EP300 and rectal neoplasm: Re-biopsy of the rectal tumor was obtained to assess for mechanisms of resistance and sequencing identified FGFR1 and EGFR gene amplifications; and an E1A binding protein p300 (EP300) mutation in codon L1755V, and a Wolf-Hirschhorn Syndrome Candidate 1-Like 1 (WHSC1L1) mutation in codon E123Q.