A correspondence published in The Lancet raises three unresolved methodological questions about the NIMBLE trial, a study of complement-blocking drugs for generalised myasthenia gravis. The letter does not dispute that the trial's central finding could matter, but it argues that several aspects of the research still need to be addressed before its conclusions can be fully accepted.
The trial, led by Tuan Vu and colleagues, compared two treatment approaches. Cemdisiran alone produced a mean reduction of 76.6 per cent in total complement haemolysis activity, measured as CH50 inhibition from baseline. The combination of cemdisiran and pozelimab reached 99.6 per cent CH50 inhibition. Despite that large difference in complement blockade, the two regimens achieved similar clinical efficacy in patients with the condition.
From those results, the authors concluded that « substantial but incomplete complement blockade might be sufficient » for controlling disease. For patients and clinicians, that suggestion is significant, because a therapy that does not need to suppress the complement system as completely could in principle carry a different balance of benefits and risks. The correspondence, however, contends that the methodological issues must be resolved before such a conclusion can be relied upon.
Generalised myasthenia gravis is a chronic autoimmune disorder in which antibodies disrupt communication between nerves and muscles, causing fatigue and muscle weakness. Complement inhibitors have become an area of active research because the complement system contributes to the damage at the neuromuscular junction. The NIMBLE findings therefore fit into a broader effort to determine how much complement blockade is needed to control symptoms.
The correspondence sits within The Lancet's ongoing scientific debate, in which published trials are scrutinised by other researchers. Such exchanges are a routine part of peer review after publication and help readers weigh a study's strengths and limitations. Because the letter's three points are central to interpreting the result, their resolution will shape how the trial's conclusion about incomplete complement blockade is understood.
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