We describe all six patients with stage IV cancer and documented MDM2 gene family amplification who received immunotherapy....Case #2: Patient with triple-negative breast cancer. While receiving local therapy against brain metastases, left lung metastasis was overall stable. However 1.5 months after the initiation of pembrolizumab, a CT scan revealed a 55% increase of the left lung mass as well as new chest wall masses and lymphadenopathy.