Case Reports:

Pseudoprogression in microsatellite instability-high colorectal cancer during treatment with combination T cell mediated immunotherapy: a case report and literature review

Young Kwang Chae _, Si Wang, Halla Nimeiri, Aparna Kalyan and Francis J. Giles

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Oncotarget. 2017; 8:57889-57897. https://doi.org/10.18632/oncotarget.18361

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Young Kwang Chae1,2,3, Si Wang2, Halla Nimeiri1,2,3, Aparna Kalyan1,2,3 and Francis J. Giles1,2,3

1 Developmental Therapeutics Program of the Division of Hematology Oncology, Northwestern University, Chicago, Illinois, USA

2 Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA

3 Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA

Correspondence to:

Young Kwang Chae, email:

Keywords: immune checkpoint inhibitors, metastatic colorectal cancer, immune-related response, anti-programmed death ligand-1 antibody, pseudoprogression

Received: December 28, 2016 Accepted: May 23, 2017 Published: June 03, 2017


Evading tumor-mediated immunosuppression through antibodies to immune checkpoints has shown clinical benefit in patients with select solid tumors. There is a heterogeneity of responses in patients receiving immunotherapy, including pseudoprogression in which the tumor burden increases initially before decreasing to reach disease control. The characteristics and basis of pseudoprogression, however, remains poorly understood. We hereby report a case of microsatellite instability (MSI)-high metastatic colorectal cancer treated with combination of OX40 agonist and programmed death ligand-1 (PD-L1) antagonist that demonstrated pseudoprogression reaching 163% increase from baseline tumor burden. Tumor regression was subsequently observed and patient has remained in stable disease. Despite the substantial radiological progression, the symptomatic improvement reported by the patient led us to the decision of treatment continuation based on the suspicion of pseudoprogression, illustrating the importance of clinical evaluation in medical decision making while managing patients on immunotherapy. Additionally, the patient’s MSI-high status contributes to his good, maintained response to PD-L1 blockade. Our case provides a frame of reference for fluctuation in tumor burden associated with pseudoprogression. Here we also evaluate the incidence and scale of pseudoprogression across solid tumor types.

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