The Medicines and Healthcare Products Regulatory Agency (MHRA) has granted a Promising Innovative Medicine (PIM) Designation to nirsevimab, an extended half-life monoclonal antibody (mAb) being investigated as a passive immunisation for the prevention of lower respiratory tract infections (LRTI) caused by a respiratory syncytial virus (RSV) in all infants in their first RSV season, from birth and up to 12 months of age; and children with chronic lung disease or with haemodynamically significant congenital heart disease in their second RSV season, up to 24 months of age.

PIM Designations are given to medicinal products that are likely to offer a major advantage for patients. For the MHRA to grant a PIM Designation, the product must meet each of the following three criteria:

Criterion 1: The conditions should be life-threatening or seriously debilitating with high unmet need, meaning there is no method of treatment, diagnosis or prevention available, or existing methods have serious limitations

Criterion 2: The medicinal product is likely to offer major advantage over methods currently used in the UK. Preliminary evidence should be submitted based on both non-clinical and clinical data

Criterion 3: The potential adverse effects of the medicinal product are likely to be outweighed by the benefits, allowing for the reasonable expectation of a positive benefit-risk balance.

“RSV is a pervasive respiratory disease, yet no approved treatments or preventative options available to all infants currently exist. The MHRA’s PIM Designation indicates nirsevimab is a promising option to help combat this still unmet need,” said Ian Gray, Sanofi UK Medical Director.

The PIM Designation was based on Phase 2b results of nirsevimab, which found a significant (70.1%; [95% CI: 52.3%-81.2%]) reduction in medically attended LRTI due to RSV in healthy preterm infants, compared to placebo. The results also showed nirsevimab achieved a 78.4% (95% CI: 51.9%-90.3%) relative reduction in the incidence of hospitalisations due to RSV LRTI in healthy preterm infants, compared to placebo. Nirsevimab had a tolerable safety profile, with no significant hypersensitivity reactions observed.