Prothena’s PRX012 Trial Begins Dosing Patients, Healthy Volunteers

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by Patricia Inacio, PhD |

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Prothena has begun testing single ascending doses (SAD) of PRX012, its investigational anti-amyloid beta antibody therapy, in a Phase 1 clinical trial with healthy volunteers and people with Alzheimer’s disease.

This follows the recent approval of the company’s investigational new drug (IND) application for PRX012 by the U.S. Food and Drug Administration.

A next-generation antibody, PRX012 is meant to bind to toxic forms of amyloid beta that underlie Alzheimer’s disease. This means the therapy may potentially neutralize toxic aggregates, or clumps, and prevent neurodegeneration.

PRX012 is designed to be given under the skin (subcutaneously) and on a patient-friendly and convenient administration schedule, which may increase treatment adherence.

“With Alzheimer’s affecting more than 50 million people worldwide, we are committed to bringing a paradigm-shifting treatment to patients as quickly as possible,” Gene Kinney, PhD, president and CEO of Prothena, said in a press release.

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“Having submitted our IND during this first quarter, we are excited to announce the initiation of this first-in-human study,” Kinney said, adding, “PRX012’s high binding potency and subcutaneous administration has the potential to serve as a foundational anti-[amyloid beta] treatment for Alzheimer’s disease.”

In the SAD part of the trial, participants are randomly assigned to a single subcutaneous injection of either PRX012 or a placebo. The study intends to assess the therapy’s safety, tolerability, and immunogenicity — its ability to provoke an immune response — as well as its pharmacokinetics, which is the movement of a compound into, through, and out of the body.

The multiple ascending dose part of the trial is expected to start by year’s end.

Previous preclinical data showed that PRX012 targeted the toxic forms of amyloid beta with high affinity, covering with efficacy the amyloid beta plaques at relatively lower doses.

Additional data suggest that the therapy can promote the clearance of different forms of amyloid beta plaques from the brain. Importantly, this was done at concentrations amenable for subcutaneous delivery. According to Prothena, this is expected to result in less variability of antibody concentrations in the brain compared with first-generation amyloid beta targeting antibodies.

“We intend to leverage our multiple decades of experience and expertise in protein dysregulation together with clinical and regulatory learnings from first generation anti-[amyloid beta] therapies to maximize the probability of success for our PRX012 program to deliver a best-in-class treatment to patients with Alzheimer’s and their families,” said Kinney.