AUTHORS
Pierre-Yves Dumas, MD, PhD, Augustin Boudry2, Mathilde Hunault3, Cecile Pautas4, Mathieu Leclerc, PhD5, Sarah Bertoli, MD, PhD6, Emmanuelle Tavernier, MD7, Pablo Lemercier8, Suzanne Tavitian, MD9, Emmanuel Raffoux, MD10, Marie Anne Hospital11, Tony Marchand, MD, PhD12, Mael Heiblig, MD13, Alice Marceau14, Sylvain Chantepie, MD15, Martin Carre, MD16, Pierre Peterlin, MD17, Maria Pilar Gallego Hernanz, MD, PhD18, Romain Guieze, PhD19, Celestine Simand20, Pascal Turlure21, Emilie Lemasle-Hue22, Ludovic Gabellier, MD23, Juliette Lambert24, Delphine Lebon, MD, PhD25, Madalina Uzunov, MD26, Jean-Valère Malfuson, MD27, Thomas Cluzeau, MD, PhD28, Samy Chraibi, MD29, Laurence Sanhes, MD30, Karine Celli-Lebras31, Ariane Mineur, N/A32, Lamya Haddaoui33, Christophe Roumier, MD34, Claude Gardin35, Norbert Ifrah, PR36, Norbert Vey, MD, PhD37, Regis Peffault De Latour, MD, PhD38, Isabelle Luquet39, Dominique Penther40, Raphael Itzykson, MD, PhD41, Eric Delabesse42, Jean-François Hamel, PhD43, Arnaud Pigneux, MD, PhD44, Herve Dombret Sr, MD45, Stéphane de Botton, MD, PhD46, Claude Preudhomme, PhD47, Christian Recher48, Nicolas Duployez, MD49
AFFILIATIONS
1 CHU Bordeaux, Service d'Hématologie Clinique et de Thérapie Cellulaire, F-33000 Bordeaux, France;BRIC (BoRdeaux Institute of onCology), UMR1312, INSERM, Univ. Bordeaux, F-33000 Bordeaux, France, Bordeaux, France
2 CHU de Lille, lille, France
3 CHU d'a, Angers, France
4 Department of Hematology and Cell Therapy, Hôpital Henri Mondor, Assistance Publique - Hôpitaux de Paris, Paris, France
5 Department of Hematology and Cell Therapy, Hôpital Henri Mondor, Assistance Publique - Hôpitaux de Paris, Paris, France
6 CHU de Toulouse, Institut Universitaire du Cancer de Toulouse Oncopole, Toulouse University Hospital, Toulouse, France
7 CHU St Etienne, St Etienne, France
8 CHU Bordeaux, Service d'Hématologie Clinique et de Thérapie Cellulaire, F-33000 Bordeaux, France;BRIC (BoRdeaux Institute of onCology), UMR1312, INSERM, Univ. Bordeaux, F-33000 Bordeaux, France, Bordeaux, France
9 CHU de Toulouse, Institut Universitaire du Cancer de Toulouse Oncopole, Toulouse University Hospital, Toulouse, France
10 Hopital St Louis, Institut de la Leucemie, Universite Paris Cité, Paris, France
11 Institut Paoli-Calmettes, Marseille, France
12 CHU de Rennes, Rennes, France
13 Centre Hospitalier Lyon Sud, Lyon, France
14 CHU de Lille, lille, France
15 CHU de caen, Caen, France
16 CHU de Grenoble, Grenoble, France
17 CHU de Nantes, Nantes, France
18 CHU de Poitiers, Poitiers, France
19 CHU de Clermont-Ferrand, Clermont-Ferrand, France
20 CHU de Strasbourg, Strasbourg, France
21 CHU de Limoges, Limoges, France
22 Centre Henri Becquerel, Rouen, France
23 CHU de Montpellier, Montpellier, France
24 CH de Versailles, Versailles, France
25 CHU AMIENS, Amiens, France
26 Department of Hematology, Hôpital Pitié-Salpêtrière, Assistance publique Hôpitaux de Paris, Paris, France
27 Service d’hématologie, HIA Percy, Clamart, France, Clamart, France
28 CHU de nice, nice, France
29 Institut Gustave Roussy, Paris, France
30 CHG de Perpignan, Perpignan, France
31 ALFA coordination, Hôpital Saint-Louis, Université Paris Cité, Paris, Paris, France
32 CHU Bordeaux, Service d'Hématologie Clinique et de Thérapie Cellulaire, F-33000 Bordeaux, France;BRIC (BoRdeaux Institute of onCology), UMR1312, INSERM, Univ. Bordeaux, F-33000 Bordeaux, France, Bordeaux, France
33 FILO Coordination, Paris, France
34 CHU de Lille, lille, France
35 Hôpital Avicenne, Bobigny, France
36 CHU d'a, Angers, France
37 Institut Paoli-Calmettes, Marseille, France
38 Hopital St Louis, Institut de la Leucemie, Universite Paris Cité, Paris, France
39 CHU de Toulouse, Institut Universitaire du Cancer de Toulouse Oncopole, Toulouse University Hospital, Toulouse, France
40 Centre Henri Becquerel, Rouen, France
41 Hopital St Louis, Institut de la Leucemie, Universite Paris Cité, Paris, France
42 CHU de Toulouse, Institut Universitaire du Cancer de Toulouse Oncopole, Toulouse University Hospital, Toulouse, France
43 CHU d'a, Angers, France
44 CHU Bordeaux, Service d'Hématologie Clinique et de Thérapie Cellulaire, F-33000 Bordeaux, France;BRIC (BoRdeaux Institute of onCology), UMR1312, INSERM, Univ. Bordeaux, F-33000 Bordeaux, France, Bordeaux, France
45 ALFA coordination, Hôpital Saint-Louis, Université Paris Cité, Paris, Paris, France
46 Institut Gustave Roussy, Paris, France
47 CHU de Lille, lille, France
48 CHU de Toulouse, Institut Universitaire du Cancer de Toulouse Oncopole, Toulouse University Hospital, Toulouse, France
49 CHU de Lille, lille, France
ABSTRACT
Background: The ELN-2025 recommendations introduced ultra-high sensitive NGS-based FLT3-ITD MRD, acknowledging that dynamics matters beyond diagnostic status. FLT3-ITD AML is defined by fragment analysis (FA) allelic ratio (AR) ≥0.05 (macroclones), while modern NGS pipelines reliably detects AR<0.05 (microclones) with recently demonstrated adverse impact. FLT3-ITD MRD has so far been studied only in macroclone carriers. Given the high propensity of microclones to expand at relapse, we hypothesized that early MRD assessment could refine risk stratification across the full allelic spectrum. We therefore evaluated FLT3-ITD MRD after intensive chemotherapy in a large cohort of both macro and microclone FLT3-ITD AML patients (pts).
Methods: Between January 2015 and July 2021, the BIG-1 trial (NCT02416388) enrolled pts aged 18-60 with newly diagnosed AML, excluding CBF and APL. Induction used a 7+3 regimen with high-dose anthracycline and cytarabine, followed by I/HDAC. FA identified FLT3-ITD macroclones (AR≥0.05), others pts underwent retrospective capture-based NGS detecting ITDs and those with AR 0.0004-0.049 were classified as microclone carriers. Midostaurin (MIDO) was introduced in July 2018. For FLT3-ITD MRD, 700 ng genomic DNA were amplified (28 PCR cycles, exons 14-15), sequenced, and quantified using FiLT3r (mutant/total reads), with a validated LOQ of 10-4. OS, RFS and CIR followed ELN2022, and MRD was assessed on the major clone per ELN-2025.
Results: Overall, 457 pts had a FLT3-ITD, including 273 with macroclone(s) (59.7%) and 184 with microclone(s) only (40.3%). Median age was 50.3y, and 253 pts were female. ELN2022 genetic risk was favorable, intermediate, and adverse in 77 (16.8%), 282 (61.7%), and 98 (21.4%) pts. A total of 283 (61.9%) also carried a NPM1 mutation.
Among 387 pts (84.7%) achieving CR/CRi (CRc) after induction, median FLT3-ITD MRD1 after the first cycle was 0.00077% in bone marrow (BM) and 0.00012% in blood. At MRD1 and MRD2 (post cycle 2), 75.8% and 84.3% of CRc pts had BM FLT3-ITD MRD<10?4, and 40.1% and 59.8% had BM FLT3-ITD MRD<limit of detection (LOD). In multivariate analysis, factors associated with BM FLT3-ITD MRD2<10?4 were WBC<30G/L (OR, 2.59 [1.09-6.40]) and NPM1 mutation (OR, 5.04 [2.06-12.80]) while AR, MIDO, sex, age, secondary AML, ECOG, ELN-2022 cytogenetic, CEBPA, and STM were not.
Median follow-up was 63.9 months. At 2 and 5y, CIR from MRD evaluation was 79.2% vs 38.3% and 81.8% vs 44.6% in pts with BM FLT3-ITD MRD2≥10?4 vs <10?4. After adjustment for confounders, including allo-HSCT in CR1 as a time-dependent variable, MIDO (sHR, 0.48 [0.32-0.72]), MRD2<10?4 (sHR, 0.12 [0.07-0.20]) and HSCT in CR1 (sHR, 0.19 [0.11-0.32]) were independently associated with reduced relapse risk while gender, secondary AML, WBC, NPM1 mutation and ELN-2022 cytogenetics were not. Micro vs macroclone status likewise showed no independent prognostic impact.
Median RFS was 5.6 (IC95% 4.2-8.0) vs 35.7 (IC95% 20.0-77.4) months, and at 2 and 5y, RFS was 18.2% vs 54.2% and 16.2% vs 44.8%, if BM FLT3-ITD MRD2 was ≥10?4 vs <10?4. Finally, MIDO (aHR: 0.46 [0.31-0.69]) and BM FLT3-ITD MRD2<10?4 (aHR: 0.16 [0.10-0.25]) were independently associated with a decreased risk of relapse or death as well as age<40y and HSCT in CR1. Micro vs macroclone status was not.
Median OS was 16.1 months (IC95% 12.8-37.3) vs NR (IC95% NR-NR), and at 2 and 5y, OS was 41.0% vs 79.0% and 30.6% vs 66.2%, if BM FLT3-ITD MRD2 was ≥10?4 vs <10?4. Finally, MIDO (aHR: 0.55 [0.34-0.91]) and BM FLT3-ITD MRD2<10?4 (aHR: 0.26 [0.16-0.41]) were independently associated with a decreased risk of death as well as age<40y. Micro vs macroclone status was not.
Sensitivity analysis restricted to microclones carriers showed 2- and 5-year CIR at 81.8% vs 38.7% and 81.8% vs 41.0%, in patients with BM FLT3-ITD MRD2≥10?4 and <10?4, respectively. After adjustment, BM FLT3-ITD MRD2<10?4 (sHR, 0.08 [0.03-0.21]) was associated with a decreased risk of relapse as well as HSCT in CR1.
Conclusion:
By extending FLT3-ITD MRD assessment to microclones, we show that clonal dynamics but not initial allelic burden drives prognosis. Pts achieving MRD2<10?4 form a more favorable group, whereas others are at very high risk of relapse. These results position FLT3-ITD MRD as a decisive biomarker to optimize post-remission management in across the full FLT3-ITD spectrum including both macro and microclone carriers.
DISCLOSURES
Pierre-Yves Dumas, MD, PhD: Novartis - Research Funding; Servier - Research Funding; Bristol Myers Squibb - Research Funding; Daiichi Sankyo - Research Funding; Astellas - Research Funding; Roche - Research Funding; Gilead - Research Funding; Janssen - Consultancy (Includes expert testimony); Bristol Myers Squibb - Consultancy (Includes expert testimony); AbbVie - Consultancy (Includes expert testimony); Jazz Pharmaceuticals - Consultancy (Includes expert testimony); Servier - Consultancy (Includes expert testimony); Daiichi Sankyo - Consultancy (Includes expert testimony); Astellas - Consultancy (Includes expert testimony); Novartis - Consultancy (Includes expert testimony)