Alnylam Pharmaceuticals has commenced an international Phase II clinical trial of lumasiran in individuals with recurrent kidney stone disease and higher urinary oxalate levels.

Intended for subcutaneous administration, lumasiran is an RNA interference (RNAi) therapy that acts on hydroxyacid oxidase 1 (HAO1), the gene encoding glycolate oxidase.

The randomised, multicentre, placebo-controlled, double-blind trial will assess the safety, efficacy, pharmacodynamics and pharmacokinetics of lumasiran in recurrent calcium oxalate kidney stone disease patients and those with raised levels of urinary oxalate.

It is expected to recruit 120 adult subjects who had two or more stone events within five years and people with elevated 24-hour urinary oxalate levels.

These subjects will be categorised into a 1:1:1 ratio to receive either 567mg or 284mg lumasiran or placebo or on day one, month three and month nine.

The percent change in 24-hour urinary oxalate on receiving the treatment for six months is the trial’s primary goal.

The percentage of subjects who attain a 20% or higher decline in 24-hour urinary oxalate and percent change in urinary calcium oxalate supersaturation following treatment for six months will be the key secondary goals.

Alnylam Pharmaceuticals Lumasiran programme general manager Jeroen Valkenburg said: “The majority of kidney stones in adults are formed from calcium oxalate crystals and are accompanied by elevated urinary oxalate.

“To that end, we believe the reductions in urinary oxalate due to silencing of hepatic HAO1 we see with lumasiran in patients with primary hyperoxaluria type 1 may potentially apply to other diseases characterised by oxalate overproduction, such as recurrent kidney stone disease, where despite standard of care, stones continue to recur.”

Currently, lumasiran is US Food and Drug Administration (FDA) approved to treat paediatric and adult individuals with primary hyperoxaluria type 1 (PH1).

Last month, the company reported positive six-month data from the Phase III ILLUMINATE-C trial of lumasiran for advanced PH1 treatment.