Identification of potential ibrutinib combinations in hematological malignancies using a combination high-throughput screen

Abstract

Matrix high-throughput screening (HTS) methods are increasingly employed to rapidly define potential therapeutic drug combinations. We used combination HTS to identify compounds showing synergistic anti-proliferative activity with ibrutinib, an irreversible, small-molecule inhibitor of Bruton's tyrosine kinase. The goal was to identify ibrutinib combinations with maximum synergistic effects in heme malignancy lines, particularly in non-Hodgkin lymphoma including diffuse large B-cell lymphoma (DLBCL). Growth inhibition (GI) was used to measure cell viability; synergy scores characterized strength of synergistic interaction. Single-agent ibrutinib demonstrated varying degrees of activity across 30 cell lines evaluated. In DLBCL lines, TMD8 was the most sensitive to ibrutinib (GI = 0.001); combinations with BCL-2 inhibitor ABT-199, and PI3K inhibitors IPI-145 and GDC-0941 showed the strongest synergistic activity. Anti-proliferative synergies were also observed with BET bromodomain inhibitor (+)-JQ1, XPO1 inhibitor selinexor, and IRAK4 inhibitor, and confirmed using apoptosis assay. These findings are intended to inform and advance treatment of B-cell malignancies.

Single and combined BTK and PI3Kδ inhibition with acalabrutinib and ACP‐319 in pre‐clinical models of aggressive lymphomas

“…In particular, the cell lines derived from MCL and ABC DLBCL presented reduction of p‐AKT and increased cytotoxicity. The benefit of the combination observed in our lymphoma models is in agreement with that observed in CLL models using the same compounds (Niemann et al , ), and also supported by data obtained using different BTK and PI3K inhibitors (Mathews Griner et al , ; Paul et al , ; Yahiaoui et al , ; Faia et al , ; Schaffer et al , ; Tarantelli et al , ; Tarantelli et al , ). Both sets of data support an on‐going clinical study (NCT02328014), which has shown positive signals of activity, especially in ABC DLBCL (Barr et al , ).…”

Direct and indirect approaches to identify drug modes of action

“…Drug combinations can also be used to reduce toxic side effects by allowing lower concentrations of toxic drugs to be used where they work synergistically. High throughput matrix combination screening is now being used to identify suitable drug combinations for cancer and malaria , whereby cell viability assays are carried out with drug pairs in perpendicular serial dilution checkerboards using 384‐well or 1536‐well tissue culture plates. Such checkerboards can show whether drug pairs synergize (e.g., by targeting different targets in parallel pathways), antagonize (by hitting different targets in the same pathway), or work additively (by targeting the same or unrelated targets).…”

“…As phenotypic screening does not focus upon any particular target directly, it removes target‐bias and potentially expands the target repertoire by allowing the identification of new lead compounds with unknown targets and those previously thought undruggable. Furthermore, it allows the testing of drug combinations (i.e., drug pairs, which have different targets) in their biological context and is proving effective in the fight against viruses [for example, HIV, ] and cancers . However, a major drawback of phenotypic screening is that much of the time the target(s) and mode of action (MOA) of the newly developed drug are unknown, making the drug difficult to further optimize for potency and selectivity, and as a consequence target identification through drug MOA studies represents a major bottleneck in the drug discovery pipeline.…”

MYC in Germinal Center‐derived lymphomas: Mechanisms and therapeutic opportunities

“…Like other drug combinations, the aforementioned synergy of Venetoclax with inhibitors of either the mitochondrial ribosome or PLK1 provide important proof‐of‐principle for the potential of combinatorial targeting against DHL, as well as a blueprint for following up on the plethora of MYC‐synthetic‐lethal interactions reported in the literature. Indeed, taking either Tigecycline or Volasertib as paradigms, we can surmise that other compounds showing synthetic‐lethality with MYC also have the potential to synergize with Venetoclax against DHL, and vice‐versa.…”