Pamela F. Schwartz

Cardiovascular Efficacy and Safety of Bococizumab in High-Risk Patients

BACKGROUND Bococizumab is a humanized monoclonal antibody that inhibits proprotein convertase subtilisin–kexin type 9 (PCSK9) and reduces levels of low‐density lipoprotein (LDL) cholesterol. We sought to evaluate the efficacy of bococizumab in patients at high cardiovascular risk. METHODS In two parallel, multinational trials with different entry criteria for LDL cholesterol levels, we randomly assigned the 27,438 patients in the combined trials to receive bococizumab (at a dose of 150 mg) subcutaneously every 2 weeks or placebo. The primary end point was nonfatal myocardial infarction, nonfatal stroke, hospitalization for unstable angina requiring urgent revascularization, or cardiovascular death; 93% of the patients were receiving statin therapy at baseline. The trials were stopped early after the sponsor elected to discontinue the development of bococizumab owing in part to the development of high rates of antidrug antibodies, as seen in data from other studies in the program. The median follow‐up was 10 months. RESULTS At 14 weeks, patients in the combined trials had a mean change from baseline in LDL cholesterol levels of ‐56.0% in the bococizumab group and +2.9% in the placebo group, for a between‐group difference of –59.0 percentage points (P<0.001) and a median reduction from baseline of 64.2% (P<0.001). In the lower‐risk, shorter‐duration trial (in which the patients had a baseline LDL cholesterol level of ≥70 mg per deciliter [1.8 mmol per liter] and the median follow‐up was 7 months), major cardiovascular events occurred in 173 patients each in the bococizumab group and the placebo group (hazard ratio, 0.99; 95% confidence interval [CI], 0.80 to 1.22; P=0.94). In the higher‐risk, longer‐duration trial (in which the patients had a baseline LDL cholesterol level of ≥100 mg per deciliter [2.6 mmol per liter] and the median follow‐up was 12 months), major cardiovascular events occurred in 179 and 224 patients, respectively (hazard ratio, 0.79; 95% CI, 0.65 to 0.97; P=0.02). The hazard ratio for the primary end point in the combined trials was 0.88 (95% CI, 0.76 to 1.02; P=0.08). Injection‐site reactions were more common in the bococizumab group than in the placebo group (10.4% vs. 1.3%, P<0.001). CONCLUSIONS In two randomized trials comparing the PCSK9 inhibitor bococizumab with placebo, bococizumab had no benefit with respect to major adverse cardiovascular events in the trial involving lower‐risk patients but did have a significant benefit in the trial involving higher‐risk patients. (Funded by Pfizer; SPIRE‐1 and SPIRE‐2 ClinicalTrials.gov numbers, NCT01975376 and NCT01975389.)

Lipid-Reduction Variability and Antidrug-Antibody Formation with Bococizumab

BACKGROUND Bococizumab, a humanized monoclonal antibody targeting proprotein convertase subtilisin–kexin type 9 (PCSK9), reduces levels of low‐density lipoprotein (LDL) cholesterol. However, the variability and durability of this effect are uncertain. METHODS We conducted six parallel, multinational lipid‐lowering trials enrolling 4300 patients with hyperlipidemia who were randomly assigned to receive 150 mg of bococizumab or placebo subcutaneously every 2 weeks and who were followed for up to 12 months; 96% were receiving statin therapy at the time of enrollment. The patients were assessed for lipid changes over time, stratified according to the presence or absence of antidrug antibodies detected during the treatment period. RESULTS At 12 weeks, patients who received bococizumab had a reduction of 54.2% in the LDL cholesterol level from baseline, as compared with an increase of 1.0% among those who received placebo (absolute between‐group difference, ‐55.2 percentage points). Significant between‐group differences were also observed in total cholesterol, non–high‐density lipoprotein cholesterol, apolipoprotein B, and lipoprotein(a) (P<0.001 for all comparisons). However, high‐titer antidrug antibodies developed in a substantial proportion of the patients who received bococizumab, which markedly diminished the magnitude and durability of the reduction in LDL cholesterol levels. In addition, among patients with no antidrug antibodies, there was wide variability in the reduction in LDL cholesterol levels at both 12 weeks and 52 weeks. Major cardiovascular events occurred in 57 patients (2.5%) who received bococizumab and in 55 (2.7%) who received placebo (hazard ratio, 0.96; 95% confidence interval, 0.66 to 1.39; P=0.83). The most common adverse event among patients who received bococizumab was injection‐site reaction (12.7 per 100 person‐years). CONCLUSIONS In six multinational trials evaluating bococizumab, antidrug antibodies developed in a large proportion of the patients and significantly attenuated the lowering of LDL cholesterol levels. Wide variation in the relative reduction in cholesterol levels was also observed among patients in whom antidrug antibodies did not develop. (Funded by Pfizer; SPIRE ClinicalTrials.gov numbers, NCT01968954, NCT01968967, NCT01968980, NCT02100514, NCT02135029, and NCT02458287.)

Safety and efficacy of inhaled human insulin (Exubera®) during discontinuation and readministration of therapy in adults with type 1 diabetes: A 3-year randomized controlled trial

OBJECTIVE To assess pulmonary safety during discontinuation and readministration of inhaled human insulin (EXU; Exubera((R)) insulin human [rDNA origin]) Inhalation Powder) therapy in adults with type 1 diabetes. METHODS Patients were randomized to receive basal insulin plus either pre-meal EXU (n=290) or a short-acting subcutaneous (SC) insulin (n=290) for 2 years (comparative phase), followed by 6 months of SC insulin (washout) and 6 months of their original therapy (readministration). Highly standardized lung function tests were performed throughout. RESULTS Small treatment group differences favoring SC insulin in change from baseline forced expiratory volume in 1s (FEV(1)) and carbon monoxide diffusing capacity (DL(CO)) occurred early and were non-progressive. These differences resolved during washout and recurred at the same magnitude during readministration. Both groups maintained glycemic control, and hypoglycemic event rates were similar. In the EXU group, insulin antibody (IAb) levels plateaued at 12 months, declined to near baseline levels during washout and increased during readministration to levels observed in the comparative phase. CONCLUSIONS FEV(1) and DL(CO) changes observed during discontinuation and readministration of EXU therapy are consistent with a reversible, non-progressive and non-pathological effect on lung function. EXU readministration is not associated with an augmented IAb response.

Body Weight Changes Associated With Insulin Therapy A retrospective pooled analysis of inhaled human insulin (Exubera) versus subcutaneous insulin in five controlled Phase III trials

Weight gain is commonly seen when patients are started on subcutaneous (SC) insulin. In the UK Prospective Diabetes Study, those assigned insulin gained 4 kg more than those assigned conventional therapy at 10 years (1). Given that the majority of patients with type 2 diabetes are overweight or obese (2,3), additional weight gain is clearly a concern. Furthermore, while patients with type 1 diabetes were historically often underweight, the greater use of an intensified treatment approach to achieve the benefits of improved glycemic control is associated with greater weight gain than conventional treatment (4). Fear of weight gain, along with factors such as reluctance to self-inject and fear of hypoglycemia, is a frequent deterrent to initiating insulin therapy and has been linked to reduced treatment adherence in patients with both type 1 and type 2 diabetes (5). In type 2 diabetes, the β-cell dysfunction that leads to impaired insulin secretion is progressive, and eventually patients will require a treatment strategy that includes insulin either alone or with oral agents (6). The aim of this pooled analysis was to compare weight changes in a large population of adult patients with type 1 or type 2 diabetes receiving a regimen involving inhaled human insulin (Exubera [rDNA origin] Inhalation Powder) versus an SC insulin–only regimen. This was a retrospective analysis of pooled 6-month data from five controlled Phase III clinical trials …

Interpretation of the odds ratio from logistic regression after a transformation of the covariate vector

Logistic regression assumes a linear relationship between the logit and the continuous covariate. When the relationship is not linear, one can employ transformations of the covariate to satisfy the linearity assumption. We present an approach that allows interpretation of the odds ratio as it relates to the continuous covariate in its original metric. A numerical example illustrates the results.

Intersession Variability in Single-Breath Diffusing Capacity in Diabetics without Overt Lung Disease

RATIONALE American Thoracic Society guidelines state that a 10% or greater intersession change in diffusing capacity of the lung (DL(CO)) should be considered clinically significant. However, little is known about the short-term intersession variability in DL(CO) in untrained subjects or how variability is affected by rigorous external quality control. OBJECTIVES To characterize the intersession variability of DL(CO) and the effect of different quality control methods in untrained individuals without significant lung disease. METHODS Data were pooled from the comparator arms of 14 preregistration trials of inhaled insulin that included nonsmoking diabetic patients without significant lung disease. A total of 699 participants performed repeated DL(CO) measurements using a highly standardized technique. A total of 948 participants performed repeated measurements using routine clinical testing. MEASUREMENTS AND MAIN RESULTS The mean intersession absolute change in DL(CO) using the highly standardized method was 1.45 ml/minute/mm Hg (5.64%) compared with 2.49 ml/minute/mm Hg (9.52%) in the routine testing group (P < 0.0001 for both absolute and percent difference). The variability in absolute intersession change in DL(CO) increased with increasing baseline DL(CO) values, whereas the absolute percentage of intersession change was stable across baseline values. Depending on the method, 15.5 to 35.5% of participants had an intersession change of 10% or greater. A 20% or greater threshold would reduce this percentage of patients to 1 to 10%. CONCLUSIONS Intersession variability in DL(CO) measurement is dependent on the method of testing used and baseline DL(CO). Using a more liberal threshold to define meaningful intersession change may reduce the misclassification of normal variation as abnormal change.

Optimizing the Precision of Toxicity Threshold Estimation Using a Two-Stage Experimental Design

An important consideration for risk assessment is the existence of a threshold, i.e., the highest toxicant dose where the response is not distinguishable from background. We have developed methodology for finding an experimental design that optimizes the precision of threshold model parameter estimation for single-chemical threshold experiments. Being interested in precisely estimating the threshold parameter, we used the D-optimality and the Ds-optimality criteria. The D-optimal design results in parameter estimates as precise as possible in the sense that the likelihood-based confidence region has minimum volume, while the Ds-optimal threshold design results in parameter estimates as precise as possible in that the variance of the threshold parameter estimate is minimized. For nonlinearmodels, optimal designs are a function of the unknown parameters via the information matrix. Therefore, estimates of the parameters must be obtained before the optimal design of the experiment can be found. For this reason, a two-stage D-Ds-optimal design is recommended where the D-optimality criterion is used in the first stage followed by the Ds-optimality criterion in the second stage. The first stage is used for range finding and to obtain good global estimates to supply to the second stage. The second stage results in precise parameter estimates with minimum variance for the threshold parameter estimate. We propose that the use of this two-stage D-Ds-optimal design will provide toxicologists with the experimental parameters necessary to accurately estimate thresholds for risk assessment purposes in a more cost-effective and timely manner.

Trough Insulin Levels in Bronchoalveolar Lavage Following Inhaled Human Insulin (Exubera) in Patients with Diabetes Mellitus

BACKGROUND/AIM There are few data regarding insulin levels in the lungs during diabetes therapy with inhaled insulin. We examined the disposition of inhaled human insulin (Exubera(®) [EXU] human insulin [recombinant DNA origin], Pfizer, New York, NY) in the lungs by measuring trough insulin levels in bronchoalveolar lavage (BAL) fluid after 12 weeks of EXU treatment. METHODS After a 4-week run-in period of subcutaneous insulin therapy, 24 subjects with type 1 diabetes mellitus (T1DM) and 26 with type 2 diabetes mellitus (T2DM) continued their basal insulin regimen and received premeal subcutaneous (SC) insulin for 13 weeks, followed by 12 weeks of premeal EXU. BAL was performed approximately 12 h after the last insulin dose at (1) baseline, (2) following SC insulin, and (3) following EXU. RESULTS Twenty patients with T1DM and 24 patients with T2DM completed all three bronchoscopies. BAL trough insulin levels were undetectable at baseline or following SC insulin. After EXU therapy, they increased to a median of 4.5 nM (1.6-9.0 nM) and 2.3 nM (0.5-9.4 nM) in T1DM and T2DM, respectively. BAL trough insulin levels did not correlate with treatment efficacy, adverse effects, plasma insulin levels, or changes in pulmonary function. A larger proportion of previous EXU doses was present in the BAL in patients with T1DM. We found no correlation between average daily insulin doses and BAL trough insulin levels. CONCLUSIONS BAL trough insulin increased following EXU therapy, but this increase did not correlate with other clinical or laboratory parameters, suggesting no significant biological action. Further studies are warranted to better understand inhaled insulin deposition and clearance and possible effects of increased insulin levels on the lungs.

Assessment of long-term immunological and pulmonary safety of inhaled human insulin with up to 24 months of continuous therapy

ABSTRACT Background: This study was performed to characterize the long-term safety and efficacy of inhaled human insulin (EXU; Exubera* (insulin human [rDNA origin]) Inhalation Powder). * Pfizer Inc, New York, NY, USA Scope: Patients with type 1 or type 2 diabetes (N = 1290) who had successfully completed one of six controlled EXU open-label trials elected to receive open-label treatment with EXU for up to 3 years, after which they were randomized to discontinue EXU or to continue therapy for 6 months, then discontinue. Immunologic safety was assessed by insulin antibody (IAb) binding, and pulmonary safety was assessed by tests for forced expiratory volume in 1 second (FEV1) and carbon monoxide diffusing capacity (DLCO). In addition, changes over time in IAbs were compared with changes in FEV1, DLCO, hypoglycemia, and efficacy. Findings: Antibody binding increased in patients with either type 1 or type 2 diabetes after initiation of EXU and plateaued within 6–12 months (increases were higher in patients with type 1 diabetes than in patients with type 2 diabetes). Decreases in FEV1 occurred primarily during the first 3–6 months of EXU therapy. Among adult patients in the All Subjects set, the mean (± SE) annualized rate of decline in FEV1 was −0.053 ± 0.007 liters/year (95% CI, −0.065, −0.040) in adult patients with type 1 diabetes, and −0.076 ± 0.005 liters/year (95% CI, −0.085, −0.067) in patients with type 2 diabetes. Changes in DLCO occurred primarily during the first 3–6 months of EXU therapy. Among adult patients, in the All Subjects set, the mean (± SE) annual decline in DLCO was −0.738 ± 0.097 mL/min/mmHg/year (95% CI, −0.927, −0.548) and −0.688 ± 0.082 mL/min/mmHg/year (95% CI, −0.849, −0.527) in patients with type 1 and type 2 diabetes, respectively. Antibody binding did not correlate with changes in glycemic control, lung function, dose, or hypoglycemia. Following discontinuation of EXU, IAbs decreased to near baseline levels. Conclusion: These results are consistent with other trials showing long-term maintenance of safety and efficacy of EXU despite insulin antibody formation and small treatment group differences in pulmonary function. A limitation of the study was the lack of a comparator therapy.

Ponezumab in mild-to-moderate Alzheimer's disease: Randomized phase II PET-PIB study

The safety, pharmacokinetics, and effect on peripheral and central amyloid β (Aβ) of multiple doses of ponezumab, an anti‐Aβ monoclonal antibody, were characterized in subjects with mild‐to‐moderate Alzheimers disease treated for 1 year.