Editors' note: Sporadic late-onset nemaline myopathy: Clinical spectrum, survival, and treatment outcomes

Abstract

In the article “Sporadic late-onset nemaline myopathy: Clinical spectrum, survival, and treatment outcomes,” Drs. Naddaf et al. reported that the overall survival among 28 patients with sporadic late-onset nemaline myopathy (SLONM)—identified by retrospective chart review—did not seem to be affected by the presence of a monoclonal protein (MP). They concluded that initial treatment with intravenous immunoglobulin (IVIg) was reasonable in all patients, followed by autologous stem cell transplant (ASCT) or chemotherapy as second-line therapy in patients with an associated MP. In response, Drs. Chahin and Karam suggest clarifying the degree of weakness and disability of those patients who received IVIg vs those who received ASCT because this could result in selection bias. They report that in their experience, patients with SLONM and MP with a severe phenotype who were treated with IVIg initially appeared stable over 6 months but then rapidly deteriorated—becoming too weak for ASCT—and died. They also cite a previous study that showed worse survival in patients with MP and posit that the absence of such a difference in this study may relate to the recent approach of aggressive treatment of such patients. In the absence of a study comparing IVIg and ASCT in such patients, they conclude that some patients with aggressive SLONM may be best treated with ASCT directly. Responding to these comments, Drs. Naddaf et al. reported no difference in the Neuropathy Impairment Score-Weakness at presentation between patients who received IVIg vs ASCT. They acknowledge the inherent limitations of referral bias and retrospective design but note that severely affected patients were still among those referred to their institution who showed good response to IVIg, with none rendered ineligible for ASCT by previous treatment failure. They counter that given the risks of morbidity, mortality, and other post-ASCT side effects, IVIg should still be the first-line treatment in the absence of evidence of superiority of ASCT, with ASCT considered for patients not responding after 2–3 months. This exchange demonstrates the clinical equipoise regarding the choice of IVIg vs ASCT as first-line therapy for patients with SLONM, particularly in the presence of MP. In the article “Sporadic late-onset nemaline myopathy: Clinical spectrum, survival, and treatment outcomes,” Drs. Naddaf et al. reported that the overall survival among 28 patients with sporadic late-onset nemaline myopathy (SLONM)—identified by retrospective chart review—did not seem to be affected by the presence of a monoclonal protein (MP). They concluded that initial treatment with intravenous immunoglobulin (IVIg) was reasonable in all patients, followed by autologous stem cell transplant (ASCT) or chemotherapy as second-line therapy in patients with an associated MP. In response, Drs. Chahin and Karam suggest clarifying the degree of weakness and disability of those patients who received IVIg vs those who received ASCT because this could result in selection bias. They report that in their experience, patients with SLONM and MP with a severe phenotype who were treated with IVIg initially appeared stable over 6 months but then rapidly deteriorated—becoming too weak for ASCT—and died. They also cite a previous study that showed worse survival in patients with MP and posit that the absence of such a difference in this study may relate to the recent approach of aggressive treatment of such patients. In the absence of a study comparing IVIg and ASCT in such patients, they conclude that some patients with aggressive SLONM may be best treated with ASCT directly. Responding to these comments, Drs. Naddaf et al. reported no difference in the Neuropathy Impairment Score-Weakness at presentation between patients who received IVIg vs ASCT. They acknowledge the inherent limitations of referral bias and retrospective design but note that severely affected patients were still among those referred to their institution who showed good response to IVIg, with none rendered ineligible for ASCT by previous treatment failure. They counter that given the risks of morbidity, mortality, and other post-ASCT side effects, IVIg should still be the first-line treatment in the absence of evidence of superiority of ASCT, with ASCT considered for patients not responding after 2–3 months. This exchange demonstrates the clinical equipoise regarding the choice of IVIg vs ASCT as first-line therapy for patients with SLONM, particularly in the presence of MP.