Antisoma presents positive data from Phase II leukemia study

Complete data are now available from the first stage of the trial, in which patients were randomized 1:2 to receive high-dose cytarabine alone (standard therapy control group) or high-dose cytarabine plus AS1411 at 10mg/kg/day. All patients entering the trial had relapsed after prior treatment or failed to respond to treatment, so few responses were expected. Accordingly, there were no responses in the control group (0/9 patients). By contrast, the response rate in the AS1411 group was 16% (3/19 patients).

As well as the three ‘objective responses’ (two CRs and one CRp) seen in the AS1411 group, a fourth patient in this group demonstrated a cytogenetic response. Additional supportive findings came from a ‘cross-over’ element in the trial, under which control group patients who failed to respond to cytarabine were given the opportunity to receive a further course of treatment with cytarabine plus AS1411. Three patients underwent cross-over treatment, one of whom experienced a 90% reduction in leukemia blast count after receiving the AS1411 regimen, the company said.

According to the company, AS1411 was well tolerated by patients treated in the first stage of the trial. No severe side-effects were attributed to the drug, and there was no evidence that AS1411 exacerbated the toxicity of high-dose cytarabine.

Enrollment has now been completed in the second stage of the trial, which has randomized around 30 more patients 1:2 to receive high-dose cytarabine or high-dose cytarabine plus AS1411 at 40mg/kg/day (a four-fold higher dose than in the first stage). Final results are expected to be available in the first half of 2009.

Glyn Edwards, Antisoma’s CEO, said: We have now seen evidence of activity with AS1411 in patients with hard-to-treat leukemia and advanced renal cancer. This supports non-clinical data suggesting that the drug has potential across a wide variety of blood and solid cancers.