Immune-mediated necrotizing myopathy with pembrolizumab: a specific neuromuscular entity

Pembrolizumab is a humanized monoclonal antibody that binds to the programmed cell-death protein-1 (PD-1) on immune T-cells, thus blocking PD-1 activity. Pembrolizumab is indicated for the treatment of advanced melanoma, metastatic non-small-cell lung cancer, and head and neck squamous cell carcinoma. However, it is associated with immune-related adverse events.

We investigated the association between pembrolizumab and immune-mediated necrotizing myopathy (IMNM). We analyzed reports in the World Health Organization's global individual case safety report database, Vigibase, up to January 2020 with the MedDRA lower level term "IMNM." The association between exposure to pembrolizumab and occurrence of the adverse event was estimated by disproportionality analysis. The reporting odds ratio (ROR) was calculated with 95% confidence intervals (CIs). We analyzed the criteria of diagnosis of the adverse reaction.

Five-hundred sixty-seven notifications were identified as IMNM of which 14 with pembrolizumab. The ROR was 17.59 (95% CI: 9.4-32.9).

The diagnosis of IMNM does not always take into account recent criteria for the diagnosis of this pathology. This study highlights the existence of a signal, as well as the need for collaboration between oncologists and neurologists for these neurological pathologies.