3599 Background: NSABP recently proposed replacing pCR with a new neoadjuvant rectal score (NAR) based on clinical downstaging from pre to post-treatment, pathologic (yp) stage. The NAR formula yields values from 0-100; higher scores indicate poor prognosis. In NSABP R04 (n=1479), the mean NAR = 15.61 with SD of 14.37, and OS hazard ratio/unit (HR) = 1.04 (p<0.0001). NAR showed a stronger association with OS than pCR, and was proposed as a new endpoint for phase II trials. We sought to evaluate the prognostic significance of NAR in two previously published datasets. Methods: Patient (pt) data from 2 IRB approved, previously published studies were used. Study 1 was a phase I/II study evaluating bevacizumab (bev) and erlotinib (erl) with neoadjuvant chemoradiation (CRT) (Ann Oncol 2014;25:121-6). Study 2 was a retrospective review of pts receiving 5-FU/RT (J Gastrointest Canc epub 2013, PMID24006244), with mutational analysis. All pts had pretreatment M0 and T3/4 or node + disease by MRI. Study 1 had 32 pts...