Alnylam Pharmaceuticals has reported positive six-month data from the Phase III ILLUMINATE-C clinical trial of its therapy, lumasiran, to treat advanced primary hyperoxaluria type 1 (PH1) patients.

An RNA interference (RNAi) therapy, lumasiran acts on the hydroxyacid oxidase 1 (HAO1), a gene that encodes glycolate oxidase.

The trial enrolled a total of 21 subjects. Of these, six requiring no dialysis were categorised into Cohort A while the other 15 subjects needing hemodialysis were in Cohort B.

The trial’s primary efficacy goal is the change in plasma oxalate (POx) in Cohort A and predialysis POx in Cohort B from baseline to six months, with an average across three to six months.

Primary analysis findings showed that the therapy provided a substantial decline in plasma oxalate (POx) in PH1 patients with stage 3b-5 chronic kidney disease, irrespective of their dialysis status.

From baseline to month six, lumasiran respectively offered 33% and 42% mean reductions in POx and predialysis POx in Cohorts A and B.

The decline in POx was noted in month one and continued until the completion of the primary assessment period of six months.

Lumasiran had a satisfactory safety profile in the trial with mild and temporary injection site reactions being the most common adverse event observed in 24% of the subjects.

Alnylam Lumasiran programme general manager Jeroen Valkenburg said: “PH1 patients progressing to or being diagnosed with end-stage kidney disease often have substantial elevations in plasma oxalate despite intensive hemodialysis.

“The ILLUMINATE-C results underscore the potential of lumasiran to achieve meaningful reductions in plasma oxalate in patients with impaired kidney function, including those on hemodialysis, who are at risk of systemic oxalosis and multiorgan damage.”

The company intends to submit the data to the US and European regulatory agencies this year to obtain a label extension for lumasiran.

Lumasiran is currently approved by the US Food and Drug Administration to reduce urinary oxalate levels in adult and paediatric PH1 patients.

In August this year, Alnylam concluded subject enrolment for the Phase III HELIOS-B trial of vutrisiran for the treatment of cardiomyopathy in patients with transthyretin-mediated amyloidosis.