Merck KGaA's Stimuvax Is First Therapeutic Vaccine For Lung Cancer In Phase III - ASCO 2006

Main Category: Lung Cancer
Also Included In: Immune System / Vaccines
Article Date: 20 Jun 2006 - 0:00 PDT

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Merck KGaA's Stimuvax (L-BLP 25), a therapeutic vaccine being developed for non-small cell lung cancer (NSCLC), should be going into Phase III testing this autumn. Over 1300 patients with stage III unresectable disease from more than 140 centres in North America and Europe will be recruited for START (Stimulating Targeted Antigenic Response to NSCLC Trial ) comparing the vaccine against placebo in patients receiving chemotherapy.

The major component of Stimuvax is the synthetic human MUC I protein consisting of a 20-amino acid tandem repeat sequence on its extracellular domain that is highly antigenic. MUC I is expressed on normal epithelial tissue as well as NSCLC tumour cells, but on tumours it is abnormally glycated and therefore able to trigger an immune response. The vaccine also contains the immunoadjuvant MPL (monophosphoryl lipid A) a non-specific stimulant designed to prime the immune system and facilitate take-up of the vaccine. Both are enclosed in a liposomal vehicle. The vaccine is delivered subcutaneously at four points of the body and is designed to be taken up by cytotoxic T lymphocytes and T-helper cells in order to potentiate the immune response.

Phase III trial is practice-based

The phase III trial will randomise patients in a ratio of 2:1 to vaccine or placebo which they will receive alongside chemotherapy and radiation therapy over 16 weeks as administered in the various trial centres. Dr Charles Butts, a medical oncologist from the Cross Cancer Institute in Edmonton, Canada and the Canadian regional principal investigator of the Stimuvax phase III trial, says: "The study is designed to mimic real-world clinical practice. Centres can administer chemotherapy and radiation therapy simultaneously or in sequence as they would normally."

Treatment administered will consist of a single iv dose of 300mg/m2 cyclophosphamide followed by eight weekly subcutaneous immunisations with Stimuvax. Maintenance immunisations will then be given at 6-week intervals. "The hope is that the vaccine will prevent relapse by mopping up residual cancer cells remaining after chemoradiation." Study endpoints are time to progression, overall survival and quality of life.

Final results at November 2005 of a phase IIb trial involving 171 patients with stage III and IV NSCLC showed median survival was 30.6 months among vaccine-treated patients compared to 13.3 months among controls. "The phase III trial will focus on Stage III patients who derived more benefit than Stage IV patients," said Dr Butts. Currently almost 50 per cent of the vaccinated group are still alive compared to 25 per cent of control group patients.

Lung cancer is the leading cause of cancer-related deaths in both men and women worldwide - killing more people than colon, breast and prostate cancers combined. Last year in the US there were around 163,500 lung cancer deaths and 172,570 new cases diagnosed of which 87 per cent were the NSCLC type. Five-year survival in NSCLC is normally 15 to 20 per cent with a median survival time of 17 to 18 months.

If the phase III trial proves positive, it is likely that the vaccine will go on to be studied in earlier stages of lung cancer following resection and at other cancer sites, he added. "One of the benefits of a vaccine using MUC 1 is that the protein is not specific for lung. MUC I is found on breast, colon and prostate tumours and even in multiple myeloma, so it has huge potential."

Stimuvax ( L-BLP-25) is being developed in Europe by Merck KgaA and in North America by Biomira Inc and EMD Pharmaceuticals.

http://www.merck.de

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