Case Report: Five-Year Experience of AKT Inhibition with Miransertib (MK-7075) in an Individual with Proteus Syndrome.

Proteus syndrome is a rare overgrowth disorder caused by postzygotic activating variants in AKT1. Individuals may develop a range of skin, bone, and soft tissue overgrowth leading to functional impairment and disfigurement. Therapy for this disorder is limited to supportive care and surgical intervention. Inhibitors of AKT, originally designed as cancer therapeutics, are a rational, targeted pharmacologic strategy to mitigate the devastating morbidity of Proteus syndrome. We present the five-year follow up of an 18-year-old male with Proteus syndrome treated with miransertib (MK-7075), an oral pan-AKT inhibitor. At completion of a planned 48-week phase 1 pharmacodynamic study, the individual derived sufficient benefit that the study was amended to permit continued use and assess the long-term safety of miransertib. The treatment has been well tolerated with mild treatment-attributed side effects including headache, transient hyperglycemia, and transient elevations of aspartate aminotransferase, alanine aminotransferase, and bilirubin. He has experienced sustained improvement of pain and slowed growth of bilateral plantar cerebriform connective tissue nevi. This case report supplements the data from our prior study extending those findings out to five years. It shows that at the doses used, miransertib has a favorable safety profile and durable benefit of improving symptoms of pain and slowing progression of overgrowth in Proteus syndrome in a single individual. While an uncontrolled single report cannot prove safety or efficacy, these data lend support to the encouraging preliminary data of our prior phase 1 pharmacodynamic study.