of Arg226 (Arg221 in murine TPMT) result in no effect on enzyme activity. The double mutant Arg152Ala/Arg226Ala exhibits a decreased V max and increased K m for 6-mercaptopurine. These observations suggest that either Arg152 or Arg226 may participate in some fashion in the TPMT reaction, with one residue compensating when the other is altered, and that Arg152 may interact with substrate more directly than Arg226, consistent with observations in the murine TPMT crystal structure.

Effect of resveratrol on 17β-estradiol sulfation by human hepatic and jejunal S9 and recombinant sulfotransferase 1E1

The purpose of this study was to investigate the sulfation of resveratrol (3,5,4′-trihydroxystilbene) and its potential to exhibit drug-drug interactions via sulfation. The possible interaction of resveratrol with 17β-estradiol (E2), a major estrogen hormone and prototypic substrate for sulfate conjugation, was studied. Resveratrol and E2 are both known to undergo sulfate conjugation catalyzed by human sulfotransferases (SULTs). Resveratrol is a phytoestrogen with mixed estrogen agonist/antagonist properties that is being developed as a chemopreventive agent. The sulfate conjugation of E2 and resveratrol were studied individually using S9 fractions from human liver and jejunum as well as recombinant human SULT isoforms. The sulfation of E2 (3–20 nM) was then investigated in the presence of various concentrations (0, 0.5, 1, and 2 μM) of resveratrol using the two S9 preparations as well as recombinant SULT1E1, the major isoform responsible for E2 sulfation. Resveratrol inhibited E2 sulfation with estimated Ki values of 1.1 μM (liver), 0.6 μM (jejunum), and 2.3 μM (SULT1E1), concentrations that could be pharmacologically relevant. The results suggest that these phytoestrogens can potentially alter the homeostasis of estrogen levels. These findings also imply that resveratrol may inhibit the metabolism of other estrogen analogs or therapeutic agents such as ethinylestradiol or dietary components that are also substrates for SULT1E1.