Dosing Begins in Phase 2 Trial of Mezagitamab, Antibody to Treat MG

A first person has been dosed in a Phase 2 trial evaluating mezagitamab (TAK-079), Takeda Pharmaceutical’s investigational antibody, as a therapy for generalized myasthenia gravis (MG), according to a press release.

The trial (NCT04159805), beginning to enroll at select sites across the U.S., Canada, Italy, Poland, Serbia and Spain, will evaluate the safety and tolerability  of TAK-079 as an add-on treatment to stable background therapy in nearly 36 adults with generalized MG. Other goals include early evidence of efficacy.

More information is available here regarding trial locations, relevant contacts, and whether these sites are currently recruiting or yet to open.

Participants will be randomly assigned to one of two doses of TAK-079 or to a placebo, all given as subcutaneous (under-the-skin) injections once a week for eight weeks.

The study’s main goal is safety by week 16, measured as the percentage of patients with treatment-emergent adverse events, serious adverse events, or side effects that lead to treatment discontinuation.

Effectiveness measures at week 16 are secondary goals, and include changes in the MG activities of daily living scale score, which assesses such activities as talking and chewing, or rising from a chair; changes in the revised 15-item MG quality of life scale, which measures patient’s perception and tolerance of MG-related dysfunction; and in terms of disease severity using the Quantitative MG Score.

MG is most commonly caused by autoantibodies — those targeting the body’s own tissues — against the acetylcholine receptor (AChR) at the neuromuscular junction, or the point where nerve cells communicate with muscle cells. People with anti-AChR autoantibodies, as well as those with autoantibodies targeting the MuSK protein, are eligible for this Phase 2 trial.

Mezagitamab, originally developed for multiple myeloma, targets the CD38 protein. This protein is found at high levels on the surface of malignant multiple myeloma cells, but also on non-malignant (normal) immune B-cells, those responsible for the production of autoantibodies.

Previous studies with another CD38-targeting antibody approved for multiple myeloma, Janssen‘s Darzalex (daratumumab), showed it was effective in lowering autoantibody levels in cancer patients, supporting the potential of this approach for autoimmune diseases such as MG.

Takeda entered a partnership with Xoma to identify antibodies that could be advanced into clinical development in 2006, and mezagitamab is a result of this work.

“Takeda has multiple early stage mezagitamab studies ongoing in several indications,” said Jim Neal, CEO of Xoma. “We applaud Takeda for advancing mezagitamab development in generalized MG.”

As part of the agreement and with the first patient being dosed in the trial, Xoma received a $2 million milestone from Takeda. The company is eligible for up to $16 million from Takeda for additional milestones, as well as royalties from sales should mezagitamab be approved as a treatment.