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This site is intended for US Healthcare Professionals only.

Pseudo-Progression and Immuno-Oncology

Pseudo-progression may reflect development of antitumor immunity

The nature of the antitumor immune response can create the appearance of disease progression, either as tumor growth or appearance of new lesions.1 This is known as pseudo-progression. Pseudo-progression does not reflect tumor cell growth, but may be misclassified as disease progression.1,2

Tumors may appear to grow or new lesions may appear when immune cells infiltrate the tumor site.1 Due to the time required to mount an adaptive immune response, pseudo-progression may also reflect continued tumor growth until a sufficient response develops.1,3

Pseudo-progression should be considered until disease progression can be confirmed

It can be difficult to differentiate pseudo-progression from disease progression.1 Histologic confirmation is not always possible, but close monitoring of the following factors may help identify pseudo-progression1,4:

While uncommon, pseudo-progression is an important consideration when evaluating response to Immuno-Oncology therapies.3 Research is ongoing to identify measures differentiating between pseudo-progression and disease progression.



1. Wolchok JD, Hoos A, O’Day S, et al. Guidelines for the Evaluation of Immune Therapy Activity in Solid Tumors: Immune-Related Response Criteria. Clin Cancer Res. 2009;15:7412-7420. 2. Chiou VL, Burotto M. Pseudoprogression and Immune-Related Response in Solid Tumors. J Clin Oncol. 2015;33:3541-3543. 3. Hales RK, Banchereau J, Ribas A, et al. Assessing oncologic benefit in clinical trials of immunotherapy agents. Ann Oncol. 2010;21:1944-1951. 4. Eisenhauer EA, Therasse P, Bogaerts J, et al. New response evaluation criteria in solid tumours: Revised RECIST guideline (version 1.1). Eur J Cancer. 2009;45(2):228-247.