- Side Effects
What is extracorporeal photopheresis?
Extracorporeal photopheresis (ECP) is a therapeutic procedure for advanced cutaneous T-cell lymphoma (CTCL), which is an immune system cancer that affects the skin. Extracorporeal photopheresis is also known as extracorporeal photochemotherapy and extracorporeal photoimmunotherapy. It may be used as adjunctive therapy in other medical problems.
Extracorporeal photopheresis procedure processes the patient’s blood to selectively treat the white cells and curb their proliferation. Extracorporeal means the entire procedure takes place outside the body. The patient’s blood passes through a device which performs photopheresis (exposure to a photosensitizing substance and then to specific light wavelengths) and returns the treated white cells and blood back into circulation.
How is extracorporeal photopheresis performed?
Extracorporeal photopheresis is performed in specialized laboratories by trained technicians. More than 200 centers worldwide are equipped to perform ECP.
The technician attaches an intravenous (IV) line to a vein in the patient’s arm or the central vein in the upper chest, neck or groin. The IV line is attached to the ECP device, and the blood flows into the device through the IV line.
The ECP device accomplishes photopheresis in three steps:
- Leukapheresis: A combination of white blood cells and platelets (buffy coat) is separated from the blood with the use of centrifugal force. The red blood cells and plasma flow out of the device and back into the patient’s vein through the IV line. This process repeats several times depending on the patient’s weight and hematocrit level, to extract about 5% to 10% of the patient’s white blood cells.
- Photoactivation: The collected buffy coat is mixed with heparin and saline to prevent clotting. A photosensitizing substance, 8-methoxypsoralen (8-MOP) is added to the combination, which then undergoes ultraviolet A (UVA) radiation. The UVA radiation enables the 8-MOP to insert itself into the white cell’s DNA.
- Reinfusion: The photoactivated white cells are reinfused into the patient through the IV line.
Extracorporeal photopheresis may be of two kinds:
- Closed ECP system: In the closed ECP system, the entire process is automated and performed by a single device. The risks of infection and improper reinfusion are minimized.
- Open ECP system: In the open ECP system, leukapheresis and photoactivation are performed in two different devices.
What are the FDA-approved ECP systems?
- UVAR XTS: Second-generation system which collects the buffy coat intermittently.
- Cellex: Third-generation system which collects the buffy coat continuously.
Extracorporeal photopheresis may take from one and a half to four hours depending on the generation of ECP system used. Cellex takes less time and requires lower volume of blood.
How does extracorporeal photopheresis work?
Photopheresis makes the white cells susceptible to apoptosis. Apoptosis is programmed cell death that occurs naturally as a biological process in the body. When apoptosis fails to happen for some reason, cells keep multiplying, which results in cancer.
Researchers are still studying the therapeutic benefits of photopheresis. The apoptosis of treated white cells may also induce apoptosis of other abnormal T-cells. The activated cells appear to also promote immune tolerance and rebalance the immune system, though this effect requires further research.
What are the conditions extracorporeal photopheresis is used for?
Cutaneous T-cell lymphoma
Cutaneous T-cell lymphoma (CTCL) is a group of T-cell cancers that cause rashes, lesions and tumors in the skin, and can progress to internal organs and lymph nodes. CTCL is the only FDA-approved condition for use of extracorporeal photopheresis. The two most common types of CTCL are
Graft versus host disease (GVHD)
Graft versus host disease is a condition that may occur after a stem cell or bone marrow transplant. The new immune cells produced after the transplant have the donor’s DNA, and attack the patient’s own healthy tissues, considering them foreign.
Autoimmune skin disorders
Autoimmune skin disorders for which extracorporeal photopheresis can be beneficial include:
- Systemic sclerosis/scleroderma
- Severe atopic dermatitis
- Epidermolysis bullosa acquisita
- Erosive oral lichen planus
- Recalcitrant pemphigus vulgaris
- Recalcitrant pemphigus foliaceous
- Rheumatoid arthritis
- Lupus erythematosus
- Nephrogenic systemic fibrosis/nephrogenic fibrosing dermopathy
Extracorporeal photopheresis can be used as an adjunct treatment for transplant rejection in patients with solid organ transplant. Studies indicate that ECP reduces the donor-specific antibodies in the transplant patient. ECP is found to be beneficial for the following conditions:
Who cannot have extracorporeal photopheresis?
Extracorporeal photopheresis cannot be performed on people with conditions such as:
What are the side effects of extracorporeal photopheresis?
Extracorporeal photopheresis is generally a safe procedure and side effects are mild and temporary. Patients are advised to avoid sun exposure for 24 hours after the procedure.
Potential side effects include: