Durable Near-Complete Response to Anti-PD-1 Checkpoint Immunotherapy in a Refractory Malignant Solitary Fibrous Tumor of the Pleura

Solitary fibrous tumor of the pleura is a rare and usually benign primary neoplasm arising from mesenchymal cells of the submesothelial tissue. We present here the case of a patient diagnosed with CD34-positive advanced malignant solitary fibrous tumor of the pleura whose disease failed to respond to combination cytotoxic chemotherapy agents, but demonstrated a prompt near-complete response to checkpoint blockade treatment using the antiprogrammed death (PD)-1 monoclonal antibody pembrolizumab, based on tumor molecular profiling revealing tumoral expression positivity for both programmed death-ligand 1 (PDL1) and PD-1. The patient experienced minimal adverse effects from the treatment with durable favorable response lasting up to cycle 26. (c) 2017 The Author(s) Published by S. Karger AG, Basel