Incannex commences phase 2 trial assessing IHL-675A for treatment of rheumatoid arthritis

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By Imelda Cotton - 
Incannex Healthcare ASX IHL Phase 2 trial IHL-675A treatment rheumatoid arthritis hydroxychloroquine cannabidiol

A total of 120 patients will be recruited for the trial of IHL-675A in rheumatoid arthritis.


Medicinal cannabinoid and psychedelic therapies developer Incannex Healthcare (ASX: IHL) has commenced a phase 2 clinical trial to assess the safety and efficacy of its proprietary anti-inflammatory combination drug IHL-675A in patients with rheumatoid arthritis.

The trial is being managed by Avance Clinical and will engage up to 10 sites across Australia and New Zealand, recruiting 120 patients in total, making it one of the largest clinical trials conducted in the sector.

The trial will assess the effect of IHL-675A on pain and function by utilising patient-reported outcomes, disease scores and inflammatory biomarker analysis over a 24-week period.

Patients who meet the criteria for joint damage may also be included in a magnetic resonance imaging (MRI) assessment sub-study.

IHL-675A is a proprietary fixed dose combination drug comprising cannabidiol (CBD) and hydroxychloroquine (HCQ).

HCQ is approved for treatment of rheumatoid arthritis and is used by a significant cohort of patients with the disease. Many are also reportedly using non-cGMP grade CBD to ameliorate their symptoms.

The intention of Incannex is to undertake clinical trials for its proprietary fixed dose combination of HCQ and CBD to achieve the US Food and Drug Administration (FDA) marketing approval for a pharmaceutical grade IHL-675A product that can be prescribed with confidence by a patient’s doctor.

Prior to conducting this phase 2 trial, IHL-675A was reported to be well tolerated in a phase 1 trial. In animal studies, IHL-675A was observed to reduce arthritis disease scores to a greater extent than HCQ.

Animal model

The animal model of rheumatoid arthritis showed IHL-675A to be more effective than a rodent equivalent, standard dose of HCQ at reducing inflammation across multiple assessments including: clinical score, paw volume, pannus score, total histology score and serum cytokine levels.

The reduction in disease assessments achieved were up to 3.52 times that observed for HCQ alone at the standard dose.

These observations led Incannex to prioritise the rapid clinical assessment of IHL-675A, particularly given that HCQ is a common long-standing treatment prescribed for rheumatoid arthritis.

Safety and efficacy

Incannex chief scientific officer Dr Mark Bleackley said the phase 2 trial would seek to establish the safety and efficacy of IHL-675A and contribute to a new drug application dossier for the FDA.

“This trial is a key milestone in our IHL-675A development program we are excited to determine whether the remarkable preclinical efficacy observed in an animal disease model for arthritis is also seen to a similar extent in humans,” he said.

“Arthritis is a disease which negatively impacts the well-being of millions of people worldwide and this trial is a big step toward potentially improving the quality of life for these patients.”

Multi-use drug

IHL-675A is being developed as a multi-use drug suitable for the prevention and treatment of inflammation, with an initial focus on rheumatoid arthritis, inflammatory lung conditions (including acute respiratory distress syndrome; chronic obstructive pulmonary disease; asthma; and bronchitis); and inflammatory bowel disease.

The treatment of these indications is believed to have a combined global market size of more than US$125 billion per year.

Incannex has completed a pre-investigational new drug (IND) meeting with the FDA to discuss the regulatory pathway for the development of IHL-675A in the US and plans to open INDs for each of the three indications.

HCQ is already approved for the treatment of rheumatoid arthritis and is used by a significant cohort of trial patients with the disease.

Subject to clinical results, if IHL-675A proves to be more efficacious than HCQ alone, then IHL may have landed on a better alternative medicine for patients with rheumatoid arthritis.