Randomized study of teriflunomide effects on immune responses to neoantigen and recall antigens.

OBJECTIVE: To evaluate immune responses to neoantigen and recall antigens in healthy subjects treated with teriflunomide. METHODS: This was a randomized, double-blind, placebo-controlled study. Subjects received oral teriflunomide (70 mg once daily for 5 days followed by 14 mg once daily for 25 days) or placebo for 30 days. Antibody responses were evaluated following rabies vaccination (neoantigen) applied at days 5, 12, and 31 of the treatment period. Occurrence of delayed-type hypersensitivity (DTH) to Candida albicans, Trichophyton, and tuberculin (recall antigens) was assessed before and at the end of treatment to investigate cellular memory response. Safety and pharmacokinetics were evaluated. RESULTS: Forty-six randomized subjects were treated (teriflunomide, n = 23; placebo, n = 23) and completed the rabies vaccination. Geometric mean titers for rabies antibodies were lower with teriflunomide at days 31 and 38 than with placebo. However, all subjects achieved sufficient seroprotection following rabies vaccination (titers well above the 0.5 IU/mL threshold). Overall, the DTH response to recall antigens in the teriflunomide group did not notably differ from responses in the placebo group. CONCLUSIONS: Following vaccination, geometric mean titers for rabies antibodies were lower with teriflunomide than with placebo. However, teriflunomide did not limit the ability to achieve seroprotective titers against this neoantigen. Evaluation of DTH showed that teriflunomide had no adverse impact on the cellular memory response to recall antigens. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that in normal subjects treated with teriflunomide, antibody titer responses to rabies vaccination are lower than with placebo but sufficient for seroprotection.

Benign elevations in serum aminotransferases and biomarkers of hepatotoxicity in healthy volunteers treated with cholestyramine.

BACKGROUND: There are currently no serum biomarkers capable of distinguishing elevations in serum alanine aminotransferase (ALT) that portend serious liver injury potential from benign elevations such as those occurring during cholestyramine treatment. The aim of the research was to test the hypothesis that newly proposed biomarkers of hepatotoxicity would not significantly rise in serum during elevations in serum ALT associated with cholestyramine treatment, which has never been associated with clinically relevant liver injury. METHODS: In a double-blind placebo-controlled trial, cholestyramine (8g) was administered for 11 days to healthy adult volunteers. Serum from subjects with elevations in alanine aminotransferase (ALT) exceeding three-fold the upper limit of normal (ULN) were utilized for biomarker quantification. RESULTS: In 11 of 67 subjects, cholestyramine treatment resulted in ALT elevation by >3x ULN (mean 6.9 fold; range 3-28 fold). In these 11 subjects, there was a 22.4-fold mean increase in serum levels of miR-122 relative to baseline, supporting a liver origin of the serum ALT. Significant elevations were noted in mean levels of necrosis biomarkers sorbitol dehydrogenase (8.1 fold), cytokeratin 18 (2.1 fold) and HMGB1 (1.7 fold). Caspase-cleaved cytokeratin 18, a biomarker of apoptosis was also significantly elevated (1.7 fold). A rise in glutamate dehydrogenase (7.3 fold) may support mitochondrial dysfunction. CONCLUSION: All toxicity biomarkers measured in this study were elevated along with ALT, confirming the liver origin and reflecting both hepatocyte necrosis and apoptosis. Since cholestyramine treatment has no clinical liver safety concerns, we conclude that interpretation of the biomarkers studied may not be straightforward in the context of assessing liver safety of new drugs.

Teriflunomide and its mechanism of action in multiple sclerosis.

Treatment of multiple sclerosis (MS) is challenging: disease-modifying treatments (DMTs) must both limit unwanted immune responses associated with disease initiation and propagation (as T and B lymphocytes are critical cellular mediators in the pathophysiology of relapsing MS), and also have minimal adverse impact on normal protective immune responses. In this review, we summarize key preclinical and clinical data relating to the proposed mechanism of action of the recently approved DMT teriflunomide in MS. Teriflunomide selectively and reversibly inhibits dihydro-orotate dehydrogenase, a key mitochondrial enzyme in the de novo pyrimidine synthesis pathway, leading to a reduction in proliferation of activated T and B lymphocytes without causing cell death. Results from animal experiments modelling the immune activation implicated in MS demonstrate reductions in disease symptoms with teriflunomide treatment, accompanied by reduced central nervous system lymphocyte infiltration, reduced axonal loss, and preserved neurological functioning. In agreement with the results obtained in these model systems, phase 3 clinical trials of teriflunomide in patients with MS have consistently shown that teriflunomide provides a therapeutic benefit, and importantly, does not cause clinical immune suppression. Taken together, these data demonstrate how teriflunomide acts as a selective immune therapy for patients with MS.

Teriflunomide effect on immune response to influenza vaccine in patients with multiple sclerosis.

OBJECTIVE: To investigate the effect of teriflunomide on the efficacy and safety of seasonal influenza vaccine. METHODS: The 2011/2012 seasonal influenza vaccine (containing H1N1, H3N2, and B strains) was administered to patients with relapsing forms of multiple sclerosis (RMS) treated for ≥6 months with teriflunomide 7 mg (n = 41) or 14 mg (n = 41), or interferon-ß-1 (IFN-ß-1; n = 46). The primary endpoint was the proportion of patients with influenza strain-specific antibody titers ≥40, 28 days postvaccination. RESULTS: More than 90% of patients achieved postvaccination antibody titers ≥40 for H1N1 and B in all groups. For H3N2, titers ≥40 were achieved in ≥90% of patients in the 7 mg and IFN-ß-1 groups, and in 77% of the 14-mg group, respectively. A high proportion of patients already had detectable antibodies for each influenza strain at baseline. Geometric mean titer ratios (post/prevaccination) were ≥2.5 for all groups and strains, except for H1N1 in the 14-mg group (2.3). The proportion of patients with a prevaccination titer <40 achieving seroprotection was ≥61% across the 3 treatment groups and 3 influenza strains. However, fewer patients in the 14-mg than the 7-mg or IFN-ß-1 groups exhibited seroprotection to H3N2 (61% vs. 78% and 82%, respectively). CONCLUSION: Teriflunomide-treated patients generally mounted effective immune responses to seasonal influenza vaccination, consistent with preservation of protective immune responses. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that teriflunomide generally does not adversely impact the ability of patients with RMS to mount immune responses to influenza vaccination.