Background Immunotherapy targeting the PD-1 axis has activity in several tumor types. We aimed to determine the efficacy and safety of pembrolizumab in patients with untreated brain metastases. Here we present results from a Phase II trial of the PD-1 inhibitor pembrolizumab in patients with new or progressive brain metastases from melanoma or non-small cell lung cancer (NSCLC). Methods Thirty-six patients were enrolled, 18 with melanoma and 18 with NSCLC. Patients had at least one untreated or progressive brain metastasis between 5 and 20 mm in longest diameter without associated neurologic symptoms or the need for corticosteroids. NSCLC patients had tumor tissue demonstrating PD-L1 expression. Patients were treated with pembrolizumab 10 mg/kg every two weeks until progression, and brain metastasis response was assessed every eight weeks by modified RECIST. The primary endpoint was brain metastasis response rate and the analysis was performed on an intent-to-treat basis. The trial is ongoing and here we present an early analysis. The study is registered with clinicaltrials.gov, number NCT02085070. Findings Brain metastasis response rate was 22% and 33% among patients with melanoma and NSCLC, respectively. Responses were durable, with all but one patient who responded demonstrating an ongoing response at the time of data analysis. Treatment-related serious and grade 3–4 adverse events were rare and included transaminitis, colitis, pneumonitis, fatigue, endocrine abnormalities, and acute kidney injury (1 patient each). Serious neurological adverse events included cognitive dysfunction and seizures (1 and 3 patients, respectively), due to pembrolizumab, metastases or both. Interpretation Pembrolizumab demonstrates activity in brain metastases in patients with melanoma or NSCLC with an acceptable safety profile, indicating that there may be a role for systemic immunotherapy in patients with untreated or progressive brain metastases. Funding Merck and the Yale Cancer Center.

Background: We performed a phase II trial of pembrolizumab in patients with NSCLC or melanoma with untreated brain metastases to determine the activity of PD-1 blockade in the CNS. Interim results were previously published, and we now report an updated analysis of the full NSCLC cohort. Methods: This was an open-label, single-institution, phase 2 study. Eligible patients were ≥ 18 years of age with advanced NSCLC with ≥1 brain metastasis 5-20mm not previously treated or progressing after prior radiation, no neurologic symptoms or corticosteroid requirement, and performance status <2. Patients were treated with pembrolizumab 10 mg/kg IV every 2 weeks. Cohort 1 was for patients with PD-L1 ≥1% and cohort 2 PD-L1 <1% or unevaluable. The primary endpoint was the proportion of patients achieving a brain metastasis response. All treated patients were analyzed for response and safety endpoints. This study is closed to accrual and is registered with Clinicaltrials.gov, number NCT02085070. Here we report the updated results of the NSCLC cohort. Findings: Between March 31, 2014 and May 21, 2018, 42 patients were treated. Median followup was 8.3 months (IQR 4.5 to 26.2 months). Eleven of 37 patients in cohort 1 had a brain metastasis response (29.7% [95% CI, 15•9-47•0%]). There were no responses in cohort 2. Grade 3-4 AEs related to treatment included 2 patients with pneumonitis, and 1 each with constitutional symptoms, colitis, adrenal insufficiency, hyperglycemia, and hypokalemia. Treatment-related serious adverse events occurred in 6 (14%) patients and included pneumonitis acute kidney injury, colitis, hypokalemia, and adrenal insufficiency. There were no treatment-related deaths. Interpretation: Pembrolizumab has activity in brain metastases from NSCLC with PD-L1 expression ≥1% and is safe in select patients with untreated brain metastases. Further investigation of immunotherapy in patients with CNS disease from NSCLC is warranted.

Medtronic. Dr. Nead has received personal fees from Medtronic. Dr. Bowling has received personal fees from Medtronic. Dr. Murgu has received personal fees from Medtronic, Boston Scientific, Pinnacle Biologics, Olympus, Cook, Auris Robotics, and Elsevier; and has stock ownership in Concordia, Boston Scientific, and Merck. Dr. Krimsky has received personal fees from Medtronic, Innovital Systems, Gala Therapeutic, SOC, and Peytant; has stock ownership with Innovital Systems and CSA Medical; and has patents pending with Medtronic and Merit. Dr. Murillo has received support from Medtronic. Dr. LeMense has received personal fees from Medtronic. Dr. Minnich has received personal fees from Medtronic. Dr. Bansal has received personal fees from Medtronic, Pinnacle Biologics, Sunovion, and Veran Medical. Dr. Ellis has received support from Medtronic. Dr. Mahajan has received personal fees from Medtronic. Dr. Gildea has received personal fees from Medtronic. Dr. Bechara has received support from Medtronic. Dr. Sztejman has received support from Medtronic. Dr. Flandes has received grants from BTG-PneumRx and Ambu; and personal fees from Medtronic, BTG-PneumRx, Olympus, Ambu, PulmonX, and Boston Scientific. Dr. Rickman has received personal fees from Medtronic, Veran Medical, BD, Olympus, and Abbvie. Dr. Benzaquen has received support from Medtronic. Dr. Hogarth has received personal fees from Medtronic, Auris Surgical Robotics, Boston Scientific, Grifols, Shire, and CSL; and has stock ownership with Auris Surgical Robotics. Dr. Linden has received support from Medtronic. Dr. Wahidi has received personal fees from Medtronic and Veran Medical. Dr. Mattingley has received personal fees from Medtronic and is current employee of Medtronic (employment began after completion of enrollment). Dr. Hood is an employee with stock ownership at Medtronic; and has stock ownership with Boston Scientific. Ms. Lin and Ms. Wolvers are employees with stock ownership at Medtronic. Dr. Khandar has received personal fees from Medtronic.

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