Table 1.

Definitions of primary and secondary resistance in advanced disease setting

Resistance phenotype	Drug exposure requirement	Best response	Confirmatory scan for PD requirement	Confirmatory scan timeframe
Primary resistance	≥6 weeks	PD; SD for <6 months*	Yes†	At least 4 weeks after initial disease progression‡
Secondary resistance	≥6 months	CR, PR, SD for >6 months*	Yes†	At least 4 weeks after disease progression‡

*Indolent tumor types might require modification of the timeframe.

†Other than when tumor growth is very rapid and patients are deteriorating clinically.

‡Per Response Evaluation Criteria in Solid Tumors 1.1.

CR, complete response; PD, programmed death; PR, partial response; SD, stable disease.