Antisoma plc announced that its aptamer drug AS1411 has been granted orphan drug status in both the United States and the European Union for the treatment of acute myeloid leukaemia (AML). The grants will provide seven years of market exclusivity in the US and ten years of exclusivity in the EU if AS1411 is approved for use in AML.

Positive phase-II data for AS1411 in AML were presented at the 2008 ASH and 2009 ASCO meetings. Addition of AS1411 to high-dose cytarabine increased response rates without significantly increasing side-effects in patients with relapsed or refractory AML. Phase-IIb trials are now planned: the first is expected to start in early 2010. Should this yield positive findings, rapid progress into a registration trial is anticipated.

AS1411 already has orphan drug status in both the US and the EU for the treatment of renal cancer. A phase-II trial in renal cancer is ongoing, and expected to report initial data before the end of this year.

Glyn Edwards, Antisoma's CEO, said, "Gaining orphan drug status in AML further strengthens the exclusivity position of AS1411 in a setting where we have positive phase-II data. This is an exciting time for AS1411, with phase-II data in renal cancer coming soon and our investigation of the compound in AML progressing to the next stage."

AS1411 belongs to a new type of drug called aptamers. These drugs are short pieces of DNA or RNA that fold into three-dimensional structures capable of targeting particular proteins.