Metabolism, pharmacokinetics and excretion of [14C]dimethyl fumarate in healthy volunteers: an example of xenobiotic biotransformation following endogenous metabolic pathways.

Delayed-release dimethyl fumarate (DMF), Tecfidera®, is approved globally for treating relapsing-remitting multiple sclerosis. The disposition of DMF was determined in humans after administration of a single oral dose of [14C]DMF, and the total recovery was estimated to be between 58.4% to 75.0%, primarily through expired air.The absorption of [14C]DMF-derived radioactivity was rapid, with Tmax at 1h postdose. Glucose was the predominant circulating metabolite, accounting for ∼60% of the total extractable radioactivity. Cysteine and N-acetylcysteine conjugates of mono- or di-methyl succinate were found to be the major urinary metabolites.In vitro studies showed that [14C]DMF was mainly metabolised to MMF, and fumarase exclusively converted fumaric acid to malic acid and did not catalyse the conversion of fumaric acid esters to malic acid. DMF was observed to bind with human serum albumin through Michael addition to the Cys-34 residue when exposed to human plasma.These findings indicate that DMF undergoes metabolism via hydrolysis, GSH conjugation, and the TCA cycle, leading to the formation of citric acid, CO2, and water. These ubiquitous and well-conserved metabolism pathways minimise the risk of drug-drug interactions and reduce variability related to pharmacogenetics and ethnicity.

Phase 1/2 study of lumiliximab combined with fludarabine, cyclophosphamide, and rituximab in patients with relapsed or refractory chronic lymphocytic leukemia.

Preclinical data demonstrate enhanced antitumor effect when lumiliximab, an anti-CD23 monoclonal antibody, is combined with fludarabine or rituximab. Clinical data from a phase 1 trial with lumiliximab demonstrated an acceptable toxicity profile in patients with relapsed or refractory chronic lymphocytic leukemia (CLL). We therefore pursued a phase 1/2 dose-escalation study of lumiliximab added to fludarabine, cyclophosphamide, and rituximab (FCR) in previously treated CLL patients. Thirty-one patients received either 375 mg/m(2) (n = 3) or 500 mg/m(2) (n = 28) of lumiliximab in combination with FCR for 6 cycles. The toxicity profile was similar to that previously reported for FCR in treatment of relapsed CLL. The overall response rate was 65%, with 52% of patients achieving a complete response (CR), which compares favorably with the CR rate previously reported for the FCR regimen alone in relapsed CLL. The estimated median progression-free survival for all responders was 28.7 months. The addition of lumiliximab to FCR therapy is feasible, achieves a high CR rate, and does not appear to enhance toxicity in previously treated patients with CLL. A randomized trial comparing lumiliximab plus FCR with FCR alone is underway to define the benefit of this combination in relapsed CLL. This trial was registered at clinicaltrials.gov as NCT00103558.

Safety and Efficacy of GFB-887, a TRPC5 Channel Inhibitor, in Patients With Focal Segmental Glomerulosclerosis, Treatment-Resistant Minimal Change Disease, or Diabetic Nephropathy: TRACTION-2 Trial Design.

INTRODUCTION: A critical unmet need exists for precision therapies for chronic kidney disease. GFB-887 is a podocyte-targeting, small molecule inhibitor of transient receptor potential canonical-5 (TRPC5) designed specifically to treat patients with glomerular kidney diseases characterized by an overactivation of the TRPC5-Rac1 pathway. In a first-in-human study, GFB-887 was found to be safe and well tolerated, had a pharmacokinetic (PK) profile allowing once-daily dosing, and dose dependently decreased urinary Rac1 in healthy adults. METHODS: TRACTION-2 is a phase 2a, double-blind, placebo-controlled, multiple-ascending dose study of GFB-887 in patients with focal segmental glomerulosclerosis (FSGS), treatment-resistant minimal change disease (TR-MCD), or diabetic nephropathy (DN) (NCT04387448). Adult patients on stable renin-angiotensin system blockade and/or immunosuppression with persistent proteinuria will be randomized and dosed in 3 ascending dose levels to GFB-887 or placebo for 12 weeks. Cohorts may be expanded or biomarker-enriched depending upon results of an adaptive interim analysis. RESULTS: The primary objective is to evaluate the effect of increasing doses of GFB-887 on proteinuria. Safety and tolerability, quality of life, pharmacokinetic/pharmacodynamic profiles, and the potential association of urinary Rac1 with efficacy will also be evaluated. The projected sample size has 80% power to detect a treatment difference in proteinuria of 54% (FSGS/TR-MCD) or 44% (DN) compared to placebo. CONCLUSION: TRACTION-2 will explore whether targeted blockade of the TRPC5-Rac1 pathway with GFB-887 is an efficacious and safe treatment strategy for patients with FSGS, TR-MCD, and DN and the potential value of urinary Rac1 as a predictive biomarker of treatment response.

Phase 1 study of lumiliximab with detailed pharmacokinetic and pharmacodynamic measurements in patients with relapsed or refractory chronic lymphocytic leukemia.

PURPOSE: Therapeutic antibodies have improved the outcome for patients with chronic lymphocytic leukemia (CLL). We conducted a phase 1, dose escalation and schedule optimization study of the primatized anti-CD23 antibody, lumiliximab, in patients with previously treated and refractory CLL. EXPERIMENTAL DESIGN: Forty-six patients were assigned sequentially to cohorts 1 through 6 and received lumiliximab at 125, 250, or 375 mg/m(2) weekly for 4 weeks; 500 mg/m(2) weekly for 4 weeks [500(A)]; 500 mg/m(2) thrice during week 1 then 500 mg/m(2) weekly for the next 3 weeks [500(B)]; or 500 mg/m(2) thrice a week for 4 weeks [500(C)], respectively. RESULTS: The median age was 62 years (range, 47-80), and the median number of prior regimens was four (range, 1-13). No partial or complete responses were observed. Toxicity was limited and unrelated to dose. The pharmacokinetics of lumiliximab was similar to other IgG(1) monoclonal antibodies with accumulation at doses > or =250 mg/m(2) and a median terminal half-life of 7 days. Pharmacodynamic studies showed dose-dependent increases in soluble CD23, but no down-regulation of CD23 antigen. Saturation of CD23 receptors occurred at 250 mg/m(2) and was maintained for > or =1 week following completion of therapy at > or =375 mg/m(2). CONCLUSIONS: Treatment with lumiliximab seemed to be well tolerated and to have clinical activity in patients with relapsed or refractory CLL.

Results of a randomized open-label crossover study of the bioequivalence of subcutaneous versus intramuscular administration of alefacept.

Alefacept selectively reduces memory T cells and inhibits T-cell activation. Large randomized trials have shown that intramuscular (IM) delivery of alefacept is safe and effective in treating plaque psoriasis. Subcutaneous (SC) administration of alefacept may provide advantages for some patients including convenience, ease of use, and reduced pain on injection. We conducted a randomized, open-label, crossover study in 50 healthy volunteers to determine if alefacept 15 mg administered SC is bioequivalent to alefacept 15 mg administered IM. The pharmacokinetic parameters used to determine bioequivalence were area under the serum concentration-time curve to the last measurable value (AUClast; primary endpoint), peak serum concentration (Cmax), and AUC to infinity (AUCinfinity). For each of these parameters, the 90 percent confidence intervals for the least squares mean ratios of alefacept SC to alefacept IM were well within the conventional bioequivalence range of 80 percent to 125 percent. These data, together with the finding that the mean serum concentration-time curves for alefacept were nearly identical following both routes of administration, demonstrate the bioequivalence of alefacept SC and alefacept IM. No clinically important differences between the pharmacodynamic profiles (total lymphocyte and lymphocyte subset counts) of the two routes of administration were observed. Alefacept SC and alefacept IM were similarly well tolerated. Our results suggest that SC dosing may represent a viable delivery option for alefacept.

Clinical pharmacokinetics and pharmacodynamics of insulin lispro mixtures.

Rapid-acting insulin analogues such as insulin lispro and insulin aspart produce a more physiological profile of insulin activity than does conventional regular human insulin because of their unique pharmacokinetics. These insulin analogues are absorbed rapidly from the subcutaneous injection site, resulting in a better matching of the appearance of insulin in the circulation with nutrient absorption from the intestine. In addition, they are shorter-acting than regular human insulin, thus decreasing the risk of late postprandial hypoglycaemia due to inappropriate hyperinsulinaemia. Because self-prepared mixtures of these rapid-acting insulin analogues with longer-acting insulins such as neutral protamine Hagedorn (NPH) insulin have been shown to be clinically useful, and because manufactured fixed-ratio mixtures of regular human insulin and NPH already represent a large proportion of insulin use, manufactured fixed-ratio mixtures of insulin lispro and a sustained-release insulin known as NPL have been developed (insulin lispro mixtures). NPL is a protamine-based insulin lispro formulation with pharmacokinetics and glucodynamics comparable to those of human NPH insulin. NPL was developed for use within insulin lispro mixtures because an exchange between soluble insulin lispro and protamine-bound human insulin within human NPH precludes prolonged storage of mixtures of these insulins. An insulin lispro mixture consisting of 25% insulin lispro and 75% NPL is now commercially available. This preparation is intended primarily as an alternative to human insulin 30/70, which is commonly used within a twice-daily injection regimen. A mixture containing 50% insulin lispro and 50% NPL is also available. The rapid activity of insulin lispro is maintained within insulin lispro mixtures, allowing injection just prior to a meal, a convenience that is not available with commercial mixtures of regular human insulin and human NPH insulin, which should be injected 30 to 45 minutes prior to meals. As with insulin lispro itself, the rapid action of insulin lispro within the insulin lispro mixtures also results in a smaller increase in blood glucose levels after meals than with comparable human insulin mixtures. In addition, data from two studies have shown that when Mix25 is injected prior to the evening meal the incidence of nocturnal hypoglycaemia is decreased in comparison with the same dose of human insulin 30/70. The combined rapid and prolonged insulin activity provided by insulin lispro mixtures has been defined both in healthy subjects without diabetes and in patients with diabetes.

Relating glucose clamp profiles to reduction of blood glucose after insulin administration.

A model was established allowing prediction of blood glucose response from glucose clamp results performed in healthy volunteers. Data from published studies performed in healthy volunteers were used to establish, test, and validate a model for the evaluation of glucose reductions from glucose clamp results. Studies included those that measured blood glucose and glucodynamic response over time after administration of 0.05 U/kg of regular human insulin (HR) and insulin lispro (LP) with and without the benefit of a glucose clamp procedure. An inhibitory effect E(max) model was used to describe the relationship; the model differed between the HR and LP responses by the intensity of the counterregulatory response as assessed by glucagon measurements. The relationships were used to predict blood glucose responses from a clamp study assessing NPH insulin and HR administrations. Glucose concentrations measured after administration of NPH insulin and HR without a clamp were compared to the model-predicted results to assess the accuracy of the model predictions. The E(max) model successfully correlated the glucose clamp results with the blood glucose depressions in the presence and absence of a counterregulatory response. However, predictions of glucose depression were only accurately modeled in the absence of a counterregulatory glucagon response. The correlations established with a minimal counterregulatory response underscore the value of glucose clamp procedures in defining the time-activity profiles of insulins when the clamp is established at fasting glucose concentrations.