MLH1 and colon adenocarcinoma: Two of the 4 PDX models with MGMT promoter methylation (625472-104-R and 997537-175-T, both colon adenocarcinomas) that did not respond to either single agent temozolomide or the combination with veliparib had very low MLH1 mRNA levels (log2[normalizedCount+1] < 4).