Moving a Carbohydrate Mimetic Peptide into the clinic

Abstract

Tumor-Associated Carbohydrate Antigens (TACAs) are broad-spectrum targets for immunotherapy. Immunization with Carbohydrate Mimetic Peptides (CMPs) is a strategy to induce broad-spectrum TACA-reactive antibodies hypothesized to interfere with cellular pathways involved in tumor cell survival. A Phase I study was conducted with a first-in-man CMP referred to as P10s, conjugated to the Pan T cell carrier PADRE, along with MONTANIDE^™ ISA 51 VG as adjuvant over a course of 5 immunizations. While designed as a safety and tolerability study, the potential for therapeutic impact was observed in a subject with metastatic lesions as evaluated before and after vaccine treatment. The subject received Vinorelbine and Trastuzumab (VT) for two months prior to study eligibility. PET scans showed partial response in the lungs and complete resolution of a previously enlarged subpectoral lymph node. Immunization with P10s vaccine resulted in responses to P10s, with serum and plasma antibodies reactive with and cytotoxic to human breast cancer cells in vitro, including the Trastuzumab-resistant HCC1954 cell line. However, the patient developed cystic masses in the brain parenchyma with no apparent evidence of metastases. The subject was switched to Docetaxel, Pertuzumab and Trastuzumab a year later, and her last PET scan showed a complete response in the lungs and lymph nodes. Incubation of cancer cells with a combination of vaccine-induced serum and docetaxel suggests that the induced antibodies sensitize tumor cells for more efficient killing upon administration of docetaxel. The data suggest that P10s-PADRE induces anti-tumor antibody response that in combination with chemotherapy can affect metastatic lesions in breast cancer patients.

Keywords: :

• immunotherapy
• vaccine
• carbohydrate mimetic peptide
• breast cancer
• Phase I trial

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

Acknowledgments

We thank the subjects that participated in this trial. This work was supported by a Clinical Translational Award from the Department of Defense Breast Cancer Program (W81XWH-06-1-0542). The project described was also supported by the Translational Research Institute (TRI), grant UL1TR000039 through the NIH National Center for Research Resources and National Center for Advancing Translational Sciences and the UAMS Center for Microbial Pathogenesis and Host Inflammatory Responses at UAMS, P20 GM103625. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.