Azacitidine (Vidaza®, Aza) and Donor Lymphocyte Infusions (DLI) In Patients with Acute Myeloid Leukemia (AML) or Myelodysplastic Syndromes (MDS) Relapsing After Allogeneic Hematopoietic Stem Cell Transplantation (HSCT): Interim-Analysis From the AZARELA-Trial (NCT-00795548).

Patients with AML or MDS who relapse after allogeneic HSCT have a poor prognosis and therapeutic options are limited. The DNA hypomethylating agent Aza has significant activity in patients (pts) with AML and MDS and retrospective analyses have recently shown encouraging results with the use of Aza +/− DLI in patients with AML and MDS, who relapsed after allogeneic HSCT (Czibere et al., 2010; Luebbert et al., 2010). In line with these clinical observations preclinical data suggest that Aza enhances a Graft-versus-Leukemia (GvL) effect while mitigating Graft-versus-Host Disease (GvHD).

To evaluate the activity and safety of Aza in combination with DLI as first salvage therapy in pts with AML or MDS relapsing after HSCT, we conducted a prospective, multicenter, single-arm phase-II trial. Pts were allowed to receive up to 8 cycles Aza (100 mg/m²/d d1-5, every 28 days) and 3 DLI with increasing dosages (1-5×10⁶ – 1–5×10⁸ cells/kg) after every 2^nd Aza treatment cycle. Additional DLI were permitted.

Between January 2009 and May 2010, 30 pts from 6 German transplant centres were included into this trial. So far, 25 pts (15 female/10 male) were evaluable and are presented in this analysis:

Of these, 23 (92%) suffered from AML (15 de novo/8 secondary following MDS), 1(4%) from a MDS (RAEB-1) and 1 (4%) from a myelodysplastic/myeloproliferative syndrome (MDS/MPS, CMML-1). Median age was 54 years (range 29–71).

Conditioning was myeloablative in 24 pts (96%) and non-myeloablative in 1 patient (4%). Eight pts (35%) received a graft from a matched sibling donor, while 15 (65%) were transplanted with a matched unrelated donor (2 pts missing data). Peripheral blood stem cells (PBSC) were used in 24 pts (96%; 1 pt missing data).

At the time of transplant 6 pts (24%) had primary induction failure, another 6 (24%) suffered from first or secondary relapse, 10 pts (40%) were in first or second complete remission (CR), while 3 pts (12%) were untreated. With regard to their molecular and genetic characteristics at diagnosis, 21 pts belonged to an adverse (9 pts) or intermediate (12 pts) group, whereas 2 pts were diagnosed with a favourable genetic phenotype (2 pts not performed).

Prior to relapse 9 (36%) and 3 (12%) pts had episodes of acute GvHD and/or chronic GvHD, respectively.

Relapse occurred in all pts after a median of 160 days (range 19–1199) following HSCT (median BM blasts: 34%, range 5–100%, median chimerism: 63% range-1-100%). At the time of relapse, karyotype was evaluable in 13 of 25 pts (52%). Of these 13 pts, 4 pts had a normal karyotype, while 9 had chromosomal aberrations including 6 pts with a complex karyotype.

Patients received a median of 3 courses Aza (range 1–8) and 18 of 25 pts (72%) received DLI (median: 1, range: 1–4, median CD3 dose 5×10⁶/kg/DLI, range: 1–207×10⁶).

Following treatment, overall response rate was 64% with 5 pts (20%) achieving a CR or CRi, 3 (12%) a partial remission (PR) and 8 (32%) a stable disease (SD). Median response duration was 266 days. Acute GvHD occurred in 6 pts (24%) (2 skin/6 liver/ 2 gut) after a median of 65 days (range 19–179) following the first DLI, while chronic GvHD was observed in 3 pts (12 %, all limited). Hematotoxicity (grade III-IV) was observed in 64% of all evaluated patients. Common adverse events were gastrointestinal side effects as well as infections.

After a median follow-up of 100 days (range 25–485) 15 of 25 pts (60%) are currently alive. Median overall survival of all pts is 184 days (range 87–281). All pts, who achieved a CR/CRi, remained in ongoing remission for a median time of 229 days. Achieving a CR (CR: not reached vs. no CR: 117 days, p .008) or any type of response (CR/CRi, PR or SD) to the combination of Aza and DLI (any response: not reached vs. no response: 79 days, p .0001) were associated with a significantly longer overall survival.

The combination of Aza and DLI as salvage treatment for patients with AML or MDS who relapse after allogeneic HSCT seems to be safe and shows significant anti-leukemic activity. Response, including CR rates, so far match those from retrospective analyses. Data presented in this interim-analysis suggest that salvage therapy with Aza and DLI is of substantial therapeutic benefit in these challenging patients.

Platzbecker:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Bug:Celgene: Honoraria. Luft:Celgene: Research Funding. Fenk:Celgene: Research Funding. Kobbe:Celgene: Research Funding.