Nedosiran

Nedosiran has not been studied in PH1 patients with severe renal impairment (eGFR <30 mL/min/1.73 m²).

Nedosiran has not been studied in patients with moderate or severe hepatic impairment (total bilirubin >1.5 ULN with any AST).

Risk Summary

Available data from reports of pregnancy in clinical trials with nedosiran 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 embryofetal 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.

There are no data on the presence of nedosiran in human or animal milk, the effects on the breastfed child, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for nedosiran and any potential adverse effects on the breastfed infant from nedosiran or from the underlying maternal condition.

Carcinogenicity

Long-term studies to assess carcinogenic risk of nedosiran have not been conducted.

Genotoxicity

Nedosiran was not genotoxic in the in vitro bacterial mutagenicity, in vitro micronucleus assays (human peripheral blood lymphocytes) and in vivo bone marrow micronucleus assay in mice.

Fertility

Weekly subcutaneous administration of nedosiran at doses of 500, 1000, or 2000 mg/kg or of a mouse-specific (pharmacologically active) analog at a dose of 10 mg/kg to male mice for 4 weeks prior to and throughout mating, and to female mice for 2 weeks prior to and throughout mating and to gestation day 7 did not affect male or female fertility or early embryonic development.

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 nedosiran 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 nedosiran. 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 nedosiran and 11 patients received placebo. Of the 18 patients treated with nedosiran, 17 patients received ≥5 months of active treatment. The most common adverse reaction was injection site reactions, which were reported in 7 patients with PH1 (39%) on nedosiran 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%).