Learning objectives
To review the response evaluation of immunotherapeutic agents with the immune – related Response Criteria (irRC),
advances made since their implementation and potential imaging pitfalls that derive from their differences.
Background
Recent developments in anti-cancer therapies had created the need to think of new response evaluation techniques,
as past criteria did not explain nor completely correlate with all clinical tumor responses.
In 2009 Immuno-related response criteria (irRC) were created.
They address new patterns of response derived from the use of immunotherapeutic agents,
as they can induce a radiological pseudo-progression due to their power to stimulate the immune system («tumor inflammation»,
also called “flare-effect”) if we are to evaluate their response-stability-progression by main «classic» criteria (RECIST 1.1)....
Findings and procedure details
1.
Target lesions
Follow RECIST1.1 rules / preferences.
As with RECIST1.1,
all lesions have to be taken into account at baseline.
The excess of measurable lesions and all true non-measurable lesions will be selected as non-target lesions at baseline and followed at subsequent CT scans.
2.
Classic patterns of response
a) CR: disappearance of all target and non-target lesions.
Lymph nodes must decrease to < 10 mm SA (small axis).
b) PR: decrease of ≥ 30% SOL (sum of lesions) relative to baseline,
without unequivocal...
Conclusion
Imaging rests as one of the most important evaluation pillars for all anti-cancer therapies,
and the use of irRC helps monitoring new types of response that correlate better with clinical responses that result from the use of these new immune agents,
avoiding that way potential pitfalls that arise from the use of prior classic response criteria.
The tendency nowadays is to use mixed irRC and RECIST1.1 criteria for a more comprehensive assessment.
References
[1] Kwak JJ,
Tirumani SH,
Van den Abbeele AD,
Koo PJ,
Jacene HA.
Cancer immunotherapy: imaging assessment of novel treatment response patterns and immune-related adverse events.
Radiographics.
2015 Mar-Apr;35(2):424-37.
[2] O.
Bohnsack,
A.
Hoos,
K.
Ludajic.
Adaptation of the immune related response criteria: irRECIST.
Annals of Oncology (2014) 25 (suppl.
4): iv361-iv372.
[3] Nishino M,
Tirumani SH,
Ramaiya NH,
Hodi FS.
Cancer immunotherapy and immune-related response assessment: The role of radiologists in the new arena of cancer treatment.
European Journal of Radiology 84 (2015) 1259-1268....