Approximately half of patients with advanced small cell lung cancer responded to Introgen Therapeutics Inc.'s INGN 225 molecular cancer vaccine in combination with subsequent chemotherapy.

The encouraging phase 2 clinical data were presented over the weekend by Introgen's collaborator Dr Scott Antonia of the H Lee Moffitt Cancer Centre and Research Institute. Patients in the study achieved a 52 per cent objective tumour response rate and 41 per cent of patients were still alive one year after receiving the immunotherapy. Historically, tumour responses to second-line chemotherapy are between 6 and 30 per cent and most patients survive for less than 6 months.

The data imply that INGN 225 immunotherapy can sensitise cancer cells to the effects of chemotherapy restoring its effectiveness. INGN 225 is a cancer vaccine containing the p53 gene. p53 is called the "Guardian of the Genome," and is known to help restore normal cellular function and to promote apoptosis, or programmed cell death in abnormal cells such as cancer cells, allowing tumours to die when treated with chemotherapy.

Dr Antonia, associate professor in the Department of Interdisciplinary Oncology and Molecular Medicine, reported the data during the Fourth Biennial Meeting of Molecular Targets in Cancer Therapy in Clearwater Beach, Florida. An interim analysis of the phase 2 clinical trial was previously published in the medical journal Clinical Cancer Research.

"Data from Introgen's study in lung cancer patients, as well as other published studies, supports the novel approach of using a combination of immunotherapy and chemotherapy to treat cancer patients," said Dr Dmitry Gabrilovich, also of H Lee Moffitt Cancer Centre and Research Institute, organizer of the conference and co-principal investigator of the clinical trial. "INGN 225 sensitised tumours to the effects of platinum and taxane chemotherapies. Of particular interest, some patients who previously failed platinum chemotherapy responded to platinum re-treatment. These findings have important implications for improving the efficacy of these widely utilized cancer chemotherapies."

INGN 225 is an immunotherapy (vaccine) that utilizes an adenovector to deliver the p53 gene to a patient's immune cells, stimulating an anti-tumour immune response. Induction of p53-specific immune responses were observed following INGN 225 therapy and were found to correlate with increased tumour responses to the administered chemotherapy.