Natalizumab (Tysabri)

Diffusion tensor MRI as a biomarker in axonal and myelin damage

Diffusion tensor imaging has been used extensively as a research tool to understand the structural changes associated with white matter pathology. Using water diffusion as the basis to construct anatomic details, diffusion tensor imaging offers the potential to identify structural and functional adaptations before gross anatomical changes, such as lesions and tumors, become apparent on conventional MRI. Over the past 10 years, further parameters, such as axial and radial diffusivity, have been developed to characterize white matter changes specific to axons and myelin. In this paper, the potential application and outstanding issues on the use of diffusion tensor imaging directional diffusivity as a biomarker in axonal and myelin damage in neurological disorders will be reviewed.

Effects of natalizumab treatment on the cerebrospinal fluid proteome of multiple sclerosis patients

Natalizumab is a very effective, relatively new drug for the treatment of relapsing remitting multiple sclerosis. Inflammatory and neurodegenerative processes in the central nervous system are presumed to cause adverse effects during the course of this disease. To monitor the effects of natalizumab treatment on the cerebrospinal fluid (CSF) proteome of patients, CSF samples were taken from patients before commencing treatment as well as after 1 year of treatment. Profiling proteomics experiments using electrospray Orbitrap mass spectrometry and pair wise comparison of patients before and after 1 year of natalizumab treatment revealed a number of candidate biomarkers that were significantly differentially abundant between the before and after treatment groups. Three proteins were subsequently validated using selected reaction monitoring (SRM) in a new, independent sample set. All three proteins, Ig mu chain C region and haptoglobin, both known inflammation-related proteins, as well as Chitinase-3-like protein 1, were confirmed by SRM to be significantly lower abundant in CSF of multiple sclerosis patients after 1 year of natalizumab treatment. The findings for Chitinase-3-like protein 1, a presumed biomarker for more rapid progression from a first clinically isolated syndrome to clinically definite multiple sclerosis, was further confirmed by ELISA measurements.

Update on idiopathic colitides

PURPOSE OF REVIEW

This article summarizes the latest developments for three types of idiopathic colitis: ulcerative colitis, Crohn's disease, and microscopic colitis.

RECENT FINDINGS

Crohn's disease and ulcerative colitis are highly related genetically. Colonoscopy remains the gold standard for making a diagnosis. The addition of chromoendoscopy can aid in identification and removal of colonic dysplasia in both disorders. The therapy for ulcerative colitis and Crohn's disease has been transformed with the introduction of anti-TNF treatment. For ulcerative colitis, recent data show that prolonged use of infliximab is effective, well tolerated and that early mucosal healing is associated with decreased risk of colectomy. There is no evidence of a significant increased risk for anti-TNF-induced malignancies. Combination therapy with azathioprine and infliximab for ulcerative colitis has now been shown to be superior to monotherapy. Natalizumab is effective in anti-TNF failures and patients can be risk stratified for progressive multifocal leukoencephalopathy by testing for John Cunningham virus antibodies. Microscopic colitis can often be related to medications, and symptoms may be worsened by coexisting celiac disease.

SUMMARY

Combination therapy with an anti-TNF and a thiopurine is currently the most effective treatment for moderate-to-severe Crohn's disease or ulcerative colitis. Stem cell therapy for perianal fistulas in patients with Crohn's disease is a promising new therapy approach.

Have we overestimated the benefit of human(ized) antibodies?

The infusion of animal-derived antibodies has been known for some time to trigger the generation of antibodies directed at the foreign protein as well as adverse events including cytokine release syndrome. These immunological phenomena drove the development of humanized and fully human monoclonal antibodies. The ability to generate human(ized) antibodies has been both a blessing and a curse. While incremental gains in the clinical efficacy and safety for some agents have been realized, a positive effect has not been observed for all human(ized) antibodies. Many human(ized) antibodies trigger the development of anti-drug antibody responses and infusion reactions. The current belief that antibodies need to be human(ized) to have enhanced therapeutic utility may slow the development of novel animal-derived monoclonal antibody therapeutics for use in clinical indications. In the case of murine antibodies, greater than 20% induce tolerable/negligible immunogenicity, suggesting that in these cases humanization may not offer significant gains in therapeutic utility. Furthermore, humanization of some murine antibodies may reduce their clinical effectiveness. The available data suggest that the utility of human(ized) antibodies needs to be evaluated on a case-by-case basis, taking a cost-benefit approach, taking both biochemical characteristics and the targeted therapeutic indication into account.