Antisoma has presented promising early data from a mid-stage trial of its AS1411 compound in relapsed and refractory acute myeloid leukaemia.

The company said that enrolment has been completed in the first, lower dose, stage of the trial, in which 33 patients were randomly assigned to be treated with either 10 mg/kg/day AS1411 plus cytarabine or cytarabine alone. Activity data are currently available from 16 patients and among 11 who received AS1411 plus cytarabine, one had a complete response (CR) and one had a complete response with incomplete recovery of platelet counts (CRP).

Antisoma said that a third patient had a cytogenetic response but had leukaemic blasts remaining. Among five patients who received cytarabine alone, none had a CR or a CRP and there were no cytogenetic responses. Furthermore, patients who did not respond to cytarabine alone could be crossed over to receive AS1411 plus cytarabine; one of them showed a 90% reduction in leukaemic blast count after treatment with the combination.

An investigator on the trial, Robert Stuart of the Medical University of South Carolina, said the initial findings from the AML Phase II trial “encourage us to treat more patients and in particular to test the potential of using a four-fold higher dose." Also a second Phase II trial of AS1411, in patients with renal cancer, is expected to start before the end of 2008.

Glyn Edwards, Antisoma's chief executive, said that there is a great need for new treatments in AML, “especially for patients with relapsed and refractory disease where response rates have historically been very poor”. He added that “we are excited about the potential of AS1411 in this indication, and look forward to seeing more extensive data".