Genzyme's woes continue as it drops investigational APB follow-up for Renvela, after poor trial results

US biotechnology major Genzyme has reported results of a Phase II/III study of its advanced phosphate binder (APB), a stronger version of its already-marketed kidney disease drug Renvela (sevelamer carbonate), which met its primary endpoint, which was to show that the APB lowered phosphate levels effectively compared to placebo in patients with chronic kidney disease. However, the APB did not show a significant improvement in phosphate lowering compared to Renvela.

Based on these results, the company is not planning to pursue further clinical development of the new APB. Genzyme was seeking to develop a product with higher potency that would more effectively bind phosphate, while maintaining
all the benefits of Renvela.

Looking to plug patent gap

Genzyme had hoped to get the new APB approved before patents on Renvela and its predecessor Renagel (sevelamer) expire in 2014. These two products generated combined sales of $680 million in 2008. The news also comes swiftly on the back of production facility problems for five of the US firm's drugs for rare diseases and an approval delay for another (The Pharma Marketletters November 16 and 17).

In the study, Renvela and the APB both effectively lowered patients' phosphorus levels. Most adverse events associated with both Renvela and the APB were mild in nature, and the most frequently reported events were gastrointestinal disorders.

The trial was a randomized, double-blind, placebo-controlled study that enrolled 349 adult hemodialysis patients with hyperphosphatemia. It included seven arms: low, medium and high dose APB; low, medium and high dose Renvela, and placebo. It included a two-week screening period, a two-week washout period, and a three-week treatment period.