Myelopreservation with the CDK4/6 inhibitor trilaciclib in patients with small-cell lung cancer receiving first-line chemotherapy: a phase Ib/randomized phase II trial.

BACKGROUND: Chemotherapy-induced damage of hematopoietic stem and progenitor cells (HSPC) causes multi-lineage myelosuppression. Trilaciclib is an intravenous CDK4/6 inhibitor in development to proactively preserve HSPC and immune system function during chemotherapy (myelopreservation). Preclinically, trilaciclib transiently maintains HSPC in G1 arrest and protects them from chemotherapy damage, leading to faster hematopoietic recovery and enhanced antitumor immunity. PATIENTS AND METHODS: This was a phase Ib (open-label, dose-finding) and phase II (randomized, double-blind placebo-controlled) study of the safety, efficacy and PK of trilaciclib in combination with etoposide/carboplatin (E/P) therapy for treatment-naive extensive-stage small-cell lung cancer patients. Patients received trilaciclib or placebo before E/P on days 1-3 of each cycle. Select end points were prespecified to assess the effect of trilaciclib on myelosuppression and antitumor efficacy. RESULTS: A total of 122 patients were enrolled, with 19 patients in part 1 and 75 patients in part 2 receiving study drug. Improvements were seen with trilaciclib in neutrophil, RBC (red blood cell) and lymphocyte measures. Safety on trilaciclib+E/P was improved with fewer ≥G3 adverse events (AEs) in trilaciclib (50%) versus placebo (83.8%), primarily due to less hematological toxicity. No trilaciclib-related ≥G3 AEs occurred. Antitumor efficacy assessment for trilaciclib versus placebo, respectively, showed: ORR (66.7% versus 56.8%, P = 0.3831); median PFS [6.2 versus 5.0 m; hazard ratio (HR) 0.71; P = 0.1695]; and OS (10.9 versus 10.6 m; HR 0.87; P = 0.6107). CONCLUSION: Trilaciclib demonstrated an improvement in the patient's tolerability of chemotherapy as shown by myelopreservation across multiple hematopoietic lineages resulting in fewer supportive care interventions and dose reductions, improved safety profile, and no detriment to antitumor efficacy. These data demonstrate strong proof-of-concept for trilaciclib's myelopreservation benefits. CLINICAL TRAIL NUMBER: NCT02499770.

Histological alterations in male A/J mice following nose-only exposure to tobacco smoke.

The incidence and multiplicity of grossly observed and microscopic lesions of the respiratory tract of A/J mice exposed nose-only to mainstream smoke (50, 200, or 400 mg total particulate matter/m3 from 2R4F cigarettes) was compared to those of filtered air controls. Animals were necropsied at the end of exposure (5 mo) or following 4 or 7 mo of recovery. Lungs were visually inspected for tumors at all necropsies and examined histopathologically at 9 and 12 mo. At 5 mo no tumors were recorded. No significant elevations in tumor incidence or multiplicity were recorded although at 9 mo multiplicity was elevated in the mid-exposure group (0.90 versus 0.55 tumors per animal for controls). At 12 mo, multiplicity was increased over the 9-mo necropsy at all exposures except 200 mg/m3; however, there were no dose-related trends in multiplicity or incidence. Histopathological alterations included hyperplasia, metaplasia, and inflammation of the nose and larynx and proliferative lesions of the lungs. At 9 mo, the multiplicity of focal lung lesions was 1.4 per animal in controls but averaged 1.0 among smoke-exposed groups. There was an inverse relation (p < .059) between smoke concentration and the percentage of hyperplastic lesions at 9 mo. At 12 mo the high-exposure group had slightly increased multiplicity of 2.3 lesions compared with 1.6 among controls, while the percentage of hyperplasic lesions was similar between groups. Nose-only inhalation of mainstream tobacco smoke resulted in chronic inflammatory changes of the respiratory tract yet failed to produce statistically significant changes in tumor incidence or multiplicity.

Phase I study of toremifene in patients with advanced cancer.

A phase I multicenter evaluation of a novel antiestrogen, toremifene, was undertaken in postmenopausal women with various advanced difficult-to-treat malignancies. One hundred and seven women were treated at one of six dosage levels (10, 20, 40, 60, 200, or 400 mg/d orally) for at least 8 weeks. Weekly evaluations for toxicity were conducted. The most common side effects were nausea (31%), vomiting (12%), and hot flashes (29%). Five patients were removed from the study for possible adverse reactions: three patients experienced hypercalcemia; one experienced tremulousness, fatigue, and inability to think clearly; and one had vaginal bleeding. Twelve patients died while on study, 11 with disease progression and one with a pulmonary embolus. Sex hormone-binding globulin (SHBG) levels increased and there was a modest decline in serum antithrombin III levels. Four of 48 assessable patients had partial responses: three with breast cancer and one with endometrial cancer. Toremifene was generally well tolerated at the doses tested.

Further evaluation of intensified and increased total dose of cyclophosphamide for the treatment of primary breast cancer: findings from National Surgical Adjuvant Breast and Bowel Project B-25.

PURPOSE: In 1989, the National Surgical Adjuvant Breast and Bowel Project initiated the B-22 trial to determine whether intensifying or intensifying and increasing the total dose of cyclophosphamide in a doxorubicin-cyclophosphamide combination would benefit women with primary breast cancer and positive axillary nodes. B-25 was initiated to determine whether further intensifying and increasing the cyclophosphamide dose would yield more favorable results. PATIENTS AND METHODS: Patients (n = 2,548) were randomly assigned to three groups. The dose and intensity of doxorubicin were similar in all groups. Group 1 received four courses, ie, double the dose and intensity of cyclophosphamide given in the B-22 standard therapy group; group 2 received the same dose of cyclophosphamide as in group 1, administered in two courses (intensified); group 3 received double the dose of cyclophosphamide (intensified and increased) given in group 1. All patients received recombinant human granulocyte colony-stimulating factor. Life-table estimates were used to determine disease-free survival (DFS) and overall survival. RESULTS: No significant difference was observed in DFS (P =.20), distant DFS (P =.31), or survival (P =.76) among the three groups. At 5 years, the DFS in groups 1 and 2 (61% v 64%, respectively; P =. 29) was similar to but slightly lower than that in group 3 (61% v 66%, respectively; P = 08). Survival in group 1 was concordant with that in groups 2 (78% v 77%, respectively; P =.71) and 3 (78% v 79%, respectively; P =.86). Grade 4 toxicity was 20%, 34%, and 49% in groups 1, 2, and 3, respectively. Severe infection and septic episodes increased in group 3. The decrease in the amount and intensity of cyclophosphamide and delays in therapy were greatest in courses 3 and 4 in group 3. The incidence of acute myeloid leukemia increased in all groups. CONCLUSION: Because intensifying and increasing cyclophosphamide two or four times that given in standard clinical practice did not substantively improve outcome, such therapy should be reserved for the clinical trial setting.

New hormonal approaches to the treatment of breast cancer.

From this data we can draw several conclusions. Although many new hormonal agents have been developed, there has not been significant improvement in tumor response to single agents over the past several decades. By applying knowledge of tumor ER and PR patient populations can be selected which will have a higher response rate to a given hormonal agent. The approach of combining chemotherapy and hormonal therapy does not appear to significantly alter the course of the disease. Sequential use of Tamoxifen, Premarin, and chemotherapy has been shown in cell lines and animal models to synchronize cells thus increasing the efficacy of chemotherapy. Clinical trials of this synchronization generally show higher response rates including significantly higher CR rates than chemotherapy alone. This approach appears promising and is undergoing further trials. LHRH agonists and tamoxifen are effective in premenopausal women with receptor positive tumors and may replace surgical ablative therapy. Aminoglutethimide is gaining wider acceptance as second-line therapy in postmenopausal ER-positive patients. The new agent 4-OHA may be as effective as AG but with fewer side effects. Toremifine a new antiestrogen and RU486 a new antiprogesterone are undergoing trials. While these new agents appear promising with fewer side effects or greater specificity of action, with the exception of sequential hormone priming/chemotherapy they represent 'the same old approach'. By this we mean manipulation of the hormonal environment of the cell in a continuous fashion acting via the estrogen receptor mechanism to achieve tumor regression. While certain new agents may be more tolerable, it is unlikely that a 'break through' will occur with this approach. The problem is the emergence of cells resistant to hormonal therapy. This occurs either through proliferation of a preexisting resistant clone or development under selective pressure of resistant tumors. Some but not all of these resistant clones have escaped by virtue of not having estrogen receptor present. Others have defects further along the action cascade of estrogen stimulation, such as a defective receptor which cannot bind effectively to the nuclear acceptor sites, or lacking certain other growth factors such as TGF-beta. Whatever the deficit, most patients eventually develop resistant tumors. It is in this direction, toward manipulating later points in the estrogen cascade which our attention should turn to achieve more effective hormonal therapy.

Methoxyresorufin: an inappropriate substrate for CYP1A2 in the mouse.

Hepatic microsomes derived from Cypla2(-/-) knockout (KO) and parental strains of mice, C57BL/6N and 129Sv, were used to examine the specificity of methoxyresorufin and acetanilide as substrates for CYP1A2 activity. In addition, animals from each group were exposed to CYP1-inducing compounds. As expected, microsomes from untreated 1a2 KO mice did not have immunodetectable CYP1A2 protein; however, methoxyresorufin-O-demethylase (MROD, 25.5+/-6.1 pmol/min/mg protein) and acetanilide-4-hydroxylation (ACOH, 0.64+/-0.04 nmol/min/mg protein) activities were still present. Furthermore, induction of ethoxyresorufin-O-deethylase (EROD) by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in 1a2 KO mice was accompanied by a greater than 70-fold increase in MROD activity. In contrast, ACOH was only induced 2-fold by TCDD. As with 1a2 KO mice, the parental strains exposed to TCDD or 2,3,4,7,8-pentachlorodibenzofuran (4-PeCDF) showed substantial EROD and MROD induction, whereas ACOH activity was induced to a lesser degree. PCB153 (2,2',4,4',5,5'-hexachlorobiphenyl) resulted in low levels of both EROD and MROD induction. Results indicate that both substrates are subject to metabolism by non-CYP1A2 sources, and the apparent contribution of CYP1A1 activity to methoxyresorufin metabolism makes MROD unsuitable for differentiating CYP1A1 and CYP1A2 activities in the mouse.

In utero and lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin alters postnatal development of seminal vesicle epithelium.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been shown to alter male reproductive development of laboratory animals through in utero and lactational exposure. As a result of exposure, the accessory glands of the male reproductive tract, including the seminal vesicle, are decreased in size as determined by total weight of the tissue. Analysis of seminal vesicle weights over time suggests that the changes may be transient. Administration of 1.0 microg/kg TCDD during gestation caused a significant decrease in seminal vesicle weights of offspring 8-11 months of age. We examined the effects of TCDD on seminal vesicles from rats exposed in utero and lactationally. Pregnant Long Evans rats were gavaged on gestation day 15 with 1.0 microg/kg TCDD in corn oil. Male pups were euthanized and necropsied on postnatal days (PND) 15, 25, 32, 49, 63, and 120. Seminal vesicles were weighed and then fixed in 10% neutral buffered formalin and processed for microscopic examination. Seminal vesicle weights were not significantly decreased until PND 32. Androgen receptor mRNA expression in PND 25 seminal vesicles was not different from control. In the present study, TCDD exposure decreased seminal vesicle epithelial branching and differentiation. Control epithelial cells had tall columnar morphology with relatively abundant cytoplasm, whereas TCDD-treated cells had rounded nuclei and less cytoplasm. In addition, immunolocalization of proliferating nuclear antigen was confined to undifferentiated basal epithelial cells of controls but was found in both basal and luminal cells of the treated seminal vesicle. Results indicate that the TCDD-induced impaired growth of the rat seminal vesicles is associated with a dramatic decrease in the development of the epithelium.

A mixture of dioxins, furans, and non-ortho PCBs based upon consensus toxic equivalency factors produces dioxin-like reproductive effects.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD; dioxin) and related polyhalogenated aromatic hydrocarbons (PHAHs) alter the reproductive development of laboratory animals. Therefore, we exposed animals to a mixture of dioxins, furans, and polychlorinated biphenyls (PCBs) that included TCDD, 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PeCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF), 1,2,3,7,8-pentachlorodibenzofuran (1-PeCDF), 2,3,4,7,8-pentachlorodibenzofuran (4-PeCDF), octachlorodibenzofuran (OCDF), 3,3',4,4'-tetrachlorobiphenyl (PCB77), 3,3',4,4',5-pentachlorobiphenyl (PCB126), and 3,3',4,4',5,5'-hexachlorobiphenyl (PCB169). The mixture composition approximated the relative abundance of these compounds in foodstuff (L. S. Birnbaum and M. J. DeVito, 1995, Toxicology Vol. 105, pp. 391-401). Following the work of Gray et al. with TCDD (1997, Toxicology and Applied Pharmacology Vol. 146, pp. 11-20), we exposed time-pregnant dams on gestation day (GD) 15 at doses up to 1.0 microgram TCDD toxic equivalency (TEQ)/kg and the development of offspring was monitored. This mixture significantly increased the time to puberty in both male and female offspring. At postnatal day (PND) 32 seminal vesicle weights were decreased; however, only ventral prostate weight was affected at PND 49 and no effects were seen at PND 63. In female offspring, the mixture caused dose-dependent increases in the incidence of vaginal thread. Ethoxyresorufin-O-deethylase (EROD) activity was higher than with TCDD the comparable TEQ exposure. Based on the slightly lowered responsiveness to the mixture, we used 2.0 microgram TEQ/kg to examine reproductive effects. This dose elicited the responses observed with 1.0 microgram TCDD/kg. Results indicate that the mixture causes a similar spectrum of effects seen with TCDD and the slightly lowered degree of response based on administered dose appears to be due to decreased transfer of mixture components to the offspring. Thus, the use of the WHO consensus TEFs (M. Van den Berg et al., 1998, Environ. Health Perspec. 106, 775-792) reasonably predicts the developmental toxicity of this mixture of dioxin-like PHAHs.

Increasing uptake and bioactivation with development positively modulate diazinon toxicity in early life stage medaka (Oryzias latipes).

Diazinon, an organophosphate pesticide, becomes biotransformed to a more potent oxon metabolite that inhibits acetylcholinesterase (AChE). Early life stages (els) of medaka, Oryzias latipes, were used to determine how development of this teleost affects sensitivity to diazinon. With developmental progression, from day of fertilization to 7-day-old larvae, we found that the 96-h LC50 and AChE IC50 values decreased, indicating greater host sensitivity to diazinon upon continued development. We then examined changes in AChE activity, its inhibition by the active metabolite diazoxon, and uptake and bioactivation of the compound. AChE activity remained low during much of development but increased rapidly just prior to hatch. In addition, in vitro incubation of tissue homogenates from embryos or larvae showed no differences in the sensitivity of AChE to diazoxon. Uptake studies with 14C-diazinon revealed greater body burdens of 14C as medaka developed. In addition, AChE IC50 values determined by in vivo exposure to diazoxon were greater in larvae than in embryos. Because diazinon is bioactivated by the P450 enzyme system, two P450 inhibitors were used in vivo to explore the role of metabolism in sensitivity. When exposure to diazinon occurred in the presence of increasing amounts of piperonyl butoxide (PBO), AChE inhibition decreased in a dose-response fashion and 2.0 x 10(-5) M PBO alleviated any difference in inhibition between larvae and embryos. However, PBO did not alter total 14C uptake when exposed simultaneously with 14C-diazinon, nor did it affect AChE inhibition using diazoxon. Controls ruled out differential effects of PBO on uptake and inhibition. In addition, a second general P450 inhibitor, 1-aminobenzotriazole, also decreased AChE inhibition. Finally, using exogenous acetylcholinesterase as a trap for the oxon metabolite, larval microsomes displayed greater bioactivation of diazinon than did a microsomal preparation from embryos. Taken together, results suggest that uptake and bioactivation are working to enhance diazinon sensitivity in this developmental model of a teleost fish.

Organophosphate-induced acetylcholinesterase inhibition and embryonic retinal cell necrosis in vivo in the teleost (Oryzias latipes).

Recent monitoring of the Sacramento-San Joaquin River system (CA) indicates that levels of the organophosphate pesticide, diazinon, exceed National Academy of Science guidelines and these levels result in toxicity in USEPA acute toxicity tests with Ceriodaphnia dubia. Since organophosphates (OPs) inhibit acetylcholinesterase (AChE), the present study examined the effects of diazinon on the embryonic nervous system of a model teleost, medaka, Oryzias latipes. Preliminary histological screens revealed limited retinal cell necrosis in control embryos with apparent increased necrosis in diazinon-exposed embryos. Subsequently, embryos were exposed to 1.8 x 10(-5), 4.4 x 10(-5), or to 8.8 x 10(-5) M diazinon and replicates were frozen for biochemical analysis or were fixed for histopathological analysis at days 3, 5, and 7 of development. Diazinon exposure significantly inhibited AChE activity within whole embryos and in homogenates of retinas from treated animals. Histological examination of embryos indicated that as the retina underwent differentiation into distinct cell layers, between days 5 and 7, small foci of necrotic cells became apparent within the inner nuclear layer and isolated individual pyknotic cells were observed in the ganglion layer. Quantification of foci of necrotic cells revealed that 8.8 x 10(-5) M diazinon increased number and area of these lesions. Enzyme histochemistry localized AChE activity to regions equivalent to sites of necrosis. Separate exposures of embryos to the OP, diisopropylphosphorofluoridate, produced large foci of necrotic cells at sites equivalent to those seen following diazinon exposure.

Phase I and II studies of toremifene.

Toremifene (Fareston) is a triphenylethylene derivative structurally similar to tamoxifen (Nolvadex) that was selected for development based on its in vitro activity against breast cancer and its lesser uterotrophic effect than tamoxifen in rat models. In phase I and II studies conducted in several countries, toremifene was well tolerated over a wide range of doses (10 to 680 mg/d). The major side effects were hot flashes, nausea, and vomiting. Toremifene's excretion half-life is 5 days. It produces a modest decline in serum levels of luteinizing hormone, follicle-stimulating hormone, and antithrombin III, as well as an increase in sex hormone-binding globulin levels. In studies in which toremifene was used as first-line therapy in patients with estrogen receptor (ER)-positive or ER-unknown tumors, response rates to doses of 40 to 60 mg/day ranged from 30% to 54%. In two larger studies of patients who had proved refractory to tamoxifen therapy, toremifene produced an objective response rate of 4% to 5%. When patients with stable disease were added to those with objective responses, 27% to 28% of patients were considered to derive clinical benefit from toremifene. The dose range chosen for further study was 40 to 60 mg/d.

A phase II trial of vinblastine, bleomycin, and cisplatin induction followed by dacarbazine and dibromodulcitol maintenance in the treatment of metastatic melanoma. A follow-up study of twenty-two patients.

Twenty-two patients with metastatic melanoma were treated with a chemotherapy regimen consisting of two cycles of induction therapy with vinblastine, bleomycin, and cisplatin, followed by maintenance therapy with dacarbazine and dibromodulcitol. A 17% response rate was noted in this patient group, with a median survival of 40 weeks. Objective responses were limited to cutaneous, nodal, pulmonary, and one adrenal site of metastatic disease. Toxicity was acceptable and was limited to myelosuppression and nausea with emesis. Further study appears warranted to define the optimal treatment plan for metastatic melanoma.

The efficacy of recombinant human granulocyte colony-stimulating factor and recombinant human granulocyte macrophage colony-stimulating factor in permitting the administration of higher doses of cyclophosphamide in a doxorubicin-cyclophosphamide combination. An NSABP pilot study in patients with metastatic or high-risk primary breast cancer. National Surgical Adjuvant Breast and Bowel Project.

Colony-stimulating factors (CSFs) shorten the duration of myelosuppression following chemotherapy and, thus, allow the administration of higher doses. This study evaluates the efficacy of granulocyte macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) in allowing administration of high-dose cyclophosphamide in combination with doxorubicin. Ninety women with metastatic, locally advanced, or high-risk (> or = 10 positive nodes) breast cancer and no prior anthracycline treatment were given doxorubicin (60 mg/m2) with progressively increased doses of cyclophosphamide (1,200 mg/m2, 1,800 mg/m2, and 2,400 mg/m2). The first 60 patients received GM-CSF; the remaining 30, G-CSF. The maximum tolerated dose was not reached with 2,400 mg/m2 of cyclophosphamide. When compared to GM-CSF, G-CSF significantly reduced the duration of granulocytopenia (P < .001). No differences in duration of thrombocytopenia were noted. The results were not sufficiently consistent to indicate a trend toward reduction in rates of febrile neutropenia with one CSF versus the other. However, patients who received G-CSF were hospitalized less frequently than those receiving GM-CSF. With CSFs, high-dose cyclophosphamide in combination with doxorubicin can be safely administered on an outpatient basis. A shorter duration of granulocytopenia resulted from the use of G-CSF than from GM-CSF.

Inefficacy of low-dose continuous oral etoposide in non-small cell lung cancer.

Etoposide is more active in small cell lung cancer when given over 5 days than as a single injection. To examine this concept further, we designed this Phase II study in NSCLC using continuous low-dose oral etoposide. We enrolled 19 patients with measurable disease and the standard eligibility criteria. 16 had no prior chemotherapy. Etoposide was given at a dose of 50 mg by mouth daily. The median duration of therapy was 63 days (14-212 days). Toxicity was mild myelosuppression and GI symptoms. Therapy was discontinued because of progression of disease in 13 patients, toxicity (GI) in 3 patients; intercurrent disease, self-removal, and other reasons in 1 patient each. No complete or partial responses were seen (95% CI: 0-17.6%). The median survival after entry into the trial was 159 days (41-571+ days). We conclude that low-dose continuous oral etoposide is a well-tolerated but ineffective regimen in non-small cell lung cancer.

A phase II trial of chlorambucil in non-small cell lung cancer.

A Phase II trial of high-dose chlorambucil at 108 mg/m2 was undertaken in non-small cell lung cancer. No complete or partial objective responses were observed, and significant toxicity, including nausea, vomiting, and seizures, was noted. Chlorambucil at this dose and schedule of administration is not recommended for the treatment of non-small cell lung cancer.

Identification and characterization of a cDNA encoding cytochrome P450 3A from the fresh water teleost medaka (Oryzias latipes).

A new member of the CYP3A gene family has been cloned from the teleost fish medaka (Oryzias latipes) by reverse-transcriptase polymerase chain reaction (RT-PCR). Degenerate primers homologous to highly conserved regions of known CYP3A sequences were used for initial RT-PCRs. Individual PCR products were cloned, sequenced, and identified as those belonging to the cytochrome P450 superfamily based on amino acid sequence similarity and the presence of the highly conserved heme-binding region. PCR products were subsequently used as probes to screen a complementary DNA library. A full-length cDNA clone was identified containing a 1758-base-pair (bp) insert with an open reading frame encoding a single peptide of 500 amino acids. Comparisons of the deduced amino acid sequence to other known cytochrome P450 sequences indicate that this gene product is most similar to the CYP3A gene family and has been designated as CYP3A38 by the cytochrome P450 nomenclature committee. Northern blot analysis identified two abundant CYP3A related transcripts in liver of both male and female adults and demonstrated quantitative differences in abundance according to gender. Similarly, Western blot analysis demonstrated the presence of two abundant cytochrome P450 related proteins in liver of both male and female adults. These results suggests that O. latipes contains multiple forms of CYP3A. Heterologous expression of CYP3A38 cDNA in HEK 293 cells produced a single protein that was reactive with anti-scup P450A (CYP3A) polyclonal antibody. Microsomes of HEK 293 cells expressing recombinant CYP3A38 protein actively catalyzed the hydroxylation of testosterone.

Alterations in physiological parameters of rainbow trout (Oncorhynchus mykiss) with exposure to copper and copper/zinc mixtures.

Rainbow trout (Oncorhynchus mykiss) were exposed to sublethal concentrations of copper (Cu, 14 microgram/liter) and zinc (Zn, 57 and 81 microgram/liter) for a 21-day period. The four treatments included a control, a Cu control, a Cu and low-Zn treatment and a Cu and high-Zn treatment. Selected parameters [e.g., hemoglobin (Hb), hematocrit (Hct), plasma glucose, lactate and cortisol, differential leukocyte count, respiratory burst, tissue metal concentrations, hepatic metallothionein (MT), brain acetylcholinesterase (AChE)] were evaluated at 2, 7, 14, and 21 days of exposure. Whole blood and plasma parameters were not altered by exposure to metals. The percentage of lymphocytes was consistently decreased in the three metal treatments, while percentages of neutrophils and monocytes were increased. Respiratory burst activity was elevated in all metal treatments. Gill Zn concentration was highly variable, with no significant alterations occurring. Gill Cu concentration was elevated above control levels in all metal treatments. Gill Cu concentration in the two Cu/Zn treatments was also elevated above levels in the Cu control. Hepatic metal concentrations and MT levels were not altered from control values. Measurements of brain AChE indicated an elevation in this parameter across metal treatments. In general, alterations in physiological parameters appeared to be due to Cu, with Zn having no interactive effect.

TCDD-mediated oxidative stress in male rat pups following perinatal exposure.

2,3,7,8-tetrachlorododibenzo-p-dioxin (TCDD) is a highly persistent trace environmental contaminant and is one of the most potent toxicants known. Exposure to TCDD has been shown to cause oxidative stress in a variety of animal models. In this study, pregnant Long Evans rats were dosed with 1 microg TCDD/kg on gestational day (GD) 15 so as to investigate oxidative stress in the liver of male pups following gestational exposure to TCDD. Lipid peroxidation (TBARS), production of reactive oxygen species (ROS), and total glutathione (GSH) were assayed to identify changes in oxidative stress parameters in the pup liver at GD 21 and postnatal days (PND) 4, 25, 32, 49, and 63. Mean ROS levels in pups were elevated at all time points tested with a significant elevation at PND 4 and PND 25. However, pup hepatic lipid peroxidation was unchanged throughout the time course. In addition, hepatic total GSH levels were not significantly changed although the means for the TCDD-treated groups were less than those of the controls at all time points except PND 49. The results indicate that although the levels of ROS are increased following gestational/lactational exposure, this increase does not translate to direct oxidative damage or significant changes to endogenous antioxidant defense mechanisms. Further investigation into the effect of gestational/lactational exposure in pups should include additional endpoints for further characterization of the time course of the response, the effect upon extrahepatic tissues, and investigation of differences between male and female offspring.

Disposition of polychlorinated dibenzo-p-dioxins, dibenzofurans, and non-ortho polychlorinated biphenyls in pregnant long evans rats and the transfer to offspring.

Pharmacokinetic properties of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDFs), and non-ortho biphenyls (PCBs) play a critical role in their relative toxicity. The present study examined the transfer of these chemicals to offspring and placenta. Pregnant Long Evans rats received 0.0 (control), 0.05, 0.2, 0.8, and 1.0 microg/kg of dioxin toxic equivalence (TEQ) by oral gavage on the 15th gestational day (GD 15), using a dosing mixture that contained 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF), 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PeCDD), 1,2,3,7,8-pentachlorodibenzofuran (1-PeCDF), 2,3,4,7,8-pentachlorodibenzofuran (4-PeCDF), octachlorodibenzofuran (OCDF), 3,3',4,4'-tetrachlorobiphenyl (PCB 77), 3,3',4,4',5-pentachlorobiphenyl (PCB 126), and 3,3',4,4',5,5'-hexachlorobiphenyl (PCB 169) in ratios approximating that in food. Rats were euthanized on GD 16, GD 21, and postnatal day 4 (PND 4). The chemical concentrations in fetus, pup, placenta, and maternal liver, serum, and adipose tissue were determined using gas chromatography/high-resolution mass spectrometry. A dose-dependent increase in hepatic sequestration was seen with TCDD, PeCDD, 4-PeCDF, OCDF, PCB 126, and PCB 169, and the transfer to offspring was reduced at higher doses. 4-PeCDF, PeCDD and PCB 126 showed higher liver affinity than TCDD. TCDF, 1-PeCDF, and PCB 77 were metabolized rapidly. On GD 16, TCDD and the three PCBs reached equilibration between the fetus and placenta, but this did not occur with PeCDD and 4-PeCDF until GD 21, according to the lipid-based concentrations. Offspring compartments received more of the dosed compounds lactationally than transplacentally (7-28% versus 0.5-3%). The behavior of each congener was dose-dependent; therefore, extrapolation of high-dose experimental data should be used with caution.

Phase I study of the tolerance and pharmacokinetics of toremifene in patients with cancer.

Toremifene is a triphenylethylene derivative structurally and pharmacologically similar to tamoxifen. This Phase I trial assessed the safety, pharmacokinetics, anti-estrogenic, and estrogenic effects of toremifene at six dose levels (10, 20, 40, 60, 200, and 400 mg/day). The most common side-effects associated with therapy included gastrointestinal (nausea/vomiting 43%), anti-estrogenic (hot flashes 29%), and CNS (dizziness/vertigo 12%). Three patients with bone metastases from breast cancer developed hypercalcemia. At doses greater than or equal to 40 mg/day a decline in LH and FSH occurred which was not statistically significant. At all doses tested SHBG rose during therapy. A dose dependent estrogenic blockade was seen on the vaginal epithelium following challenge with transdermal estradiol. Steady-state concentrations of toremifene were reached within 4 weeks, and at doses greater than or equal to 60 mg/day ranged from 879-3445 ng/ml. The half-life was found to be 5 days, and at three weeks following discontinuation of treatment concentrations greater than 24 ng/ml were detected. The N-desmethyl and 4-hydroxy metabolites achieved steady state levels within 4 weeks and had half-lives of 6 and 5 days respectively. Partial responses were seen in 4 patients, 3 with breast cancer treated at 200 mg/day and 1 with endometrial cancer treated at 400 mg/day.