PHYOS: Primary HYperoxaluria Observational Study

PHYOS: Primary HYperoxaluria Observational Study


PHYOS was an international, multicenter, observational study that collected data on key biochemical parameters implicated in the pathogenesis of PH1 to better understand the baseline disease state, knowledge that will help guide long-term drug development plans. The study’s primary objective was to measure changes in oxalate, glycolate and other metabolites over a six-month period in patients with PH1. PHYOS investigators also collected data on the clinical manifestations of PH1, fluid intake, and quality of life.

The study population consisted of two cohorts:

  • Cohort A included patients age 12 years or older, as individuals in this age group will be considered for upcoming trials of potential PH1 therapeutics
  • Cohort B consisted of patients aged 6 to 11.9 years, after determination that patients of this age group may be enrolled in PH1 clinical trials

In July 2017, at the 12th International Workshop on Primary Hyperoxaluria for Professionals, Patients and Families in Tenerife, Spain, Dicerna reported interim data from the study’s 20 enrolled patients with a median age at screening of 21 years (range 12-61 years). The patients had been diagnosed at a median age of seven years (range 1-59 years), and 14 patients (74%) had a medical history of renal stones. Results included:

  • Over the six-month observation period, the variability (coefficient of variation) between 24-hour urine measurements of oxalate at different time points was 28%.

Our clinical team is using these data to design clinical studies using 24-hour urinary oxalate excretion as a surrogate marker for clinical benefit.

We expect to publish data from PHYOS in 2019.

Clinical Trial Detail