Immune Checkpoint Inhibition for High Grade Meningiomas: A Systematic Review

World Health Organization grade II/III meningiomas frequently recur despite maximal safe surgical resection and adjuvant radiation. Notoriously resistant to medical therapy, no well-established guidelines for pharmacologic treatment currently exist. In recent years, a small number of clinical trials have investigated immune checkpoint inhibitors (ICIs) for patients with recurrent grade II/III meningiomas. We reviewed the existing literature to 1) summarize the clinical responses that have been observed and 2) identify tumor genomic characteristics that may predict a better response to ICI therapy.

PubMed was searched following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to include studies reporting clinical data for recurrent grade II or grade III meningiomas treated with ICIs. Clinical features, available tumor genomics, and outcomes were analyzed.

Four studies were included comprising 59 patients; 74.6% had World Health Organization grade II meningiomas and 25.4% had grade III meningiomas. Thirt-two patients (54%) received nivolumab, 26 (44%) received pembrolizumab, and 1 (2%) received an ICI not named. While tumor genomic data was not consistently reported across studies, favorable response was most associated with mismatch repair deficiency and high tumor mutational burden. Common adverse effects included liver/pancreas enzyme elevations (11.5%), fatigue (11.5%), and leukopenia/infection (9%).

Checkpoint inhibitors represent a promising investigational therapy for patients with recurrent grade II/III meningiomas. These drugs may be more efficacious for tumors with mismatch repair deficiency or high tumor mutational burden. Future investigations would benefit from research consortia with prospective enrollments of patients, descriptive characterization of tumor genomics, and standardized assessment of radiographic response.