Incidence and risk factors for secondary malignancy in patients with neuroblastoma after treatment with (131)I-metaiodobenzylguanidine

Several reports of second malignant neoplasm (SMN) in patients with relapsed neuroblastoma after treatment with (131)I-MIBG suggest the possibility of increased risk. Incidence of and risk factors for SMN after (131)I-MIBG have not been defined. This is a multi-institutional retrospective review of patients with neuroblastoma treated with (131)I-MIBG therapy. A competing risk approach was used to calculate the cumulative incidence of SMN from time of first exposure to (131)I-MIBG. A competing risk regression was used to identify potential risk factors for SMN. The analytical cohort included 644 patients treated with (131)I-MIBG. The cumulative incidence of SMN was 7.6% (95% confidence interval [CI], 4.4-13.0%) and 14.3% (95% CI, 8.3-23.9%) at 5 and 10 years from first (131)I-MIBG, respectively. No increase in SMN risk was found with increased number of (131)I-MIBG treatments or higher cumulative activity per kilogram of (131)I-MIBG received (p = 0.72 and p = 0.84, respectively). Thirteen of the 19 reported SMN were haematologic. In a multivariate analysis controlling for variables with p < 0.1 (stage, age at first (131)I-MIBG, bone disease, disease status at time of first (131)I-MIBG), patients with relapsed/progressive disease had significantly lower risk of SMN (subdistribution hazard ratio 0.3, 95% CI, 0.1-0.8, p = 0.023) compared to patients with persistent/refractory neuroblastoma. The cumulative risk of SMN after (131)I-MIBG therapy for patients with relapsed or refractory neuroblastoma is similar to the greatest published incidence for high-risk neuroblastoma after myeloablative therapy, with no dose-dependent increase. As the number of patients treated and length of follow-up time increase, it will be important to reassess this risk.

Collapsing glomerulopathy associated with hepatitis B infection: A case report

Collapsing glomerulopathy has been classified as a variant of focal segmental glomerulosclerosis. It is associated with infections, inflammations, and certain medications. While its association with human immunodeficiency virus has been well established its occurrence with hepatitis B has not been reported. We present here a case of collapsing glomerulopathy in a child with hepatitis B infection.

Treatment of neuroblastoma in congenital central hypoventilation syndrome with a PHOX2B polyalanine repeat expansion mutation: New twist on a neurocristopathy syndrome

Neuroblastoma in patients with congenital central hypoventilation syndrome (CCHS) as part of a neurocristopathy syndrome is a rare finding and has only been associated with paired-like homeobox 2b (PHOX2B) non-polyalanine-repeat-expansion mutations. To the best of our knowledge, we report the first case of a child with CCHS and Hirschsprung disease who had a PHOX2B polyalanine-repeat-expansion mutation (PARM) (genotype 20/33) and developed high-risk neuroblastoma. We further describe his treatment including chemotherapy and therapeutic I(131) -metaiodobenzylguanidine. This case highlights the need to consider neuroblastoma in patients with CCHS and the longest PHOX2B PARMs and to individualize treatment based on co-morbidities.

Abstract 1610: Development of meta-[211At]astatobenzylguanidine ([211At]MABG) as an alpha particle emitting systemic targeted radiotherapeutic for neuroblastoma

BACKGROUND Neuroblastoma (NB) is a radiosensitive malignancy and NB cells express the norepinephrine transporter (NET) enabling uptake of NET ligands. The majority of relapsed NBs remain sensitive to radiation therapy even after extensive therapy. The currently employed targeted radiotherapeutic [131I]MIBG is a highly active β -particle emitting NET ligand useful for cytoreduction of bulk tumor. However, [131I]MIBG does not target isolated tumor cells, and thus targeted radiotherapy with [211At]MABG (α-particle emitter with higher biological effectiveness) can address this critical problem due to the short path length that should lead to the killing of isolated tumor cells.

METHODS 211At was synthesized using a bismuth target via the 209Bi(α,2n)211At reaction and used for solid-phase radiosynthesis of [211At]MABG. Cellular models were created by first determining NET (SLC6A2) mRNA and protein expression in 35 human NB cell lines, and then creating isogenic pairs by forced overexpression of NET in 4 NB cell models. We then performed [211At]MABG uptake assays, as well as biodistribution experiments, using these models. We are defining the toxicity of [211At]MABG in mice via ongoing dose escalation and monitoring laboratory parameters every 3 weeks after dosing. A linear mixed effects model was used to determine the differences in the parameters between the treated groups and controls. Finally, clonogenic assays and therapeutic trials in mouse models comparing [131I]MIBG with [211At]MABG are ongoing.

RESULTS We synthesized [211At]MABG (radiochemical yield of 25-50%, radiochemical purity &gt; 99%) and showed NET-specific uptake in NB1691 cells. Specificity was demonstrated by competition assays with the blocking agent desipramine. NET-overexpressing cell lines showed 4-10 fold higher uptake of NET ligands than parental isogenic lines, and demonstrated tumor-specific [211At]MABG uptake in vivo with tumor-muscle ratios of 7.37. Toxicity studies have shown that doses of 10 and 25 uCi of [211At]MABG were well tolerated, but there was weight loss observed at higher doses (P = 0.01). There was also an expected trend towards thrombocytopenia (P = 0.06), but no detectable impact on white blood cell counts, (P = 0.74), hemoglobin (P = 0.41), bilirubin (P = 0.53) or creatinine (P = 0.10). Clonogenic assays show [211At]MABG to be potently cytotoxic (1000 fold higher than [131I]MIBG), and murine efficacy studies are ongoing.

CONCLUSIONS We have synthesized 211At-MABG in quantities sufficient for our preclinical experiments, and will scale this up for clinical applications. The uptake and biodistribution of [211At]MABG is similar to the currently used radiotherapeutic [131I]MIBG, and to date there was no unanticipated toxicity. Preliminary results from clonogenic assays suggest that [211At]MABG may be an effective agent for salvage therapy for children with refractory/relapsed NB.

Citation Format: Vandana Batra, Pietro Ranieri, Mehran Makvandi, Matthew Tsang, Catherine Hou, Yimei Li, Ganesan Vaidyanathan, Daniel A. Pryma, John M. Maris. Development of meta-[211At]astatobenzylguanidine ([211At]MABG) as an alpha particle emitting systemic targeted radiotherapeutic for neuroblastoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1610. doi:10.1158/1538-7445.AM2015-1610

Abstract 3494: Combined MEK1/2 and PI3K inhibition induces synergistic caspase-dependent apoptosis in neuroblastoma

Background: Neuroblastoma is a pediatric cancer of the developing sympathetic nervous system that is often widely metastatic at diagnosis. Despite the intensive multimodal therapy patients receive including surgery, chemoradiotherapy, stem cell transplantation and immunotherapy, cure rates remain less than 40% for patients with high-risk disease. The identification of MAPK pathway genomic aberrations (NRAS mutations, loss of NF1) in primary and relapsed disease lends relevance to the use of MEK1/2 inhibitors in the treatment of neuroblastoma. Although PI3K and PTEN mutations are rarely detected in neuroblastoma, activation of the PI3K/Akt axis is described in primary tumors and is a well-defined mechanism of resistance to MEK inhibition in other solid tumors. We hypothesize that combined inhibition of MEK and PI3K will synergize to reduce neuroblastoma cell survival and proliferation.

Methods: A panel of human-derived neuroblastoma cell lines (N = 15) was used to analyze the effect of combined binimetinib (MEK162, MEK1/2 inhibitor) and alpelisib (BYL719, alpha-specific PI3K inhibitor) treatment. Effects on cell survival were assayed with CellTiter-Glo® and pathway (MAPK, PI3K/Akt, mTOR) inhibition was analyzed following both single agent and combination treatments. Synergy was determined using the Chou-Talalay method. Additional cell death analysis included flow cytometry (sub-G1, Annexin V) and immunoblotting (BIM, cleaved-PARP). In vivo efficacy testing is ongoing in neuroblastoma xenograft models (N = 3) with defined MAPK aberrations.

Results: Treatment with both binimetinib and alpelisib in 15 neuroblastoma cell line models induced a synergistic (N = 14; CI value range 0.098-0.637) or additive (N = 1; CI = 0.951) anti-proliferative response. The mechanism for the additive cytotoxicity was the conversion of binimetinib-induced cell cycle arrest to the induction of programmed cell death, as measured by morphology, sub-G1 analysis and PARP cleavage. Furthermore, the cell death response was rescued by treatment with the caspase inhibitory peptide, QVD-OPh. By immunoblot analysis, combination treatment decreased the levels of phospho-ERK, phospho-Akt, phospho-S6K, beyond that observed with ether single agent. Neuroblastoma xenograft studies are ongoing with models selected based on the presence of MAPK pathway aberrations, including NRAS mutations and copy number loss of NF1, and in vitro sensitivity to the combination.

Conclusions: Synergistic activity of combined MEK1/2 and PI3K inhibition in human neuroblastoma cell lines via the induction of apoptosis was observed. Combined binimetinib and alpelisib treatment suppresses the activation of MAPK, PI3K/Akt and mTOR. The in vitro studies and preclinical in vivo models are expected to form the basis of testing binimetinib-alpelisib in neuroblastoma clinical trials designed to enrich for subjects with canonical MAPK activating lesions.

Citation Format: Lori S. Hart, Lucy Chen, Vandana Batra, Matthew Tsang, Pichai Raman, Giordano Caponigro, Shiva Krupa, Markus Boehm, Malte Peters, John M. Maris. Combined MEK1/2 and PI3K inhibition induces synergistic caspase-dependent apoptosis in neuroblastoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3494. doi:10.1158/1538-7445.AM2015-3494

Abstract B48: Preclinical development of meta-[211At] astatobenzylguanidine ([211At] MABG) targeted radiotherapy for neuroblastoma

Background: Neuroblastoma (NB) is a radiosensitive malignancy accounting for 10% of childhood cancer mortality. NB cells frequently express the norepinephrine transporter (NET) providing a specific mechanism for uptake of NET-ligands. Meta-[131I]iodobenzylguanidine ([131I]MIBG) is a NET-ligand radiotherapeutic that shows single-agent response rates in refractory NB of 40-50%. However, due to the long path lengths of 131 I beta (β)-emission, and low biological effectiveness compared to alpha (α)-emitting radionuclides, [131I]MIBG is generally not curative, perhaps due to non-targeting of isolated circulating tumor cells. Here we report our efforts to optimize NET-targeted radiotherapy by developing relevant preclinical models of refractory NB for α-particle therapeutic [211At] MABG therapy.

Methods: We first determined NET (SLC6A2) mRNA and protein expression in 35 human NB cell lines using quantitative RT-PCR and western blotting. We then chose 5 lines with absent to intermediate levels of native NET expression (NB1691, SKNSH, IMR5, NLF and SKNBE2) for dual forced overexpression of human NET and luciferase cDNAs. We used [125I]MIBG for cell-based uptake assays in all isogenic pairs and biodistribution experiments in athymic mice bearing three separate NET-transduced xenografts (N=5 per cell line). These cell lines were also treated with [131I]MIBG and/or external beam radiation (XRT) followed by multi-log cytotoxicity assays. Therapeutic trials of [131I]MIBG (25 mCi/kg) in NB1691 subcutaneous xenograft and metastatic mouse models were also conducted. In parallel, [211At] MABG was synthesized by: (i) cyclotron-production of 211 At via 209 Bi(α,2n)211At reaction (ii) distillation of 211 At from the target, and (iii) solid phase no-carrier-added synthesis of [211At] MABG by radioastato-destannylation. [211At] MABG uptake studies were performed in isogenic NB cell lines.

Results: Unlike primary human NBs, NET expression was low in the majority of 35 cell-lines studied (median normalized expression value = 0.145; range 0.000-1.005), but all transduced lines showed significant overexpression (0.860-1.107) comparable to human primary tumors. Transduced lines showed 4-10 fold higher uptake of [125I]MIBG than non-transduced isogenic parental cell lines in vitro, and demonstrated significant tumor-specific uptake and retention in vivo with tumor-muscle ratios ranging from 13.80 to 29.48. In vitro cytotoxicity experiments using [131I]MIBG showed NET-expressing cell lines to be more susceptible to treatment compared to non-NET expressing pairs (IC50 of 2.937nCi vs. 15.99 nCi). Treatment of mice bearing NB1691-NET xenografts with [131I]MIBG showed tumor growth delay (p=0.0065), but no significant impact on survival, likely due to de novo radioresistance (1200 cGy of XRT had no impact on NB1691 proliferation; IMR-05 showed 97% decreased cell viability). Lastly, we successfully synthesized [211At] MABG, with radiochemical yields of ∼20% and showed NET specific uptake of [211At] MABG into 1691 NET transfected cells.

Conclusions: Development of targeted radiotherapy for neuroblastoma has been limited by the lack of preclinical models and alternative therapeutics. Our development of multiple isogenic pairs with varying NET expression, documentation of de novo radiation sensitivity, and the production of [211At] MABG, will allow for rapid assessment of targeted radiotherapeutic strategies (including combination approaches) to support clinical development of alpha-particle therapeutics in a childhood cancer.

Citation Format: V Batra, AM Chacko, M Gagliardi, C Hou, J L. Mikitsh, R H. Freifelder, A Kachur, B C. LeGeyt, A Schmitz, L Toto, G Vaidyanathan, M R. Zalutsky, K K. Matthay, W A. Weiss, W C. Gustafson, D Pryma, J M. Maris. Preclinical development of meta-[211At] astatobenzylguanidine ([211At] MABG) targeted radiotherapy for neuroblastoma. [abstract]. In: Proceedings of the AACR Special Conference on Pediatric Cancer at the Crossroads: Translating Discovery into Improved Outcomes; Nov 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;74(20 Suppl):Abstract nr B48.

Abstract B82: MEK 1/2 inhibition and biomarkers of response in preclinical models of neuroblastoma

Background: Despite an aggressive treatment regime, 40% of patients with high-risk neuroblastoma die of their disease. The mitogen-activated protein kinase (MAPK) signaling cascade is hyperactive in many cancers, including a subset of high-risk neuroblastomas. We, therefore, sought to determine the efficacy of MEK inhibition in neuroblastoma and develop a responder hypothesis of anti-tumor activity based on molecular genetic features.

Methods: MEK162 (Novartis Pharmaceuticals), an orally available MEK1/2 inhibitor, is currently in adult clinical trials for advanced malignancies harboring RAS/RAF mutations. In determining MEK162 IC50 values, we employed the RT-CES cell impedance assay as it measures both cytostatic and cytotoxic responses in a temporal manner. Additional in vitro analysis of MEK162 activity included immunoblotting, cell cycle analysis with flow cytometric methods, and phosphorylation arrays across a panel of 23 neuroblastoma cell lines. Four of these cell lines (2 sensitive and 2 resistant) were also tested in vivo in subcutaneous xenograft models with tumor volume endpoints. The cell line IC50 ranking was cross-referenced with HuGene1.0ST expression microarrays (Affymetrix), phosphorylation arrays (Full Moon Biosystems), and exome sequencing in order to identify the genetic and proteomic underpinnings predictive of response to MEK inhibition. Microarray analysis was performed using the Limma package (Bioconductor/R), unsupervised clustering, and gene set enrichment (GSEA).

Results: Neuroblastoma cell lines (N=23) showed a wide range of sensitivity to MEK162 across a 4-log dose range (median IC50 = 771 nM, range 5 nM-10 μM). Sensitive cell lines demonstrated G1 arrest within 24 hours of exposure to MEK162. In vivo subcutaneous xenograft experiments recapitulated the in vitro response of MEK162 sensitivity in each of the cell lines tested. In order to identify determinants of sensitivity, we profiled the genomic signature of 23 cell lines in the exponential growth phase prior to confluence. Of the ten most sensitive cell lines, six possessed mutations predicted to be damaging and indicative of RAS/MAPK pathway hyperactivation (NRAS-Q61K, NF1 copy number loss, KRAS-G12D). No resistant lines possessed genetic evidence of RAS hyperactivation. However, baseline phosphorylated-ERK status was not robustly predictive of drug activity. For the purpose of biomarker discovery, we considered a total of 4 cells lines as sensitive (IC50&lt; 200 nM) and 4 resistant (IC50&gt; 3,000 nM). Unsupervised clustering and GSEA of the most differentially expressed genes derived from comparing sensitive (N=4) and resistant (N=4) cell lines confirmed increased baseline MAPK pathway activity in the sensitive cell lines. In addition, resistance to MEK162 was found to be associated with MYCN expression (R=.70/p=0.00043), suggesting that MYCN may serve as a biomarker of MEK162 resistance. Independently, we have demonstrated a correlation between MYCN-amplification and sensitivity to CDK4/6 inhibition (p=0.0227), suggesting the combination of MEK and CDK4/6 inhibition may synergize in the inhibition of neuroblastoma growth.

Conclusions: MEK inhibition is effective in a definable subset of human-derived neuroblastoma preclinical models. Canonical activation of the RAS/MAPK pathway via RAS mutation and/or NF1 inactivation partially account for sensitivity to MEK inhibition, however, biomarkers predictive of sensitivity to MEK inhibition remain to be identified. We demonstrate that both MYCN expression and CDK4/6 activity are associated with MEK resistance, providing a basis for defining MEK162 combination strategies in the treatment of neuroblastoma.

Citation Format: Lori S. Hart, Vandana Batra, Pichai Raman, Maria Gagliardi, JulieAnn Rader, Lucy Chen, Christine Fritsch, Giordano Caponigro, Malte Peters, Markus Boehm, John M. Maris. MEK 1/2 inhibition and biomarkers of response in preclinical models of neuroblastoma. [abstract]. In: Proceedings of the AACR Special Conference on Pediatric Cancer at the Crossroads: Translating Discovery into Improved Outcomes; Nov 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;74(20 Suppl):Abstract nr B82.

Long-term survival of children less than six years of age enrolled on the CCG-945 phase III trial for newly-diagnosed high-grade glioma: a report from the Children's Oncology Group

BACKGROUND

We analyzed the long-term survival of children under 6 years of age (<6 years) enrolled upon the Children's Cancer Group (CCG)-945 high-grade glioma (HGG) study to determine the impact of intrinsic biological characteristics as well as treatment upon both survival and quality of life (QOL) in this younger age population.

PROCEDURE

Analyses were undertaken on patients <6 years with institutionally diagnosed HGG enrolled on the CCG-945 trial. Comparisons of survival were performed for patients <3 years of age (<3 years) (treated with intent to avoid irradiation) versus those between 3 and 6 years of age (3-6 years) (treated with irradiation and chemotherapy) at diagnosis. Discordance between the institutional diagnoses of HGG and consensus-reviewed diagnoses led us to perform further survival analyses for both groups. We compared the two groups of patients for biological markers, and evaluated the neuropsychological and QOL outcomes of long-term survivors.

RESULTS

Patients <3 years (n = 49, 19.5% of all enrolled patients) at diagnosis had a 10-year EFS and OS of 29 ± 6.5% and 37.5 ± 7%, respectively, while for patients 3-6 years (n = 34, 13.5% of all enrolled patients) 10-year EFS and OS were 35 ± 8% and 36 ± 8%, respectively. Molecular marker analysis showed that a smaller proportion of patients <3 years harbored TP53 mutations (P = 0.05). Analysis of QOL outcomes with a median length of follow-up of 15.1 years (9.5-19.2) showed comparable results.

CONCLUSIONS

QOL and survival data were similar for the two groups. A larger prospective study is justified to study the efficacy of chemotherapy only regimens in younger children.

Initial testing (stage 1) of SGI-1776, a PIM1 kinase inhibitor, by the pediatric preclinical testing program

The PIM kinase inhibitor, SGI-1776, was tested against the PPTP in vitro (1.0 nM-10 µM) and in vivo panels (148 mg/kg daily × 5 days for 3 weeks). SGI-1776 exhibited cytotoxic activity in vitro with a median relative IC(50) of 3.1 µM. SGI-1776 induced significant differences in EFS distribution in vivo in 9 of 31 solid tumor xenografts and in 1 of 8 of the evaluable ALL xenografts. SGI-1776 induced tumor growth inhibition meeting criteria for intermediate EFS T/C activity in 1 of 39 evaluable models. In contrast, SGI-1776 induced complete responses of subcutaneous MV4;11 (B myeloid leukemia).

A novel mutation in MPL (Y252H) results in increased thrombopoietin sensitivity in essential thrombocythemia

Essential thrombocythemia (ET) is a rare type of myeloproliferative neoplasm characterized by clonal expansion of the megakaryocyte and platelet lineage. Here, we describe a novel mutation (Y252H) in the thrombopoietin (TPO) receptor, or MPL, in a JAK2 mutation-negative ET patient. The bone marrow examination revealed increased numbers of dysmorphic megakaryocytes with focal clustering. The x-inactivation pattern suggested clonal expansion of hematopoietic cells in the bone marrow. Furthermore, we found that the patient's bone marrow cells were hypersensitive to TPO in generating megakaryocyte colonies in vitro. More importantly, we demonstrated that this MPL Y252H mutant confers increased TPO/MPL-mediated cell growth and increased cell survival upon cytokine withdrawal in BaF3 cells, indicating it is a disease-driving mutation and may contribute to the development of ET in vivo. In summary, this is the first report describing a mutation in the extracellular domain of MPL underlying ET.

Assessment of a multiple-dose drug interaction between ezetimibe, a novel selective cholesterol absorption inhibitor and gemfibrozil

OBJECTIVE

Ezetimibe is a novel lipid-lowering drug that prevents intestinal absorption of dietary and biliary cholesterol leading to significant reduction in total-C, LDL-C, Apo B, and TG and increases in HDL-C in patients with hypercholesterolemia. Gemfibrozil, a fibric acid derivative, is an effective lipid-modulating agent that increases serum high-density lipoprotein cholesterol and decreases serum TG. The objective of this study was to evaluate the potential for a pharmacokinetic (PK) interaction between ezetimibe and gemfibrozil.

METHODS

This was a randomized, open-label, 3-way crossover, multiple-dose study in 12 healthy adult male volunteers. All subjects received the following 3 treatments orally for 7 days: ezetimibe 10 mg once daily, gemfibrozil 600 mg every 12 hours, and ezetimibe 10 mg once daily plus gemfibrozil 600 mg every 12 hours. A washout period of > or = 7 days separated the 3 treatments. In each treatment, blood samples were collected on day 7 to assess the steady-state PK of ezetimibe and gemfibrozil. The oral bioavailability of ezetimibe coadministered with gemfibrozil relative to each drug administered alone was evaluated with an analysis-of-variance model.

RESULTS

Ezetimibe was rapidly absorbed and extensively conjugated to its glucuronide metabolite. Ezetimibe did not alter the bioavailability (based on AUC) of gemfibrozil. The mean AUC0-12 of gemfibrozil was 74.7 and 74.1 microg h/ml with and without ezetimibe coadministration, respectively (log-transformed geometric mean ratio (GMR) = 99.2; 90% confidence interval (CI) = 92 - 107%). Conversely, gemfibrozil significantly (p < 0.05) increased the plasma concentrations of ezetimibe and total ezetimibe (i.e. ezetimibe plus ezetimibe-glucuronide). Exposure to ezetimibe and total ezetimibe was increased approximately 1.4-fold and 1.7-fold, respectively (CI = 109 - 173% for ezetimibe and 142 - 190% for total ezetimibe), however, this increase was not considered to be clinically relevant. Ezetimibe and gemfibrozil administered alone or concomitantly for 7 days was well tolerated.

CONCLUSIONS

The coadministration of ezetimibe and gemfibrozil in patients is unlikely to cause a clinically significant drug interaction. The coadministration of these agents is a promising approach for patients with mixed dyslipidemia. Additional clinical studies are warranted.

Bronchoalveolar lavage fluid concentrations of transforming growth factor (TGF)-beta1, TGF-beta2, interleukin (IL)-4 and IL-13 after segmental allergen challenge and their effects on alpha-smooth muscle actin and collagen III synthesis by primary human lung fibroblasts

RATIONALE

Asthmatic airway remodelling is characterized by myofibroblast hyperplasia and subbasement membrane collagen deposition. We hypothesized that cytokines and growth factors implicated in asthmatic airway remodelling are increased in bronchoalveolar lavage (BAL) fluid of asthmatics after segmental allergen challenge (SAC), and that these growth factors and cytokines increase alpha-smooth muscle actin (alpha-SMA) and collagen III synthesis by human lung fibroblasts (HLFs).

METHODS

Transforming growth factor (TGF)-beta1, TGF-beta2, IL-4 and IL-13 levels were measured in BAL fluid from 10 asthmatics and 9 non-asthmatic controls at baseline and then 1 day, 1 week and 2 weeks after SAC. Confluent cultures of HLFs were stimulated by exogenous addition of TGF-beta1, TGF-beta2, IL-4 or IL-13 (concentration range 0.01-10 ng/mL) over 48 h. Collagen III was measured in culture supernates and alpha-SMA in cell lysates by Western blot.

RESULTS

At baseline, there was no difference in BAL fluid concentrations of TGF-beta1, IL-4 and IL-13 between asthmatics and controls; however, non-asthmatics had higher concentrations of total TGF-beta2. In asthmatics, BAL fluid concentrations of all four factors increased significantly 1 day after SAC. TGF-beta1, TGF-beta2 and IL-13 concentrations returned to baseline by 1 week after SAC, but BAL fluid IL-4 concentration remained elevated for at least 2 weeks. TGF-beta1, TGF-beta2 and IL-4 significantly increased alpha-SMA in fibroblasts, but only IL-4 caused corresponding increases in collagen III synthesis. IL-13 had no direct effects on collagen III synthesis and alpha-SMA expression.

CONCLUSIONS

Because IL-4 caused a dose-dependent increase in alpha-SMA and collagen III synthesis, it may be an important cytokine mediating asthmatic airway remodelling. TGF-beta1 and TGF-beta2 may also play a role in airway remodelling by stimulating phenotypic change of fibroblasts to myofibroblasts. Additionally, collagen III synthesis appears to be independent of myofibroblast phenotype and is apparently regulated by different growth factors and cytokines.

Twenty-first century tobacco use: it is not just a risk factor anymore

Despite availability of effective treatments for nicotine addiction, smoking remains prevalent with serious health consequences. Most smokers recognize the ill effects of smoking but are unable to quit. Nicotine addiction may be viewed as any other chronic illness that results from exposure to a recognizable agent (tobacco) and manifests with a well-documented set of signs and symptoms. Much like any chronic disease, both environmental and genetic factors determine the occurrence and severity of this affliction. There has been recent focus on uncovering the genetic basis of nicotine addiction. In this article, we have attempted to briefly review the current evidence for the role of genetics in smoking as well as comment on available pharmacotherapeutic options for treating nicotine dependence.

Staphylococcal acalculous cholecystitis in a child

Acute acalculous cholecystitis is inflammation of the gallbladder in the absence of gallstones. It usually occurs in critically ill patients and is rare in the pediatric age group. We describe a 12-year-old boy who presented with fever, jaundice, and abdominal pain and was found to have acute acalculous cholecystitis, sacroiliitis, and pelvic osteomyelitis associated with bacteremia as a result of Staphylococcus aureus. Antibiotic therapy without surgical intervention was effective. A high index of suspicion is required to make an early diagnosis and institute appropriate treatment for children with this condition. Although cholecystectomy has been considered the standard therapy, medical treatment alone can be successful.

Double-blind, placebo-controlled study of the efficacy and tolerability of nimesulide administered orally in acute bronchial asthma

In this double-blind, placebo-controlled study, children with acute exacerbation of bronchial asthma between the ages of 1 and 12 years not responding to conventional therapy with bronchodilators and injectable steroids were enrolled. A total of 60 children (two groups of 30 each) was studied. The overall response to therapy was assessed based on the guidelines and recommendations of the National Heart, Lung and Blood Institute. The efficacy parameters included respiratory and heart rates, degree of dyspnea, accessory muscle usage, color, wheeze, and degree of oxygen saturation. Children with moderate to severe exacerbation received either nimesulide suspension 1.5 mg/kg per dose or identical placebo orally as per random protocol. To assess the clinical progress, all the efficacy parameters were reassessed after 30 minutes and 1, 2, and 6 hours. A significant difference was observed in the overall assessment of response at 1, 2, and 6 hours in the two treatment groups. A greater number of children showed a good overall response in the nimesulide group compared with the placebo group at 1, 2, and 6 hours (P <.01). No side effects were reported in any of the patients in either group. None of the patients was withdrawn prematurely from either group. It is evident from the current study that nimesulide showed good efficacy and tolerability. Therefore, nimesulide could be administered to asthmatic patients whenever there is a need for such therapy.

The plasma concentration and LDL-C relationship in patients receiving ezetimibe

Ezetimibe is a novel selective inhibitor of intestinal cholesterol absorption, which has been shown to significantly decrease low-density lipoprotein cholesterol (LDL-C). In this article, the relationship between plasma ezetimibe concentrations and lowering of LDL-C is determined using Emax and regression models. Data from two phase II double-blind placebo-controlled studies (n = 232 and 177) were used in which daily doses of ezetimibe ranging from 0.25 to 10 mg were administered for 12 weeks. Ezetimibe concentrations correlated significantly with percentage change in LDL-C from baseline (%LDL-C). Reductions in %LDL-C of 10%, 15%, and 20% were achieved with concentrations in the ranges 0 to 2, 2 to 15, and > 15 ng/ml, respectively, as compared with placebo. To achieve > 15% reduction in LDL-C, patients need to maintain trough concentrations > 15 ng/ml, taking plasma concentrations as a surrogate for concentrations at the enterocyte. Based on the doses administered, the 10 mg dose had the highest likelihood of sustaining such concentrations, confirming that a daily 10 mg dose of ezetimibe is an optimal therapeutic dose in the treatment of hypercholesterolemia.

Pharmacokinetic and safety profile of desloratadine and fexofenadine when coadministered with azithromycin: a randomized, placebo-controlled, parallel-group study

BACKGROUND

Significant cardiac toxicity has been associated with some older antihistamines (eg, terfenadine and astemizole) when their plasma concentrations are increased. There is thus a need for a thorough assessment of the cardiac safety of newer antihistamine compounds.

OBJECTIVE

This study was undertaken to assess the effects of coadministration of desloratadine or fexofenadine with azithromycin on pharmacokinetic parameters, tolerability, and electrocardiographic (ECG) findings.

METHODS

Healthy volunteers aged 19 to 46 years participated in this randomized, placebo-controlled, parallel-group, third-party-blind, multiple-dose study. Subjects received desloratadine 5 mg once daily, fexofenadine 60 mg twice daily, or placebo for 7 days. An azithromycin loading dose (500 mg) followed by azithromycin 250 mg once daily for 4 days was administered concomitantly starting on day 3. Group 1 received desloratadine and azithromycin, group 2 received desloratadine and placebo, group 3 received placebo and azithromycin, group 4 received fexofenadine and azithromycin, and group 5 received fexofenadine and placebo.

RESULTS

The results of the pharmacokinetic analysis revealed little change in mean maximum concentration (Cmax) and area under the concentration-time curve (AUC) values for desloratadine with concomitant administration of azithromycin: Cmax ratio, 115% (90% CI, 92-144); AUC, ratio 105% (90% CI, 82-134). The corresponding ratios for 3-hydroxydesloratadine were 115% (90% CI, 98-136) and 104% (90% CI, 88-122), respectively. A substantial increase was observed in mean Cmax and AUC values for fexofenadine when administered with azithromycin: Cmax, ratio, 169% (90% CI, 120-237); AUC ratio, 167% (90% CI, 122-229). Compared with the group receiving desloratadine and azithromycin, subjects receiving fexofenadine and azithromycin also displayed greater variability in pharmacokinetic parameters for the antihistamine. Mean Cmax and AUC values of azithromycin were slightly higher when administered with desloratadine (Cmax ratio, 131% [90% CI, 92-187]; AUC ratio, 112% [90% CI, 83-153]) but were lower when given in combination with fexofenadine (Cmax ratio, 87% [90% CI, 61-124]; AUC ratio, 88% [90% CI, 65-1201). The most common adverse event for all regimens was headache, reported in 20 (22%) subjects. All combinations of desloratadine or fexofenadine with and without azithromycin were well tolerated, and no statistically significant changes in PR, QT, or QT, interval, QRS complex, or ventricular rate were observed.

CONCLUSIONS

Small increases (<15%) in mean pharmacokinetics of desloratadine were observed with coadministration of azithromycin. By contrast, peak fexofenadine concentrations were increased by 69% and the AUC was increased by 67% in the presence of the azalide antibiotic. Based on the reported adverse-events profile and the absence of changes in ECG parameters, the combination of desloratadine and azithromycin was well tolerated. This study suggests that desloratadine has a more favorable drug-interaction potential than does fexofenadine.

PhRMA perspective on population and individual bioequivalence

The Food and Drug Administration (FDA) issued a second-draft guidance in August 1999 on the subject of in vivo bioequivalence, which is based on the concepts of individual and population bioequivalence (IBE and PBE, respectively). The intention of this guidance is to replace the 1992 guidance that requires that in vivo bioequivalence be demonstrated by average bioequivalence (ABE). Although the concepts of population and individual bioequivalence are intuitively reasonable, a detailed review of the literature has not uncovered clinical evidence to justify the additional burden to the innovator and generic companies as well as the consumer that the new guidelines would impose. The criteria for bioequivalence described in the draft guidance employ aggregate statistics that combine information about differences in bioavailability between formulation means and differences in bioavailability variation of formulations between and within subjects. The purely technical aspects of the statistical approach are reasonably sound. However, PhRMA believes that important operational issues remain that need to be resolved before any changes to current practice are implemented. PhRMA believes that the ideals of prescribability and switchability are intuitively reasonable, but it is uncertain of the extent to which the proposed guidance can achieve these goals. It is not clear whether the attainment of such goals is necessary in the evaluation of bioequivalence given the role this plays in drug development, and the lack of clinical evidence argues against a pressing need to change current practice. PhRMA is concerned that the trade-off offered by the aggregate criteria may ultimately represent more harm than good to the public interest. PhRMA recommends more rigorous evaluation of methods based on two-way crossover designs before moving to methods that require more complex designs. One such method is identified herein and contains procedures for estimating prescribability and switchability. The possibility of a phase-in or trial period to collect replicate crossover data to further evaluate IBE and PBE and possibly allow market access based on these criteria as they are being evaluated has been proposed. PhRMA believes this is unprecedented and will offer little additional information beyond that which can be obtained by simulation or has already been collected by the FDA. Simulation studies have the advantage of allowing evaluation of the sensitivity of various procedures to represent the data patterns as created within the simulation. Operating characteristics by which proposed criteria can be adequately judged have not yet been defined. The limitations of ABE for highly variable drugs and narrow therapeutic drugs are well appreciated and may be addressed by means other than a wholesale change in the current criteria.