The Effects of Cetuximab Alone and in Combination With Radiation and/or Chemotherapy in Lung Cancer

Purpose: The epidermal growth factor receptor (EGFR) overexpressed in approximately 80% of non-small cell lung cancers (NSCLC) is a target for novel therapeutics. Concurrent chemoradiation is the current standard of care for treatment of patients with locally advanced NSCLC. However, < 20% of patients remain disease-free at 5 years despite this aggressive treatment. Cetuximab is a humanized monoclonal antibody that recognizes the human EGFR, and in previous studies, inhibited the growth of EGFR-expressing human cancer cell lines. In this report, we investigated the cellular and molecular effects of cetuximab alone and in combination with radiation and/or chemotherapy in human NSCLC cell lines with varying levels of EGFR overexpression in vitro and in vivo.

Experimental Design: We evaluated the EGFR status of a panel of human NSCLC cancer cell lines by immunohistochemistry and flow cytometry. We then evaluated cetuximab effects on growth, cell cycle distribution, and downstream intracellular signaling molecules in this panel of NSCLC cancer cell lines. NSCLC cell lines were treated with cetuximab alone or in combination with radiation, chemotherapy, or chemoradiation to determine the cooperative effects of cetuximab both in vitro and in vivo in athymic nude mice bearing NSCLC xenografts.

Results: Cetuximab alone inhibited the in vitro growth of some but not all EGFR-expressing NSCLC cell lines in a dose-dependent manner. Flow cytometric analysis of cell cycle distribution after 24 hours of cetuximab treatment revealed a shift into the G0/G1 phase of the cell cycle in cetuximab-sensitive EGFR-expressing cell lines and at concentrations that were growth-inhibitory. There were no cell cycle changes in the EGFR-negative cell lines. After 4 hours of exposure, cetuximab reduced epidermal growth factor (EGF)-induced phosphorylation of EGFR (pEGFR) and HER-2 (pHER2) in cetuximab-sensitive cell lines but not in cetuximab-resistant cell lines. Cetuximab reduced EGF-induced phosphorylation of extracellular signal-regulated kinase-1/2 (pERK) in all EGFR-expressing cell lines. In the absence of EGF, cetuximab alone increased the level of pEGFR and pHER2 above that seen in untreated control cells in both sensitive and resistant cell lines that were EGFR- and HER2-positive, but not in EGFR- or HER2-negative lines. Despite the cetuximab-induced increase in phosphorylation of EGFR and HER2, peak EGF-induced levels of pEGFR and pHER2 were reduced by cetuximab in the cetuximab-sensitive lines but not in the resistant lines. Cooperative (combination index values < 1.0) growth inhibitory effects were observed in vitro combination assays with cetuximab and radiation only in cetuximab-sensitive NSCLC cell lines. A lack of cooperation was seen in cetuximab-insensitive NSCLC cell lines. Similar findings were observed with in vitro combination studies of cetuximab plus cisplatin or paclitaxel. In nude mice bearing EGFR-expressing, cetuximab-sensitive, NSCLC cell line xenografts, cetuximab plus radiation induced a marked improvement in tumor growth inhibition over either agent alone. The growth inhibitory effects of cetuximab-radiation were similar to the growth inhibitory effects of concurrent chemoradiation. Triple combination therapy of cetuximab and chemoradiation yielded a nonsignificant advantage in tumor growth control over doublet combinations (cetuximab and radiation or chemoradiation) in vivo.

Conclusions: Similar results in tumor growth inhibition observed in mice treated with cetuximab-radiation and cisplatin-radiation provide a rationale for the clinical investigation of cetuximab with concurrent radiation in selected patients with locally advanced NSCLC. Local tumor control and treatment toxicity should be evaluated between cetuximab-radiation and chemoradiation regimens. Proper patient selection will be critical to the success of such trials and further studies are needed to identify optimal patient selection criteria.

The effects of cetuximab alone and in combination with radiation and/or chemotherapy in lung cancer

PURPOSE

The epidermal growth factor receptor (EGFR) overexpressed in approximately 80% of non-small cell lung cancers (NSCLC) is a target for novel therapeutics. Concurrent chemoradiation is the current standard of care for treatment of patients with locally advanced NSCLC. However, < 20% of patients remain disease-free at 5 years despite this aggressive treatment. Cetuximab is a humanized monoclonal antibody that recognizes the human EGFR, and in previous studies, inhibited the growth of EGFR-expressing human cancer cell lines. In this report, we investigated the cellular and molecular effects of cetuximab alone and in combination with radiation and/or chemotherapy in human NSCLC cell lines with varying levels of EGFR overexpression in vitro and in vivo.

EXPERIMENTAL DESIGN

We evaluated the EGFR status of a panel of human NSCLC cancer cell lines by immunohistochemistry and flow cytometry. We then evaluated cetuximab effects on growth, cell cycle distribution, and downstream intracellular signaling molecules in this panel of NSCLC cancer cell lines. NSCLC cell lines were treated with cetuximab alone or in combination with radiation, chemotherapy, or chemoradiation to determine the cooperative effects of cetuximab both in vitro and in vivo in athymic nude mice bearing NSCLC xenografts.

RESULTS

Cetuximab alone inhibited the in vitro growth of some but not all EGFR-expressing NSCLC cell lines in a dose-dependent manner. Flow cytometric analysis of cell cycle distribution after 24 hours of cetuximab treatment revealed a shift into the G(0)/G(1) phase of the cell cycle in cetuximab-sensitive EGFR-expressing cell lines and at concentrations that were growth-inhibitory. There were no cell cycle changes in the EGFR-negative cell lines. After 4 hours of exposure, cetuximab reduced epidermal growth factor (EGF)-induced phosphorylation of EGFR (pEGFR) and HER-2 (pHER2) in cetuximab-sensitive cell lines but not in cetuximab-resistant cell lines. Cetuximab reduced EGF-induced phosphorylation of extracellular signal-regulated kinase-1/2 (pERK) in all EGFR-expressing cell lines. In the absence of EGF, cetuximab alone increased the level of pEGFR and pHER2 above that seen in untreated control cells in both sensitive and resistant cell lines that were EGFR- and HER2-positive, but not in EGFR- or HER2-negative lines. Despite the cetuximab-induced increase in phosphorylation of EGFR and HER2, peak EGF-induced levels of pEGFR and pHER2 were reduced by cetuximab in the cetuximab-sensitive lines but not in the resistant lines. Cooperative (combination index values < 1.0) growth inhibitory effects were observed in vitro combination assays with cetuximab and radiation only in cetuximab-sensitive NSCLC cell lines. A lack of cooperation was seen in cetuximab-insensitive NSCLC cell lines. Similar findings were observed with in vitro combination studies of cetuximab plus cisplatin or paclitaxel. In nude mice bearing EGFR-expressing, cetuximab-sensitive, NSCLC cell line xenografts, cetuximab plus radiation induced a marked improvement in tumor growth inhibition over either agent alone. The growth inhibitory effects of cetuximab-radiation were similar to the growth inhibitory effects of concurrent chemoradiation. Triple combination therapy of cetuximab and chemoradiation yielded a nonsignificant advantage in tumor growth control over doublet combinations (cetuximab and radiation or chemoradiation) in vivo.

CONCLUSIONS

Similar results in tumor growth inhibition observed in mice treated with cetuximab-radiation and cisplatin-radiation provide a rationale for the clinical investigation of cetuximab with concurrent radiation in selected patients with locally advanced NSCLC. Local tumor control and treatment toxicity should be evaluated between cetuximab-radiation and chemoradiation regimens. Proper patient selection will be critical to the success of such trials and further studies are needed to identify optimal patient selection criteria.

A Phase I and Pharmacokinetic Study of Exisulind and Docetaxel in Patients with Advanced Solid Tumors

PURPOSE

Exisulind (sulindac sulfone, FGN-1, Aptosyn) is a sulindac metabolite that induces apoptosis via inhibition of cyclic GMP-phosphodiesterase. This agent demonstrated tumor growth inhibition in rodent models of colon, breast, prostate, and lung carcinogenesis. In an orthotopic model of human non-small-cell lung cancer, the combination of exisulind and docetaxel prolonged survival in athymic nude rats, forming the basis of this phase I combination study.

EXPERIMENTAL DESIGN

This study evaluated the toxicity and pharmacokinetics of combining exisulind (150-250 mg) given orally twice daily and docetaxel (30-36 mg/m2) administered intravenously on days 1, 8, and 15 of a 4-week cycle.

RESULTS

Twenty patients with a range of advanced solid tumors (median age, 59 years; age range, 35-77 years; median performance status, 1) received a total of 70 courses. Observed adverse events were mild to moderate, and there was no dose-limiting toxicity at any level. Grade 3 gastrointestinal toxicities were present in 10 of the 70 cycles (10%) and included nausea, vomiting, dyspepsia, and elevated alkaline phosphatase. Neutropenia was present in four cycles in patients treated with a docetaxel dose of 36 mg/m2. Pharmacokinetic analysis did not demonstrate a clear effect of exisulind on docetaxel pharmacokinetics and vice versa. Relationships were evident between the plasma concentration of exisulind and the development of grade 2 or greater toxicities. One third of patients maintained stable disease for 3 to 12 cycles, but no objective responses were observed.

CONCLUSIONS

The combination of docetaxel (36 mg/m2, weekly) and exisulind (500 mg/d) was reasonably well tolerated, and it is undergoing phase II testing in patients with non-small-cell lung cancer.

ATP-Binding Cassette Transporter G8 Gene As a Determinant of Apolipoprotein B-100 Kinetics in Overweight Men

OBJECTIVE

We examined the influence of genetic variation of the ATP-binding cassette (ABC) transporter G8 on apolipoprotein B (apoB) kinetics in overweight/obese men.

METHODS AND RESULTS

Very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) apoB kinetics were determined in 47 men (body mass index 32+/-3 kg/m2) using stable isotope and multicompartmental modeling to estimate production rate (PR), fractional catabolic rate (FCR), and VLDL to LDL-apoB conversion. Relative to the wild-type (400TT), subjects carrying the ABCG8 400K allele had significantly decreased plasma concentrations of triglycerides, sitosterol, and campesterol, lower PR of VLDL-apoB, and higher VLDL to LDL-apoB conversion (P<0.05). The PR and FCR of LDL-apoB were also significantly higher with 400K allele (P<0.05). No association was found with ABCG8 D19H. Compared with APOE2 or APOE3, APOE4 carriers had significantly higher plasma LDL-cholesterol concentrations and lower LDL-apoB FCR. During multiple regression analysis including age, homeostasis model assessment score, plasma concentrations of sitosterol, and lathosterol, ABCG8 and apoE genotypes were independent determinants of VLDL-apoB PR and LDL-apoB FCR, respectively (P<0.05).

CONCLUSIONS

Variation in the ABC transporter G8 appears to independently influence the metabolism of apoB-containing lipoproteins in overweight/obese subjects. This may have therapeutic implications for the management of dyslipidemia in these subjects.

Annexin 2 expression is reduced in human osteosarcoma metastases

Osteosarcoma is an aggressive primary bone cancer affecting primarily children and young adults. The development of valuable diagnostic indicators and therapeutic agents will be enhanced by the identification and characterization of genes that contribute to its aggressive behavior. We used representational difference analysis to isolate genes differentially expressed between primary human osteosarcoma tumors and subsequent metastatic lung lesions to identify genes potentially involved in metastatic potential. Several genes were differentially expressed between the two tumor populations, including annexin2. The levels of annexin2 mRNA and protein inversely correlated with metastatic potential in a subset of human osteosarcoma tumor specimens, as well as in a human osteosarcoma cell line selected for increased metastatic potential. Annexin2 has been described in several cellular localizations with various functional implications, many of which may be relevant to metastatic potential. Therefore, the subcellular localization of endogenous annexin2 protein was evaluated biochemically by subcellular fractionation and immunologically by flow cytometry and immunofluorescence in osteoblastic cells. Annexin2 was localized to the cytoplasm and intracellular aspect of the plasma membrane, excluded from the nucleus and undetectable on the cell surface or in the conditioned medium. Overexpression of annexin2 in osteosarcoma cells did not alter several in vitro phenotypes often used to assess metastatic potential including motility, adhesion, and proliferation. However, our previous data have implicated annexin2 in the mineralization process of osteoblastic cells in vitro. Consistent with an increase in differentiation-induced mineralization, there was diminished tumorigenicity and experimental metastatic potential of osteosarcoma cells overexpressing annexin2. These data suggest that annexin2 may downregulate osteosarcoma aggressiveness by inducing a more differentiated state in osteoblastic cells.

Effect of a statin on hepatic apolipoprotein B-100 secretion and plasma campesterol levels in the metabolic syndrome

OBJECTIVE

We aimed to study the effect of atorvastatin, a statin, on cholesterol synthesis and absorption and VLDL-apoB metabolism in obese men with the metabolic syndrome.

METHODS

A total of 25 dyslipidaemic obese men were randomized to atorvastatin (n=13) (40 mg/day) or matching placebo (n=12) for 6 weeks. Hepatic secretion and fractional catabolic rate (FCR) of VLDL-apoB was measured using an intravenous bolus of d(3)-leucine before and after treatment. ApoB isotopic enrichment was measured using GCMS and multicompartmental modelling. Plasma lathosterol: cholesterol and campesterol:cholesterol ratios were determined to assess cholesterol synthesis and cholesterol absorption, respectively.

RESULTS

Compared with placebo, atorvastatin significantly decreased (P<0.05) total cholesterol, triglyceride, LDL-cholesterol and VLDL-apoB. Plasma lathosterol:cholesterol ratio decreased from 26.4+/-2.4 to 8.8+/-0.8, while the campesterol:cholesterol ratio increased from 26.5+/-4.4 to 38.6+/-5.8 (P<0.01). Atorvastatin also increased VLDL-apoB FCR from 3.82+/-0.33 to 6.30+/-0.75 pools/day (P<0.01), but did not significantly alter VLDL-apoB secretion (12.8+/-1.7 to 13.8+/-2.0 mg/kg/day).

CONCLUSIONS

In obesity, atorvastatin inhibits cholesterogenesis but increases intestinal cholesterol absorption. The increased cholesterol absorption may counteract the inhibitory effect on hepatic VLDL-apoB secretion, but it does not apparently influence enhanced catabolism of VLDL-apoB.

Waist circumference, waist-to-hip ratio and body mass index as predictors of adipose tissue compartments in men

BACKGROUND

The accumulation of fat in visceral and posterior subcutaneous adipose tissue compartments is highly correlated with the metabolic abnormalities that contribute to increased risk of diabetes mellitus and cardiovascular disease.

AIM

To determine which of waist circumference (WC), waist-to-hip ratio (WHR) and body mass index (BMI) was the best predictor of intraperitoneal and posterior subcutaneous abdominal adipose tissue mass in men.

METHODS

We studied 59 free-living men with a wide range of BMI. WC, WHR and BMI were determined using standard methods. Intraperitoneal, retroperitoneal, anterior subcutaneous and posterior subcutaneous abdominal adipose tissue masses (IPATM, RPATM, ASAATM and PSAATM, respectively) were quantified using magnetic resonance imaging.

RESULTS

In univariate regression analysis, WC, WHR and BMI were all significantly and positively correlated (all p < 0.05) with IPATM, RPATM, ASAATM and PSAATM. To assess the relative strength of these associations, we used non-nested regression models. There was no significant difference between WC and WHR in predicting IPATM and RPATM; WC was a stronger predictor of ASAATM (p < 0.001) and PSAATM (p < 0.001) than WHR; WC was also a stronger predictor of IPATM (p = 0.042) and RPATM (p = 0.045) than BMI, but the relative strengths of WC and BMI in predicting ASSATM and PSAATM did not different significantly (p > 0.05); there was no significant difference between BMI and WHR in predicting IPATM and RPATM (p>0.05), but BMI was a stronger predictor of ASAATM (p = 0.036) and PSAATM (p < 0.001) than WHR.

DISCUSSION

In men WC is the anthropometric index that most uniformly predicts the distribution of adipose tissue among several fat compartments in the abdominal region, there apparently being little value in measuring WHR or BMI.

Exisulind-induced apoptosis in a non-small cell lung cancer orthotopic lung tumor model augments docetaxel treatment and contributes to increased survival

We reported previously a significant increase in survival of nude rats harboring orthotopic A549 human non-small cell lung cancer tumors after treatment with a combination of exisulind (Sulindac Sulfone) and docetaxel (D. C. Chan, Clin. Cancer Res., 8: 904-912, 2002). The purpose of the current study was to determine the biochemical mechanisms responsible for the increased survival by an analysis of the effects of both drugs on A549 orthotopic lung tumors and A549 cells in culture. Orthotopic A549 rat lung tissue sections from drug-treated rats and A549 cell culture responses to exisulind and docetaxel were compared using multiple apoptosis and proliferation analyses [i.e., terminal deoxynucleotidyl transferase-mediated nick end labeling, active caspase 3, the caspase cleavage products cytokeratin 18 and p85 poly(ADP-ribose) polymerase, and Ki-67]. Immunohistochemistry was used to determine cyclic GMP (cGMP) phosphodiesterase (PDE) expression in tumors. The cGMP PDE composition of cultured A549 cells was resolved by DEAE-Trisacryl M chromatography and the pharmacological sensitivity to exisulind, and additional known PDE inhibitors were determined by enzyme activity assays. Exisulind inhibited A549 cell cGMP hydrolysis and induced apoptosis of A549 cells grown in culture. PDE5 and 1 cGMP PDE gene family isoforms identified in cultured cells were highly expressed in orthotopic tumors. The in vivo apoptosis rates within the orthotopic tumors increased 7-8-fold in animals treated with the combination of exisulind and docetaxel. Exisulind increased the in vivo apoptosis rates as a single agent. Docetaxel, but not exisulind, decreased proliferative rates within the tumors. The data indicate that exisulind-induced apoptosis contributed significantly to the increased survival in rats treated with exisulind/docetaxel. The mechanism of exisulind-induced apoptosis involves inhibition of cGMP PDEs, and these results are consistent with a cGMP-regulated apoptosis pathway.

Comparison of intraperitoneal and posterior subcutaneous abdominal adipose tissue compartments as predictors of VLDL apolipoprotein B-100 kinetics in overweight/obese men

AIMS

The influence of different regional adipose tissue (AT) compartments on insulin resistance and dyslipidaemia may account for variations in risk of diabetes and cardiovascular disease. The purpose of this study was to examine the association of intraperitoneal and posterior subcutaneous abdominal AT with very-low-density lipoprotein apolipoprotein B-100 (VLDL-apoB) kinetics in overweight/obese men.

METHODS

Intraperitoneal, anterior subcutaneous and posterior subcutaneous abdominal AT mass (IPATM, ASAATM and PSAATM respectively) were quantified in 51 overweight/obese men using magnetic resonance imaging. Hepatic secretion of VLDL-apoB was measured using an intravenous infusion of 1-[13C]-leucine. Isotopic enrichment of VLDL-apoB was measured using gas chromatography mass spectrometry and a multicompartmental model used to estimate VLDL-apoB metabolic parameters. Insulin resistance was estimated by homeostasis model assessment (HOMA) score.

RESULTS

In univariate analysis, IPATM, ASAATM and PSAATM were significantly associated with HOMA score (r = 0.554, 0.425 and 0.440 respectively; p < 0.01). Intraperitoneal abdominal AT mass was also associated with plasma triglycerides (r = 0.292, p < 0.05), VLDL-apoB concentrations (r = 0.407, p < 0.01) and VLDL-apoB secretion (r = 0.390, p < 0.05). Intraperitoneal abdominal AT mass remained significantly associated with VLDL-apoB secretion (r = 0.344, p < 0.05) and HOMA score (r = 0.368, p < 0.01) after adjusting for total body fat. In multiple regression analysis including IPATM, non-esterified fatty acids and age, IPATM was the best predictor of VLDL-apoB secretion (R2 = 17%, p < 0.01) and HOMA score (R2 = 32%, p < 0.001). None of the fat compartments were significantly associated with VLDL-apoB catabolism.

CONCLUSIONS

In overweight/obese men the intraperitoneal AT mass is a better predictor of VLDL-apoB secretion and insulin resistance than either posterior or anterior subcutaneous abdominal AT mass.

Silibinin induces growth inhibition and apoptotic cell death in human lung carcinoma cells

BACKGROUND

The high systemic toxicity of chemotherapeutic agents limits their use to treat clinical lung cancer. These limitations could be minimized/overcome by using non-toxic phytochemicals, like, silibinin.

MATERIALS AND METHODS

We used small cell lung carcinoma cells (SCLC) SHP-77 and non-small cell lung carcinoma cells (NSCLC) A-549, analyzing cell growth inhibition and death with Trypan blue exclusion, indices of the cell cycle progression with flow cytometry and apoptosis with propidium iodide and Hoechst 33342.

RESULTS

Silibinin (25, 50 and 100 microM) treatment of SHP-77 and A-549 cells resulted in their growth inhibition and cell death. Cell cycle studies showed a small increase in G0-G1 population at all the time intervals in SHP-77 cells, however, in A-549 cells, a slight increase in G0-G1 but strong increase in S-phases was observed at lower treatment times, and a strong increase in G0-G1 population at 72 hours. Quantitative apoptotic studies showed that silibinin causes apoptotic cell death in both a dose- and a time-dependent manner with SHP-77 cells showing more apoptotic effect than A-549 cells.

CONCLUSION

Silibinin significantly induces growth inhibition, a moderate cell cycle arrest and a strong apoptotic death in both small cell and non-small cell human lung carcinoma cells, which warrants further studies to assess the efficacy of this non-toxic agent in animal lung tumor models.

Bradykinin antagonists as new drugs for prostate cancer

Bradykinin (BK) is an autocrine growth factor for lung and prostate cancers. BK also facilitates tumor extension by increasing tissue permeability and stimulating angiogenesis. Peptide BK antagonists are in development as potential new drugs for lung cancer. Newer nonpeptide BK antagonists have even higher potency against lung cancer, in vitro and in vivo. These compounds have now been applied to the study of prostate cancers, and have been found to be effective. Prostate cancer cell line PC3 is derived from a late-stage, hormone-independent, metastatic tumor; its growth is difficult to inhibit. Our established BK antagonists, while less effective against this line of prostate cancer in xenografts in nude mice than against lung cancer, are active and have led the way to development of new peptide and nonpeptide agents for prostate cancer. In addition to inhibiting cancer cell growth directly, they inhibit angiogenesis mediated by vascular endothelial growth factor, and inhibit increased tissue permeability mediated by membrane metalloproteases in these tumors. This class of compounds offers hope for development of new drugs for refractory prostate cancer.

Factorial study of the effects of atorvastatin and fish oil on dyslipidaemia in visceral obesity

BACKGROUND

Dyslipidaemia may account for increased risk of cardiovascular disease in central obesity. Pharmacotherapy is often indicated in these patients, but the optimal approach remains unclear. We investigated the effects of atorvastatin and fish oil on plasma lipid and lipoprotein levels, including remnant-like particle-cholesterol and apolipoprotein C-III, in dyslipidaemic men with visceral obesity.

METHODS

We carried out a 6-week randomized, placebo-controlled, 2 x 2 factorial intervention study of atorvastatin (40 mg day(-1)) and fish oil (4 g day(-1)) on plasma lipids and lipoproteins in 52 obese men (age 53 +/- 1 years, BMI 33.7 +/- 0.55 kg m(-2)) with dyslipidaemia and insulin resistance. Treatment effects were analysed by general linear modelling.

RESULTS

Atorvastatin had significant main effects in decreasing triglycerides (-0.38 +/- 0.02 mmol L(-1), P = 0.002), total cholesterol (-1.89 +/- 0.17 mmol L(-1), P = 0.001), LDL-cholesterol (-1.78 +/- 0.14 mmol L(-1), P = 0.001), remnant-like particle-cholesterol (-0.08 +/- 0.04 mmol L(-1), P = 0.035), apolipoprotein B (-49 +/- 4 mg dL(-1), P = 0.001), apolipoprotein C-III (-12.6 +/- 6.1 mg L(-1), P = 0.044) and in increasing HDL-cholesterol (+0.10 +/0- 0.04 mmol L(-1), P = 0.007). Fish oil had significant main effects in decreasing triglycerides (-0.38 +/- 0.11 mmol L(-1), P = 0.002) and in increasing HDL-cholesterol (+0.07 +/- 0.04 mmol L(-1), P = 0.041). There were no significant changes in weight or insulin resistance during the study.

CONCLUSIONS

Atorvastatin and fish oil have independent and additive effects in correcting dyslipidaemia in viscerally obese men. Improvement in abnormalities in remnant lipoproteins may occur only with use of atorvastatin. Combination treatment with statin and fish oil may, however, offer an optimal therapeutic approach for globally correcting dyslipidaemia in obesity.

Bradykinin antagonist dimer, CU201, inhibits the growth of human lung cancer cell lines in vitro and in vivo and produces synergistic growth inhibition in combination with other antitumor agents

Small cell lung cancers (SCLCs), many non-SCLCs, and other cancers have neuroendocrine features, including paracrineand autocrine growth stimulation by various neuropeptides. Interference with this pathway is an attractive target for novel therapies. We developed a novel bradykinin antagonist dimer, CU201 (B9870), that acts as a "biased agonist" for neuropeptides by blocking G(alphaq) signaling and activating G(alpha12,13) signaling. CU201 induced apoptosis and complete growth inhibition in various lung cancer and other cancer cell lines. CU201 was 10-fold more potent than substance P derivatives and was stable in serum for >7 days. In this study, we evaluated the ability of CU201 to produce additive or synergistic growth inhibition in combination with various antitumor agents used in lung cancer therapy. We found that CU201 produced additive or synergistic growth inhibition when combined with doxorubicin, etoposide, cisplatin, vinorelbine, and paclitaxel for SCLC lines and with paclitaxel and ZD1839, an epidermal growth factor receptor tyrosine kinase inhibitor, for non-SCLC cell lines. Pharmacokinetic parameters associated with the i.v. administration of CU201 were evaluated in normal mice, and the effects of CU201 on the growth of human lung cancer xenografts were evaluated in athymic nude mice. In CD2F1 mice given an i.v. bolus infusion of 5 mg/kg, the c(max) was 5773 ng/ml (5 microM), and the decay was biexponential. When fitted to a two-compartment model, the t(1/2alpha) was 14.4 min, and the t(1/2beta) was 44.3 h, indicating a long terminal half-life consistent with the prolonged in vitro effects. CU201 inhibited the growth of human lung cancers in athymic nude mice by the intratumoral, s.c., and i.p. routes at a dose of 5 mg/kg/day. This dose is >10-fold less than the dose of substance P derivatives used to inhibit SCLC xenografts in nude mice. We conclude that CU201 should undergo further preclinical toxicology studies in its development as a novel targeted therapy for the treatment of lung cancers with neuroendocrine features. These studies are in progress through the NCI RAID mechanism.

Preclinical studies of gemcitabine and trastuzumab in breast and lung cancer cell lines

Overexpression of the HER2/neu oncogene and receptor protein has been reported in 20%-30% of patients with breast cancer and is associated with a poor prognosis. HER2/neu expression in breast cancer patients assessed by fluorescence in situ hybridization or immunohistochemistry is a predictor for response to trastuzumab, a humanized monoclonal antibody against the HER2/neu cell-surface protein. Data regarding HER2/neu expression in lung cancer are more limited, and there is little information regarding HER2/neu expression and response to trastuzumab alone or in combination with chemotherapeutic agents. Gemcitabine is an active agent against non-small-cell lung cancer (NSCLC) and has demonstrated activity in breast cancer as well. In vitro modified tetrazolium salt growth assays were performed to determine whether the combination of trastuzumab/gemcitabine produced synergistic or additive effects on breast and lung cancer cell lines. The effects of trastuzumab alone, gemcitabine alone, and the trastuzumab/gemcitabine combination was evaluated on 4 NSCLC cell lines, 1 small-cell lung cancer (SCLC) cell line, and 2 breast cancer cell lines. HER2/neu surface protein expression was assessed by fluorescence flow cytometry and immunohistochemistry. Fluorescence in situ hybridization analysis was used to study gene expression. Trastuzumab treatment alone resulted in growth inhibition in all cell lines expressing HER2/neu and the inhibitive effect correlated with the level of cell surface HER2/neu protein expression. Treatment with gemcitabine alone resulted in growth inhibition in both breast and NSCLC cell lines. A synergistic growth inhibition effect was seen with the trastuzumab/ gemcitabine combination as indicated by combination index values < 1. The degree of synergy observed did not directly correlate with the level of surface protein expression, as synergy was seen even in cancer cell lines expressing low levels of HER2/neu. No treatment effect was seen in the SCLC cell line, which did not express HER2/neu. These preclinical studies indicate a need to study the clinical synergistic effects of the gemcitabine/trastuzumab combination in breast cancer and NSCLC patients whose tumors overexpress HER2/ neu.

Bradykinin-related compounds as new drugs for cancer and inflammation

Bradykinin (BK) (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg) is an important growth factor for small-cell lung cancer (SCLC) and prostate cancer (PC). These cancers have cells of neuroendocrine origin and express receptors for a variety of neuropeptides. BK receptors are expressed on almost all lung cancer cell lines and on many PC cells. Our very potent BK antagonist B9430 (D-Arg-Arg-Pro-Hyp-Gly-lgl-Ser-D-Igl-Oic-Arg) (Hyp, trans-4-hydroxy-L-proline; Ig1, alpha-2-indanylglycine; Oic, octahydroindole-2-carboxylic acid) is a candidate anti-inflammatory drug but does not inhibit growth of SCLC or PC. When B9430 is dimerized by N-terminal cross-linking with a suberimide linker, the product B9870 is a potent growth inhibitor for SCLC both in vitro and in vivo in athymic nude mice. Daily i.p. injection at 5 mg x kg(-1) day(-1) beginning on day 8 after SCLC SHP-77 cell implantation gave 65% inhibition of tumor growth. B9870 stimulates apoptosis in SCLC by a novel "biased agonist" action. We have also developed new small mimetic antagonists. BKM-570 (F5C-OC2Y-Atmp) (F5C, pentafluorocinnamic acid; OC2Y, O-2,6-dichlorobenzyl tyrosine; Atmp, 4-amino-2,2,6,6-tetramethylpiperidine) is very potent for inhibition of SHP-77 growth in nude mice. When injected daily i.p. at 5 mg x kg(-1), M-570 gave 90% suppression of tumor growth. M-570 is more potent than the well-known anticancer drug cisPlatin (60% inhibition) or the recently developed SU5416 (40% inhibition) in this model. M-570 also showed activity against various other cancer cell lines in vitro (SCLC, non-SCLC, lung, prostate, colon, cervix) and inhibited growth of prostate cell line PC3 in nude mice. M-570 and related compounds evidently act in vivo through pathways other than BK receptors. These compounds have clinical potential for treatment of human lung and prostate cancers.

Exisulind in combination with docetaxel inhibits growth and metastasis of human lung cancer and prolongs survival in athymic nude rats with orthotopic lung tumors

Docetaxel, a semisynthetic taxane, improves the survival of stage IIIB and IV non-small cell lung cancer patients. However, the 5-year survival remains poor, and few patients experience a complete remission. In this report, we evaluated the effects of exisulind, a novel proapoptotic agent that is a sulfone metabolite of sulindac, in combination with docetaxel on the growth of the human non-small cell lung cancer cell line A549 in vitro and in vivo. Exisulind is a novel sulindac metabolite in that it does not inhibit cyclooxygenase enzymes and has been shown to induce apoptosis in a variety of human cancers by inhibiting cyclic GMP-dependent phosphodiesterase. Exisulind alone increased the fraction of cells in the G(1) phase of the cell cycle from 46% to 65%, whereas it decreased the fraction of cells in the S phase from 38% to 14%. Docetaxel increased the fraction of cells in the S phase from 17% to 19%, and 10 nM docetaxel increased the G2-M phase by 23%. Docetaxel alone induced apoptosis from 11% to 64% at 12-24 h after incubation. The combination of exisulind with concentrations of docetaxel (in concentrations that alone did not alter cell cycle distribution) reduced the G(1) accumulation induced by exisulind, increased the fraction of cells in G(2)-M (9-17%), and increased apoptosis (5-62%). The IC(50) for in vitro growth inhibition by exisulind alone was approximately 200 microM and 2.5 nM for docetaxel. The in vitro combination of exisulind and docetaxel produced an additive to synergistic growth inhibition. In athymic nude rats with A549 orthotopic lung cancers, both exisulind and docetaxel alone moderately prolonged survival, inhibited tumor growth and metastases, and increased apoptosis compared with control animals treated with a carrier. However, the combination of exisulind with docetaxel significantly prolonged survival (P = < 0.0004), inhibited tumor growth and metastases (P = < 0.0001), and increased apoptosis (P = < 0.001) when compared with control animals. These results provide rationale for conducting clinical trials using the combination of exisulind and docetaxel in patients with advanced lung cancer.

Preclinical and clinical studies of docetaxel and exisulind in the treatment of human lung cancer

Lung cancer is the leading cause of cancer death in the United States. The majority of patients with non-small cell lung cancers present with inoperable disease because of the presence of metastases to regional lymph nodes or other metastatic sites. About one third of patients have stage IV disease with metastases to distant organs at the time of diagnosis. The prognosis for these patients is very poor. With best supportive care the median survival is only 4 months and the 1-year survival rate is 10% to 15%. Current chemotherapy combinations improve the survival and quality of life for patients with advanced non-small cell lung cancer. With two-drug combinations, median survival is increased to 8 months or more and 1-year survival is increased to 35% to 40%. Still, complete response rates are low and more than 80% of patients die within 1 year of diagnosis. The improvements created by current therapies led to studies of chemotherapy in the second-line setting. Docetaxel has been shown to improve survival of patients who failed platinum-based chemotherapy and was approved by the U.S. Food and Drug Administration for therapy in this setting. However, response rates were very low and survival very short. Therefore, new therapies are urgently needed. Exisulind is a novel oral anticancer agent that holds promise for the treatment of patients with advanced non-small cell lung cancer. Exisulind was originally developed as a chemoprevention agent for colorectal cancer. Preclinical studies showed that exisulind could prevent polyp formation and inhibit the growth of colorectal cancers. Subsequent preclinical studies showed that exisulind also inhibited the growth of human breast, prostate, and lung cancers. Phase I clinical studies showed that twice-daily oral doses could be given safely and would provide peak concentrations that were equivalent to those required for in vitro effects. These observations lead to the studies of the combination of exisulind and docetaxel in preclinical and clinical studies in human lung cancer described in this article.

Preliminary experience with a new stable isotope breath test for chylomicron remnant metabolism: a study in central obesity

We aimed to investigate the metabolism of chylomicron remnants in the postabsorptive state employing a new stable isotope breath test in centrally obese men without overt hyperlipidaemia. Groups of 12 centrally obese and 12 non-obese men of similar age and with similar plasma cholesterol and triacylglycerol (triglyceride) levels were studied. The catabolism of chylomicron remnants was measured using an intravenous injection of a remnant-like emulsion containing cholesteryl [(13)C]oleate. Isotopic enrichment of (13)CO(2) in breath was determined using isotope-ratio mass spectrometry, and a multi-compartmental model (SAAM II program) was used to estimate the fractional catabolic rate (FCR) of the chylomicron remnant-like particles. The plasma concentrations of low-density lipoprotein (LDL)-cholesterol, non-high-density lipoprotein (HDL)-cholesterol and insulin were significantly higher (P<0.05) in the obese than the control subjects. The obese subjects had significantly lower HDL-cholesterol (P<0.05) and, in particular, a decreased FCR of the remnant-like particles compared with lean subjects (0.061+/-0.014 and 0.201+/-0.048 pools/h respectively; P=0.016). In the obese group, the FCR of remnant-like particles was inversely associated with the waist/hip ratio, and with plasma triacylglycerol, cholesterol, LDL-cholesterol and non-HDL-cholesterol levels. In multiple regression analysis, the waist/hip ratio was the best predictor of the FCR of the emulsion. In conclusion, this new test suggests that postabsorptive chylomicron remnant catabolism is impaired in centrally obese subjects without overt hyperlipidaemia. This defect may be due to the degree of adiposity.

Expression of Her-2/neu in human lung cancer cell lines by immunohistochemistry and fluorescence in situ hybridization and its relationship to in vitro cytotoxicity by trastuzumab and chemotherapeutic agents

Overexpression of the Her-2/neu oncogene and receptor protein was reported in approximately 20% of breast cancers and was associated with a poor prognosis. Her-2/neu expression was a predictor for response to trastuzumab, a monoclonal antibody that recognizes the Her-2/neu cell surface receptor. Data regarding the expression of Her-2/neu in lung cancer are far more limited, and there is little information regarding the influence of Her-2/neu expression and response to trastuzumab alone or in combination with chemotherapeutic agents. In this report we evaluated Her-2/neu gene expression by fluorescence in situ hybridization (FISH) and the cell surface expression of the Her-2/neu receptor by immunohistochemistry using the HercepTest and by FACS analysis in 31 lung cancer cell lines with 5 breast cancer cell lines as controls. By FACS, we found Her-2/neu overexpression (mean fluorescence intensity >8) in 2 of the 22 non-small cell lung cancer (NSCLC) cell lines (9%), none of 11 small cell lung cancer (SCLC) cell lines, and 4 of 5 breast cancer cell lines. A positive HercepTest (2+ or 3+) was found in 6 of 19 NSCLC cell lines (26%, 2+; 5%, 3+), 1 of 3 SCLC cell lines (33%), and 4 of 5 breast cancer cell lines (80%). One of 6 NSCLC cell lines examined (17%) had gene amplification with >32 copies of Her-2/neu/cell and had homogeneous staining regions. One NSCLC cell line had a maximum of 14 copies of Her-2/neu/cell, and 3 had modest increases in Her-2/neu gene copy number without gene amplification (maximum 5-8 copies/cell). None of the SCLC cell lines had more than a maximum of 4 copies/cell, whereas the 2 breast cancer cell lines had maximum Her-2/neu copy numbers of 80 and 5, respectively. Aneusomy rather than true amplification was the major cause of increased Her-2/neu expression in most of the NSCLC cell lines. There was a strong correlation when the results of fluorescence-activated cell sorter, HercepTest results, and FISH were compared in pairs. Furthermore, Trastuzumab produced a G(1) cell cycle arrest and growth inhibition only in cell lines expressing Her-2/neu. The IC(50) for growth inhibition was correlated with cell surface Her-2/neu expression. The combination of trastuzumab and chemotherapeutic agents produced more than additive growth inhibition in cell lines expressing Her-2/neu, but the level of additivity was not related to the amount of Her-2/neu expression. These data indicate that trastuzumab alone and in combination with chemotherapeutic agents should be tested in NSCLC patients and that Her-2/neu should be assessed by both immunohistochemistry and FISH methods in these studies to determine which test is the best predictor of outcome.

Structural studies on bioactive compounds. 34. Design, synthesis, and biological evaluation of triazenyl-substituted pyrimethamine inhibitors of Pneumocystis carinii dihydrofolate reductase

The triazenyl-pyrimethamine derivative 3a (TAB), a potent and selective inhibitor of Pneumocystis carinii DHFR, was selected as the starting point for a lead optimization study. Molecular modeling studies, corroborated by a recent crystal structure determination of the ternary complex of P. carinii DHFR--NADPH bound to TAB, predicted that modifications to the acetoxy residue of the lead inhibitor could exploit binding opportunities in the vicinity of an active site pocket bounded by residues Ile33, Lys37, and Leu72. Substitutions in the benzyl moiety with electron-donating and electron-withdrawing groups were predicted to probe face-edge interactions with amino acid Phe69 unique to the P. carinii enzyme. New triazenes 10a--v and 12a--f were prepared by coupling the diazonium tetrafluoroborate salt 6b of aminopyrimethamine with substituted benzylamines or phenethylamines. The most potent of the new inhibitors against P. carinii DHFR was the naphthylmethyl-substituted triazene 10t (IC(50): 0.053 microM), but a more substantial increase in potency against the rat liver DHFR led to a reduction in selectivity (ratio rat liver DHFR IC(50)/P. carinii DHFR IC(50): 5.36) compared to the original lead structure 3a (ratio rat liver DHFR IC(50)/P. carinii DHFR IC(50): 114).

Curing potential of dual-polymerizable resin cements in simulated clinical situations

STATEMENT OF PROBLEM

Little is known about the ability of dual-polymerizable resin cements to polymerize when they are used in various clinical scenarios. Purpose. This study was conducted to determine whether any of 6 commercially available dual-polymerizable resin cements should be classified as an "all-purpose" resin cement.

MATERIAL AND METHODS

Chemical conversion values (C=C converted to C-C, or the extent of the curing reaction) of 6 commercially available dual-polymerizable resin cements were determined with infrared spectroscopy in 5 clinically relevant scenarios. Scenarios included: using each cement in a dual-polymerizable mode (mixing of 2 pastes); light polymerizing curing through Mylar sheets (dual-Mylar), which served as the control; light polymerizing through 3-mm porcelain (dual-3 mm); and no exposure to light (dual-no light). The single-component light-polymerizable product was also tested as follows: exposed directly through Mylar (light-Mylar) or exposed through 3 mm of porcelain (light-3 mm).

RESULTS

For each product, dual-Mylar treatment yielded the highest conversion value of all treatments (control for each product). For all products, dual-3 mm conversion was at least 97% of control and equivalent to control, with the exception of Lute-It!. Dual-no light conversion was less than control treatment but at least 86% of control for all products except for Variolink II (62% of control). For all products in dual-no light mode, except Choice and Variolink II, conversion was at least equal to the light-Mylar values. Only 1 product (Variolink II) did not demonstrate increased conversion values for dual-Mylar compared with light-Mylar treatments. For most other products (Calibra, Insure, and Lute-It!), conversion values for light-3 mm were significantly less than for light-Mylar. Conversion values for Nexus, Choice, and Variolink II were equivalent between light-Mylar and light-3 mm treatments.

CONCLUSION

The choice of a dual-polymerizable cement should be based on its intended use because not all products polymerize adequately in every clinical situation. Although no cement met the stated criteria for an "all-purpose" cement, those tested did produce a range of product-specific results.

Custom matrix adaptation with elastic cords

Proper placement of the matrix and wedge is critical to the success of proximal amalgam and posterior resin composite restorations. This paper has presented an easy technique for adaptation of the matrix in cases where the gingival cavosurface margin involves a concavity. Special case considerations were also discussed.