In RECIST 1.1 the usual principle used is that once a PR has been assigned, and confirmed (if required), then the best response is always PR even is subsequent TP measurements no longer quite meet the criteria (providing that the criteria for PD are not met). The same principles hold for iRECIST as shown below.
Baseline | TP1 | TP2 | TP3 | TP4 | TP5 | |
T lesions (sum) | 100 | 70 | 70 | 80 | 80 | 80 |
NT lesions | Pres | No change | No change | No change | No change | No change |
New lesions | – | – | – | – | – | |
TP response (R) | PR | PR | PR | PR | PR | |
TP response (iR) | iPR | iPR | iPR | iPR | iPR |