A phase II study of Hsp-7 (SGN-00101) in women with high-grade cervical intraepithelial neoplasia

Approximately 2 million women worldwide are infected with high-risk human papillomaviruses (HPV), resulting in a substantial risk for the development of invasive lower genital malignancies. This study was undertaken to determine the effects of vaccination with a protein encoding a bacterial heat shock protein fused to sequences from the oncogenic E7 protein of HPV-16 in women with high-grade cervical intraepithelial neoplasia. Endpoints included lesion regression, immune response, and viral clearance.

Twenty-one women were prospectively entered into an IRB-approved Phase II study. All women had biopsy-proven high-grade cervical intraepithelial neoplasia and persistent post-biopsy lesions visible by colposcopy. Four injections of HPV-16 Hsp E7 fusion protein at a dose of 500 mug were given 3 weeks apart after which Loop Electrosurgical Excision of the Transformation Zone (LLETZ) was performed. Immune parameters were evaluated pre-vaccine and at the time of LLETZ, and HPV testing was performed at intervals before and after LLETZ. Study subjects were followed for 1 year after LLETZ.

Seven of 20 women (35%) evaluable for response had complete regression of their intraepithelial neoplasia at the time of LLETZ, 1 (5%) had regression to CIN I, 11 (55%) had stable disease and 1 (5%) had progression due to enlargement of her lesion. Immune responses were seen in 9 of the 17 women tested; 5 of the 7 complete responders had an immune response. Only 5 of 21 women had HPV-16 or -18. HPV clearance was not associated with lesion regression.

Hsp-7 (SGN-00101), at this dose and schedule induced lesion regression in women with high-grade intraepithelial neoplasia. The fact that regression was correlated with immune response suggests that enhancing the immunogenicity of this vaccine may lead to improvement in the rate of lesion eradication.