Effect of dimethyl fumarate on lymphocytes in RRMS: Implications for clinical practice.

OBJECTIVE: To assess functional changes in lymphocyte repertoire and subsequent clinical implications during delayed-release dimethyl fumarate (DMF) treatment in patients with multiple sclerosis. METHODS: Using peripheral blood from several clinical trials of DMF, immune cell subsets were quantified using flow cytometry. For some patients, lymphocyte counts were assessed after DMF discontinuation. Incidence of adverse events, including serious and opportunistic infections, was assessed. RESULTS: In DMF-treated patients, absolute lymphocyte counts (ALCs) demonstrated a pattern of decline followed by stabilization, which also was reflected in the global reduction in numbers of circulating functional lymphocyte subsets. The relative frequencies of circulating memory T- and B-cell populations declined and naive cells increased. No increased incidence of serious infection or malignancy was observed for patients treated with DMF, even when stratified by ALC or T-cell subset frequencies. For patients who discontinued DMF due to lymphopenia, ALCs increased after DMF discontinuation; recovery time varied by ALC level at discontinuation. T-cell subsets closely correlated with ALCs in both longitudinal and cross-sectional analyses. CONCLUSIONS: DMF shifted the immunophenotype of circulating lymphocyte subsets. ALCs were closely correlated with CD4+ and CD8+ T-cell counts, indicating that lymphocyte subset monitoring is not required for safety vigilance. No increased risk of serious infection was observed in patients with low T-cell subset counts. Monitoring ALC remains the most effective way of identifying patients at risk of subsequently developing prolonged moderate to severe lymphopenia, a risk factor for progressive multifocal leukoencephalopathy in DMF-treated patients. TRIAL REGISTRATION NUMBERS: EUDRA CT 2015-001973-42, NCT00168701, NCT00420212, NCT00451451, and NCT00835770.

Gastrointestinal Tolerability of Delayed-Release Dimethyl Fumarate in a Multicenter, Open-Label Study of Patients with Relapsing Forms of Multiple Sclerosis (MANAGE).

BACKGROUND: In phase 3 trials, delayed-release dimethyl fumarate (DMF; also known as gastroresistant DMF) demonstrated efficacy in relapsing-remitting multiple sclerosis (MS). Gastrointestinal (GI) events were associated with DMF treatment. The single-arm, open-label MANAGE study examined the incidence, severity, duration, and management of GI events in adults with relapsing MS initiating DMF treatment in clinical practice in the United States shortly after marketing approval. PATIENTS AND METHODS: Patients (N = 233) took DMF for up to 12 weeks and recorded information regarding GI events using an eDiary and numerical rating scales. RESULTS: Overall, 54.1% of patients used symptomatic therapy and had GI symptoms. The incidence of GI events was highest in the first month of treatment. The duration of GI events varied by event type, and severity was generally mild to moderate. Decreased severity was seen in patients treated with antacids, bismuth subsalicylate, acid-secretion blockers, antidiarrheals, and antiemetics. Less than 10% of patients were using symptomatic therapy for GI events by week 12 of DMF treatment. A modest reduction in severe GI events was observed in patients who regularly took DMF with food compared with patients who did not. The incidence of GI-related events was comparable in patients with or without a history of GI abnormalities and in patients who did or did not use alcohol or tobacco. CONCLUSIONS: Gastrointestinal events associated with DMF are generally transient, mild to moderate in severity, and manageable. Symptomatic therapy and dosing with food may mitigate these events.

Silencing Nociceptor Neurons Reduces Allergic Airway Inflammation.

Lung nociceptors initiate cough and bronchoconstriction. To elucidate if these fibers also contribute to allergic airway inflammation, we stimulated lung nociceptors with capsaicin and observed increased neuropeptide release and immune cell infiltration. In contrast, ablating Nav1.8(+) sensory neurons or silencing them with QX-314, a charged sodium channel inhibitor that enters via large-pore ion channels to specifically block nociceptors, substantially reduced ovalbumin- or house-dust-mite-induced airway inflammation and bronchial hyperresponsiveness. We also discovered that IL-5, a cytokine produced by activated immune cells, acts directly on nociceptors to induce the release of vasoactive intestinal peptide (VIP). VIP then stimulates CD4(+) and resident innate lymphoid type 2 cells, creating an inflammatory signaling loop that promotes allergic inflammation. Our results indicate that nociceptors amplify pathological adaptive immune responses and that silencing these neurons with QX-314 interrupts this neuro-immune interplay, revealing a potential new therapeutic strategy for asthma.