[citation needed] ADEPT has shown antitumor activity in animal tumor models of human choriocarcinoma and colonic and breast carcinoma.
The first pilot-scale clinical trial of ADEPT was carried out at Charing Cross Hospital, London, using an anti-CEA F(ab′)2 antibody conjugated to the bacterial enzyme carboxypeptidase G2 (CPG2).
[6] Several patients received ciclosporin since it had been shown in rabbits that this could delay the appearance of host antibodies to soluble proteins.
Proof-of-principle examples have shown delivery to target organs of enzymes that specifically release cytotoxics to treat tumours.
PDEPT uses polymer-drug conjugates, drugs contained within a polymer 'shell' such as pHPMA and designed to be released only by a specific enzyme.
[13] Perhaps the most challenging issue in cancer treatment is how to reduce the side effects of the injected anti-cancer agents, which are of a high cytotoxicity potential.
[16] (Originally, Parker and co-workers[17] showed that the injection of Clostridium histolyticum spores to the transplanted sarcomas of mice results in significant tumour lysis.