Levocarnitine for vismodegib-associated muscle spasms: A pilot randomized, double-blind, placebo-controlled, investigator-initiated trial

Background: Smoothened inhibitors (SIs) are a new targeted therapy approved by the United States Food and Drug Administration (FDA) for the treatment of advanced basal cell carcinoma (BCC). However, no placebo-controlled studies exist on management of their most common side-effect, muscle spasms, which affect up to 80% of patients taking SIs and are the most common reason for drug discontinuation despite tumor response. Based on anecdotal observations of exercise exacerbating SI-associated spasms, and existing evidence that levocarnitine (LC) can reduce markers of exercise induced stress, we explored the effect of oral LC usage on muscle spasms occurring after initiation of vismodegib, an SI.