We investigated a next-generation phosphoinositide-3-kinase-δ inhibitor (PI3K-δi), umbralisib, plus a Bruton tyrosine kinase inhibitor (BTKi), ibrutinib, in relapsed or refractory chronic lymphocytic leukaemia and mantle cell lymphoma.
Together, these results indicate that dual inhibition of CK2 and CDK4/6 may be an efficient treatment of MCL and T-ALLs displaying upregulation of CK2/PI3K and CDK4 signaling pathways.
Two agents are already approved in the USA and Europe: ibrutinib, a BTK inhibitor, for the treatment of chronic lymphatic leukaemia (CLL), mantle cell lymphoma (MCL) and Waldenström's macroglobulinemia; and idelalisib, a PI3Kδ inhibitor, for the treatment of CLL and follicular lymphoma.
Consistently, PI3Kδ inhibitors enhanced AID expression and translocation frequency to IGH and AID off-target sites in human chronic lymphocytic leukaemia and mantle cell lymphoma cell lines, and patients treated with idelalisib, but not ibrutinib, showed increased somatic hypermutation in AID off-targets.
Additionally, specific FAK and PI3K inhibitors reduce SOX11-enhanced MCL cell migration and stromal interactions and revert cell adhesion-mediated drug resistance (CAM-DR) to the same levels as SOX11<sup>-</sup> MCL cells.
Recent studies investigating the biology of MCL have revealed crucial importance of B-cell receptor (BCR), nuclear factor-kappa B (NF-κB), phosphoinositide 3-kinase (PI3K), and BCL2 signaling for the molecular pathogenesis of MCL.
Strong synergism was observed with pimasertib combined with the PI3K inhibitor idelalisib and the BTK inhibitor ibrutinib in cell lines derived from diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma.
In the present study, we demonstrated that PF-04691502, a novel PI3K/mTOR inhibitor has potent activity in a panel of aggressive B-NHL cell lines including diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma (MCL).
Cell-cycle reprogramming for PI3K inhibition overrides a relapse-specific C481S BTK mutation revealed by longitudinal functional genomics in mantle cell lymphoma.
Clinical trials with Ibruitinib (Bruton's Tyrosine Kinase inhibitor) or Idelalisib (PI3K inhibitor) have demonstrated excellent clinical activity in MCL patients.
Because the relative importance of the class IA PI3K isoforms p110α, p110β, and p110δ in MCL is not clear, we studied expression of these isoforms and assessed their contribution to PI3K signaling in this disease.
PIK3IP1, a negative PI3K regulator, appears to mediate pG1 sensitization to PI3K inhibition; it is markedly reduced in MCL tumor cells compared with normal peripheral B cells, profoundly induced in pG1 and required for pG1 sensitization to GS-1101.
We demonstrate that inhibition of mTORC1 by rapamycin or blocking of mTORC1 and mTORC2 in conjunction with PI3K by NVP-BEZ235 reduces proliferation of MCL cell lines to a similar extent.
Despite the central role of FOXO3 as a tumour suppressor and phosphatidylinositol 3-kinase (PI3K)/AKT effector, little is known about its involvement in mantle cell lymphoma (MCL) biology.
Taken together, SAHA caused a rapid decrease of cyclin D1 in MCL by blocking the translation of cyclin D1 by inhibiting the phosphatidylinositol 3-kinase (PI3K)/Akt/mTOR/eIF4E-BP pathway, probably by PI3K inhibition.