Successful use of immune checkpoint Inhibition in a patient with myasthenia gravis and recurrent endometrial cancer- expanding access beyond initial clinical trial eligibility.

BACKGROUND

The use of immune checkpoint inhibitors (ICI) has transformed the treatment of patients with advanced stage or recurrent mismatch repair deficient (dMMR) endometrial cancer. Importantly, however, ICI are commonly contraindicated in patients with preexisting autoimmune conditions. Immune related myasthenia gravis (irMG) is the second most common neurologic immune related adverse event (irAE) with ICIs, and there have been several case reports of ICI induced myasthenia gravis (MG) as well as cases of MG flares associated with ICI treatment.

CASE PRESENTATION: This case report describes the successful use of pembrolizumab in combination with carboplatin and paclitaxel and then continued as maintenance in a 70-year-old patient with recurrent dMMR endometrial cancer and myasthenia gravis. Utilizing a multidisciplinary treatment team, the patient received plasmapheresis every 3 weeks, preceding pembrolizumab infusion, without clinical evidence of MG symptom flare. The patient remains in clinical remission 8 months following completion of maintenance therapy.

CONCLUSION

Pembrolizumab was safely administered, without identifiable irAEs, and a robust clinical response in a patient with dMMR EC, where the clinical benefit of immunotherapy has been well established. Historically, patients with MG have been excluded from enrollment and treatment on clinical trials. Real world, pragmatic, clinical data may help inform expanded utilization beyond trial eligibility criteria.