Mixed response in a patient with chordoma. A 61-year-old male with a sacral chordoma underwent surgery, radiation and multiple systemic therapies with continued progressive disease. His right iliac mass (A) was irradiated approximately 3.5 months prior to enrollment. A, C, and E, Baseline, first restaging, and most recent restaging MRI of the right iliac mass, which was previously irradiated. Mass decreased from 5.9 to 4.4 to 2.6 cm. B, D, and F, Baseline, first restaging, and most recent restaging CT scan of left paraspinal mass, which was not previously irradiated. This mass increased in size from 5.5 cm to 6.9 cm at first restaging, and growth was halted after radiation was given (6.9 to 6.6 cm on follow-up scan) while patient remained on study.