Small US trial of Parkinson’s cell therapy hits ‘important milestone’

Kenai Therapeutics has completed patient enrollment in a small, early clinical trial testing the safety and effectiveness of RNDP-001, its direct-to-the-brain cell therapy for treating an underlying cause of Parkinson’s disease.

The Phase 1b/2a REPLACE trial (NCT07106021), now underway at three sites in the U.S., has recruited 12 adults with moderate to severe idiopathic Parkinson’s, meaning their disease has no known cause. Eligible participants ranged in age from 45 to 75, and were enrolled at study centers in Arizona, California, and Ohio. The trial dosed its first patient last year.

The experimental treatment is designed to replace lost nerve cells, with a goal of restoring motor function and potentially halting disease progression in people with Parkinson’s, according to the developer.

“Completing enrollment in the REPLACE trial is an important milestone for Kenai and a meaningful step in advancing our program for patients with Parkinson’s,” Nick Manusos, Kenai’s CEO, said in a company press release. “We thank the patients, caregivers, investigators, and clinical site teams for their participation and support in making this achievement possible.”

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Parkinson’s is caused by the loss of dopaminergic neurons, the nerve cells that produce dopamine, a chemical messenger involved in motor control. Impaired dopamine signaling leads to disease symptoms, such as tremor, rigidity, and slowed movement.

Cell therapy RNDP-001 targets nerve cell loss in Parkinson’s

RNDP-001 is designed to replace lost dopaminergic neurons. It uses induced pluripotent stem cells obtained from mature cells from a donor’s skin or blood, reprogrammed into a stem-cell-like state. These cells are then guided into dopaminergic neuron precursors, which are stored at low temperatures.

Progenitor cells can be surgically administered directly into a patient’s brain, where they may differentiate into dopaminergic neurons and increase dopamine levels. This is expected to ease Parkinson’s symptoms and potentially halt disease progression.

“Existing therapies for [idiopathic Parkinson’s] address symptoms but do not replace neurons lost to the disease,” said Howard Federoff, MD, PhD, Kenai’s scientific cofounder, chief medical officer, and executive vice president of corporate medicine and science. “RNDP-001 represents a different investigational approach intended to restore dopaminergic neurons and neural circuitry.”

According to Federoff, “REPLACE will provide early clinical data to evaluate that potential.”

The trial is open-label, meaning that participants and researchers both know the treatment being given. It will assess RNDP-001’s safety and tolerability, as well as evaluate its preliminary clinical activity at two dose levels: one low and one high. These two doses will be given in two patient groups; a third will then be treated with the best dose, the company noted.

Existing therapies for [Parkinson’s] address symptoms but do not replace [nerve cells] lost to the disease. … RNDP-001 represents a different investigational approach.

The trial’s main goal is the treatment’s safety and tolerability. Secondary goals include changes in on time, or periods when symptoms are well controlled with the medication. Researchers also will assess the brain’s dopaminergic function and activity among patients.

The REPLACE trial was supported in part by funding from the California Institute for Regenerative Medicine (CIRM), with a recent $8 million grant and an earlier award of $4 million in 2023.

The treatment was granted fast-track status by the U.S. Food and Drug Administration, a designation that aims to accelerate the development and review of therapies for serious or life-threatening conditions.