H.P. Acthar Gel (repository corticotropin injection) is an investigational treatment for amyotrophic lateral sclerosis (ALS) being developed by Mallinckrodt Pharmaceuticals. It is administered as an injection.

The drug is currently approved to treat various other conditions, including multiple sclerosis (MS).

How H.P. Acthar Gel works

ALS is a neurodegenerative disorder, where the progressive death of motor neurons results in an increasing loss of control over particular muscles. The exact cause of the disease is unknown. However, one potential cause of the progression of the disease is neuroinflammation, or swelling of the nervous tissue, caused by the immune response. This can cause further damage to the nerves.

H.P. Acthar Gel contains a highly purified preparation of the adrenocorticotropic hormone (ACTH). ACTH stimulates the release of naturally produced steroid hormones (such as cortisol, corticosterone, and aldosterone) from the adrenal gland located on top of the kidneys. These steroid hormones are involved in the regulation of many biological functions, including immune response, metabolism, and blood pressure.

Through tests in mouse models, it has been suggested that H.P. Acthar Gel could act by affecting the immune system through these hormones and prevent neuroinflammation.

H.P. Acthar Gel in clinical trials

A double-blind, placebo-controlled, Phase 2b clinical trial called PENNANT (NCT03068754) is currently recruiting participants at various locations in the U.S. to test H.P. Acthar Gel. The study aims to assess the safety and the effectiveness of the drug in an estimated 195 ALS patients, ages 18 to 75, who have started experiencing symptoms less than two years ago.

At the end of a 36-week treatment period, the effect of 0.2 mL of H.P. Acthar Gel compared to a placebo will be assessed using the ALS Functional Rating Scale-Revised (ALSFRS-R).

This trial was initiated following the results of a short eight-week Phase 2 pilot study (NCT01906658) testing the safety and tolerability of the H.P. Acthar Gel in ALS patients, which showed that the treatment was well-tolerated. These results were used to support Mallinckrodt’s Investigational New Drug (IND) application to the U.S. Food and Drug Administration (FDA). The company has been given Fast Track designation for the IND application, allowing it to distribute the treatment to clinical trial centers across different states.

Other information

Patients taking H.P. Acthar Gel may experience a number of different side effects. Some of the most common side effects include an increased risk of infections, diarrhea, high blood pressure, acne, convulsions, irritability, and cushingoid (an excess of cortisol that can cause face puffiness and weight gain).

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