Efficacy of add-on mepolizumab in adolescents with severe eosinophilic asthma

Adolescents (12-17 years of age) with severe eosinophilic asthma experience frequent exacerbations and reduced lung function leading to poor health-related quality of life. Mepolizumab is approved for add-on maintenance therapy in patients with severe eosinophilic asthma ≥ 6 years of age in the EU and ≥ 12 years of age in other regions (including the USA), based on a Phase II/III program demonstrating reduced exacerbation rates with 4-weekly treatment. A total of 34 adolescent patients were recruited across the Phase III mepolizumab trials. Consistent with outcomes in the overall population, there was a reduction in the annual rate of clinically significant exacerbations, along with a reduction in blood eosinophil counts in response to mepolizumab in adolescent patients. The safety profile in adolescent patients was consistent with that seen in the overall population. Data from the Phase III clinical development program provide evidence for comparable efficacy and safety of mepolizumab between adolescents with severe eosinophilic asthma and the overall population. Clinical trial registration DREAM, NCT01000506 [MEA112997]; MENSA, NCT01691521 [MEA115588]; SIRIUS, NCT01691508 [MEA115575]; MUSCA, NCT02281318 [200862]; COSMOS, NCT01842607 [MEA115661].

Association of depressive symptoms with health status and markers of uncontrolled severe asthma

Background: There are limited data that describe the association between markers of asthma control and depressive symptoms in severe asthma. Objective: To evaluate the association between depressive symptoms and markers of asthma control in patients with uncontrolled severe eosinophilic asthma. Methods: Baseline data from the MENSA and SIRIUS studies (N = 681) of mepolizumab intervention in severe eosinophilic asthma was used. We analyzed the relationships between depressive symptom severity by using the Beck Depression Inventory (BDI-II) and quality of life by using the St. George's Respiratory Questionnaire (SGRQ), asthma control questionnaire-5 (ACQ-5), polypharmacy, and sleep symptoms. Results: When compared with patients with less severe depressive symptoms, patients with more severe depressive symptoms were predominantly female (81% versus 54%), had a higher mean body mass index (30.56 versus 27.67 kg/m²), were more likely to have a blood eosinophil count of ≥300 cells/uL within the previous 12 months (81% versus 68%), and to have experienced a near-fatal asthma event (16% versus 7%). The mean SGRQ score was higher in the severe BDI-II category compared with the minimal depressive symptoms category, which indicated a worse quality of life (71.6 versus 41.4, p < 0.001). Eighty-nine percent of the patients in the severe BDI-II category had poorly controlled asthma (ACQ-5 score ≥ 1.5) compared with 63% in the minimal category (p < 0.001). Conclusion: Increased severity of depressive symptoms was associated with worse respiratory-related quality of life and asthma control in the patients with severe eosinophilic asthma. These findings highlight the need for a multidimensional approach for the management of uncontrolled asthma, including timely identification of depressive symptoms. Additional research is needed to further explore the interactions between the two common conditions.Clinical trials NCT01691521 and NCT01619508, <ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.clinicaltrials.gov">www.clinicaltrials.gov</ext-link>.

Meta-analysis of asthma-related hospitalization in mepolizumab studies of severe eosinophilic asthma

BACKGROUND

Studies show that mepolizumab can reduce the frequency of clinically significant exacerbations in patients with severe eosinophilic asthma, compared with placebo. However, important events such as hospitalizations and emergency room visits are rare and difficult to characterize in single studies.

OBJECTIVE

We sought to compare hospitalization or hospitalization and/or emergency room visit rates in patients with severe eosinophilic asthma treated with mepolizumab or placebo in addition to standard of care for at least 24 weeks.

METHODS

This study was conducted and reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement. PubMed and the GSK Clinical Study Register were searched for suitable studies. The primary end points were the rate of exacerbations requiring hospitalization and the rate of exacerbations requiring hospitalization/emergency room visit. The proportion of patients with 1 or more event was also assessed. All mepolizumab doses were combined and individual patient-level data were analyzed.

RESULTS

Four studies (n = 1388) were eligible for inclusion. Mepolizumab significantly reduced the rate of exacerbations requiring hospitalization (relative rate, 0.49; 95% CI, 0.30-0.80; P = .004) and hospitalization/emergency room visit (relative rate, 0.49; 95% CI, 0.33-0.73; P < .001) versus placebo. Significant reductions of 45% and 38% were also observed for the proportion of patients experiencing 1 or more hospitalization and hospitalization and/or emergency room visit, respectively.

CONCLUSIONS

Mepolizumab approximately halved exacerbations requiring hospitalization and/or emergency room visits compared with placebo in patients with severe eosinophilic asthma. This treatment addresses a key outcome in a patient population with a high unmet need (GSK Study 204664).

Long-term Efficacy and Safety of Mepolizumab in Patients With Severe Eosinophilic Asthma: A Multi-center, Open-label, Phase IIIb Study

PURPOSE

Patients with severe eosinophilic asthma often experience recurrent asthma exacerbations despite intensive inhaled corticosteroid therapy. In 2 previous double-blind studies (MENSA [NCT01691521] and SIRIUS [NCT01691508]), treatment with intravenous or subcutaneous mepolizumab was associated with significantly reduced annualized exacerbation rates and oral corticosteroid (OCS) requirements compared with placebo. The purpose of this study was to assess the long-term safety and efficacy of subcutaneous mepolizumab treatment in patients with severe eosinophilic asthma.

METHODS

COSMOS was a 52-week, open-label extension study in patients who received mepolizumab or placebo in MENSA or SIRIUS. Patients received subcutaneous mepolizumab regardless of prior treatment allocation and continued to receive appropriate standard-of-care asthma therapy throughout. The primary objective was to assess the long-term safety of mepolizumab; end points included adverse events (AEs) and serious AEs (SAEs). Efficacy assessments included the annualized exacerbation rate and durability of response (defined as the exacerbation rate and OCS dose reduction when combined with MENSA and SIRIUS data, respectively).

FINDINGS

In total, 558 (86%; previous mepolizumab: 358; previous placebo: 200) and 94 (14%; previous mepolizumab: 58, previous placebo: 36) patients experienced on-treatment AEs and SAEs, respectively. No fatal AEs were reported. Totals of 13 (2%) and 29 (4%) patients experienced systemic and local site reactions, respectively. There were no reports of mepolizumab-related anaphylaxis. Mepolizumab treatment was shown to exert a durable response, with patients who previously received mepolizumab in MENSA or SIRIUS maintaining reductions in exacerbation rate and OCS dosing throughout COSMOS. Patients who previously received placebo in MENSA or SIRIUS demonstrated improvements in these end points following treatment with mepolizumab in COSMOS.

IMPLICATIONS

These data demonstrate a favorable safety profile of mepolizumab and indicate a durable and stable effect over time, supporting long-term treatment in patients with severe eosinophilic asthma. ClinicalTrials.gov identifier: NCT01842607.

Retrospective cohort analysis of healthcare claims in the United States characterising asthma exacerbations in paediatric patients

Background

Asthma is the most common chronic disease in childhood and places a significant burden on public and private health systems. This retrospective cohort analysis utilised administrative healthcare claims data (US Clinformatics™ Multiplan database; compliant with the US Department of Health & Human Services Health Insurance Portability and Accountability Act) to characterise asthma exacerbations requiring intervention in a US paediatric patient population.

Methods

Patients aged > 1–17 years with a recorded asthma diagnosis and receiving treatment were identified in the US Clinformatics™ Multiplan database over a 9-year period (2004–2012). Both incident and prevalent cases of asthma were included, with the most recently recorded asthma diagnosis designated as the index date. The 12-month period following the index date was analysed for asthma exacerbations, defined as an event requiring treatment with systemic corticosteroid or resulting in an asthma-related hospitalisation or emergency department visit.

Results

Data from 734,114 children with asthma (41.5 % females, 58.5 % males) were analysed, of this cohort 34.4 % experienced ≥ 1 exacerbation during the follow-up period. The proportion who experienced ≥ 1 exacerbation increased from 28.9 % in 2004 to 36.3 % in 2012, based on the reported index date. Their mean annual exacerbation frequency was 1.4; 85.8 % of exacerbations were defined by systemic corticosteroids use. A consistent trend of increased exacerbation incidence in the fall and early winter was observed, in particular exacerbations defined by systemic corticosteroid use. A greater proportion of asthma-related hospitalisations were associated with younger age.

Conclusions

Approximately one-third of children experienced ≥ 1 exacerbation in real-world clinical practice. A targeted treatment approach with a focus on those with a history of recurrent exacerbations is recommended to improve asthma control. This targeted approach could also minimise the frequent systemic corticosteroid exposure particularly at an early age when side effects of systemic corticosteroids are more pronounced.

Severe eosinophilic asthma treated with mepolizumab stratified by baseline eosinophil thresholds: a secondary analysis of the DREAM and MENSA studies

BACKGROUND

Findings from previous studies showed that mepolizumab significantly reduces the rate of exacerbations in patients with severe eosinophilic asthma. To assess the relationship between baseline blood eosinophil counts and efficacy of mepolizumab we did a secondary analysis of data from two studies, stratifying patients by different baseline blood eosinophil thresholds.

METHODS

We did a post-hoc analysis of data, which was completed on Sept 25, 2015, from two randomised, double-blind, placebo-controlled studies of at least 32 weeks duration (NCT01000506 [DREAM] and NCT01691521 [MENSA]) done between 2009 and 2014. In these studies, mepolizumab (

DREAM

75 mg, 250 mg, or 750 mg intravenously; MENSA: 75 mg intravenously or 100 mg subcutaneously) versus placebo was given at 4-week intervals in addition to standard care (high-dose inhaled corticosteroids plus ≥1 additional controller with or without daily oral corticosteroids) to patients aged 12 years or older with a clinical diagnosis of asthma, a history of at least two exacerbations in the previous year that required systemic corticosteroid treatment, and evidence of eosinophilic airway inflammation. The primary endpoint in both studies was the annual rate of clinically significant exacerbations (defined as worsening of asthma that required the use of systemic corticosteroids, or admission to hospital, or an emergency-room visit, or a combination of these occurrences). In our analysis, the primary outcome was the annualised rate of exacerbations in patients stratified by baseline eosinophil counts (≥150 cells per μL, ≥300 cells per μL, ≥400 cells per μL, and ≥500 cells per μL) and baseline blood eosinophil ranges (<150 cells per μL, ≥150 cells per μL to <300 cells per μL, ≥300 cells per μL to <500 cells per μL, and ≥500 cells per μL). We based our analysis on the intention-to-treat populations of the two original studies, and all mepolizumab doses were combined for analysis.

FINDINGS

Of 1192 patients, 846 received mepolizumab and 346 received placebo. The overall rate of mean exacerbations per person per year was reduced from 1·91 with placebo to 1·01 with mepolizumab (47% reduction; rate ratio [RR] 0·53, 95% CI 0·44-0·62; p<0·0001). The exacerbation rate reduction with mepolizumab versus placebo increased progressively from 52%; 0·48, 0·39-0·58) in patients with a baseline blood eosinophil count of at least 150 cells per μL to 70%; 0·30, 0·23-0·40]) in patients with a baseline count of at least 500 cells per μL. At a baseline count less than 150 cells per μL, predicted efficacy of mepolizumab was reduced.

INTERPRETATION

Our analysis has shown a close relationship between baseline blood eosinophil count and clinical efficacy of mepolizumab in patients with severe eosinophilic asthma and a history of exacerbations. We noted clinically relevant reductions in exacerbation frequency in patients with a count of 150 cells per μL or more at baseline. The use of this baseline biomarker will help to select patients who are likely to achieve important asthma outcomes with mepolizumab.

FUNDING

GlaxoSmithKline.

Oral glucocorticoid-sparing effect of mepolizumab in eosinophilic asthma

BACKGROUND

Many patients with severe asthma require regular treatment with oral glucocorticoids despite the use of high-dose inhaled therapy. However, the regular use of systemic glucocorticoids can result in serious and often irreversible adverse effects. Mepolizumab, a humanized monoclonal antibody that binds to and inactivates interleukin-5, has been shown to reduce asthma exacerbations in patients with severe eosinophilic asthma.

METHODS

In a randomized, double-blind trial involving 135 patients with severe eosinophilic asthma, we compared the glucocorticoid-sparing effect of mepolizumab (at a dose of 100 mg) with that of placebo administered subcutaneously every 4 weeks for 20 weeks. The primary outcome was the degree of reduction in the glucocorticoid dose (90 to 100% reduction, 75 to less than 90% reduction, 50 to less than 75% reduction, more than 0 to less than 50% reduction, or no decrease in oral glucocorticoid dose, a lack of asthma control during weeks 20 to 24, or withdrawal from treatment). Other outcomes included the rate of asthma exacerbations, asthma control, and safety.

RESULTS

The likelihood of a reduction in the glucocorticoid-dose stratum was 2.39 times greater in the mepolizumab group than in the placebo group (95% confidence interval, 1.25 to 4.56; P=0.008). The median percentage reduction from baseline in the glucocorticoid dose was 50% in the mepolizumab group, as compared with no reduction in the placebo group (P=0.007). Despite receiving a reduced glucocorticoid dose, patients in the mepolizumab group, as compared with those in the placebo group, had a relative reduction of 32% in the annualized rate of exacerbations (1.44 vs. 2.12, P=0.04) and a reduction of 0.52 points with respect to asthma symptoms (P=0.004), as measured on the Asthma Control Questionnaire 5 (in which the minimal clinically important difference is 0.5 points). The safety profile of mepolizumab was similar to that of placebo.

CONCLUSIONS

In patients requiring daily oral glucocorticoid therapy to maintain asthma control, mepolizumab had a significant glucocorticoid-sparing effect, reduced exacerbations, and improved control of asthma symptoms. (Funded by GlaxoSmithKline; SIRIUS ClinicalTrials.gov number, NCT01691508.).

Mepolizumab treatment in patients with severe eosinophilic asthma

BACKGROUND

Some patients with severe asthma have frequent exacerbations associated with persistent eosinophilic inflammation despite continuous treatment with high-dose inhaled glucocorticoids with or without oral glucocorticoids.

METHODS

In this randomized, double-blind, double-dummy study, we assigned 576 patients with recurrent asthma exacerbations and evidence of eosinophilic inflammation despite high doses of inhaled glucocorticoids to one of three study groups. Patients were assigned to receive mepolizumab, a humanized monoclonal antibody against interleukin-5, which was administered as either a 75-mg intravenous dose or a 100-mg subcutaneous dose, or placebo every 4 weeks for 32 weeks. The primary outcome was the rate of exacerbations. Other outcomes included the forced expiratory volume in 1 second (FEV1) and scores on the St. George's Respiratory Questionnaire (SGRQ) and the 5-item Asthma Control Questionnaire (ACQ-5). Safety was also assessed.

RESULTS

The rate of exacerbations was reduced by 47% (95% confidence interval [CI], 29 to 61) among patients receiving intravenous mepolizumab and by 53% (95% CI, 37 to 65) among those receiving subcutaneous mepolizumab, as compared with those receiving placebo (P<0.001 for both comparisons). Exacerbations necessitating an emergency department visit or hospitalization were reduced by 32% in the group receiving intravenous mepolizumab and by 61% in the group receiving subcutaneous mepolizumab. At week 32, the mean increase from baseline in FEV1 was 100 ml greater in patients receiving intravenous mepolizumab than in those receiving placebo (P=0.02) and 98 ml greater in patients receiving subcutaneous mepolizumab than in those receiving placebo (P=0.03). The improvement from baseline in the SGRQ score was 6.4 points and 7.0 points greater in the intravenous and subcutaneous mepolizumab groups, respectively, than in the placebo group (minimal clinically important change, 4 points), and the improvement in the ACQ-5 score was 0.42 points and 0.44 points greater in the two mepolizumab groups, respectively, than in the placebo group (minimal clinically important change, 0.5 points) (P<0.001 for all comparisons). The safety profile of mepolizumab was similar to that of placebo.

CONCLUSIONS

Mepolizumab administered either intravenously or subcutaneously significantly reduced asthma exacerbations and was associated with improvements in markers of asthma control. (Funded by GlaxoSmithKline; MENSA ClinicalTrials.gov number, NCT01691521.).

Long-term safety of mepolizumab for the treatment of hypereosinophilic syndromes

BACKGROUND

Hypereosinophilic syndromes (HESs) are chronic disorders that require long-term therapy to suppress eosinophilia and clinical manifestations. Corticosteroids are usually effective, yet many patients become corticosteroid refractory or develop corticosteroid toxicity. Mepolizumab, a humanized monoclonal anti-IL-5 antibody, showed corticosteroid-sparing effects in a double-blind, placebo-controlled study of FIP1L1/PDGFRA-negative, corticosteroid-responsive subjects with HESs.

OBJECTIVE

We evaluated long-term safety and efficacy of mepolizumab (750 mg) in HES.

METHODS

MHE100901 is an open-label extension study. The primary end point was the frequency of adverse events (AEs). Optimal dosing frequency, corticosteroid-sparing effect of mepolizumab, and development of antimepolizumab antibodies were also explored.

RESULTS

Seventy-eight subjects received 1 to 66 mepolizumab infusions each (including mepolizumab infusions received in the placebo-controlled trial). Mean exposure was 251 weeks (range, 4-302 weeks). The most common dosing interval was 9 to 12 weeks. The incidence of AEs was 932 events per 100 subject-years in the first year, declining to 461 events per 100 subject-years after 48 months. Serious AEs, including 1 death, were reported by the investigator as possibly due to mepolizumab in 3 subjects. The median daily prednisone dose decreased from 20.0 to 0 mg in the first 24 weeks. The median average daily dose for all subjects over the course of the study was 1.8 mg. Sixty-two percent of subjects were prednisone free without other HES medications for ≥ 12 consecutive weeks. No neutralizing antibodies were detected. Twenty-four subjects withdrew before study completion for death (n = 4), lack of efficacy (n = 6), or other reasons.

CONCLUSION

Mepolizumab was well tolerated and effective as a long-term corticosteroid-sparing agent in PDGFRA-negative HES.

An antibody against IL-5 reduces numbers of esophageal intraepithelial eosinophils in children with eosinophilic esophagitis

BACKGROUND & AIMS

The role of interleukin (IL)-5 in the pathogenesis of eosinophilic esophagitis (EoE) has been established in animal models; anti-IL-5 therapy has been reported to be effective in adults. We investigated whether IL-5 has a role in accumulation of esophageal eosinophils in children with EoE and whether therapy with mepolizumab, an antibody against IL-5, reduces the number of esophageal intraepithelial eosinophils in children with EoE.

METHODS

We performed an international, multicenter, double-blind, randomized, prospective study of 59 children with EoE, defined as baseline peak count of esophageal intraepithelial eosinophils of ≥ 20 in at least 1 high-power field (hpf). Patients received an infusion every 4 weeks (a total of 3 infusions) of 0.55, 2.5, or 10 mg/kg mepolizumab. No placebo group was used.

RESULTS

Baseline peak and mean esophageal intraepithelial eosinophil counts were (mean ± SE) 122.5 ± 8.78 and 39.1 ± 3.63 per hpf, respectively. Four weeks after the third infusion, peak eosinophil counts were <5 per hpf in 5 of 57 children (8.8%); we did not observe differences among groups given different doses of mepolizumab. Reduced peak and mean eosinophil counts, to <20 per hpf, were observed in 18 of 57 (31.6%) and 51 of 57 (89.5%) children, respectively. Peak and mean esophageal intraepithelial eosinophil counts decreased significantly to 40.2 ± 5.17 and 9.3 ± 1.25 per hpf, respectively (P < .0001). An analysis to evaluate predictors of response associated a higher mean baseline esophageal intraepithelial eosinophil count with a greater reduction in mean count (P < .0001).

CONCLUSIONS

IL-5 is involved in the pathogenesis of EoE in children. Mepolizumab, an antibody against IL-5, reduces esophageal eosinophilic inflammation in these patients.

Body mass index and response to asthma therapy: fluticasone propionate/salmeterol versus montelukast

We studied the relationship between body mass index (BMI) on responses to asthma therapy using a retrospective analysis of four previously reported clinical trials. Fluticasone propionate (FP)/salmeterol via Diskus 100/50 microg twice daily and montelukast (MON) 10 mg daily were compared. BMI was classified as underweight (less than 20 kg/m(2)), normal (20-24.9 kg/m(2)), overweight (25-29.9 kg/m(2)), obese-1 (30-34.9 kg/m(2)), obese-2 (35-39.9 kg/m(2)), or obese-3 (at least 40 kg/m(2)). Outcomes assessed included forced expiratory volume in one second (FEV(1)), asthma symptom score, and albuterol use. FP/salmeterol produced greater improvements compared to MON in each of the asthma outcomes studied over the entire BMI range at the week-12 endpoint, with statistically significant differences noted among normal, overweight, obese-1, and obese-3 subjects. The within-treatment responses to FP/salmeterol across BMI ranges at the week-12 endpoint was statistically significantly greater in normal compared to obese-3 for FEV(1) and albuterol use, and in overweight compared to the obese-3 for each outcome studied. The within-treatment comparisons of MON across BMI ranges were significant for albuterol use in normal and underweight compared to obese-3 at the week-12 endpoint. Compared to subjects with normal BMI, the onset to peak FEV(1) may require longer treatment exposure in the very obese. Treatment responses to FP/salmeterol were consistently greater compared to MON and persisted at higher BMI.

Comparative effect of body mass index on response to asthma controller therapy

Increases in body mass index (BMI) are reported to influence asthma severity and response to treatment. This analysis was designed to explore whether increasing BMI altered the comparative response to treatment with either fluticasone propionate (FP) or montelukast. Two double-blind, randomized, parallel-group trials of 12-weeks duration comparing FP, 88 micrograms, twice daily or montelukast, 10 mg, daily were evaluated. Subjects with mild-moderate persistent asthma were retrospectively stratified by BMI of <20 kg/m(2) (underweight), 20-24.9 kg/m(2) (normal weight), 25-29.9 kg/m(2) (overweight), and > or =30 kg/m(2) (obese). Outcomes included mean changes in forced expiratory volume in 1 second (FEV(1)) and morning peak flow, daily albuterol use, and daily symptom scores. There were 1052 subjects evenly distributed between FP and montelukast by baseline parameters, including BMI. FP was statistically superior to montelukast for all BMI categories of normal, overweight, and obese subjects for FEV(1) (p < 0.008), morning peak flow (p < 0.002), albuterol use (p < 0.02), and symptom scores (p < 0.05). FP produced a significantly greater clinical response for normal, overweight, and obese subjects compared with montelukast. Irrespective of BMI, FP appears to be the more effective asthma controller therapy.

Adding montelukast to fluticasone propionate/salmeterol for control of asthma and seasonal allergic rhinitis

Limited information exists comparing fluticasone propionate/salmeterol combination (FSC) versus montelukast (MON) in patients with coexistent asthma and allergic rhinitis. The purpose of this study was to compare the addition of MON to patients receiving FSC on asthma control while experiencing asthma and allergy symptoms. Additionally, the effect of fluticasone propionate aqueous nasal spray (FPANS) and MON were assessed in allergic rhinitis control. Symptomatic patients (n = 1385) with asthma and seasonal allergic rhinitis were randomized to receive FSC, 100/50 micrograms twice daily; FSC twice daily + FPANS, 200 micrograms once daily; FSC twice daily + MON, 10 mg once daily; or MON once daily for 4 weeks during the allergy pollen season. Patients recorded peak expiratory flow, rescue albuterol use, and asthma and rhinitis symptoms. No additional improvements in overall asthma control were seen when MON was added to FSC. Treatment with FSC produced significant (p < 0.001) improvements in all clinical and patient-reported measures versus MON. FSC + FPANS was superior to FSC + MON (p < or = 0.001) in improving daytime and nighttime total nasal symptom scores. Adverse events were similar. In patients with asthma and allergic rhinitis, adding MON to FSC provided no additional benefit in asthma control. FSC resulted in superior improvement in asthma control compared with MON. FPANS also provided superior nasal symptom control versus MON in allergic patients treated with FSC for asthma. Optimal disease control in patients with asthma and allergic rhinitis should be achieved by the most effective therapy directed toward each disease component.

Low-dose fluticasone propionate with and without salmeterol in steroid-naïve patients with mild, uncontrolled asthma

BACKGROUND

The role of combination ICS/LABA as initial controller therapy in mild, persistent asthma is uncertain. Therefore, the objective of this study was to compare the efficacy of initial controller therapy with fluticasone propionate (FP) 100 microg twice daily to the efficacy of fluticasone propionate/salmeterol xinafoate (FSC) 100/50 microg twice daily in patients with persistent asthma symptoms while using as-needed SABA alone.

METHODS

This randomized, double-blind, parallel-group study was conducted at 45 general practice and 15 specialist centers. A total of 526 adult patients were randomized to receive FP or FSC for 24 weeks. The primary efficacy endpoint was change in morning peak expiratory flow (PEF) from baseline. Secondary efficacy endpoints included symptom- and rescue-free days; asthma exacerbation rate; asthma-related health-care utilization; and the onset of effect. Safety was assessed by monitoring adverse events.

RESULTS

Mean morning PEF was significantly greater in the FSC versus the FP group (P<0.001); this greater effect was evident as early as the first week of treatment (P<0.001). The percentages of symptom-free days and rescue-free days in the FSC group were 7.7% (P=0.009) and 8.4% (P=0.001) higher than the FP group, respectively. Trends toward lower exacerbation-related health care-utilization for FSC versus FP were not statistically significant and exacerbation rates were not significantly different. The incidence of adverse events was low with both treatments.

CONCLUSIONS

:Treatment with FSC was a more effective initial controller therapy than FP monotherapy in ICS-naïve patients who had uncontrolled asthma while using as-needed SABA alone.

Beta2-receptor polymorphisms in patients receiving salmeterol with or without fluticasone propionate

RATIONALE

Retrospective pharmacogenetic studies have questioned whether patients with asthma who are arginine homozygous at the beta(2-)adrenergic receptor (position 16) should use long-acting beta-agonists.

OBJECTIVES

To examine whether the response to salmeterol alone or in combination with an inhaled corticosteroid is influenced by beta- receptor polymorphisms.

METHODS

Subjects using only as-needed albuterol were screened and completed two sequential open-label run-in periods (8 wk on as-needed albuterol; 8 wk on as-needed ipratropium). Five hundred forty-four subjects were randomized by Arg16Gly genotype to salmeterol alone or with fluticasone propionate for 16 weeks. Change from baseline in morning peak expiratory flow was the primary endpoint.

MEASUREMENTS AND MAIN RESULTS

Lung function responses were sustained over treatment and no statistically significant changes from baseline between genotypes within treatments were observed. Overall mean changes in morning peak flow for salmeterol with fluticasone propionate were 32.6 L/min (Arg/Arg vs. Gly/Gly, 95% confidence interval [CI], -6.3, 22.1), 25.9 L/min (Arg/Arg vs. Arg/Gly, 95% CI, -7.1, 21.3), and 24.9 L/min (Arg/Gly vs. Gly/Gly, 95% CI, -13.0, 14.6), and for salmeterol alone were 19.4 L/min (Arg/Arg vs. Gly/Gly, 95% CI, -1.7, 21.4), 24.6 L/min (Arg/Arg vs. Arg/Gly, 95% CI, -13.0, 10.6), and 12.4 L/min (Arg/Gly vs. Gly/Gly, 95% CI, -0.2, 22.3) for Arg/Arg, Arg/Gly, and Gly/Gly genotypes, respectively. Other measures of asthma control showed similar responses.

CONCLUSIONS

The results showed no evidence of a pharmacogenetic effect of beta-receptor variation on salmeterol response. Clinical trial registered with www.clinicaltrials.gov (NCT 00102882).

Effects of fluticasone propionate and salmeterol hydrofluoroalkane inhalation aerosol on asthma-related quality of life

BACKGROUND

Current asthma guidelines emphasize domains of impairment and risk for assessing severity and control, noting the need to consider separately the effects of asthma on asthma quality of life and functional capacity. Proper treatment to control asthma should result in improvements in patient well-being and functional status.

OBJECTIVE

To assess asthma-related quality of life after treatment with combination fluticasone propionate and salmeterol delivered via hydrofluoroalkane 134a metered-dose inhaler compared with the individual components alone.

METHODS

Asthma-related quality of life was assessed as part of two 12-week, randomized, double-blind, placebo-controlled clinical trials comparing the fluticasone propionate-salmeterol combination administered via a single metered-dose inhaler with salmeterol, fluticasone propionate, and placebo administered via traditional chlorofluorocarbon metered-dose inhaler. The Asthma Quality of Life Questionnaire was completed at baseline and end point. Score changes, overall and for the 4 separate domains, were compared within and among the treatment groups.

RESULTS

A total of 720 of 725 patients completed a baseline Asthma Quality of Life Questionnaire and were included in the analyses. In both studies, all mean scores improved significantly from baseline with the fluticasone propionate-salmeterol combination, with significantly greater improvement in the overall score compared with salmeterol alone, fluticasone propionate alone, and placebo groups. Improvements with the combination were also clinically meaningful compared with changes with salmeterol and placebo in both studies and with fluticasone propionate in study 1.

CONCLUSIONS

Treatment with combination fluticasone propionate and salmeterol delivered via hydrofluoroalkane metered-dose inhaler resulted in significantly greater improvements in asthma-related quality of life compared with individual components and placebo administered via traditional chlorofluorocarbon metered-dose inhaler.

Pharmacokinetic, pharmacodynamic, efficacy, and safety data from two randomized, double-blind studies in patients with asthma and an in vitro study comparing two dry-powder inhalers delivering a combination of salmeterol 50 microg and fluticasone propionate 250 microg: implications for establishing bioequivalence of inhaled products

BACKGROUND

The use of dry-powder inhalers (DPIs) to administer respiratory medicines is increasing, and new DPIs are likely to be developed because of expiring patents. However, there is considerable debate concerning the extent to which DPIs are interchangeable without altering disease control or the safety profile of the treatment.

OBJECTIVE

This study was designed to compare the pharmacokinetic (PK), pharmacodynamic (PD), efficacy, and safety data for 2 DPIs delivering a combination of salmeterol 50 microg plus fluticasone propionate (FP) 250 microg (SFC 50/250) to investigate assumptions of bioequivalence.

METHODS

Three studies compared SFC 50/250 delivery using a reservoir powder inhalation device (RPID) and a Diskus multiple-dose inhaler: an in vitro assessment of fine-particle-mass (FPM) profiles of the emitted doses; a PK/PD study of SFC 50/250 administered in two 14-day crossover treatment periods to 22 adults with moderate, persistent asthma to determine the equivalence of the RPID and Diskus inhaler in terms of drug delivery and systemic exposure; and a 12-week clinical efficacy and safety study of SFC 50/250 in 270 patients > or =12 years of age with moderate, persistent asthma to assess the equivalence of the RPID and Diskus inhaler based on peak expiratory flow (PEF) rates. FPM was summed from the quantity of active pharmaceutical ingredient deposited on stages 1 to 5 of a cascade impactor, representing an aerodynamic particle size range of 0.8 to 6.2 microm. Systemic exposure to SFC 50/250 was declared no greater with RPID than with the Diskus inhaler if the upper limit of the 90% CI for the ratio of FP AUC for the 2 devices was below the upper limit of the equivalence range (ie, <1.25). Adverse events, clinical laboratory test results, and vital signs were recorded throughout the 2 clinical studies.

RESULTS

In vitro, mean FPM values for the RPID and Diskus inhaler, respectively, were 13.1 and 12.8 microg/dose for salmeterol (P = NS) and 66.8 and 66.2 microg/dose for FP (P = NS). The only notable differences were mean FP for particle sizes 2.3 to 3.2 microm (21.4 microg/dose for RPID, 25.6 microg/dose for Diskus) and for sizes 4.0 to 6.2 microm (17.3 microg/dose for RPID, 11.7 microg/dose for Diskus). In the PK/PD study, there were 22 patients (16 men and 6 women), most (86%) of whom were white. Mean (SD) age was 26.0 (5.0) years (range, 19-35 years), and mean (SD) weight was 67.3 (8.9) kg. The 2 inhalers did not meet the criteria for declaring bioequivalence: estimated ratios (RPID:Diskus) were 2.00 (90% CI, 1.56 to 2.55) for FP AUC up to the time point of next dosing and 1.92 (90% CI, 1.64 to 2.25) for salmeterol maximum observed plasma concentration at the end of the dosing interval (at steady state). Urine cortisol (0-24 hours) was significantly lower for the RPID than for the Diskus inhaler (ratio, 0.74 [95% CI, 0.57 to 0.96]; P = 0.026); no significant difference in plasma cortisol was noted between the 2 inhalers (ratio, 0.85 [95% CI, 0.7 to 1.04]). A small but statistically significant increase in maximum heart rate (5 beats/min) was noted in the RPID group (ratio, 1.05 [95% CI, 1.01 to 1.10]; P = 0.029). No notable differences in other PD end points were observed. Drug-related adverse events occurred in both groups (2 [dysphagia and tremor] in the RPID group and 3 [2 cases of dysphonia, 1 case of mucous-membrane irritation] in the Diskus group). There were 270 patients (136 females, 134 males) in the clinical efficacy and safety study, most (94%) of whom were white; mean (SD) age was 37.2 (17.0) years (range, 11-77 years) in the RPID group and 35.4 (17.2) years (range, 12-77 years) in the Diskus group. The RPID and the Diskus inhaler met the predefined equivalence criteria (+/-15 L/min) in terms of mean change in morning PEF from baseline: 3.9 L/min (95% CI, -3.1 to 11.0). The 2 SFC 50/250 inhalers were well tolerated; the most frequently reported adverse event was bronchitis, reported by 12% of the patients in the RPID group and 9% of those in the Diskus group. The only serious adverse event, which occurred in the RPID group and was related to bronchial infection, was considered unrelated to treatment.

CONCLUSIONS

In vitro particle size distribution data were potentially superimposable for the RPID and the Diskus inhaler. The 2 devices were considered to be clinically equivalent in terms of mean morning PEF but were not considered equivalent in terms of PK systemic exposure. The 2 SFC 50/250 inhalers were well tolerated and had comparable safety profiles; no serious adverse events were attributed to the study product.

Fluticasone propionate/salmeterol and exercise-induced asthma in children with persistent asthma

RATIONALE

Exercise is a common trigger in children with persistent asthma and inhaled corticosteroids have been shown to effectively treat clinical manifestations of persistent asthma, including protection from decrements in lung function caused by exercise. The goal of this study was to evaluate the effectiveness of fluticasone propionate/salmeterol 100/50 mcg compared with fluticasone propionate 100 mcg for the prevention of airflow limitation triggered by standardized exercise challenge in pediatric and adolescent patients with persistent asthma.

METHODS

Multicenter, randomized, double-blind, parallel group trial of 248 subjects with persistent asthma (age 4-17 years) randomized to receive fluticasone propionate/salmeterol (100/50 mcg twice daily) or fluticasone propionate alone (100 mcg twice daily) via Diskus for 4 weeks. Exercise challenge tests were performed during screening and approximately 8 hr after administration of the blinded study medication on Treatment Day 28.

RESULTS

After 4 weeks of therapy both treatments provided protection following exercise challenge. The protection estimated by the maximal fall in FEV(1) was significantly better for fluticasone propionate/salmeterol (9.5 +/- 0.8% [mean +/- SE]) compared with fluticasone propionate alone (12.7 +/- 1.1%, P = 0.021). Statistically significant differences were not observed for asthma rescue-free days and asthma symptom-free days.

CONCLUSION

Chronic dosing with fluticasone propionate/salmeterol in a single device provides superior protection compared with an inhaled corticosteroid alone in protecting against exercise-induced asthma in children with persistent asthma.

Acute and chronic lung function responses to salmeterol and salmeterol plus fluticasone propionate in relation to Arg16Gly beta(2)-adrenergic polymorphisms

OBJECTIVE

There is conflicting clinical evidence describing the response to long-acting beta-agonist (LABA) bronchodilators for patients with Arg16Gly beta(2)-adrenergic receptor (ADRB2 ) genotype differences. Furthermore, the role of inhaled corticosteroids (ICS) in modulating Arg16Gly clinical responses is not well understood. The objective of this study was to investigate the effects of Arg16Gly polymorphism on the 12 hour post-dose bronchodilator response to the LABA salmeterol (SAL) or SAL plus fluticasone propionate (FSC) on first administration and following 12 weeks of treatment.

RESEARCH DESIGN AND METHODS

Genotyping was retrospectively performed in patients with persistent asthma randomized to SAL or FSC who were participating in three similar double-blind clinical trials of 12 week duration. The primary outcome was area under the curve (AUC) for 12 hour serial FEV(1) by treatment and Arg16Gly genotype, recorded on Day 1 and Week 12. In addition, other single nucleotide polymorphisms (SNPs) associated with asthma outcomes we assessed at positions -47, +79 and +491 as well as common ADRB2 haplotypes.

RESULTS

No statistically significant associations between Arg16Gly genotypes and serial FEV(1) clinical responses to SAL and FSC were observed following acute assessment. In addition, the FEV(1) response was preserved following 12 weeks of treatment with SAL and FSC and was not altered by Arg16Gly genotypes analyzed. These results may not be generalizable to other ethnic groups since they are derived predominantly from Caucasians.

CONCLUSIONS

In subjects with persistent asthma, the ADRB2 Arg16Gly polymorphism does not alter lung function responses to SAL or FSC over the 12 hour dosing interval following acute and chronic dosing.

Factor analysis in the Genetics of Asthma International Network family study identifies five major quantitative asthma phenotypes

BACKGROUND

Asthma is a clinically heterogeneous disease caused by a complex interaction between genetic susceptibility and diverse environmental factors. In common with other complex diseases the lack of a standardized scheme to evaluate the phenotypic variability poses challenges in identifying the contribution of genes and environments to disease expression.

OBJECTIVE

To determine the minimum number of sets of features required to characterize subjects with asthma which will be useful in identifying important genetic and environmental contributors. Methods Probands aged 7-35 years with physician diagnosed asthma and symptomatic siblings were identified in 1022 nuclear families from 11 centres in six countries forming the Genetics of Asthma International Network. Factor analysis was used to identify distinct phenotypes from questionnaire, clinical, and laboratory data, including baseline pulmonary function, allergen skin prick test (SPT).

RESULTS

Five distinct factors were identified:(1) baseline pulmonary function measures [forced expiratory volume in 1 s (FEV(1)) and forced vital capacity (FVC)], (2) specific allergen sensitization by SPT, (3) self-reported allergies, (4) symptoms characteristic of rhinitis and (5) symptoms characteristic of asthma. Replication in symptomatic siblings was consistent with shared genetic and/or environmental effects, and was robust across age groups, gender, and centres. Cronbach's alpha ranged from 0.719 to 0.983 suggesting acceptable internal scale consistencies. Derived scales were correlated with serum IgE, methacholine PC(20), age and asthma severity (interrupted sleep). IgE correlated with all three atopy-related factors, the strongest with the SPT factor whereas severity only correlated with baseline lung function, and with symptoms characteristic of rhinitis and of asthma.

CONCLUSION

In children and adolescents with established asthma, five distinct sets of correlated patient characteristics appear to represent important aspects of the disease. Factor scores as quantitative traits may be better phenotypes in epidemiological and genetic analyses than those categories derived from the presence or absence of combinations of +ve SPTs and/or elevated IgE.

Retrospective characterization of airway reversibility in patients with asthma responsive to bronchodilators

BACKGROUND

National and international asthma guidelines recommend the use of reversibility to assist in the diagnosis of asthma.

SCOPE

This retrospective pooled analysis assessed the reversibility characteristics of a large cohort of patients (n = 30 816) selected from 106 clinical trials conducted by GlaxoSmithKline in which bronchodilator reversibility (> or = 12%) was required for participation in the trials.

FINDINGS

Patients (n = 1434) with a baseline forced expiratory volume in 1 second (FEV1) between 40% and < 50% at screening had a mean reversibility of 42% and those (n = 550) with a baseline FEV1 between 90% and < 100% had a mean reversibility of 18%. In general, the lower the patient's baseline lung function, the higher the reversibility. Further, in a subset of studies (n = 7; 1477 patients) that provided reversibility data at study baseline and endpoint, the mean reversibility for patients receiving placebo or fluticasone propionate (FP) was 26%. At study completion, nearly 30% fewer patients receiving placebo were shown to be reversible and approximately half of the patients receiving fluticasone propionate were no longer reversible.

CONCLUSION

This analysis shows that airway reversibility is affected by asthma severity as measured cross-sectionally by spirometry, pharmacotherapeutic interventions, including placebo, and time. Additional studies are needed to confirm this finding in broader populations as studies in this analysis were limited to those conducted in the US by GlaxoSmithKline.

Needs and Opportunities for Research in Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis (HP) develops after inhalation of many different environmental antigens, causing variable clinical symptoms that often make diagnosis uncertain. The prevalence of HP is higher than recognized, especially its chronic form. Mechanisms of disease are still incompletely known. Strategies to improve detection and diagnosis are needed, and treatment options, principally avoidance, are limited. A workshop recommended: a population-based study to more accurately document the incidence and prevalence of HP; better classification of disease stages, including natural history; evaluation of diagnostic tests and biomarkers used to detect disease; better correlation of computerized tomography lung imaging and pathologic changes; more study of inflammatory and immune mechanisms; and improvement of animal models that are more relevant for human disease.

Fatal asthma from powdering shark cartilage and review of fatal occupational asthma literature

BACKGROUND

Work-related asthma (WRA) is the most common work-associated respiratory disease in developed countries.

METHOD

We report shark cartilage dust as a new potential cause of occupational asthma (OA) in the context of other fatal OA case reports.

RESULTS

A 38-year-old white male worked for 8 years in a facility which primarily granulated and powdered various plastics. Sixteen months prior to his death, the plant began grinding shark cartilage. After 10 months of exposure, he reported chest symptoms at work in association with exposure to shark cartilage dust and a physician diagnosed asthma. Six months later, he complained of shortness of breath at work and died from autopsy-confirmed asthma. The latency from onset of exposure to symptoms and from symptom onset to death was shorter than 10 previously reported OA fatalities.

CONCLUSION

Recognition of occupational causes and triggers of asthma and removal of affected individuals from these exposures is critical and can prevent progression to irreversible or even fatal asthma.

Use of specific inhalation challenge in the evaluation of workers at risk for occupational asthma: a survey of pulmonary, allergy, and occupational medicine residency training programs in the United States and Canada

STUDY OBJECTIVES

To document the current practice of occupational asthma (OA) diagnosis and use of specific inhalation challenge (SIC).

DESIGN, SETTING, AND PARTICIPANTS

A survey evaluating the current practice of SIC was mailed to 259 residency training programs in adult pulmonary diseases, allergy and immunology, and occupational medicine accredited in the United States and Canada during the year 2000.

RESULTS

Forty-six percent (123 of 259 programs) participated. Ninety-two programs reported that patients with OA were seen during the previous year, 15 programs reported that SIC had been performed, and 10 programs reported that patients had been referred to other sites for SIC. A total of 259 patients underwent SIC. No unexpected adverse reactions were reported. Forty-one programs reported that they had been willing to undertake SIC but were unable to do so. The most common barriers cited were lack of availability of SIC within the evaluating institution, inability to locate a site for referral, concerns about reimbursement, and lack of an appropriate diagnostic reagent for use in SIC. Seventy-four programs indicated that SIC was useful, and 34 programs included training in the use of SIC was part of the residency curriculum.

CONCLUSION

Although SIC is considered the "gold standard" for objective documentation of OA, the test is performed in only a few institutions in the United States and Canada. Many institutions indicate that SIC is not available, even when desired for patient management. Only a minority of participating residency training programs include SIC as a formal part of the training curriculum.

Respiratory symptoms among crab processing workers in Alaska: epidemiological and environmental assessment

BACKGROUND

Crab processing workers may develop respiratory symptoms and specific IgE responses, but the risk factors have not been fully described.

METHODS

In 1998, 107 workers at a crab processing facility completed a survey both at the beginning and end of the processing season. The surveys included standardized symptom questionnaires, spirometry, and serological testing, as well as measurement of workplace airborne crab allergens and microscopic analysis of aerosolized materials.

RESULTS

Over the crab processing season, asthma-like symptoms developed in 26% of study participants and bronchitic symptoms in 19%. Only 9% of those with new asthma-like symptoms were IgE-sensitized to crab at the end of the season. Among the crab processing jobs, butchering and degilling workers had the highest incidence of respiratory symptoms.

CONCLUSIONS

Both personal and process-related factors appear to affect the development of respiratory symptoms in crab processing workers. In this study, crab specific IgE was not detected in most of the workers with new symptoms. Published 2001 Wiley-Liss, Inc.

Lymphocyte proliferative response and tissue distribution of methylmercury sulfide and chloride in exposed rats

The immunotoxic effects and tissue distribution of different forms of methylmercury compounds were studied in rats. Methylmercury sulfide or methylmercury chloride was fed to rats at concentrations of 5 or 500 microg/L in drinking water for 8 wk. T-cell lymphocyte proliferative response to phytohemagglutinin (PHA) and determination of tissue distribution of mercury by gas chromatography using electron capture were assayed. Four different forms of mercury compounds were employed: MeHgS-, (MeHg)2S, (MeHg)3S+, and MeHgCl. Results indicated that exposure to methylmercury significantly enhanced lymphocyte responsiveness in most of the exposed groups at the low concentration of 5 microg/L, with the highest proliferative response (fourfold increase) in the MeHgCl group. At 500 microg/L, a significant decrease in the lymphocyte proliferative response was observed in the (MeHg)3S+ and MeHgCl groups; conversely, the MeHgS(-)- and (MeHg)2S-exposed animals had a modest increase of the lymphocyte proliferative response. The largest concentrations of all four mercury forms were detected in the kidney and spleen. The levels of mercury found in kidney, spleen, liver, brain, and testis were lower in the MeHgCl group than in those exposed to (MeHg)2S and (MeHg)3S+. These data indicate that the organ distribution of mercury and immune alteration may vary according to the chemical structure of the compound. This observation may have important implications in humans potentially exposed to low levels of methylmercury present in the environment, since the immune system plays an important regulatory role in the host-defense mechanisms.

Immune system alteration in the rat after indirect exposure to methyl mercury chloride or methyl mercury sulfide

Methyl mercury is a well-recognized health hazard. It is an environmental contaminant that accumulates in the food chain. The primary source of mercury exposure for humans is through the consumption of contaminated fish. We studied the effects of indirect methyl mercury exposure on the immune system of Sprague-Dawley rats. The effects of different forms of methyl mercury on immune system development were studied in Sprague-Dawley rats at 6 and 12 weeks of age. Rats were indirectly exposed to mercury during gestation and during nursing by exposing pregnant rats to either 5 or 500 micrograms/liter of methyl mercury chloride (CH3HgCl) or 5 micrograms/liter of methyl mercury sulfide [(CH3Hg)2S] in their drinking water. Total body, splenic, and thymic weights were measured, and NK cell cytolytic activity and lymphoproliferative response to T and B cell mitogens were evaluated in the offspring. At 6 weeks of age, total body and splenic weights were significantly increased in both high- and low-dose methyl mercury chloride-exposed groups. Rats exposed to methyl mercury sulfide had a significant increase in thymic weight at 6 weeks of age. At 12 weeks, the total body and organ weights were not different from controls. The lymphocyte proliferative response of splenocytes to PWM was enhanced at 6 weeks in both CH3HgCl exposed groups and not affected in the (CH3Hg)2S exposed group. NK cell activity was not affected in either group at 6 weeks of age. At age 12 weeks, NK cell activity was statistically significantly decreased by 56.6% in both CH3HgCl-exposed groups and not affected in the (CH3Hg)2S-exposed rats. The lymphocyte proliferative response of splenocytes to the B cell mitogen pokeweed remained increased in the CH3HgCl groups. Indirect exposure of rats (during gestation and nursing) to different forms of methyl mercury reveals that chloride forms have prolonged predominantly enhancing effects on lymphoproliferative response of splenocytes, followed by significant depression of NK cell activity.

Neuroimmunological effects of exposure to methylmercury forms in the Sprague-Dawley rats. Activation of the hypothalamic-pituitary-adrenal axis and lymphocyte responsiveness

The effects of different methylmercury (MeHg) forms on the immune system and the hypothalamic pituitary adrenal (HPA) axis were assessed. The lymphocyte response to Concanavalin A (Con A) stimulation, blood levels of interleukin-6 (IL-6), adrenocorticotrophin hormone (ACTH), and corticosterone in the presence of different MeHg compounds was measured. Rats were exposed to methylmercury sulfide [(MeHg)2S] and methylmercury chloride (MeHgCl) at concentrations of 5 and 500 micrograms per liter in the drinking water for 8 or 16 weeks. Short-term exposure (8 weeks) at both, low- and high-doses of (MeHg)2S significantly enhanced lymphocyte responsiveness. MeHgCl only induced increased lymphocyte responsiveness at the low-dose exposure. Circulating levels of IL-6 after short-term exposure were increased in the MeHgCl-exposed group. The HPA axis activation was demonstrated by increased levels of ACTH and corticosterone levels. This response was predominant in low-dose exposed animals. Long-term (16 weeks) exposure resulted in a reduction in lymphocyte prolife ration after both low- and high-dose MeHgCl exposures. The (MeHg)2S exposure resulted in a 3-fold increase in the proliferative response. Levels of ACTH were elevated 3-fold in the (MeHg)2S-exposed group and no increase of corticosterone was observed in the high-dose exposed group at 8 weeks, no effect of (MeHg)2S was observed at 16 weeks. The MeHgCl exposed group showed an increase in ACTH and corticosterone levels at 8 weeks; this response was not observed at 16 weeks. These data indicate that exposure to MeHg compounds enhances T-cell proliferation in most of the cases, in a dose- and time-dependent fashion. Release of IL-6 also depends on the length of exposure. Early increases in circulating ACTH at 8 weeks also suggest activation of the HPA axis. This may contribute to the production of IL-6 and surveillance of regulatory homeostatic responses against environmental agents that mimic stress-like responses.