Speaking at the company's first quarter results, its CEO Dr Raymond Warrell said that "securing the earliest possible regulatory approval of Genasense on a worldwide basis is our highest priority." Genta has been denied approval for Genasense both as a treatment for melanoma and, more recently, for chronic lymphocytic leukaemia (CLL).

Those rejections from the US Food and Drug Administration (FDA) and the European Medicines Agency (EMeA) dealt a blow to the antisense drug industry in general, with the sector having already suffered several setbacks . Antisense drugs were once heralded as a major breakthrough for the pharmaceutical industry as they are highly specific. However their exact mechanism of action - via the degredation of messenger RNA - is not yet fully understood, according to Isis Pharmaceuticals, one of the sector's main players.

Recently, Genta indicated that it intends to file a formal complaint and 'request for correction of information' with FDA. Genta believes that the FDA used an incorrect statistical analysis relating to Genasense for melanoma back in 2004 and that this led to a study showing that Genasense improved progression free survival was wrongly discredited.

Last month, Genta also announced a new Phase III trial aimed at proving Genasense's efficacy to regulators. The company has sought advice from both the FDA and the EMEA, and will recruit patients using a biomarker that, in previous trials, identified those patients most likely to benefit from Genasense.

At the same time, Genta has asked the EMEA to re-examine its Marketing Authorization Application (MAA) for Genasense in melanoma. Specifically, the company has asked that a specialist oncology scientific advisory group be convened. If granted, Genta said it expects a final decision later this year.

Genta has also filled a similar appeal with the FDA regarding Genasense's application as a leukaemia treatment. The decision on this appeal should come even earlier, that is, within thre months, according to Genta.