Neurologic complications of immune checkpoint inhibitors

Purpose of review In recent years, advances in the understanding of the regulatory mechanisms of the immune system has led to the development of new approaches for cancer treatment. Currently, immune checkpoint inhibitors are the first successful examples of this approach and several agents that target cytotoxic lymphocyte-associated protein 4 (CTLA-4) and programmed cell death-1 (PD-1) have been approved for various oncologic situations. The aim of this review is to describe the neurologic adverse event profiles for these new immune therapeutic approaches and to discuss their appropriate management. Recent findings The immune checkpoint inhibitor ipilimumab against CTLA-4 and nivolumab or pembrolizumab against PD-1 show a unique spectrum of toxic effects. The most common toxicities include rash, colitis, hepatitis, endocrinopathies, and pneumonitis. Neurologic side-effects are rare but include cases of immune polyneuropathies, Guillain Barré syndrome, myasthenia gravis, posterior reversible encephalopathy syndrome, aseptic meningitis, enteric neuropathy, transverse myelitis as well as immune encephalitis. Summary It is essential that neurologic immune-related adverse events are recognized and treated as soon as possible, as early treatment increases the odds of a complete recovery.