Table 1.

Comparison between WHO criteria and the irRC

WHOirRC
New, measurable lesions (i.e., ≥5 × 5 mm)Always represent PDIncorporated into tumor burden
New, nonmeasurable lesions (i.e., <5 × 5 mm)Always represent PDDo not define progression (but preclude irCR)
Non-index lesionsChanges contribute to defining BOR of CR, PR, SD, and PDContribute to defining irCR (complete disappearance required)
CRDisappearance of all lesions in two consecutive observations not less than 4 wk apartDisappearance of all lesions in two consecutive observations not less than 4 wk apart
PR≥50% decrease in SPD of all index lesions compared with baseline in two observations at least 4 wk apart, in absence of new lesions or unequivocal progression of non-index lesions≥50% decrease in tumor burden compared with baseline in two observations at least 4 wk apart
SD50% decrease in SPD compared with baseline cannot be established nor 25% increase compared with nadir, in absence of new lesions or unequivocal progression of non-index lesions50% decrease in tumor burden compared with baseline cannot be established nor 25% increase compared with nadir
PDAt least 25% increase in SPD compared with nadir and/or unequivocal progression of non-index lesions and/or appearance of new lesions (at any single time point)At least 25% increase in tumor burden compared with nadir (at any single time point) in two consecutive observations at least 4 wk apart