DNA Damage Response Inhibitor Combinations Exert Synergistic Antitumor Activity in Aggressive B-Cell Lymphomas

Abstract

The DNA damage response (DDR) kinases ATR, Chk1, and Wee1 play vital roles in the response to replication stress and in maintaining cancer genomic stability. Inhibitors of these kinases are currently under clinical investigation. Mantle cell lymphoma (MCL) and diffuse large B-cell lymphoma (DLBCL) are aggressive lymphomas whose clinical outcome is still largely unsatisfactory. These cell lymphoma subtypes are highly dependent on both Chk1 and Wee1 for survival. We investigated the activity of the ATR inhibitor AZD6738 as single agent and in combination with either Chk1 (AZD6738) or Wee1 (AZD1775) inhibitors in several preclinical models of MCL and DLBCL. This study included preclinical in vitro activity screening on a large panel of cell lines, both as single agent and in combination, and validation experiments on in vivo models. Cellular and molecular mechanisms of the observed synergistic effect as well as pharmacodynamic analysis of in vivo samples were studied. AZD6738 exerted a strong synergistic cytotoxic effect in combination with both AZD7762 and AZD1775 in the 2 lymphoma subtypes regardless of their TP53, MYC, and ATM mutational status. These DDR inhibitor combinations, similarly to the Chk1/Wee1 inhibitor combination, caused a marked S-phase delay, with an increase in cyclin-dependent kinases (CDK) activity, increased DNA damage, and decreases in Wee1, MYC, and RRM2 protein levels. The synergistic in vitro activity translated to striking in vivo antitumor activity. DDR-DDR inhibitor combinations could potentially offer promising novel therapeutic strategies for patients with B-cell lymphoma.

Aggressive morphologic variants of mantle cell lymphoma characterized with high genomic instability showing frequent chromothripsis, CDKN2A/B loss, and TP53 mutations: A multi‐institutional study

“…ATR inhibition has shown in‐vitro activity in ATM‐deficient MCL 42 . Moreover, ATR inhibitors have shown strong cytotoxic and in‐vivo antitumor activity in MCL and diffuse large B‐cell lymphoma regardless of their TP53 , MYC , and ATM mutation status 43 …”

Identification of PLK1 as a New Therapeutic Target in Mucinous Ovarian Carcinoma

“…To assess the effect of the combination of PLK1 inhibitors (onvansertib and volasertib) with cisplatin and/or paclitaxel and/or eribulin and/or PI3K inhibitor (PIK75), cells were seeded, and 48 h after, treated simultaneously with a growing concentration of the drugs, and cell viability was measured 72 h after by MTS assay. Results were examined by isobologram analysis with Calcusyn Software (Biosoft, Cambridge, UK), and combination index (CI) values at the IC 50 were calculated to assess the efficacy of the combination, as already reported [21]. All the experiments were performed in triplicate and repeated at least twice.…”

“…For flow cytometric analysis of DNA content, cells were fixed in ice-cold 70% ethanol; washed in PBS; resuspended in 1 mL of 25 µg/mL of propidium iodide and 12.5 µL of RNase (1 mg/mL); and stained for 2h at room temperature in the dark. Cell cycle analysis was done on at least 10,000 cells for each sample using the FACS Calibur (Becton Dickinson, Franklin Lakes, NJ, USA) [21].…”

Targeting the DNA damage response for patients with lymphoma: Preclinical and clinical evidences

“…CHK1 inhibitors synergize with proteasome or BTK inhibitors [111,112]. Combination of the proteasome inhibitor ixazomib with the CHK1 inhibitor AZD7762 achieves strong downregulation of MYC and induction of cell death in T-cell lymphomas [111].…”

“…Combination of the proteasome inhibitor ixazomib with the CHK1 inhibitor AZD7762 achieves strong downregulation of MYC and induction of cell death in T-cell lymphomas [111]. Preclinical evidence of synergism between CHK1 inhibitors and the BTK inhibitor ibrutinib is available for MCL cell lines [112]. Some activity has also been observed for the combination with psoralen plus ultraviolet A (PUVA) photochemotherapy in cutaneous T-cell lymphoma (CTCL) cell lines [113].…”