Table 2.

Comparison of response evaluation criteria by RECIST 1.1, irRS, and irRECIST

	RECIST 1.1	irRS	irRECIST
Baseline tumor assessment	Tumor burden calculated as the sum of diameters of all target lesions— unidimensional measurements	Tumor burden calculated as the sum of the products of the longest perpendicular diameters (SPD) of all index lesions—bidimensional measurements	Calculated as the sum of diameters of all target lesions—unidimensional measurements
Subsequent tumor assessment	Tumor burden calculated as the sum of diameters of all target lesions (unidimensional measurements)	Total tumor burden at follow-up includes SPD of the index lesions and any new measurable lesions	Total measured tumor burden at follow-up is calculated as the sum of diameters of all target lesions and new measurable lesions
Target lesions	All measurable lesions up to a maximum of 5 total (max 2 per organ)	All measurable lesions (up to 5 per organ, up to 10 visceral and 5 cutaneous index lesions)	All measurable lesions up to a maximum of 5 total (max 2 per organ)
Evaluation of response
CR	Disappearance of all target lesions	irCR: Complete disappearance of all lesions, whether measurable or not and no new lesions	irCR: Complete disappearance of all measurable and nonmeasurable lesions
PR	>30% decrease in the sum of diameters of target lesions compared to baseline sum diameters	irPR: >50% decrease in tumor burden relative to baseline	irPR: >30% decrease in tumor burden relative to baseline and no unequivocal progression of new nonmeasurable lesions
PD	>20% increase in the sum of diameters of target lesions compared to nadir, or appearance of new lesions	irPD: >25% increase in tumor burden relative to nadir	irPD: >20% increase in tumor burden and minimum 5 mm absolute increase in tumor burden compared with nadir or irPD for nontarget or new nonmeasurable lesions
SD	Not meeting criteria for PR or PD	irSD: not meeting criteria for irCR or irPR in the absence of irPD	irSD: not meeting criteria for irCR or irPR in the absence of irPD
New lesions Confirmation of response	Represent PD Confirmation of response is not mandatory	Do not necessarily represent PD Any response other than SD has to be confirmed at least 4 weeks apart after the first assessment	Do not necessarily represent PD Confirmation of response is not mandatory; however, confirmation of irPD is recommended for patients with minimal total measured tumor burden increase especially during the first 12 weeks of treatment

Abbreviations: CR, complete response; irRS, immune-related response criteria; PD, progressive disease; PR, partial response; RECIST, response evaluation in solid tumors; SD, stable disease.