Long Term Outcome of Patients with Steroid Refractory Acute Intestinal Graft Versus Host Disease after Treatment with Pentostatin.

Steroid refractory intestinal acute Graft versus Host Disease (aGvHD) is a mayor complication after allogeneic hematopoietic cell transplantation. Survival rate of severe intestinal aGvHD is low. No therapy has been proven to increase the survival rate in steroid refractory aGvHD so far. A promising strategy is the use of pentostatin, a purine nucleotide analogue and inhibitor of adenosine deaminase, which is known to decrease function and number of lymphocytes. Here we report the six year follow-up of a pilot study on salvage therapy of aGvHD by pentostatin. We treated 18 patients with steroid refractory intestinal aGvHD stage III or IV with Pentostatin (8 female and 10 male patients). The mean age was 45 (range: 25–61 years). The underlying diseases were ALL (4), AML (10), Multiple Myeloma (2), Hodgkin’s Disease (1) and CML (1). Eight patients were allografted with HLA-identical sibling donors, three with related donors with a single HLA class I mismatch, seven with matched unrelated donors. All patients were allografted with peripheral blood stem cells. As GvHD prophylaxis ciclosporine A in combination with mycophenolate mofetil or methotrexate were used. Eleven patients had aGvHD stage III, seven stage IV. All patients had a severe gastrointestinal-tract involvement (grade III or IV). After failure of steroid treatment (prednisolone >2 mg/kg for at least 3 days) pentostatin was applied as a salvage therapy (1 mg/m² for three consecutive days). Eight patients received between one and three further courses of pentostatin every three to four weeks. Therapy was well tolerated. No severe neutropenia was observed. Except one case of hemolytic uremic syndrome (HUS) no impairment of renal function was observed. Eleven patients achieved a complete, five a partial remission of aGvHD. Time until a clinical improvement could be observed was 12–14 days. Two patients died before day 12 without improvement of GvHD symptoms. Seven patients (39%) are alive (510–2060 days post first cycle of pentostatin), two with extensive chronic GvHD. All one-year-survivors stayed alive. Eleven patients died (two due to relapse of leukemia, nine transplant related [1 x interstitial pneumonitis, 1 x pneumonia, 1 x chronic GvHD, 4 x aGvHD and multiple organ failure (MOF), 1 x parvo B19 infection and MOF, 1 x HUS and MOF]). In conclusion, in this pilot study pentostatin has been demonstrated to be a highly effective and well tolerated drug for salvage therapy of steroid refractory acute GvHD with intestinal involvement. Moreover, compared with earlier studies on steroid refractory aGvHD a high rate of long term survivors could be observed. By a multicenter prospective randomised study we are currently investigating whether pentostatin can improve the outcome in steroid refractory intestinal aGvHD.