How Do Selective T-Cell Costimulation Blockers Work?

Selective T-cell costimulation blockers are a class of drugs used in the prophylaxis of organ rejection (attack on a transplanted organ by the immune system of a person who received the organ) in adult patients receiving a kidney transplant. The only content (belatacept) approved in this class is a soluble fusion protein which links human cytotoxic T-lymphocyte-associated antigen 4 to the modified Fc fragment (fragment crystallizable region is the tail region of an antibody that interacts with the cell surface receptors called Fc receptors, which allows antibodies to activate the immune system) of a human IgG1 immunoglobulin (the most common type of antibody found in blood circulation).

Selective T-cell costimulation blockers are prescription-only medicines and are administered intravenously (through a vein) over 30 minutes, usually given on the day of the transplant, five days after transplant, at the end of weeks two and four, and then once every four weeks.

Selective T-cell costimulation blockers work in the following ways:

• They belong to a class called "Immunosuppressants."
• They work by decreasing the activity of the immune system to prevent it from attacking the transplanted kidney.
• They inhibit the activity of T lymphocytes (T-cells are a part of the immune system that focuses on specific foreign particles).
• In addition, they selectively block the process of T-cell activation.

Selective T-cell costimulation blocker belatacept is used in kidney transplant rejection prophylaxis.

Other potential use for "reltecimod" is pending approval from the Food and Drug Administration for suspected organ dysfunction or failure in patients aged ≥12 years with necrotizing soft tissue infection (a rare and very severe type of bacterial infection that can destroy the muscles, skin, and underlying tissues).

Receiving belatacept injection may increase the risk of posttransplant lymphoproliferative disorder (a serious condition with rapid growth of certain white blood cells, which may develop into a type of cancer).

Some of the common side effects include:

• Headache
• Diarrhea
• Nausea
• Vomiting
• Cough 
• Malaise (a sense of unease or a lack of well-being)
• Constipation

Other rare side effects include:

• Leukopenia (low white blood cell count)
• Pyrexia (fever)
• Hyperkalemia (high blood potassium level)
• Hypokalemia (low blood potassium level)
• Dyslipidemia (an abnormal level of cholesterol and other lipids [fats] in the blood)
• Hypotension (low blood pressure)
• Arthralgia (joint pain)
• Hyperglycemia (high blood glucose level)
• Tachycardia (a fast heart rate—more than 100 beats per minute)
• Insomnia (trouble falling and/or staying asleep)
• Urinary tract infection
• Peripheral edema (swelling of lower legs or hands)
• Dysuria (painful urination)
• Hypercholesterolemia (high blood cholesterol level)
• Dizziness (feeling faint, weak, or unsteady)

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of selective T-cell costimulation blockers include:

• Belatacept
• Nulojix
• Reltecimod