Clinical importance of including new and nontarget lesion assessment of disease progression (PD) to predict overall survival (OS): Implications for randomized phase II study design.

Abstract

2543 Background: Fridlyand (2011) retrospectively compared PFS vs. change in tumor burden as a primary endpoint in phase II non-small cell lung cancer (NSCLC) trials to inform phase III decision making and found the use of PFS was superior. Since the classic tumor burden model only uses measurements of target lesions, we investigated whether the model could be strengthened by incorporating new and non-target lesion progression. The ability to use a strong tumor burden model has the benefit of potentially earlier decision making and considerable timeline savings. Methods: We analyzed five phase III trials of combination chemotherapy ± targeted therapies with an OS primary endpoint: 1st, 2nd line NSCLC (ATTRACT-1, -2), 1st, 2nd line colorectal carcinoma (CONFIRM-1, -2), and 2nd line ovarian cancer (EPO906A2303). We applied Cox’s proportional hazards model to OS using the covariates of baseline tumor burden, 1st tumor assessment percentage change from baseline, new lesions, and non-target PD. Results: See table. Conclusions: We show that predictive models for OS should consider new and non-target lesions for PD, as well as target lesion tumor burden, findings independently corroborated by Suzuki (2011). We propose a longitudinal rank-based randomized phase II design, ranking a patient’s risk of death, differentially weighting PDs by type and time of PD, and percentage change in tumor burden. This may be more informative for phase II decision making for phase III trials based on OS, than PFS which only uses time of PD. Further studies with other tumor types and treatment modalities are warranted. [Table: see text]