Orencia (abatacept) is a therapy that Bristol-Meyers Squibb hopes regulators will approve for myasthenia gravis, or MG.

Regulatory agencies have already authorized it for treating rheumatoid arthritis, juvenile arthritis, and psoriatic arthritis.

How Orencia works

MG is a condition caused by the immune system mistakenly attacking neuromuscular junctions. These are points where the nervous system meets muscles, transmitting chemical messages for the muscles to contract.

Part of the damaging immune response comes from the immune system producing antibodies against acetylcholine receptors, or AChRs. Antibodies are immune system proteins designed to attack a specific target.  AChR is a protein essential to transmitting messages from nerves cells to muscle cells. When antibodies attack AChR, they disrupt the message transmission.

Orencia is an immunosuppressive drug, which means that it stops part of the immune system from working. It is also a fusion protein — that is, Bristol-Meyers Squibb makes it by combining the immune proteins CTLA-4 and immunoglobulin. CTLA-4 helps inhibit immune cells known as T-cells. One of activated T-cells’ roles is producing antibodies.

By preventing T-cell activation, Orencia causes the immune system to produce fewer antibodies against AChR. The idea is to improve nerve signaling to muscles, providing relief from symptoms of MG.

Some people may be predisposed to developing MG because of CTLA-4 abnormalities. This means Orencia could be more effective in some subsets of MG patients.

Orencia in clinical trials

Successful preclinical-trial studies in animal models of MG prompted Bristol-Meyers Squibb to start a Phase 1 pilot trial (NCT03059888) of Orencia in humans. The trial will assess whether Orencia is safe, and whether patients tolerate it well. It will also assess whether the treatment can be effective in MG patients who failed to respond to standard treatments.

Researchers plan to recruit 20 patients, who will receive Orencia once a week for a year. The team wil measure changes in the severity of patients’ disease with a number of tests, including muscle strength evaluations, the MG composite scale, MG quality of life-15 survey, and changes in antibody concentrations.

Orencia has been extensively tested in clinical trials for arthritis patients. It proved effective and safe. It has been less effective against other autoimmune conditions, such as inflammatory bowel disease, trials have shown.

Other information

Orencia’s exact side effects in MG patients are not known. In rheumatoid arthritis patients, common side effects include headaches, high blood pressure, the common cold, heartburn, dizziness, urinary tract infections, cough, rashes, back pain, and pain in extremities such as fingers and toes.

Myasthenia Gravis News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.