Comparative Effectiveness of Natalizumab, Fingolimod, and Injectable Therapies in Pediatric-Onset Multiple Sclerosis: A Registry-Based Study.

BACKGROUND AND OBJECTIVES: Patients with pediatric-onset multiple sclerosis (POMS) typically experience higher levels of inflammation with more frequent relapses, and though patients with POMS usually recover from relapses better than adults, patients with POMS reach irreversible disability at a younger age than adult-onset patients. There have been few randomized, placebo-controlled clinical trials of multiple sclerosis (MS) disease-modifying therapies (DMTs) in patients with POMS, and most available data are based on observational studies of off-label use of DMTs approved for adults. We assessed the effectiveness of natalizumab compared with fingolimod using injectable platform therapies as a reference in pediatric patients in the global MSBase registry. METHODS: This retrospective study included patients with POMS who initiated treatment with an injectable DMT, natalizumab, or fingolimod between January 1, 2006, and May 3, 2021. Patients were matched using inverse probability treatment weighting. The primary outcome was time to first relapse from index therapy initiation. Secondary study outcomes included annualized relapse rate; proportions of relapse-free patients at 1, 2, and 5 years; time to treatment discontinuation; and times to 24-week confirmed disability worsening and confirmed disability improvement. RESULTS: A total of 1,218 patients with POMS were included in this analysis. Patients treated with fingolimod had a significantly lower risk of relapse than patients treated with injectable DMTs (hazard ratio [HR], 0.49; 95% confidence interval [CI], 0.29-0.83; p = 0.008). After adjustment for prior DMT experience in the unmatched sample, patients treated with natalizumab had a significantly lower risk of relapse than patients treated either with injectable DMTs (HR, 0.15; 95% CI 0.07-0.31; p < 0.001) or fingolimod (HR, 0.37; 95% CI 0.14-1.00; p = 0.049). The adjusted secondary study outcomes were generally consistent with the primary outcome or with previous observations. The findings in the inverse probability treatment weighting-adjusted patient populations were confirmed in multiple sensitivity analyses. DISCUSSION: Our analyses of relapse risk suggest that natalizumab is more effective than fingolimod in the control of relapses in this population with high rates of new inflammatory activity, consistent with previous studies of natalizumab and fingolimod in adult-onset patients and POMS. In addition, both fingolimod and natalizumab were more effective than first-line injectable therapies. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that patients with POMS treated with natalizumab had a lower risk of relapse than those with fingolimod.

Key points to consider when studying RNA remodeling by proteins.

Cellular RNAs depend on proteins for efficient folding to specific functional structures and for transitions between functional structures. This dependence arises from intrinsic properties of RNA structure. Specifically, RNAs possess stable local structure, largely in the form of helices, and they have abundant opportunities to form alternative helices and tertiary contacts and therefore to populate alternative structures. Proteins with RNA chaperone activity, either ATP-dependent or ATP-independent, can promote structural transitions by interacting with single-stranded RNA (ssRNA) to compete away partner interactions and then release ssRNA so that it can form new interactions. In this chapter we review the basic properties of RNA and the proteins that function as chaperones and remodelers. We then use these properties as a foundation to explore key points for the design and interpretation of experiments that probe RNA rearrangements and their acceleration by proteins.

Ground-state coordination of a catalytic metal to the scissile phosphate of a tertiary-stabilized Hammerhead ribozyme.

Although the Hammerhead ribozyme (HHRz) has long been used as a model system in the field of ribozyme enzymology, several details of its mechanism are still not well understood. In particular, significant questions remain concerning the disposition and role of catalytic metals in the HHRz. Previous metal-rescue experiments using a "minimal" HHRz resulted in prediction of a catalytic metal that is bound in the A9/G10.1 site in the ground state of the reaction and that bridges to the scissile phosphate further along the reaction pathway. "Native" or extended HHRz constructs contain tertiary contacts that stabilize a more compact structure at moderate ionic strength. We performed Cd(2+) rescue experiments on an extended HHRz from Schistosoma mansoni using stereo-pure scissile phosphorothioate-substituted substrates in order to determine whether a metal ion makes contact with the scissile phosphate in the ground state or further along the reaction coordinate. Inhibition in Ca(2+)/Mg(2+) and rescue by thiophilic Cd(2+) was specific for the R(p)-S stereoisomer of the scissile phosphate. The affinity of the rescuing Cd(2+), measured in two different ionic strength backgrounds, increased fourfold to 17-fold when the pro-R(p) oxygen is replaced by sulfur. These data support a model in which the rescuing metal ion makes a ground-state interaction with the scissile phosphate in the native HHRz. The resulting model for Mg(2+) activation in the HHRz places a metal ion in contact with the scissile phosphate, where it may provide ground-state electrostatic activation of the substrate.

The identity of the nucleophile substitution may influence metal interactions with the cleavage site of the minimal hammerhead ribozyme.

Potential metal interactions with the cleavage site of a minimal hammerhead ribozyme (mHHRz) were probed using (31)P NMR-detected Cd(2+) titration studies of HHRz constructs containing a phosphorothioate (PS) modification at the cleavage site. The mHHRz nucleophile position was replaced by either a 2'-F or a 2'-NH(2) in order to block cleavage activity during the study. The 2'-F/PS cleavage site mHHRz construct, in which the 2'-F should closely imitate the atom size and electronegativity of a 2'-OH, demonstrates low levels of metal ion association (<1 ppm (31)P chemical shift changes). This observation indicates that having an atom size and electrostatic properties that are similar to the 2'-OH are not the governing factors in allowing metal interactions with the scissile phosphate of the mHHRz. With a 2'-NH(2) substitution, a large upfield change in (31)P NMR chemical shift of the phosphorothioate peak (Delta approximately 3 ppm with 6 equiv of added Cd(2+)) indicates observable Cd(2+) interactions with the substituted site. Since a 2'-NH(2), but not a 2'-F, can serve as a metal ligand, these data suggest that a metal ion interaction with the HHRz cleavage site may include both the scissile phosphate and the 2' nucleophile. Control samples in which the 2'-NH(2)/PS unit is placed either next to the mHHRz cleavage site (at U16.1), in a duplex, or in a (am)U(PS)U dinucleotide show much weaker interactions with Cd(2+). Results with these control samples indicate that simply the presence of a 2'-NH(2)/PS unit does not create a strong metal binding site, reinforcing the possibility that the 2'-NH(2)-moderated Cd-PS interaction is specific to the mHHRz cleavage site. Upfield chemical shifts of both (31)P and H-2' (1)H resonances in (am)U(PS)U are observed with addition of Cd(2+), consistent with the predicted metal coordination to both 2'-NH(2) and phosphorothioate ligands. These data suggest that metal ion association with the HHRz cleavage site may include an interaction with the 2'-OH nucleophile.