Clinical outcomes of melanoma brain metastases treated with stereotactic radiation and anti-PD-1 therapy

Background: The anti-programmed death-1 (anti-PD-1) therapy nivolumab has significant clinical activity in patients with metastatic melanoma. However, little is known about the safety and outcomes in patients receiving anti-PD-1 therapy and stereotactic radiation for the treatment of brain metastases (BMs).

Patients and methods: Data were analyzed retrospectively from two prospective nivolumab protocols enrolling 160 patients with advanced resected and unresectable melanoma at a single institution. Patients were included if BMs were diagnosed and treated with stereotactic radiation within 6 months of receiving nivolumab. The primary end point of this study was neurotoxicity; secondary end points included BM control and survival.

Results: Twenty-six patients with a total of 73 BMs treated over 30 sessions were identified. Radiation was administered before, during and after nivolumab in 33 lesions (45%), 5 lesions (7%), and 35 lesions (48%), respectively. All BMs were treated with stereotactic radiosurgery (SRS) in a single session except 12 BMs treated with fractionated stereotactic radiation therapy, nine of which were in the postoperative setting. One patient experienced grade 2 headaches following SRS with symptomatic relief with steroid treatment. No other treatment-related neurologic toxicities or scalp reactions were reported. Eight (11%) local BM failures with a ≥20% increase in volume were noted. Of these lesions, hemorrhage was noted in 4, and edema was noted in 7. Kaplan-Meier estimates for local BM control following radiation at 6 and 12 months were 91% and 85%, respectively. Median overall survival (OS) from the date of stereotactic radiation and nivolumab initiation was 11.8 and 12.0 months, respectively, in patients receiving nivolumab for unresected disease (median OS was not reached in patients treated in the resected setting).

Conclusions: In our series, stereotactic radiation to melanoma BMs is well tolerated in patients who received nivolumab. BM control and OS appear prolonged compared with standard current treatment. Prospective evaluation is warranted.