Page 225 - 2021_10-Haematologica-web

Letters to the Editor
CD44 by HA. In contrast, the anti-IL-6 antibody failed to sensitize ABC-DLBCL cells to IRAKi-based treatment (Online Supplementary Figure S1B). Thus, these results sug- gest a significant activity of the drug combination towards CD44 downstream signaling, while IL-6 expression may not be directly involved in the effect of these agents.
Finally, in order to assess the efficacy of the drug combi- nation in vivo, NSG mice were subcutaneously injected with OCI-LY3 cells, and tumor-bearing animals received daily doses of either IRAKi (5 mg/kg, intraperitoneal [i.p.], BID), CPI203 (2.5 mg/kg, i.p., BID), the combination of both agents, or the equivalent volume of vehicle, for 11 days. Figure 3C shows that CPI203 and IRAKi single agents induced a 31.5% and 46.3% tumor growth inhibition (TGI), respectively, while the combination of both drugs significantly improved this effect with a 65.6% TGI, when compared to vehicle-receiving animals (*P=0.011; **P=0.007). No significant toxicity was observed in any of the treatment arms. Histological analysis of the corresponding tumors revealed an improved reduction of mitotic index together with an accumulation of apoptotic cells by the combination therapy, as assessed by phospho- histone H3 and activated-caspase-3 staining (Figure 3D). In agreement with the in vitro results, an enhanced reduction in the levels of CD44 and MCL-1, and an improved downregulation of nuclear p50 used as a read of NF-κB activity, was observed in the combination group when compared with the other arms (Figure 3D).
Collectively, our results suggest that IRAK1/4 inhibition is modestly effective in in vitro and in vivo models of ABC- DLBCL with MYD88 L265P, achieving only a partial inhi- bition of NF-κB signaling. We confirm that BET inhibition is an efficient strategy to counteract NF-κB over-activation in these models, offering synergistic anti-tumoral and pro- apoptotic activities with IRAK inhibition, mediated by the downregulation of the NF-κB-regulated factors, CD44 and MCL-1, and the consequent blockade of cell motility and triggering of tumor cell death.
Ivan Dlouhy,1,2* Marc Armengol,3* Clara Recasens-Zorzo,2 Marcelo L. Ribeiro,3,4 Patricia Pérez-Galán,2 Francesc Bosch,5 Armando López-Guillermo1,2# and Gaël Roué3#
1Department of Hematology, Hospital Clínic, BarceIona, Spain; 2Division of Hematology and Oncology, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), CIBERONC, Barcelona, Spain; 3Lymphoma Translational Group, Josep Carreras Leukemia Research Institute (IJC), Badalona, Spain; 4Post Graduate Program in Health Science, Universidade São Francisco (USF), Bragança Paulista, Brazil and 5Laboratory of Experimental Hematology, Department of Hematology, Vall d'Hebron Institute of Oncology (VHIO), Vall d’Hebron University Hospital, Universitat Autònoma de Barcelona, Barcelona, Spain
*ID and MA contributed equally as co-first authors. #ALG and GR contributed equally as co-senior authors. Correspondence:
GAËL ROUÉ - groue@carrerasresearch.org doi:10.3324/haematol.2020.278258
Received: December 25, 2020.
Accepted: May 5, 2021.
Pre-published: May 13, 2021.
Disclosures: GR received research support from Celgene Corp and TG Therapeutics. CPI203 was kindly provided by Constellation Pharmaceuticals.
Contributions: ID and MA performed experiments, analyzed data and co-wrote the manuscript; CRZ provided support in animal studies; MLR interpreted the results and reviewed the manuscript; PP-G helped in analyzing the gene expression data; FB evaluated the data and reviewed the manuscript critically; AL-G and GR conceived and designed the study, analyzed data and wrote the manuscript.
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