Merck Serono and its US partner BioMarin have presented promising late-stage data for Phenoptin, their new experimental treatment for phenylketonuria, a genetic disorder which causes excessive build-up of an amino acid in the blood.

The Phase III 11-week trial enrolled 90 patients between the ages of four and 12 years with PKU who were under dietary control. Data from the placebo-controlled study showed that patients who had been randomised to receive Phenoptin (sapropterin), demonstrated a significant increase in phenylalanine tolerance and a reduction in blood phenylalanine levels.

Dr Harvey Levy, Professor of Pediatrics at Harvard Medical School, stated that, if approved, Phenoptin offers patients “a real opportunity to relax their diets and the possibility to perhaps reduce or even eliminate the need for nutritional supplementation from medical food."

Merck Serono and BioMarin said that they remain on track to file Phenoptin in the USA and Europe during the second and third quarters respectively. Under a licensing agreement between the companies, BioMarin has rights to market Phenoptin in the USA , while Merck Serono has exclusive rights to the drug elsewhere in the world, except Japan.

Enrolment for new MS drug trial complete

Meantime, Merck Serono said it has completed patient enrolment into a Phase III trial of cladribine, its experimental oral treatment for multiple sclerosis.

More than 1,300 people have been enrolled for the two-year trial for cladribine, which has been awarded fast-track status by the US Food and Drug Administration. Franck Latrille, Merck Serono's head of product development, said that the news “brings us one step closer to our objective of offering patients the first oral therapy for first-line treatment of MS, with the convenience of short courses of therapy given intermittently."

Analysts believe cladribine might now beat Novartis' FTY720 (fingolimod) to market as the first oral MS therapy, with an expected launch in 2010 or 2011. Novartis said last month it was on track to complete enrolment for its trial by mid-2007.

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