Patterns of Salvage Therapy in Patients with Acute Myeloid Leukemia Treated Upfront with Azacitidine or Decitabine: Results from the Pethema AML Registry
Authors: Labrador Jorge , de la Fuente Adolfo , Martínez-Cuadrón David , Rodríguez-Veiga Rebeca , Serrano Josefina , Tormo Mar , Pérez-Simón Jose , Ramos Fernando , Bernal del Castillo Teresa , López-Pavía Maria , Trigo Fernanda , Martinez Sanchez Pilar , Rodriguez-Gutierrez Juan Ignacio , Rodriguez Carlos , Gil Cristina , Garcia Daniel , Vives Susana , Foncillas Maria Angeles , Perez Encinas Manuel , Novo Andrés , Recio Isabel , Rodriguez Macias Gabriela , Bergua Burgues Juan Miguel , Noriega Concepcion Victor , Lavilla Esperanza , Roldán Pérez Alicia , Sanz Miguel A. , Montesinos Pau 
Published: November 2021

Abstract

INTRODUCTION
The hypomethylating agents (HMAs), decitabine (DEC) and azacitidine (AZA), are a common choice for initial treatment in elderly patients with acute myeloid leukemia (AML). However, about 60% of patients are resistant and most will relapse after a complete response (including CR/CRi). Although relapse or refractoriness to HMAs is very common, very little is known about the therapeutic management of these relapsed or refractory AML (RR-AML) patients after HMAs.
METHODS
We conducted a retrospective study to describe and compare salvage treatment patterns and real-life clinical outcomes of those AML patients treated upfront with AZA or DEC included in the PETHEMA-AML Registry.
RESULTS
Between 2006 and 2019, we included 626 AML patients treated in first-line with HMAs, 487 (78%) received AZA and 139 (22%) received DEC.
Overall response rate (CR/CRi+PR) was 33.7%, 32% in the AZA vs 39.5% in the DEC group (p=0.120). Patients treated with DEC had a higher median relapse free survival than those treated with AZA (25.6 vs. 17.5 months, p=0.027). No differences were observed in the overall survival between AZA and DEC.
We observed 59.7% resistance after HMAs, 60% after AZA and 58.8% after DEC; and 6.5% had other type of response (&lt; PR), 7.9% with AZA and 1.6% with DEC. In addition, 76/121 patients who achieved CR/CRi (62.8%) relapsed, 66/90 in the AZA group (73.3%) vs 10/31 in the DEC group (32.3%) (p=0.000).
After relapse or resistance, 74.5% of patients received supportive care only (BSC), which included patients receiving transfusions and other supportive measures, including oral agents to control the white blood cell counts; 71.5% of patients in the AZA group and 84.3% of patients in DEC group (p= 0.004). No differences were observed in baseline characteristics at diagnosis of patients treated with BSC only, except for a higher proportion of patients with adverse cytogenetic risk in the AZA group (46.6% vs. 33.7%, p=0.039).
Only 135 patients received a salvage therapy, 116 in the AZA group and 19 in the DEC group.
Thirty-five out of 135 RR-AML treated patients (26%) continued receiving HMAs: 31 (26%) in the AZA group and 4 (22%) in the DEC group. In the AZA group, 19 (16%) patients continued with AZA and 12 (10%) switched to DEC, while in the DEC group 2 patients (11%) continued with DEC and 2 (11%) switched to AZA.
Fifty-one patients (37.8%) received FLUGA (fludarabine and Ara-C), FLAG-IDA-Lite (fludarabine, Ara-C and idarubicin), Low-dose Ara-C or other non-intensive regimens, 43 patients (37%) in the AZA group and 8 (42%) in the DEC group.
Other salvage therapies were administered in 34% of patients (33% in the AZA group and 37% in the DEC group). Salvage therapy was not available in 1% of patients.
Response assessment was available in 113/135 of RR-AML treated patients, 98 in the AZA group and 15 in the DEC group. In the AZA group, 13.2% of the patients achieved a CR (n=13), 5.1% achieved CRi (n=5), 6.1% achieved a PR (n=6), 65.3% resistance (n=64) and 8.1% died (n=8). However, no patients in the decitabine group responded to salvage therapy, 86.7% resistance (n=13) and 13.3% died (n=2). If we exclude those patients who died before response was evaluated, the ORR (CR/CRi+PR) after salvage therapy was statistically significant between AZA (n=24/90, 26.7%) and DEC group (n=0/13, 0%), p=0.035.
CONCLUSIONS
This study shows and compares, for the first time to our knowledge, the patterns of salvage therapy in patients with RR-AML treated upfront with HMAs.
Despite the similar response rate with both HMAs, the relapse free survival was lower after AZA. The absence of responses in patients with RR-AML initially treated with DEC could justify the similar OS between AZA and DEC observed. However, we should be very cautious due to the low number of RR-AML patients treated.

Disclosures
de la Fuente: BMS: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Abbie: Consultancy, Speakers Bureau; Novartis: Research Funding. Tormo: Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Pérez-Simón: Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Montesinos: Forma Therapeutics: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Stemline/Menarini: Consultancy; Teva: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Glycomimetics: Consultancy; Tolero Pharmaceutical: Consultancy; Agios: Consultancy; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas Pharma, Inc.: Consultancy, Honoraria, Other: Advisory board, Research Funding, Speakers Bureau.