Time to relapse after an allogeneic stem cell transplant and the extent of graft versus host disease (GVHD) are the two key factors predicting outcome in patients with relapsed acute myeloid leukaemia (AML).

A retrospective study of 386 patients from around Australia found relapse within six months of transplant and grade 3-4 acute GVHD preceding relapse were associated with inferior overall survival (Hazard ratio 2.4 and 2.0 respectively).

Haematologist Dr Andrew Lim, from the Austin Hospital, told the limbic the findings were consistent with the international experience in patients with AML.

“While survival is 15-20% at two years, we’ve all had survivors,” he said. “The dilemma in patients who are often young is: when is it worth pushing for another procedure with all the attendant risks and costs?”

Dr Lim said mild oral and skin manifestations of GVHD were a sign the graft was working and associated with longer survival.

“Having a bit of GVHD that we can see, but they can’t feel, provides the best outcome.”

However chronic GVHD and other potential factors such as primary induction failure, bone marrow blast percentage and extramedullary relapse were not significant on multivariate analysis.

The study found 60% of patients received salvage therapy – chemotherapy, re-transplantation or donor lymphocyte infusion. As a group, the five-year survival was about 14%.

Those patients who didn’t receive salvage therapy had a significantly worse five-year overall survival of 2%.

Patients who had a form of donor cell therapy also did better than those who received chemotherapy (five-year overall survival from salvage 23% v 5%).

When restricted to patients without the adverse prognostic features of early relapse or severe GVHD, those who had donor cell therapy had five-year overall survival from salvage of 32% compared to 9% in patients who received chemotherapy.

Information on immunosuppression withdrawal, which can help induce remission, was unfortunately not available.