Genzyme Corp has suffered a setback with the news that the first of two late-stage studies looking at tolevamer, an investigational new drug for bacteria-related diarrhoea, has not met its primary endpoint.

The study compared tolevamer liquid, which is a non-antibiotic, polymer therapy for patients with Clositridium difficile associated with diarrhoea (CDAD), to the standard prescribed oral dose of the antibiotic vancomycin. However the data did not show non-inferiority of Genzyme’s drug to the antibiotic, although the firm did note that high rates of CDAD recurrences appeared in patients treated with vancomycin or metroidazole but not in those on tolevamar liquid. The latter was well-tolerated with no unanticipated safety concerns, according to the company.

Genzyme chief executive Henri Termeer said that "these are disappointing results that alter our expectations about the potential for commercialising tolevamer in the near future". He added that the results of the second Phase III study will be available later this year “and will help us determine what contribution tolevamer might be able to make in addressing this serious unmet medical need”.

The news led to a 6% decline in Genzyme shares and the setback was revealed just a day after the company said that another of its new therapies, hylastan, for pain associated with osteoarthritis of the knee showed no significant improvement on traditional steroids.

Analysts weighed up the damage to Genzyme of this latest data and Christopher Raymond of Robert W Baird & Co issued a note saying that “we had feared that demonstrating non-inferiority to vancomycin would be challenging”, as the latter has shown symptom relief in over 90% of patients''. JP Morgan analyst Geoffrey Meacham took things a stage further saying he believed the tolevamer programme is probably “dead”, saying that “we do not have high hopes for the second Phase III trial, where even in the event of a positive result, the approvability looks unlikely. We would not be surprised to see tolevamer development discontinued”.

The news comes at a time when questions are being asked about Genzyme’s ability to move away from its reliance on its drugs that treat rare conditions, such as the Gaucher disease treatment Cerezyme (imiglucerase), the Fabry disease drug Fabrazyme (agalsidase beta) and Myozyme (alglucosidase alfa) for Pompe disease. It is certainly trying to do so, and is in the process of acquiring partner Bioenvision, in order to gain exclusive rights to the leukaemia drug clorafabine.