Cell‐free dna kinetics decipher potential mechanisms of action of ibrutinib combination therapy in mantle cell lymphoma (mcl)

Introduction: The European MCL Network trial TRIANGLE (NCT02858258) evaluated the addition of ibrutinib to standard treatment with autologous stem cell transplantation (ASCT) (arm A+I) in comparison to ASCT alone (arm A) and ibrutinib plus chemoimmunotherapy without ASCT (arm I) demonstrating significant and clinically relevant superiority of additional ibrutinib on outcome. Cell-free (cf)DNA captures tumor genetics and can be used to assess disease kinetics and minimal residual disease (MRD). We used capture based targeted sequencing for genotyping and MRD monitoring in cfDNA in the TRIANGLE trial to gain insight into the mechanisms of action of Ibrutinib and to identify patients (pts) with high risk of relapse. Methods: Peripheral blood (PB) and plasma samples from 57 pts with a PB infiltration of ≥10% at baseline (BL) and samples at mid induction (MI, n = 57) and end of induction (EoI, n = 53) were sequenced using the EuroClonality (EC)-NDC assay (Univ8® Genomics UK) to detect immunoglobulin and T-cell receptor (IG/TR) rearrangements, structural- (SV) and single nucleotide variants (SNVs) in 72 genes. Bioinformatics by ARResT/Interrogate with adaptations for cfDNA. Pts were considered MRD+ by detecting ≥1 read of a lymphoma-specific IG, SV or SNV. MRD in PB was analyzed by ASO-qPCR. Results: cfDNA levels were high at BL (mean 93 ng/mL) and MI (124 mg/mL) and decreased at EoI (12 ng/mL). BL cfDNA levels correlated with MIPI scores and identified pts with poor outcome. Genotyping by EC-NDC showed fully concordant IG clonotypes and SVs among 57 paired PB gDNA and cfDNA samples. 126 SNVs were identified (VAF 2.7%–75%, median 30%) in genes described as drivers in MCL, ATM (44%), TP53 (19%), KMT2D (16%), SAMHD1 (8%), CCND1 (8%) and 18 others. On average, 6 MRD markers were identified per patient (range 3-10). Copy number variation analysis revealed deletions in ATM (10%), CDKN2A (16%) and TP53 (5%) pts. TP53 mutations/deletions are a poor prognostic indicator in MCL, but therapy in arms A+I/I (n = 6) overcomes this poor outcome in comparison to arm A (n = 5). At MI, total cfDNA and ctDNA levels were significantly increased in arms A+I/I as compared to arm A (p = 0.049). 20/57 (35%) pts were MRD+ in PB and 35/55 (64%) in cfDNA. ctDNA was detected in 17/21 pts (81%) in Arm A and 18/34 pts (53%) in Arms A+I/I, suggesting effective disease clearance in the lymph nodes by ibrutinib. ctDNA detection at MI predicted outcome only in arm A. At EoI 8/53 (15%) pts were MRD+ in PB and 20/40 (50%) pts were MRD+ in cfDNA. ctDNA was detected in 12/18 pts (66%) in Arm A and 8/22 pts (36%) in Arms A+I/I. Similar to MI, ctDNA at EoI predicted outcome only in arm A. Keywords: combination therapies, liquid biopsy, minimal residual disease Conflicts of interests pertinent to the abstract S. Ferrero Consultant or advisory role: EUSA Pharma, Jannsen Honoraria: Servier Research funding: Gilead, Morphosys, Jannsen V. H. van der Velden Other remuneration: EuroFlow: Patents and Royalties R. García Sanz Honoraria: Janssen, BeiGene, Gilead, Astellas, Amgen, Takeda Research funding: Janssen, Gilead, Astellas, Takeda Educational grants: Janssen M. Dreyling Consultant or advisory role: Novartis, Lilly/Loxo, AstraZeneca, Roche, Janssen, Gilead/Kite, BMS/Celgene, Beigene Honoraria: Novartis, Lilly/Loxo, Amgen, AstraZeneca, Roche, Janssen, Gilead/Kite Research funding: Roche, Janssen, Bayer, AbbVie A. W. Langerak Research funding: Genentech, Roche Other remuneration: Spearkers Bureau: Janssen, Gilead D. Gonzalez de Castro Employment or leadership position: Founder and director of Univ8 Genomics Ltd.