ePHex: a phase 3, double-blind, placebo-controlled, randomized study to evaluate long-term efficacy and safety of Oxalobacter formigenes in patients with primary hyperoxaluria

Ariceta G, Collard L, Abroug S, Moochhala SH, Gould E, Boussetta A, et al.

Published in Pediatr Nephrol, Vol. 38 (2), pp. 403-415

Methodology

Phase 3, double-blind, placebo-controlled randomised trial. Patients aged 2 years or older with primary hyperoxaluria and maintained but reduced kidney function (eGFR below 90 mL/min/1.73 m2) took Oxabact (freeze-dried Oxalobacter formigenes) or placebo twice daily for 52 weeks. Primary endpoint: change in plasma oxalate at week 52.

Key Findings

25 patients were recruited. O. formigenes was established in the gut of treated patients. Plasma oxalate fell on Oxabact and was stable or rose on placebo, but the difference was not significant (treatment difference -3.80 umol/L; 95% CI -7.83 to 0.23; p = 0.064). Kidney function remained stable in both groups. Adjudicated kidney stone events were 7 in 13 treated patients and 8 in 12 on placebo (p = 0.12).

Conclusions

The authors concluded Oxabact may have stabilised or reduced plasma oxalate versus a rise on placebo, but the 12-month difference was not statistically significant.

Limitations

Very small sample, missed primary endpoint, heterogeneous disease progression, and dropout mainly from the placebo arm. Designed, funded and managed by the product's manufacturer.