IGH::FENDRR and specific KRAS mutations define a novel B-ALL molecular subtype with poor chemotherapy response

S Sonja Bendig (1Department of Internal Medicine II (Hematology/Oncology), University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany) A Alina M. Hartmann (Medical Department II, Hematology/Oncology, University Hospital Schleswig-Holstein, Kiel, Germany) W Wiebke Wessels T Thomas Beder R Rathana Kim (2Institut de Recherche Saint-Louis, Université Paris Cité, Paris, France) M Marie Passet (2Institut de Recherche Saint-Louis, Université Paris Cité, Paris, France) Q Qingsong Gao (2Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN) N Nadine Wolgast (Medical Department II, Hematology/Oncology, University Hospital Schleswig-Holstein, Kiel, Germany) J Johanna M. Horns (1Department of Internal Medicine II (Hematology/Oncology), University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany) L Leonardo Alves Santos (Medical Department II, Hematology/Oncology, University Hospital Schleswig-Holstein, Kiel, Germany) K Katharina Iben (1Department of Internal Medicine II (Hematology/Oncology), University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany) F Fabio D. Steffen (Department of Oncology and Children's Research Center, University Children's Hospital, Zurich, Switzerland) L Loredana Cantoni (Department of Oncology and Children's Research Center, University Children's Hospital, Zurich, Switzerland) B Britta Kehden (Medical Department II, Hematology/Oncology, University Hospital Schleswig-Holstein, Kiel, Germany) G Guranda Chitadze (1Department of Internal Medicine II (Hematology/Oncology), University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany) A Axel Künstner H Hauke Busch B Beat Bornhauser J Jean-Pierre Bourquin T Thibaut TL Leguay (Hematology Department, CHU de Bordeaux, Hôpital du Haut-Levêque, Pessac, France) N Nicolas Boissel N Nicola Gökbuget (26Department of Medicine II, Hematology/Oncology, Goethe University Frankfurt, University Hospital, Frankfurt, Germany) I Ilaria Iacobucci (2Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN) C Charles G. Mullighan E Emmanuelle Clappier (2Institut de Recherche Saint-Louis, Université Paris Cité, Paris, France) C Claudia D Baldus (Medical Department II, Hematology/Oncology, University Hospital Schleswig-Holstein, Kiel, Germany) M Monika Brüggemann (1Department of Internal Medicine II (Hematology/Oncology), University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany) L Lorenz Bastian

Abstract

Large scale sequencing efforts have defined up to 27 diagnostic entities in B-ALL, leaving few samples without subtype assignment. Extended genomic and transcriptomic profiling in routine diagnostics broadens the sample collection and holds the potential to identify novel B-ALL subtypes. By analyzing an aggregated set of 4,857 B-ALL patients from three cohorts, we identified a novel group of twenty cases (age 18-66 years, median: 34 years) characterized by a previously undescribed IGH::FENDRR rearrangement exclusive to this subtype (n=17/20), KRAS p.A146T/V/P mutations (n=17/20 vs. n=86/4,857; p<0.001) and distinct DNA-methylation/gene expression profiles, including overexpression of the lncRNA FENDRR and the transcription factor FOXF1 ('FOXF1/FENDRR') as well as JAK/STAT and RAS signaling signatures. A gene expression machine learning classifier identified FOXF1/FENDRR cases in two independent cohorts with high accuracy. Patients treated according to GMALL/GRAALL protocols showed very poor chemotherapy response with n=8/13 having induction failure or MRD ≥10-3 and n=8/12 remaining MRD positive after 1st consolidation / salvage. MRD-stratified intensification including blinatumomab (n=10) and/or allogenic stem cell transplantation (n=12) resulted in ongoing molecular remission in 13/16 cases. FOXF1/FENDRR patients represent a novel B-ALL subtype which might benefit from early immunotherapeutic treatment or targeted interventions.

Article Details

Journal Blood
Volume / Issue Vol. 1, Issue 1
Published March 27, 2026
ISSN 0006-4971
Publisher Elsevier BV

Journal Info

Blood

Elsevier BV

ISSN: 0006-4971 Health Sciences

Authors (28)

S

Sonja Bendig

1Department of Internal Medicine II (Hematology/Oncology), University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany

A

Alina M. Hartmann

Medical Department II, Hematology/Oncology, University Hospital Schleswig-Holstein, Kiel, Germany

W

Wiebke Wessels

T

Thomas Beder

R

Rathana Kim

2Institut de Recherche Saint-Louis, Université Paris Cité, Paris, France

M

Marie Passet

2Institut de Recherche Saint-Louis, Université Paris Cité, Paris, France

Q

Qingsong Gao

2Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN

N

Nadine Wolgast

Medical Department II, Hematology/Oncology, University Hospital Schleswig-Holstein, Kiel, Germany

J

Johanna M. Horns

1Department of Internal Medicine II (Hematology/Oncology), University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany

L

Leonardo Alves Santos

Medical Department II, Hematology/Oncology, University Hospital Schleswig-Holstein, Kiel, Germany

K

Katharina Iben

1Department of Internal Medicine II (Hematology/Oncology), University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany

F

Fabio D. Steffen

Department of Oncology and Children's Research Center, University Children's Hospital, Zurich, Switzerland

L

Loredana Cantoni

Department of Oncology and Children's Research Center, University Children's Hospital, Zurich, Switzerland

B

Britta Kehden

Medical Department II, Hematology/Oncology, University Hospital Schleswig-Holstein, Kiel, Germany

G

Guranda Chitadze

1Department of Internal Medicine II (Hematology/Oncology), University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany

A

Axel Künstner

H

Hauke Busch

B

Beat Bornhauser

J

Jean-Pierre Bourquin

T

Thibaut TL Leguay

Hematology Department, CHU de Bordeaux, Hôpital du Haut-Levêque, Pessac, France

N

Nicolas Boissel

N

Nicola Gökbuget

26Department of Medicine II, Hematology/Oncology, Goethe University Frankfurt, University Hospital, Frankfurt, Germany

I

Ilaria Iacobucci

2Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN

C

Charles G. Mullighan

E

Emmanuelle Clappier

2Institut de Recherche Saint-Louis, Université Paris Cité, Paris, France

C

Claudia D Baldus

Medical Department II, Hematology/Oncology, University Hospital Schleswig-Holstein, Kiel, Germany

M

Monika Brüggemann

1Department of Internal Medicine II (Hematology/Oncology), University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany

L

Lorenz Bastian