INTRODUCTION Epidermal growth factor (EGF) is normally present as EGF_1–53. A variety of C terminal truncated forms have been used in preliminary trials for treating gastrointestinal injury but their relative potency and stability when used in a clinical setting are unclear. Therefore, we compared the biological activity of recombinant EGF_1–53, EGF_1–52, EGF_1–51, and the C terminal peptides EGF_44–53 and EGF_49–53.

RESULTS Biological activity assays of EGF_1–53, EGF_1–52, and EGF_1–51 gave almost identical thymidine uptake dose-response curves (maximal responses increasing baseline uptake from 4400 (600) cpm (mean (SEM)) to about 22 000 (2000) cpm when EGF was added at 1.6 nM). EGF_44–53 and EGF_49–53 did not stimulate ³H thymidine uptake. Control rats had 47 (4) mm² damage/stomach, EGF_1–51, EGF_1–52, and EGF_1–53 at 0.16 and 0.80 nmol/kg/h each reduced gastric injury by about 50% and 80%, respectively (both doses p<0.01 compared with control but no significant difference between the different forms). EGF was stable at room temperature for seven days but biological activity decreased by 35% and 40% at two and three weeks, respectively (both p<0.01). Exposure to light did not affect bioactivity.

CONCLUSION EGF_1–51and EGF_1–52 are as biologically active as full length EGF_1–53 but the C terminal penta- and decapeptides are ineffective. Clinical trials of EGF can probably use infusion systems for at least 48 hours at room temperature and with exposure to light, without reducing biological efficacy.