Figure 7: Inhibition of the PI3K-AKT-mTOR pathway overcomes IR in ex vivo and in vivo using patient derived xenografts (PDX) model.

(a–c) AZD8055 treatment in combination with ibrutinib more substantially inhibited cell viability measured by CCK8 assay in IR MCL cells (a), more substantially inhibited β1 expression (b) in two IR primary samples and cell adhesion (c) in four IR primary MCL patient samples. *P<0.05 and **P≥0.05 (Student's t-test). (d,e) AZD8055 treatment led to a reduction in tumour growth that was enhanced in combination with ibrutinib (co-treatment). (d) the co-treatment of AZD8055 and ibrutinib markedly reduced pAKT, p4EBP and CD29 levels (e) in murine xenografts as indicated. (f) Combinatorial treatments of BEZ235 or AZD8055 with ibrutinib induced more dramatic anti-MCL activity in a patient-derived xenograft from IR MCL (PDX). The NSG mice bearing the PDXs were randomly divided into six groups (5 per group), with growing tumours subsequently treated with solvent (equal volume of vehicle, blue), ibrutinib 25 mg kg⁻¹ alone (orange), AZD8055 5 mg kg⁻¹ alone (purple), BEZ235 10 mg kg⁻¹ alone (green), ibrutinib 25 mg kg⁻¹ with AZD8055 5 mg kg⁻¹ (red), or ibrutinib 25 mg kg⁻¹ with BEZ235 10 mg kg⁻¹ (green) all by oral gavage daily. Tumour burden was assessed by tumour volume measurements at days 1, 12 and 19 after treatment. (g) A simplified IR model showing enforced interaction of the MCL-stromal cells and IR development under ibrutinib treatment. β1 contributed to the PI3K-AKT-mTOR1 activation through forming complex with ILK and mTORC2 and that PI3K-AKT, in turn, induced β1 expression, thereby generating a positive feedback loop, ensuring high level and sustained TME–lymphoma interaction and allowing cells to acquire a more permanent and complex drug resistance phenotype in MCL cells. Results in a,c are shown as mean+s.d. from at least three biological replicates. See also Supplementary Figs 7, 8 for full gel scan of the WB.