Antisoma plc, announced the presentation of positive data from its phase II trial of AS1404 in ovarian cancer. Investigators' assessments of tumour response are now available for all patients. These show a response rate of 75 per cent for those treated with AS1404 plus chemotherapy compared with 63 per cent for patients receiving chemotherapy alone. Addition of AS1404 to chemotherapy was well tolerated.

The findings were presented at the International Gynecological Cancer Society (IGCS) meeting in Santa Monica by Dr Michael Jameson of Waikato Hospital, Hamilton, New Zealand, an investigator in the trial.

Improvements in efficacy endpoints have now been observed in three separate phase II trials of AS1404. In a lung cancer study, patients receiving AS1404 alongside chemotherapy experienced a 5.2-month increase in median survival compared with those on chemotherapy alone. A study in prostate cancer showed PSA response rates of 57 per cent with AS1404 plus chemotherapy versus 35 per cent with chemotherapy alone.

The phase II studies in ovarian and prostate cancers are ongoing and will report further data on time to progression and survival over the coming year. The lung cancer trial is complete and Antisoma is now preparing for phase III development in this indication.

Dr Michael Jameson said "It's great to see the data from the ovarian cancer trial of AS1404 heading in the same direction as the positive lung and prostate cancer findings."

Commenting, Glyn Edwards, CEO of Antisoma, said: "We are very pleased with the pattern of data coming out of our phase II studies on AS1404. Ovarian cancer is a significant disease in its own right, and this latest news also adds further support to the idea that AS1404 has broad potential across a wide range of tumour types."

The AS1404 trial in ovarian cancer included 77 women with ovarian cancer that had recurred six months or more after treatment with platinum chemotherapy. Patients were randomized to receive either AS1404 plus carboplatin and paclitaxel ('AS1404 group') or carboplatin and paclitaxel alone ('control group'). Outcomes were assessed according to RECIST (Response Evaluation Criteria In Solid Tumours). 36 patients were valuable for efficacy in the AS1404 group: 27 (75.0 per cent) had a complete or partial response, 7 (19.4 per cent) had stable disease and 2 (5.6 per cent) had progressive disease. 38 patients were valuable for efficacy in the control group: 24 (63.2 per cent) had a complete or partial response, 11 (28.9 per cent) had stable disease and 3 (7.9 per cent) had progressive disease. All of these outcomes are confirmed except 7 in the AS1404 group and 6 in the control group.

AS1404 (DMXAA) is a small-molecule vascular disrupting agent which targets the blood vessels that nourish tumours. The drug was discovered by professors Bruce Baguley and William Denny and their teams at the Auckland Cancer Society Research Centre, University of Auckland, New Zealand. It was in-licensed by Antisoma from Cancer Research Ventures Limited (now Cancer Research Technology) in August 2001.