More than half of children responded to pentostatin for steroid-refractory GVH disease

Results of a phase-2 study conducted at 24 institutions showed that pentostatin — a nucleoside that is a potent inhibitor of adenosine deaminase — was active against refractory chronic graft-versus-host disease in children.

The Pediatric Blood and Marrow Transplant Consortium enrolled 51 children with a median age of 9.8 years into a phase-2 trial. Patients were administered 4 mg/m² IV pentostatin every two weeks for 12 months. All patients in the study had been diagnosed with treatment-refractory chronic GVH; 69% had a history of prior acute GVH, 34% had progressive-onset chronic GVH and 59% had severe chronic GVH.

The researchers observed a 53% overall response rate (95% CI, 40%-64%) following treatment, with seven complete responses and 20 partial responses. Median duration of response was 185 days.

Only 21 patients were administered the full 12 months of therapy. Thirteen were removed from treatment for chronic GVH progression and 13 others for toxicity. Two patients relapsed and an additional two were lost to follow-up.

Among the 29 patients who responded within three months of treatment, 13 continued on the study and maintained a partial or complete response at 12 months.

Three of the 22 patients who did not respond within three months continued on the study. Two eventually had partial response and one had complete response.

OS was 84% (95% CI, 74%-94%) at one year. Projected three-year OS was 60% (95% CI, 45%-75%). Three years after enrollment, projected survival was 69% (95% CI, 49%-89%) for patients who responded to pentostatin compared with 50% (95% CI, 29%-71%) for those who did not respond.

Jacobsohn DA. Blood. 2009;doi:10.1182/blood-2009-05-224840.