Table 3.

Minimum exposure and best response definition for primary resistance to immune checkpoint inhibitor−chemotherapy combinations in advanced tumor settings

Resistance phenotype	Exposure requirement	Timing of RECIST progression*	Confirmatory scan
Primary resistance†	6–8 weeks‡	≤6 months	Not required
Secondary or late resistance†	>6 months	>6 months	Not required

*Regardless of best response.

†For patients that experience recurrent disease after stopping therapy for reasons other than toxicity, no uniform clinical definitions of resistance applicable across disease states could be described.

‡For rapidly progressing disease, any exposure is adequate.

RECIST, Response Evaluation Criteria In Solid Tumors.