Allogeneic Transplantation with a Treosulfan-Fludarabine Conditioning Regimen Is Feasible and Effective in Elderly Patients with Refractory or Relapsed Acute Myeloid Leukaemia (AML) and Myelodysplastic Syndrome (MDS); Preliminary Results From a Single Center Experience.
Authors: Bernardi Massimo , Peccatori Jacopo , Tassara Michela , Crotta Alessandro , Messina Carlo , Stanghellini Maria Teresa Lupo , Forno Barbara , Girlanda Stefania , Assanelli Andrea , Clerici Daniela , Mastaglio Sara , Ruggeri Annalisa , Malato Simona , Giglio Fabio , Corti Consuelo , Guggiari Elena , Carrabba Matteo Giovanni , Bonini Chiara , Ciceri Fabio 
Published: October 2019

Abstract
Abstract 4318

Background
the majority of AML and poor risk MDS cases in the elderly (>60 years) are resistant to induction chemotherapy or relapse after initial response; thereafter, most of these patients (pts) receive only supportive treatments, with an expected survival of few weeks. Allogeneic (allo) stem cell transplantation (SCT) could be the only potentially salvage strategy; actually, for the high probability of letal toxicites due to the conditioning regimen, acute graft-versus-host disease (aGvHD) and infections, these pts are rarely offered this procedure.
Since 2005, we have transplanted 12 pts, age>60, with refractory or relapsed AML/MDS, from an allogeneic donor. Data on feasibility and outcome are here reported.

Aim
to retrospectively evaluate data on alloSCT in elderly pts with refractory or relapsed AML and MDS, transplanted at our Institute.

Patients and Methods
period 9/2005 to 4/2009, 12 pts, median age 65 (61-72). Performance status (Karnofsky): median 90% (80-100), HCT-CI: median score 1 (0-4). Diagnosis (WHO): AML 3, AMLMD 4, RAEB2 2, MDS/MPD 2, therapy-related AML 1. Median number of chemo cycles before SCT: 2 (1-7), all pts received at least 1 cycle with intermediate or high-dose cytarabine, 2 pts also received an autologous SCT. Donors: matched sibling 2, matched unrelated 2, related haploidentical 7, cord blood 1. Disease status at SCT: primary refractory 7, relapsed 5. Conditioning regimen: treosulfan (TREO) 14 g/sqm for 3 days, fludarabine (FLU) 30 mg/sqm for 5 days, ATG 10 mg/kg for 3 days for SCT from alternative donors. GvHD prophylaxis: T-cell depletion in 2 cases, cyclosporine (CSA)/methotrexate in 7, rapamycin/mycophenolate mofetil (MMF) in 3.

Results
11/12 (92%) pts engrafted and were in CR at day +30, with 95-100% donor chimerism (VNTR). Deaths within day 30 and day 100 were 0 and 3 (25%), respectively. Acute GvHD: 6 pts (55%), grade II (3) or III (3), only of skin in 3 cases, skin+liver in 1, only intestinal in 2. Relapses were 4 (36%). Overall TRM was 25% (3 pts), with all deaths due to infections during immunosuppression for aGVHD; 5 more pts died because of disease progression. Median OS from SCT of all 12 pts was 180 (56-1150) days, DFS (11 pts) was 128 (24-1114) days. At last follow-up (FU) 4 pts (33%) are alive, all in CR with a median FU of 406 (128-1150) days.

Conclusions
alloSCT proved to be feasible in our elderly pts with AML/MDS refractory to induction or relapsed after initial complete remission. Early letal toxicities, due to the conditioning treatment, were absent; aGVHD, infections and relapses were the principal causes of mortality. Up to now, prolonged survival (>1 year) free from disease has been obtained in 25% of pts; of the 4 pts alive in CR, only 1 is receiving immunosuppression (CSA), for chronic GVHD. In conclusion, the TREO-FLU association showed a reduced-toxicity profile in these frail pts and a substantial anti-leukemic effect. Better prevention of aGVHD should be obtained, expecially after SCT from alternative donors, possibly with the rapamycin/MMF combination, which we are currently investigating at our Institute. AlloSCT after TREO-FLU conditioning can be considered an effective option for AML/MDS elderly pts with active disease after failure of previous intensive treatments.

Disclosures:
bonini: MolMed S.p.A.: Consultancy.