Drug exposure and best response requirements for secondary resistance to ICI combinations
| Resistance phenotype | Drug exposure requirement | Best response | Confirmatory scan for PD requirement | Confirmatory scan time frame |
| Secondary resistance* | >6 months | CR, PR, or SD ≥6 months† | Yes, if clinically stable | At least 4 weeks after PD, if clinically feasible |
*For ICI combinations administered as induction dosing (ie, one agent is dropped after a set number of cycles) secondary resistance is defined for the monotherapy that was continued.
†For aggressive tumors such as mesothelioma and NSCLC, 3 months is required.
CR, complete response; ICI, immune checkpoint inhibitor; NSCLC, non-small cell lung cancer; PD, progressive disease; PR, partial response; SD, stable disease.