A pharmacokinetic and biomarker study of delayed-release dimethyl fumarate in subjects with secondary progressive multiple sclerosis: evaluation of cerebrospinal fluid penetration and the effects on exploratory biomarkers

BACKGROUND

Biomarkers are a useful and reliable measure of disease activity in many fields of medicine. Axonal and glial biomarkers in multiple sclerosis (MS) are being applied more often as technology is improving and becoming increasingly reliable. Nonclinical studies have shown dimethyl fumarate (DMF) to have cytoprotective and anti-inflammatory effects. The purpose of this study is to explore the pharmacokinetics (PK) of DMF (by measuring MMF, the active compound) in serum and cerebrospinal fluid (CSF) as well as relevant biomarker data for patients with secondary progressive MS (pwSPMS) and whether there is objective evidence for neuroprotection in pwSPMS treated with DMF.

METHODS

Sixteen pwSPMS had serum and cerebrospinal fluid (CSF) evaluation for PK studies levels of MMF at various time points after ingestion of DMF. The CSF biomarkers neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), ubiquitin carboxyo-terminal hydrolase isozyme L1 (UCH-L1) and total tau (T-tau) were measured at baseline, week 6 and week 28 after initiating DMF with a starting dose of 120 mg twice daily for 4 weeks, followed by a maintenance dose of 240 mg twice daily. Clinical correlation of these patients with EDSS and MRI at these same time periods were made with the biomarkers. Four normal human volunteers had CSF studies for biomarkers at baseline.

RESULTS

PK data showed CSF MMF concentration 11% of plasma with Tmax of plasma at 5 hr and Tmax of CSF at 7 hr. Biomarker data showed that CS NfL and to a lesser extent, GFAP, but not UCH-L1 nor T-tau showed relevant changes with clinical data. Some pwSPMS receiving DMF showed clinical improvements in Expanded Disability Status Scale (EDSS). Biomarker changes, but not MRI, correlated with clinical measures in this group of pwSPMS over the observation period.

CONCLUSIONS

PK data showed that the Tmax of CSF MMF peaked only 2 hours later than that of plasma with 11% measured in the CSF so that MMF readily crossed the blood brain barrier allowing potential direct penetration into the brain. NfL CSF levels, and to a lesser extent, GFAP CSF levels, showed correlation to disease activity in pwSPMS . These data suggest that DMF may have some benefit in reducing disease activity in pwSPMS if studied for a longer duration and larger well-controlled studies are warranted. DMF was reasonably well tolerated but 3 of the 16 patients did discontinue DMF at 6 weeks due to persistent side effects. NfL appeared to be more clinically relevant biomarker than brain MRI in this this group during the 28-week study period.

Phase II Dose Selection for Alpha Synuclein-Targeting Antibody Cinpanemab (BIIB054) Based on Target Protein Binding Levels in the Brain

This modeling and simulation analysis was aimed at selecting doses of cinpanemab (BIIB054), a monoclonal antibody targeting aggregated α‐synuclein, for a phase II study in Parkinson’s disease (PD). Doses and regimens were proposed based on anticipated target concentration in brain interstitial fluid (ISF); in vitro/in vivo data on the affinity of monoclonal antibodies to the target protein; and safety, tolerability, and pharmacokinetic data (1–135 mg/kg intravenous administration) from a phase I single ascending dose (SAD) study. A population pharmacokinetic modeling approach was used to select intravenous doses of 250, 1,250, and 3,500 mg every 4 weeks, to maintain 50%, 90%, and > 90% of target binding in ISF of PD participants. A favorable safety profile from the SAD study—which showed that cinpanemab was generally well‐tolerated at doses up to 90 mg/kg, supported by modeling and simulations of the anticipated safety margins—allowed implementation of a fixed‐dose approach.

Randomized phase I clinical trial of anti-α-synuclein antibody BIIB054

BACKGROUND

Pathological and genetic evidence implicates toxic effects of aggregated α-synuclein in the pathophysiology of neuronal dysfunction and degeneration in Parkinson's disease. Immunotherapy targeting aggregated α-synuclein is a promising strategy for delaying disease progression.

OBJECTIVE

This study (NCT02459886) evaluated the safety, tolerability, and pharmacokinetics of BIIB054, a human-derived monoclonal antibody that preferentially binds to aggregated α-synuclein, in healthy volunteers and participants with Parkinson's disease.

METHODS

A total of 48 healthy volunteers (age 40-65, 19 women) and 18 Parkinson's disease participants (age 47-75, 5 women, Hoehn and Yahr stage ≤2.5) were in the study. Volunteers were enrolled into 6 single-dose cohorts of BIIB054 (range 1-135 mg/kg) or placebo, administered intravenously; Parkinson's disease participants received a single dose of BIIB054 (15 or 45 mg/kg) or placebo. All participants were evaluated for 16 weeks with clinical, neuroimaging, electrocardiogram, and laboratory assessments. Serum and cerebrospinal fluid BIIB054 concentrations were measured. BIIB054/α-synuclein complexes were measured in plasma.

RESULTS

Most adverse events were mild and assessed by investigators as unrelated to the study drug. Pharmacokinetic parameters for volunteers and the Parkinson's disease participants were similar. BIIB054 serum exposure and maximum concentrations were dose proportional during the dose range studied. In volunteers and the Parkinson's disease participants, the serum half-life of BIIB054 was 28 to 35 days; the cerebrospinal fluid-to-serum ratio ranged from 0.13% to 0.56%. The presence of BIIB054/α-synuclein complexes in plasma was confirmed; all Parkinson's disease participants showed almost complete saturation of the BIIB054/α-synuclein complex formation.

CONCLUSIONS

BIIB054 has favorable safety, tolerability, and pharmacokinetic profiles in volunteers and Parkinson's disease participants, supporting further clinical development. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Conditional approval of cancer drugs in Canada: accountability and impact on public funding

Background

We examined how conditional market approval of cancer pharmaceuticals by Health Canada (hc) affects public funding recommendations by the pan-Canadian Oncology Review (pcodr). We were also interested to see how often hc conditions are enforced.

Methods

Health Canada and pcodr databases for 2010-2017 were analyzed for patterns in hc conditional authorization and post-authorization reviews of cancer drugs and for correlation with pcodr reimbursement recommendations.

Results

Between 2010 and 2017, pcodr reviewed 105 unique drug-indication pairings; 21% (n = 22) had conditional hc authorization. In all cases, conditional authorization was given on the basis of preliminary data in a surrogate endpoint and was contingent on further data showing benefit in more robust outcome measures (for example, overall survival). Of those 22 drugs, 36% did not have updated data, 36% had updated data that met hc conditions, and 27% had data that met some, but not all, conditions. During the period considered, hc never revoked conditional authorization for failure to meet conditions. None of the 22 drugs was given an unconditional positive recommendation for public reimbursement by pcodr. A conditional recommendation was given to 11 of the drugs (50%), and reimbursement was not recommended for 6 drugs (27%) because of insufficient evidence.

Conclusions

One fifth of the cancer drugs reviewed for public reimbursement in Canada were conditionally authorized by hc based on preliminary data. Conditional authorization was associated with a recommendation against public funding by pcodr. No drugs had their conditional market authorization revoked for failure to meet conditions, suggesting that a more robust hc reappraisal framework is needed.

Understanding the reasons for provincial discordance in cancer drug funding-a survey of policymakers

Background

Cancer drug-funding decisions between provinces shows discordance. The pan-Canadian Oncology Drug Review (pcodr) was implemented in 2011 partly to address uneven drug coverage and lack of transparency in the various provincial cancer drug review processes in Canada. We evaluated the underlying reasons for ongoing provincial discordance since the implementation of pcodr.

Methods

Participation in an online survey was solicited from participating provincial ministries of health (mohs) and cancer agencies (cas). The 4-question survey (with both multiple-choice and free-text responses) was administered between 4 March 2015 and 1 April 2015, inclusive. Anonymity was ensured. Descriptive statistics were used to evaluate responses.

Results

Data were available from 9 provinces (all Canadian provinces except Quebec), with a response rate of 100%. The 12 responses received each came from a senior policymaker with more than 5 years' experience in cancer drug funding decision-making (5 from mohs, 7 from cas). Responses for 3 provinces came from both a moh representative and a ca representative. The most common reason for funding a drug not recommended by pcodr was political pressure (64%). The most common reason not to fund a drug recommended by pcodr was budget constraints (91%). The most common reason for a province to fund a drug before completion of the pcodr review was also political pressure (57%).

Conclusions

Political pressure and budgetary constraints continue to affect equity of access to cancer drugs for patients throughout Canada.

Impact of the pan-Canadian Oncology Drug Review on provincial concordance with respect to cancer drug funding decisions and time to funding

BACKGROUND

The pan-Canadian Oncology Drug Review (pcodr) was implemented in 2011 to address uneven drug coverage and lack of transparency with respect to the various provincial cancer drug review processes in Canada. We evaluated the impact of the pcodr on provincial decision concordance and time from Notice of Compliance (noc) to drug funding.

METHODS

In a retrospective review, Health Canada's Drug Product Database was used to identify new indications for cancer drugs between January 2003 and May 2014, and provincial formulary listings for drug-funding dates and decisions between 1 January 2003 and 31 December 2014 were retrieved. Multiple linear models and quantile regressions were used to evaluate changes in time to decision-making before and after the implementation of the pcodr. Agreement of decisions between provinces was evaluated using kappa statistics.

RESULTS

Data were available from 9 provinces (all Canadian provinces except Quebec), identifying 88 indications that represented 51 unique cancer drugs. Two provinces lacked available data for all 88 indications at the time of data collection. Interprovincial concordance in drug funding decisions significantly increased after the pcodr's implementation (Brennan-Prediger coefficient: 0.54 pre-pcodr vs. 0.78 post-pcodr; p = 0.002). Nationwide, the median number of days from Health Canada's noc date to the date of funding significantly declined (to 393 days from 522 days, p < 0.001). Exploratory analyses excluding provinces with incomplete data did not change the results.

CONCLUSIONS

After the implementation of the pcodr, greater concordance in cancer drug funding decisions between provinces and decreased time to funding decisions were observed.

A new quaternary ammonium cysteine analogue as a trapping reagent for reactive metabolites screening

The novel cysteine-cholamine (Cys-chol) trapping reagent was synthesized by coupling N-(tertbutoxycarbonyl)- S-trityl-L-cysteine with cholamine in the presence of HBTU (O-(benzotriazol-1-yl)- N,N,N',N'-tetramethyluronium hexafluorophosphate), and then deprotecting by trifluoroacetic acid. Cys-chol reagent enhanced the sensitivity of reactive metabolite screening 4 to 20 times without introducing additional sample preparation or derivatization steps. Retention of Cys-chol conjugates on reversed-phase column is higher than for respective GSH conjugates which helps in reduction of background interference. The use of Cys-chol trapping reagent can potentially improve sensitivity and specificity of routine reactive metabolite screening assay in drug discovery.

Quantitative determination of hippuric and benzoic acids in urine by LC-MS/MS using surrogate standards

An LC-MS/MS method for simultaneous determination of hippuric acid (HA) and benzoic acid (BA) in monkey urine after direct injection was developed. Since HA and BA are endogenous compounds in urine, surrogate standards ((13)C(6)-hippuric and (13)C(6)-benzoic acid) were employed to generate calibration curves. l-Phenylalanine-ring-D5 served as an internal standard. Multiple reaction monitoring in the negative ionization mode with an APCI source was used for detection of all components in the assay. The developed method is intended for determination of HA and BA in the range of 0.25-250 and 0.1-100microg/ml, respectively. Weighted (1/x) quadratic regression (r(2)>0.99) was used to generate calibration curves. Precision and accuracy of the method were assessed by analyzing 3 quality control samples (concentrations at low, medium, and high range of calibration curve) prepared in monkey urine. Stability for 48h at room temperature and after 3 freeze-thaw cycles was also evaluated. The proposed method was successfully utilized for analysis of urine samples from female monkeys following the administration of everninomicin alone and in combination with gentamicin. The concentrations of endogenous HA and BA were calculated based on the peak area ratio of the analyte to the internal standard using a regression equation for corresponding surrogate standard.

Human radiolabeled mass balance studies: objectives, utilities and limitations

The determination of metabolic pathways of a drug candidate through the identification of circulating and excreted metabolites is vitally important to understanding its physical and biological effects. Knowledge of metabolite profiles of a drug candidate in animals and humans is essential to ensure that animal species used in toxicological evaluations of new drug candidates are appropriate models of humans. The recent FDA final guidance recommends that human oxidative metabolites whose exposure exceeds 10% of the parent AUC at steady-state should be assessed in at least one of the preclinical animal species used in toxicological assessment. Additional toxicological testing on metabolites that have higher exposure in humans than in preclinical species may be required. The metabolite profiles in laboratory animals and humans are generally accomplished by mass balance and excretion studies in which radiolabeled drugs are administered to these species. The biological fluids are collected, analysed for total radioactivity and evaluated for a quantitative profile of metabolites. Thus, these studies not only determine the rates and routes of excretion but also provide very critical information on the metabolic pathways of drugs in preclinical species and humans. In addition, these studies are required by regulatory agencies for the new drug approval process. Despite the usefulness of these radiolabeled mass balance studies, there is little concrete guidance on how to perform or assess these complex studies. This article examines the objectives, utilities and limitations of these studies and how these studies could be used for the determination of the metabolite exposure in animals and humans.