Managing PR when TP measurements change slightly over time.

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