Rapamune Misses Renal Function Endpoint

Pfizer has posted top-line results from a Phase IIIb/IV study of Rapamune (sirolimus) evaluating kidney transplant patients who transitioned from tacrolimus-based therapy (TAC) to Rapamune three to five months after transplant. The primary endpoint of the study was not achieved as there was not a statistically significant difference in renal function improvement between patients who continued receiving TAC and those who switched to Rapamune.

For patients who were switched to Rapamune, 33.7% of patients achieved the primary endpoint of a ≥ 5 ml/min/1.73m² renal function improvement based on glomerular filtration rate (GFR) from randomization to 24 months post-transplantation and 42.3% of patients continuing to take TAC achieved the primary endpoint.

The study was an open-label, randomized, comparative, multi-center, multi-national study conducted in Europe, Latin America, North America, and the Pacific Region. There were 256 subjects randomized at three to five months after transplant, with two subjects not receiving any medication. Group I included 131 subjects receiving Rapamune; the dose was adjusted to sirolimus blood levels of 7-15 ng/mL during the first year post-transplantation and 5-15 ng/mL thereafter. Group II, the control group, included 123 subjects who continued receiving the same TAC-based treatment that was being administered prior to randomization. Subjects in both groups were evaluated at a pre-randomization visit, at the day of randomization, four-weeks after randomization, and six-, 12-, 18- and 24-months post transplantation.