Table 1.

Mutational status and number of tumors regressed more than 50% of initial size as on day 28

XenograftGenetic backgroundGEMGEM + MK-1775
P53K-rasSMAD4
PANC286WTMUTWT0 (8)0 (6)
PANC420WTWTWT0 (10)0 (8)
JH033WTMUTWT0 (8)0 (9)
PANC198MUTMUTMUT1 (8)8 (8)
PANC215MUTMUTWT1 (9)5 (7)
PANC185MUTMUTMUT1 (10)3 (8)
PANC281MUTMUTMUT3 (10)8 (10)
PANC354MUTWTMUT1 (10)0 (8)
PANC374MUTMUTWT0 (8)1 (8)
Total with p53 MUT7/55 (12.72%)25/49 (51.10%)
Total with p53 WT0/26 (0%)0/23 (0%)

NOTE: Animals were treated with vehicle, MK-1775, GEM, or GEM + MK-1775 for 4 weeks. Tumors that regressed greater than 50% of its size on day 28 in each xenograft were counted. Numbers in parenthesis denotes total number of tumors in that xenograft. Over all,7 of 55 (12.72%) tumors with p53-deficient (MUT) status regressed in the GEM treatment group. However, 25 of 49 (51.10%) of tumors with p53 MUT status regressed in the GEM + MK-1775 group. None of the tumors with p53 wild-type (WT) regressed in GEM + MK-1775 (0 of 23) or GEM (0 of 26) treatment groups. K-ras and SMAD4 status do not influence the tumor regression pattern in these xenografts.