Low Intensity Salvage Therapy after Failure of Standard (7 +3) Induction Regimen in Acute Myeloid Leukemia (AML). a Single Center Experience from United Arab Emirates

Abstract

Hypomethylating agent (HMA) and venetoclaxR as salvage therapy for Acute Myeloid Leukemia (AML) failing intensive induction therapy. A single center experience from United Arab Emirates. Introduction: Patients with AML who are younger and fit for therapy are treated with intensive chemotherapy. Complete remissions (CRs) range from 40-80% (Kantarjian, Blood vol. 116,22 (2010): 4422-9). Non-CR patients can be treated with salvage therapy as a bridge to Allogeneic hematopoietic cell transplant (AlloHCT). Salvage regimens have included high dose cytarabine based therapies (FLAG, MEC, HAM) which can be more toxic limiting the use of AlloHCT. Lower intensity and more targeted therapy could decrease toxicity with improved responses. We describe our experience with a low intensity regimen as salvage treatment after failure of intensive induction therapy and bridge to AlloHCT. Methods: This is a retrospective analysis of AML patients treated at Tawam Hospital, UAE from 01/2019 to 06/2022. Patient data was collected from the medical records including: demographics, hemogram at presentation, bone marrow biopsies, karyotyping, treatment and response. Results: Eighty patients were diagnosed with AML during this period. The median age was 45 years (range 16-95 years). Fifty-seven patients received therapy while twenty-three patients refused or were not eligible due to comorbidities and / or performance status. Intensive chemotherapy (infusional cytarabine and idarubicin 7+3 or FLAG) was used for thirty-three patients. The median age was 35 years (range 16 - 63 years). Cytogenetics (Metaphase Karyotyping and FISH): normal, n=7; good risk n=6 (inv 16 or t (8;21), growth failure n=5, poor risk n=10 (Complex = 3, Del 7 = 3, 11q abnormalities = 3, trans 6;9 =1) other n=5. Molecular testing for NPMI, FLT3, IDH1 and IDH2 was not available. Three patients died during induction and are excluded from analysis. Fifteen patients attained CR after 1 cycle of induction (50%). Twelve patients not in CR received outpatient, low intensity salvage therapy with HMA (5 azacitidine 75 mg/m2 daily x 7 days subcutaneously with Venetoclax 100 mg orally daily x 21 days along with antimicrobial prophylaxis with azoles in 28 days cycles). Bone marrow was repeated after the second cycle. The median number of cycles is 3 (range 1-9). Eight (67 %) achieved CR1. There were no treatment related deaths. This is comparable to our report of FLAG salvage therapy (Hassan IB. Int J Hematol. 2018 Oct;108(4):390-401). Four of the eight patients who achieved remission went for AlloHCT while one is awaiting AlloHCT. One patient is unable to go for HCT and is in remission after 9 cycles of therapy. Two patients after achieving CR relapsed and died of disease progression. With a median follow up of 123 days (range 33 -1107 days) five patients are alive and in remission, one has been lost to follow-up while the other six have died from progressive disease and complications. Conclusion. Low Intensity therapy with HMA and Venetoclax is a reasonable and effective alternative to intensive chemotherapy as first line salvage with minimal morbidity and zero treatment related mortality. Treatment was well tolerated and no patients required hospitalization for complications. This regimen is easily administered as an outpatient, serving as a bridge to AlloHCT