mesoblast (ASX:MSB) announced that the U.S. Food and Drug Administration (FDA) has granted advanced regenerative therapy designation to Revascor (rexlemestrocel-L) for children with hypoplastic left heart syndrome (HLHS).

This is based on the rare pediatric disease (RPD) and orphan drug (OD) status that the FDA has designated for this therapy.

Mesoblast develops allogeneic (off-the-shelf) cell medicines to treat serious and life-threatening inflammatory conditions. These treatments target the disease by modulating the immune system’s response and reducing harmful inflammation.

Hypoplastic left heart syndrome

HLHS is a severe heart defect in which the left side of the heart, including the left ventricle, aorta, and mitral valve, is underdeveloped. This prevents the heart from pumping oxygenated blood to the body effectively. Without prompt surgery, this defect is usually fatal.

This syndrome affects approximately 2 to 3 infants per 10,000 live births. It accounts for 2-9% of all congenital heart defects and is responsible for approximately 25-40% of neonatal cardiac deaths.

Revascor demonstrated promising results in a randomized controlled trial in 19 children with HLHS. Its impacts include:

• Promotes the formation of new blood vessels (“angiogenesis”) in the underdeveloped left ventricle.
• It reduces inflammation, prevents the immune system from attacking healthy tissue, and creates a favorable environment for tissue growth (“immunomodulation”).

Status of Regenerative Medicine Advanced Therapies (RMAT)

The FDA’s RMAT designation accelerates the development of treatments to address life-threatening conditions.

Benefits include staged review, priority review eligibility, and an expedited regulatory pathway for Biologics License Applications (BLAs). Mesoblast plans to work with the FDA on approval strategies.

CEO Silviu Itescu commented: “FDA support recognizes the potential impact that Revascor has on long-term outcomes in critically ill children. We are committed to advancing this therapy to address their unmet needs. looking forward to it.”

Following this announcement, Mesoblast’s stock price fell alarmingly. It is now down 7.1% at $1.64.