Funding sources This work was conducted with financial assistance from Peplin Biotech Pty Ltd and an Australian Commonwealth Government Industry Research and Development Board R&D START grant.
Conflicts of interest J.H.A. and G.L.R. were, and P.W. and S.O. are currently, employees of Peplin Inc. (formerly Peplin Biotech Pty Ltd). J.R.R., A.S. and P.G.P. were consultants to Peplin Biotech Pty Ltd. Peplin Inc. is now wholly owned by LEO Pharma.
Background The sap from Euphorbia peplus, commonly known as petty spurge in the U.K. or radium weed in Australia, has been used as a traditional treatment for a number of cancers.
Objective To determine the effectiveness of E. peplus sap in a phase I/II clinical study for the topical treatment of basal cell carcinomas (BCC), squamous cell carcinomas (SCC) and intraepidermal carcinomas (IEC).
Methods Thirty-six patients, who had refused, failed or were unsuitable for conventional treatment, were enrolled in a phase I/II clinical study. A total of 48 skin cancer lesions were treated topically with 100–300 μL of E. peplus sap once daily for 3 days.
Results The complete clinical response rates at 1 month were 82% (n =28) for BCC, 94% (n =16) for IEC and 75% (n =4) for SCC. After a mean follow-up of 15 months these rates were 57%, 75% and 50%, respectively. For superficial lesions < 16 mm, the response rates after follow-up were 100% for IEC (n =10) and 78% for BCC (n =9).
Conclusions The clinical responses for these relatively unfavourable lesions (43% had failed previous treatments, 35% were situated in the head and neck region and 30% were > 2 cm in diameter), are comparable with existing nonsurgical treatments. An active ingredient ofE. peplus sap has been identified as ingenol mebutate (PEP005). This clinical study affirms community experience with E. peplus sap, and supports further clinical development of PEP005 for the treatment of BCC, SCC and IEC.