Abstracts

Mycobacterial Heat Shock Protein (Hsp) Fusions: A Novel Class of Immunotherapeutics for the Treatment of Human Papillomavirus (HPV) Infection

Abstract presented at 5th Annual Conference on Vaccine Research - Baltimore, MD May 6-8, 2002

Chu, N.R.; Wu B., Liu H.; Wisniewski J., Recktenwald A., Rowse G.; Boux H.A.; Boux L. (2), Mizzen L.; Siegel M.I. (2)

Stressgen Biotechnologies Corporation, Victoria, BC, Canada
2) Stressgen Biotechnologies, Inc., Collegeville, PA, USA

Cell-mediated immunity (CMI) to HPV16 E7 (E7) is associated with the resolution of HPV-related lesions. An in-frame fusion protein comprised of mycobacterial Hsp65 and E7 (SGN-00101) induces CMI and tumor regression preclinically and provides clinical benefit in phase II immunotherapy trials of anogenital HPV diseases. To test other Hsp fusions, a series of constructs using different Hsp fused to E7 were tested for activity. DNA constructs or recombinant proteins comprised of full-length Hsp10, Hsp40, Hsp65 or Hsp70 from M. tuberculosis fused with full-length HPV16 E7 were used (without adjuvant) to treat C57Bl/6 mice with pre-established, E7-expressing TC-1 tumor. Primed splenocytes from mice immunized with Hsp fusion proteins were tested for cytolytic and cytokine-producing activity. Tumor regression was observed in mice treated with pCMV/SGN-00101, but not pCMV/Hsp65, pCMV/E7, or pCMV/Hsp65 + pCMV/E7, confirming that the activity is a property intrinsic to the Hsp fusion. Treatment with SGN-00101, but not its constituent proteins, Hsp65, and E7, regresses tumor. Similarly, Hsp10-E7, Hsp40-E7 and E7-Hsp70 fusion protein treatment leads to tumor regression. Primed splenocytes from E7-Hsp70- or SGN-00101-immunized mice were cytolytic for E7-expressing targets and released IFN-gamma upon E7 restimulation. Immunization of mice with plasmids encoding Hsp-E7 fusion proteins, or Hsp-E7 fusion proteins, induces E7-specific CMI and regresses E7-expressing tumor. These results suggest that Hsp-E7 fusions are a potentially new class of immunotherapeutics for HPV-associated disease.