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About 35%-50% of hematopoietic stem cell transplant (HSCT) recipients will develop acute Graft versus host disease (GVHD). Given the number of transplants performed, it is estimated that about 5500 patients/year will develop acute GVHD.

Three organs are involved: the skin (rash/dermatitis), liver (hepatitis/jaundice), and gastrointestinal tract (abdominal pain/diarrhea). Either one or more of these organs may be affected.

The exact risk is dependent on the stem cell source, age of the patient, conditioning, and GVHD prophylaxis used.

GVHD is a clinical diagnosis that may be supported with appropriate biopsies. The reason to pursue a tissue biopsy is to help differentiate from other diagnoses which may mimic GVHD, such as a viral infection (hepatitis, colitis) or drug reaction (causing skin rash). Acute GVHD is staged and graded (grade 0-IV) by the number and extent of organ involvement.

Generally the patient is treated by optimizing immunosuppression and adding methylprednisolone to the treatment regimen. About 50% of patients will have a solid response to methylprednisolone. If patients progress after 3 days or show no improvement after 7 days, they should receive a salvage (second-line) immunosuppressive therapy for which there is currently no standard-of-care. Well-organized clinical trials are imperative for better defining second-line therapies for this disease. Additional management issues are attention to wound infections in skin GVHD and fluid/nutrition management in gastrointestinal GVHD.

About 50% of patients with acute GVHD will eventually have manifestations of chronic GVHD. Patients with grade III/IV acute GVHD tend to have a poor outcome.