Rivfloza Drug Information

is indicated to lower urinary oxalate levels in children 2 years of age and older and adults with primary hyperoxaluria type 1 (PH1) and relatively preserved kidney function, e.g., eGFR ≥30 mL/min/1.73 m 2, Clinical Studies (‎ 14.1 )]. RIVFLOZA is an LDHA -directed small interfering RNA indicated to lower urinary oxalate levels in children 2 years of age and older and adults with primary hyperoxaluria type 1 (PH1) and relatively preserved kidney function, e.g., eGFR ≥30 mL/min/1.73 m 2. (‎ 1 )

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The safety of RIVFLOZA has been evaluated in one placebo-controlled clinical trial (PHYOX2) and one open-label extension study (PHYOX3). Across these studies, 29 adults and 12 children with PH1 have been treated with RIVFLOZA. Patients with PH1 in these studies ranged in age from 9 to 46 years at first dose. The median duration of exposure was approximately 15 months (range 1-29 months). Overall, 38 patients with PH1 were treated for at least 6 months, 24 patients for at least 12 months, and 16 patients for at least 18 months.

In the randomized, placebo-controlled, double-blind PHYOX2 trial in pediatric and adult patients 9 to 46 years of age, 18 patients with PH1 received RIVFLOZA and 11 patients received placebo. Of the 18 patients treated with RIVFLOZA, 17 patients received ≥5 months of active treatment. The most common adverse reactions were injection site reactions, which were reported in 7 patients with PH1 (39%) on RIVFLOZA as compared to no patients on placebo.

Injection site reactions included erythema, pain, bruising, and rash and were generally mild and did not lead to discontinuation of treatment. In the single-arm extension study (PHYOX3) that included 40 patients with PH1, additional injection site reactions included atrophy in 1 patient (3%). The safety of RIVFLOZA has additionally been evaluated in one single-arm clinical study (PHYOX8) in 15 pediatric patients 2 to less than 12 years of age with PH1 and an eGFR > 30 mL/min/1.73 m 2. Injection site reactions were reported in 2 patients (13%). Overall, the RIVFLOZA safety profile was similar to that seen in PHYOX2.

Pregnancy Risk Summary Available data from reports of pregnancy in clinical trials with RIVFLOZA are insufficient to evaluate for a drug-associated risk of major birth defects, miscarriage or other adverse maternal or fetal outcomes. In animal reproduction studies, no adverse developmental effects were observed when nedosiran was administered to pregnant mice at doses up to approximately 58 times the maximum recommended human dose (MRHD) of 160 mg nedosiran (equivalent to 170 mg nedosiran sodium) per dose, based on body surface area (BSA) or upon administration of a mouse-specific (pharmacologically active) analog. Subcutaneous administration of nedosiran to pregnant rabbits during the period of organogenesis at doses approximating the MRHD resulted in increased fetal loss in the presence of maternal toxicity.

Adverse developmental outcomes (fetal cardiovascular and skeletal malformations) were observed at a dose approximately 2 times the MRHD (see Data). Nedosiran is not pharmacologically active in rabbits or mice. The cause for the embryo-fetal toxicities observed in rabbits remains unclear. The estimated background risk of major birth defects and miscarriage in the indicated population is unknown.

All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Animal Data In mice, subcutaneous administration of nedosiran at doses up to 2000 mg/kg/dose (approximately 58 times the MRHD based on BSA) or a mouse-specific (pharmacologically active) analog (10 mg/kg/dose) during organogenesis (dosing on gestation days 6, 8, 10, 12, and 14 for nedosiran; gestation days 3 and 10 for the analog) did not have adverse effects on embryo-fetal development.

Subcutaneous administration of nedosiran (0, 2, 6 or 20 mg/kg/dose) to pregnant rabbits during organogenesis (dosing on gestation days 7, 9, 11, 13, 15, 17, and 19) resulted in maternal toxicity on the basis of body weight loss of up to 6.5% following the first dose in the 6 and 20 mg/kg/dose groups. Higher post-implantation loss and lower numbers of live fetuses occurred at ≥6 mg/kg/dose (exposures equivalent to the MRHD based on BSA), and fetal cardiovascular and skeletal malformations occurred at the 20 mg/kg/dose (2 times the MRHD based on BSA). At the 2 mg/kg/dose, which is below the MRHD, no adverse findings were seen. In a pre- and postnatal study in mice, subcutaneous administration of nedosiran (0, 250, 500, or 1000 mg/kg/dose) or a mouse-specific (pharmacologically active) analog (10 mg/kg/dose) from implantation (dosing on gestational days 6, 8, 10, 12, 14, 16) to weaning (dosing on lactation days 1, 8, 15, 20) did not have adverse effects on the growth, viability, development and reproductive performance of the offspring.

Pediatric Use The safety and effectiveness of RIVFLOZA have been established in pediatric patients aged 2 years and older. Use of RIVFLOZA in these age groups is supported by evidence from an adequate and well-controlled trial in adult and pediatric patients 9 years of age and older (PHYOX2), and a single-arm study in pediatric patients 2 to less than 12 years of age (PHYOX8) . The safety and effectiveness of RIVFLOZA in patients younger than 2 years of age have not been established.