Disease progression after targeted therapy interruption. (A) Sagittal and axial MRI images of case 28, with CNS-AXG showing response of brain lesions to conventional therapies and targeted treatment with vemurafenib. After an initial PR to vemurafenib, targeted treatment was interrupted because of discontinued insurance coverage. Hereafter, brain lesions slowly progressed. Vemurafenib was restarted 3.6 years after interruption and quickly resulted in a decrease of brain lesions, with almost no lesions discernible at last follow-up. (B) Sagittal MRI images of case 27, with CNS-JXG showing relapse of a contrast-enhanced intramedullary spinal cord tumor after targeted therapy interruption. In this young child, treatment with dabrafenib and trametinib was interrupted after 1.6 years of therapy, while in complete radiologic remission. As an exit strategy, trametinib was stopped first, followed by dabrafenib 2 weeks later. MRI after stop of trametinib revealed persistent radiologic CR. However, MRI 2 weeks after stop of dabrafenib revealed recurrence of contrast-enhancement, consistent with a relapse of disease. MRI 2 weeks after restart of dabrafenib and trametinib showed that the radiologic response was recaptured. JXG, juvenile XG; MPS, methylprednisolone.