Presence of oncogenic driver mutations

Measurable lesion located within 10mm of the optic chiasm or optic nerve, or within the brainstem

Known leptomeningeal involvement.

Midline shift

Serious non-healing wound, ulcer or bone fracture

Baseline inability to participate or complete neurocognitive testing

Major surgical procedure (including craniotomy and open brain biopsy) or significant traumatic injury within 14 days prior to registration

Receipt of a non-CNS minor surgical procedure (e.g. core biopsy or fine needle aspiration) within three days prior to registration

History of allergic reactions attributed to monoclonal antibodies (mAb), compounds of similar chemical or biologic composition to Pembrolizumab

Clinically significant cardiovascular disease

Patients with uncontrolled intercurrent illness

Patients with psychiatric illness/social situations that would limit compliance with study requirements

Pembro+Chemo in Brain Mets