Outcome of Relapse After Allogeneic Stem Cell Transplantation (SCT) In Patients with acute Myeloid Leukaemia (AML).

Although allogeneic SCT is associated with the lowest rates of relapse, 20% to 30% relapse. For these patients there is no standard therapy. They may receive intensive salvage, donor lymphocyte infusion (DLI) or palliative chemotherapy. Recently, new agents such as lenalidomide showed promising activity (Vij et al. ASH 2009Abs#842). We retrospectively analyse the outcome of 46 patients from our Institution who relapsed from AML following allo SCT.

We selected patients with a diagnosis of AML according to WHO criteria who relapsed between Jan 2000 and Apr 2010 from our database. Primary endpoint was response rate and duration after salvage treatment. Secondary end points were the overall survival (OS) and disease free survival (DFS) for responsive patients. At relapse, patients received either curative (anthracycline and/or high dose cytarabine and/or gemtuzumab) or non curative salvage (low dose cytarabine and/or oral chemotherapy or best supportive care (BSC)). OS was calculated from the date of relapse.

Initial patients characteristics included: median age=46 years [range: 16–69], favourable-risk (n=1; 2%) intermediate-risk (n=25; 57%) or poor-risk cytogenetics (n=18; 41%). Thirty patients were transplanted in complete remission (28 [61%] in CR1 and 2 [4%] in CR2), and 16 (35%) with refractory disease. The conditioning regimen was myeloablative conditioning (MAC) and reduced intensity conditioning (RIC) for 9 (20%) and 37 (80%) patients respectively. 27 patients (59%)received an allograft from matched related donor (MRD) HLA sibling donor, 7 (15%) from unrelated donor (MUD), 11 (24%) from cord bloods and 1 (2%) from haplomismatch donor. Median time from SCT to relapse was 3.8 months, 28 patients (61%) relapsed <6 months after SCT. 19 patients (41%) received curative salvage treatment, 17 (37%) non intensive chemotherapy and 10 (22%) BSC. Among the 19 patients who received intensive salvage therapy, 13 achieved CR (68%) and 1 achieved PR. There were 2 (10%) toxic deaths. Median response duration was 6.8 [range: 0.7–17.9] months and 1-year DFS was 20%.

The overall median survival (OS) was 3.6 months. Factors influencing survival were: treatment (curative vs non curative: OS= 7.7 vs 1.8 months, p=0.005), time between allo SCT and relapse (>6 months versus <6 months, OS= 7.7 months versus 1.9 respectively; p=0.032) and status at SCT (CR vs non CR, 5.1 vs 1.8 months, p= 0.02).

Our results confirm that the prognosis of the patients who relapse after allo SCT is very poor with a median 3.6 months survival underlining the need for new therapies. Initial CR duration, status at transplant and salvage treatment significantly affect survival after relapse. In a selected group of 41% of patients who relapsed after allo SCT and received intensive chemotherapy, 68% achieved CR and survived significantly longer.

No relevant conflicts of interest to declare.