Vaccine 22 (2004) 3738–3743 ISCOMATRIX TM adjuvant: an adjuvant suitable for use in anticancer vaccines Trina J. Stewart a , Debbie Drane b , Jim Malliaros b , Heidi Elmer b , Karen M. Malcolm a , John C. Cox b , Stirling J. Edwards b , Ian H. Frazer a , Germain J.P. Fernando a,∗ a Centre for Immunology and Cancer Research, University of Queensland, Princess Alexandra Hospital, Brisbane, QLD 4102, Australia b CSL Limited, Parkville, Vic. 3052, Australia Received 25 October 2003; received in revised form 24 December 2003; accepted 4 March 2004 Available online 9 April 2004 Abstract Human Papillomavirus type 16 (HPV16) E6 and E7 oncoproteins are associated with cervical cancer development and progression and can therefore be used as target antigens for cancer immunotherapy. In this study we evaluated the immunogenicity in mice, of different vaccine formulations using recombinant HPV16 derived E6E7 or E7GST fusion proteins. When co-administered with ISCOMATRIX TM adjuvant, these E6E7 proteins consistently induced E7 specific CTL, in vivo tumor protection, antibody and DTH responses. ISCOMATRIX TM adjuvant has been developed for use in the formulation of novel human vaccines and has been evaluated for safety and toxicity in human trials. A formulation containing aluminum hydroxide (Al(OH) 3 ) gave a lesser degree of E7 specific antibody, and no local E7 specific CTL response but similar DTH and tumor protection. These findings demonstrate the potential of ISCOMATRIX TM adjuvant to stimulate both cellular and humoral immune responses to endogenously processed target antigens, and hence is the preferred adjuvant when CTL responses are desirable. © 2004 Elsevier Ltd. All rights reserved. Keywords: Cancer vaccine; Tumor protection; Adjuvant 1. Introduction At least 95% of cervical cancers are associated with infection of the cervical epithelium with human papillo- mavirus (HPV) [1]. HPV-associated cervical cancer is the leading cause of cancer mortality in women under 50, and the second most common cause of death from cancer in women [2,3]. A vaccine based on killed or attenuated virus is not possible due to the oncogenic properties of HPV and an inability to grow the virus in vitro. Expression of the papillomavirus encoded proteins, E6 and E7, are required for transformation of infected epithelial cells into cervical carcinoma cells [4]. These HPV16 E6 and E7 oncoproteins are recognized as tumor specific antigens and are therefore putative targets for immunotherapy [5]. In general, subunit or synthetic vaccines are poorly im- munogenic and require immunopotentiation to become effective. Adjuvants are compounds used to augment the immune response, but are highly variable in their mode of ∗ Corresponding author. Fax: +61-7-3240-5946. E-mail address: gfernando@cicr.uq.edu.au (G.J.P. Fernando). action and effect. There are limited adjuvants available for use in humans. ISCOMATRIX TM adjuvant is comprised of ISCOPREP TM saponin (a highly purified saponin fraction from the bark extract of the Quillaja saponaria tree [6]), phospholipid and cholesterol. Other ISCOMATRIX TM ad- juvant containing vaccines have been shown to induce both humoral and cell-mediated immune responses to protein antigens [7]. ISCOMATRIX TM adjuvant has been devel- oped for use in the formulation of novel human vaccines and has been evaluated for safety and toxicity in human trials. It has now been recognized that the capacity of an ad- juvant to elicit the correct type of immune response and the magnitude of the response induced are important in the study of new vaccine formulations. Measurement of adju- vant quality will depend on the nature of the optimal im- mune response required for disease attenuation/prevention. Induction of a cytotoxic T lymphocyte (CTL) response is particularly important for vaccines against viral infections and for tumor immunotherapy. We have previously shown by in vivo depletion of CD8 + effector cells that they are nec- essary and sufficient to induce tumor protection in the tumor model used in the present study [14]. The use of saponin 0264-410X/$ – see front matter © 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.vaccine.2004.03.026