Introduction: We evaluated the local control of melanoma brain metastases (MBM) following stereotactic radiosurgery (SRS) in the setting of treatment with or without sequential/concurrent immunotherapy.
Methods: A single-institution IRB-approved retrospective review was conducted on 68 MBM patients with 228 total metastases treated with SRS between November 2008 to February 2017. We compared local control of metastases in the setting of no immunotherapy versus sequential/concurrent immunotherapy (ipilimumab) versus sequential/concurrent immunotherapy (nivolumab or pembrolizumab with ipilimumab). Local failure was defined as an increase of at least 20% in the sum of longest diameter of a metastasis and its perpendicular diameter. Statistical analysis was performed using Kaplan-Meier estimates with log-rank testing using SPSS
Results: The 6-month LC rate for all lesions was 76.4%. 96 of the 228 lesions (42.1%) received ipilimumab treatments while 60 of the 228 lesions (26.3%) received nivolumab or pembrolizumab with ipilimumab. The 6-month LC rate for the metastases treated only with ipilimumab was 67.7% and the 6-month LC rate for the metastases treated with combined immunotherapy was 92.6%. In comparison, the 6-month LC rate for metastases in the cohort not treated with immunotherapy was 58.9% (p<0.0003). Patient pre-treatment characteristics including GPA score, number of brain metastases treated, and treatment volume were not significantly different between the immunotherapy and non-immunotherapy treatment groups. The mean initial (p<0.002) and 6 month (p<0.0003) volumetric response following SRS was significantly improved for patients receiving combined immunotherapy versus no immunotherapy or ipilimumab alone.
Conclusions: Addition of immunotherapy in melanoma brain metastases treated with stereotactic radiosurgery may improve local intracranial tumor control. Our study suggests that local control is significantly impacted by the class of immunotherapy used. Additional studies on volumetric response and radiation necrosis rates following combined radiosurgery/immunotherapy are underway.
Patient Care: By further understanding the synergistic effect of immunotherapy and radiosurgery on local control of melanoma brain metastases.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Identify an effective treatment for melanoma brain metastases.
2. Evaluate outcomes for melanoma brain metastases treated with stereotactic radiosurgery in the setting of sequential/concurrent immunotherapy.
3. Discuss, in small groups, the synergistic effect of immunotherapy and radiosurgery on local control for melanoma brain metastases.