PARIS ¿ Transghne S.A. called ¿encouraging¿ the initial results of a Phase II clinical trial of its VV-MUC1-IL2 gene therapy vector (TG 1031) as it presented at the 22nd annual San Antonio Breast Cancer Symposium last week.

The Strasbourg, France-based gene therapy company said these findings, coming on top of preclinical study data and the results of clinical trials of the same therapy in prostate cancer, ¿show that tolerance of the treatment is high and that there is antitumor activity in some patients suffering from advanced tumors.¿

TG1031 is an attenuated recombinant vaccinia virus containing sequences coding for human MUC1 and the immunostimulatory cytokine interleukin-2. It was tested on patients suffering from MUC1-positive metastatic breast cancer in an open-label, randomized study comparing two dose levels. The primary aim was to evaluate antitumor activity, while secondary objectives were to determine the optimal dosing regimen, the therapy¿s safety when administered on a multidose schedule and the cellular and humoral response to MUC1 following repeated administration of TG1031.

Of the 31 patients enrolled in the trial, a partial response was observed in two who had previously failed to respond to either chemotherapy or hormone therapy. The disease stabilized for at least six weeks in 15 patients and for at least 15 weeks in four patients. In addition, immune responses to the vector were observed in all patients, although two of them had no T-cell proliferation to the vector. There were few adverse events and they were minor.

The multicenter trial was carried out in the UK, France, Belgium, the Netherlands and Israel, and according to David Miles of Guy¿s Hospital in London, ¿these results are particularly interesting insofar as we were able to establish systemic antitumor activity. The ability to induce partial remission in patients with visceral metastases and whose disease is progressing despite intensive chemotherapy highlights the potential role of therapeutic vaccines in the treatment of cancer.¿

Echoing that, Transghne¿s medical director, Michael Ross, said ¿using vaccines in cases of advanced cancers could be a new and important avenue for treating cancer. The MUC1 tumor antigen opens a way of attacking breast and prostate cancers, as well as other types of cancer.¿

A new and improved formulation of the same vaccine virus, MVA-MUC1-IL2, is now in Phase I trials. It is based on the MVA strain of the virus and carries genes coding for antigens of the type 16 human papilloma virus (HPV), which is responsible for more than half of cervical cancers.

Altogether, Transghne has four Phase II clinical trials of different vectors under way, three of which are for the treatment of various cancers and one for cystic fibrosis. Three of the products are being tested in the U.S., where the company has established a subsidiary near Boston.