Introduction: Stereotactic radiosurgery and chemotherapeutics are used together for treatment of metastatic melanoma, and have been linked to delayed radiation-induced vascular leukoencephalopathy (DRIVL). There have been reports of more intense interactions with new immunotherapeutics targeting programmed cell death 1 receptor (PD1), but their interactions have not been well described, and may result in an accelerated response to GKRS. Here we present data on subjects treated with this combination from a single institution.
Methods: Records from patients who underwent treatment for metastatic melanoma to the brain with GKRS 2011 to 2016 were reviewed. Demographics, date of brain metastasis diagnosis, cause of death when applicable, immunotherapeutics, and imaging findings were recorded. The timing of both radiation therapy and medications were documented, as well as need for additional surgical intervention. Pathologic specimens were recorded when available.
Results: A total of 33 subjects (61.8% male) were treated with GKRS, and 25 patients underwent treatment with both GKRS and immunotherapy. Regarding the 13 patients treated with PD1-antagonists, 10 received pembrolizumab and 3 received nivolumab. Seven patients developed changes concerning for progression on subsequent MRI, and two underwent resection, but were not found to have residual or new tumor. All 7 had GKRS within 1 month of starting PD1-antagonists. The others without progression had GKRS 1-3 years prior to starting PD1-antagonists, or after stopping PD1-antagonists.
Conclusions: This abstract offers descriptive data for patients with metastatic melanoma after being treated with multiple treatments. In this cohort, there appears to be a combined effect of GKRS and anti-PD1 therapies. Our data suggests that to see an accelerated response to GKRS, PD1-antagonists should be administered after GKRS, and within a time window of several months.
Patient Care: A better understanding of the relationship between gamma knife radiosurgery and immunotherapies could lead to an improvement in treatment algorithms.
Learning Objectives: To evaluate radiation-induced changes in patients with diagnosis of brain metastasis secondary to malignant melanoma who received treatment with GKRS and PD1-antagonists.