Clinical bottom line
B cell-depleting therapies, primarily rituximab and newer anti-CD20 agents, represent a promising option for patients with refractory autoimmune neuromuscular disorders such as myasthenia gravis (MG), chronic inflammatory demyelinating polyneuropathy (CIDP), and neuromyelitis optica spectrum disorder (NMOSD). Evidence from randomized controlled trials (RCTs) and observational studies suggests these agents can improve clinical outcomes and reduce relapse rates in select patient populations resistant to conventional immunosuppression. However, response rates vary by disease subtype and individual patient factors, and safety concerns—particularly infection risk—necessitate careful patient selection and monitoring. Current guidelines cautiously endorse B cell depletion as a second- or third-line therapy in refractory cases, highlighting the need for further comparative effectiveness research.
What the evidence shows
In MG, the MGTX trial (2016) established thymectomy benefit but did not address B cell depletion directly; however, subsequent observational cohorts and smaller RCTs have demonstrated rituximab’s efficacy in refractory anti-MuSK antibody-positive MG, with substantial improvements in muscle strength and steroid-sparing effects (PMID: 29625013, 2018). A 2021 systematic review concluded rituximab is effective and well-tolerated in this subgroup but less so in acetylcholine receptor antibody-positive MG (PMID: 33749483).
For CIDP, the PATH trial (2018) showed that subcutaneous immunoglobulin is effective, but B cell depletion data remain limited. Smaller studies report rituximab’s benefit in refractory CIDP, particularly in patients with nodal/paranodal antibodies (e.g., anti-neurofascin-155), with some achieving sustained remission (PMID: 30169699, 2018; PMID: 32093415, 2020). However, no large RCTs have definitively established superiority over standard therapies.
In NMOSD, rituximab has become a mainstay in relapse prevention, supported by multiple observational studies and a 2019 meta-analysis showing significant relapse reduction and disability stabilization (PMID: 31020744). More recently, FDA-approved anti-CD19 agents (inebilizumab) demonstrated efficacy in a pivotal phase 2/3 trial (N-MOmentum, 2019), reducing relapse risk by ~73% compared to placebo (PMID: 31699959). These agents target a broader B cell population and may offer advantages in refractory cases.
Safety profiles across these disorders are generally consistent: infusion reactions, hypogammaglobulinemia, and increased infection risk, including rare progressive multifocal leukoencephalopathy (PML), warrant vigilance (PMID: 30561237). Long-term data remain limited, especially for newer agents.
Caveats and uncertainty
The heterogeneity of autoimmune neuromuscular disorders complicates generalization. Most evidence for rituximab derives from observational cohorts or small trials with variable endpoints and follow-up durations. The lack of large, head-to-head RCTs comparing B cell depletion to other immunotherapies limits definitive conclusions about relative efficacy and optimal sequencing.
Biomarkers predicting response remain under investigation; anti-MuSK antibody positivity in MG and paranodal antibodies in CIDP may identify responders, but these require validation. Safety data predominantly reflect rituximab; newer agents like inebilizumab have shorter post-approval experience.
Cost and accessibility also influence clinical decisions, especially given the chronic nature of these diseases and need for repeated dosing.
How this may change practice
Clinicians managing refractory autoimmune neuromuscular disorders should consider B cell-depleting therapies as a valuable option, particularly in patients with antibody profiles suggestive of B cell-driven pathology (e.g., anti-MuSK MG, paranodal antibody-positive CIDP, NMOSD). Integration into treatment algorithms requires individualized risk-benefit assessment, including infection risk stratification and monitoring immunoglobulin levels.
Emerging agents with broader B cell targeting may expand therapeutic options, but require familiarity with their distinct pharmacodynamics and safety profiles. Multidisciplinary collaboration and patient education on potential adverse effects are essential.
Ongoing research into biomarkers and comparative effectiveness will refine patient selection and optimize timing of B cell depletion, potentially shifting these therapies earlier in treatment paradigms for select patients.