A company in Hanover, Germany, Vakzine Projekt Management, reports positive clinical trial results with their therapeutic prostate cancer vaccine VPM4001. The results will be presented at the annual meeting of the American Society for Clinical Oncology (ASCO) in Chicago, USA.

A clinical phase I/II study with 30 patients completed in 2006 showed that 73% of patients suffering from advanced, hormone-resistant prostate carcinoma responded positively to the VPM4001 therapy. The primary study parameter, the PSA doubling time, was increased from 63 days to 114 days on average. This promising result has a high statistical significance (p=0.0035), the company says. PSA doubling time is a surrogate parameter well correlated to survival: higher PSA doubling times mean higher probabilities to survive a five year period. In this trial, the median survival time came to 981 days.

VPM4001 also showed an “excellent” tolerability profile, the company says. The study was carried out at the Institute for Experimental Oncology (Prof. Dr. med. B. Gansbacher) and at the Clinic for Urology (Prof. Dr. med. R. Hartung) of Munich Technical University.

A panel of international experts from the USA, Germany and the Netherlands has recommended the continuation of clinical development of the vaccine as fast as possible.

VPM4001 is an allogeneic vaccine for treatment of prostate carcinoma. An allogeneic (aka allogenic) vaccine is composed of tumor cells cultured from a line of cells isolated — perhaps years ago — from the tumor of a single patient, now administered to one or many patients today. Before being administered to current patients, the cells are killed and processed. The aim is to stimulate cancer-cell killing (cytotoxic) immune responses to a similar tumor cell type. The cells found in this type of whole-cell vaccine express many cell-surface tumor-associated antigens. This vaccine is frequently administered with an adjuvant immunostimulant (See National Cancer Institute, allogenic vaccine, compare autologous vaccine)

In the case of VPM4001, the vaccine consists of irradiated human LNCaP cells that have been genetically modified to permanently secrete interferon-gamma and interleukin-2 (LNCaP/IL-2/IFN-γ). Interferon-γ enhances presentation of tumor antigens, whereas interleukin-2 stimulates T cells.

An open label, single armed phase I/II trial has been completed with 30 progressive, hormone refractory prostate carcinoma (HRPC) patients with PSA (prostate specific antigen) doubling time as primary parameter. Median PSA doubling time was prolonged from 63 to 114 days (81%, Intention to Treat, p=0.0035). The median survival time came to 981 days. The medication was well tolerated. The rate of response was 73%. PSA doubling time is a surrogate parameter well correlated to survival: higher PSA doubling times mean higher probabilities to survive a five year period.

VPM globally has a number of exclusive licenses for promising vaccines, with a group of other projects in the pipeline. VPM4001 has been licensed from Sloan Kettering Institute for Cancer Research, New York. Patents have been granted in European countries. Patent applications in Canada and the US are pending.

VPM website is acessible in German and in English.