Table 1. Statistical regression model output.

Xenograft	Time coefficient (p-value)	Time2 coefficient (p-value)	Model AIC
PDX-SCC-M0	0.0291 (< 0.0001)		518.0
	0.0123 (< 0.0001)	0.00004 (< 0.0001)	446.7
PDX-SCC-M1	0.0192 (< 0.0001)		350.4
	−0.0032 (0.0033)	0.00005 (< 0.0001)	263.7
PDX-SCC-M11	0.0150 (< 0.0001)		192.4
	0.0004 (0.8583)	0.00004 (< 0.0001)	181.5
UM-PDX-HACC-5	0.0541 (< 0.0001)		406.9
	0.0248 (< 0.0001)	0.0002 (< 0.0001)	393.4

For PDX-SCC-M0, PDX-SCC-M1, PDX-SCC-M11, and UM-PDX-HACC-5 respectively, we fit linear mixed models for log-relative tumor volume versus time. We compared the linear models including time to the quadratic models including time and time². For each of our PDX models, the model fit as measured by AIC improved with the quadratic model.