Johnson & Johnson (J&J) has secured breakthrough therapy designation (BTD) from the US Food and Drug Administration (FDA) for nipocalimab to treat alloimmunised pregnant individuals at increased risk for severe haemolytic disease of the foetus and newborn (HDFN).

Nipocalimab is an investigational, fully human, aglycosylated, effectorless, monoclonal antibody.

It is designed to selectively inhibit neonatal fragment crystallisable receptor (FcRn) and reduce circulating immunoglobulin G (IgG) antibodies.

J&J vice president and autoantibody and maternal-fetal immunology disease area leader Katie Abouzahr said: “Nipocalimab represents a novel approach for the treatment of patients at risk of severe HDFN who need proven, safe, non-surgical solutions to help address the serious health consequences of this condition.

“We are committed to addressing the substantial unmet need in this devastating disease.”

The BTD was based on results from the proof-of-concept Phase 2 open-label UNITY clinical trial, whose results were announced in June last year.

The multi-centre, international, non-blinded trial assessed Nipocalimab’s efficacy, safety, pharmacodynamics and pharmacokinetics.

Its primary endpoint was defined as the live birth at or post-gestational age of 32 weeks, without the need for an intrauterine transfusion throughout the pregnancy.

UNITY met this primary endpoint with 54% of pregnant subjects who received Nipocalimab achieving a live birth.

These results were compared against the historical reference point of 10%, taken from published and unpublished data.

The incidence of severe or serious adverse events was generally low and correlated with birth weight, gestational age at birth, and HDFN.

The fast-track designation for the drug candidate was awarded in July 2019, and the orphan drug classification by the FDA in June 2020.

Additionally, the European Medicines Agency in October 2019 granted orphan medicinal product designation for the HDFN indication.

Furthermore, pregnant women at risk for severe HDFN who have previously had severe HDFN are being enrolled in the AZALEA Phase 3 trial.