The primary objectives of this Phase 1 are:
- To assess the occurrence of adverse events of special interest (AESIs) in participants treated with repeated subcutaneous (SC) doses of REGN10933+REGN10987 compared to placebo
- To assess the concentrations of REGN10933 and REGN10987 in serum over time after single and repeated SC administration
The secondary objectives are:
- To assess the safety and tolerability of repeated SC doses of REGN10933+REGN10987 compared to placebo
- To assess attainment of target concentrations of REGN10933 and REGN10987 in serum after single and repeated SC administration
- To assess the immunogenicity of REGN10933 and REGN10987
On November 11, 2021, MedRxiv published the non-peer-reviewed results of this Phase 1 study.
In total, 969 subjects were treated. Repeat monthly dosing of SC REGEN-COV led to a 92.4% relative risk reduction in clinically-defined COVID-19 compared to placebo (3/729 [0.4%] vs 13/240 [5.4%]; odds ratio: 0.07 [95% CI, 0.01–0.27]), and a 100% reduction in laboratory-confirmed COVID-19 (0/729 vs 10/240 [4.2%]; odds ratio 0.00). The development of anti-drug antibodies was low (<5% subjects). No grade ≥3 injection-site reactions (ISRs) or hypersensitivity reactions were reported. A slightly higher percentage of subjects reported TEAEs with REGEN-COV (54.9%) than placebo (48.3%), due to ISRs (all grade 1-2). Serious adverse events were rare and occurred at similar percentages in the REGEN-COV and placebo groups. No deaths were reported in the 6-month treatment period.
Repeated monthly administration of 1200 mg SC REGEN-COV was well-tolerated with low immunogenicity, and showed a substantial risk reduction in COVID-19 occurrence.