B) Treatment of chronic GVHD:
Although prophylaxis or “giving a drug for fear of” is quite well delineated in acute GVHD, it is less so in chronic GVHD. The main reason behind this is that the mechanism of chronic GVHD is less well-known, owing to the multitude of factors at play and the time lapse between the grafting and symptoms. With that said, two main measures are done as a prophylaxis for chronic GVHD:
- The use of anti-thymocyte globulin -antibody- before the grafting.
- The use of cyclophosphamide, which is a chemotherapeutic agent, during the first week following the grafting.
If chronic GVHD is established, several lines of treatment can be employed and tailored according to the patient’s response. Initial therapy consists of many agents used in acute GVHD like cyclosporine, tacrolimus and steroids. If initial therapy fails, several options exist for secondary therapy albeit with reduced efficacy:
- Mycophenolate mofetil with steroids have a greater response rate than other agents combined with steroids. Steroid resistance is especially challenging because they remain the cornerstone of treatment and the previous combination can be the best option for such condition.
- PUVA or ultraviolet radiation with psoralen especially for skin manifestations.
- Rituximab, one of the agents used in chronic leukemia can be used. It is specific against a receptor on lymphocytes called CD-20.
- Low dose radiotherapy.
- Ibrutinib which is also an agent used in leukemia.
You will notice that many regimens that are used in cancer are also employed against GVHD. This is because the main goal of immunosuppression is central in the management of both conditions.