HPV as a model for the development of prophylactic and therapeutic cancer vaccines

Pre-immature dendritic cells (PIDC) pulsed with HPV16 E6 or E7 peptide are capable of eliciting specific immune response in patients with advanced cervical cancer

BACKGROUND

The protein products of the early genes E6 and E7 in high-risk HPV types 16 and 18 have been implicated in the oncogenic capability of these viruses. Therefore, these peptides represent attractive vaccine therapy targets.

METHODS

Thirty-two patients with advanced cervical cancer (HPV16 or 18 positive) were treated with HPV16 E6 (18-26) (Arm A) or HPV16 E7 (12-20) peptide (Arm B) pulsed on PBMCs in order to illicit immune response against the relevant peptide on both arms. These PBMCs were cultured for a short time (48 hours only) and in the presence of GM- CSF, accordingly, they were identified as "Pre-Immature Dentritic Cells".

RESULTS

51Cr release assay and ELISPOT demonstrated evidence of specific immune response against the relevant peptide in 10/16 (63%) evaluable patients in arm A and 7/12 (58%) in arm B. HPV16 E6 was found to be homologous to HPV18 E6 in both vivo and vitro. The median overall survival (OS) and progression free survival (PFS) for the full cohort was 10.0 and 3.5 months, respectively. There were no RECIST responses in any patient. The majority of toxicities were grade I and II.

CONCLUSIONS

We demonstrated the feasibility and ability of Pre-Immature Dentritic Cells pulsed with HPV16 E6 (18-26) or HPV16 E7 (12-20) to induce a specific immune response against the relevant peptide despite the advanced disease of the cervical cancer patients treated on this trial. We believe that this observation deserves further investigations.

Therapeutic vaccines for gastrointestinal cancers

Despite progress in the management of gastrointestinal malignancies, these diseases remain devastating maladies. Conventional treatment with chemotherapy and radiation is still only partially effective and highly toxic. In the era of increasing knowledge of the molecular biology of tumors and the interaction between the tumor and immune system, the development of targeted agents, including cancer vaccines, has emerged as a promising modality. In this paper, we discuss the principals of vaccine development, and we review most of the published trials on gastrointestinal cancer vaccines that have been conducted over the last decade. Many antigens and various treatment approaches have already been tested in colon, pancreatic, and other cancers. Some of these approaches have already shown some clinical benefit. In this paper, we discuss these different strategies and some of the future directions for targeting gastrointestinal malignancies with vaccines.