Enhancing direct cytotoxicity and response to immune checkpoint blockade following ionizing radiation with Wee1 kinase inhibition

Abstract

Tumor cells activate the G2/M cell cycle checkpoint in response to ionizing radiation (IR) and effector immune cell-derived granzyme B to facilitate repair and survival. Wee1 kinase inhibition reverses the ability of tumor cells to pause at G2/M. Here, we hypothesized that AZD1775, a small molecule inhibitor of Wee1 kinase, could sensitize tumor cells to IR and T-lymphocyte killing and improve responses to combination IR and programmed death (PD)-axis immune checkpoint blockade (ICB). Multiple models of head and neck carcinoma, lung carcinoma and melanoma were used in vitro and in vivo to explore this hypothesis. AZD1775 reversed G2/M cell cycle checkpoint activation following IR, inducing cell death. Combination IR and AZD1775 induced accumulation of DNA damage in M-phase cells and was rescued with nucleoside supplementation, indicating mitotic catastrophe. Combination treatment enhanced control of syngeneic MOC1 tumors in vivo, and on-target effects of systemic AZD1775 could be localized with targeted IR. Combination treatment enhanced granzyme B-dependent T-lymphocyte killing through reversal of additive G2/M cell cycle block induced by IR and granzyme B. Combination IR and AZ1775-enhanced CD8 + celldependent MOC1 tumor growth control and rate of complete rejection of established tumors in the setting of PD-axis ICB. Functional assays demonstrated increased tumor antigen-specific immune responses in sorted T-lymphocytes. The combination of IR and AZD1775 not only lead to enhanced tumor-specific cytotoxicity, it also enhanced susceptibility to T-lymphocyte killing and responses to PD-axis ICB. These data provide the pre-clinical rationale for the combination of these therapies in the clinical trial setting.

Scientifically based combination therapies with immuno‐oncology checkpoint inhibitors

“…In preclinical studies, WEE1 kinase inhibitor, AZD1775, prevented tumour cells halting at G2/M phase of the cell cycle after ionising radiation treatment thus inducing cell death. Combination of AZD1775 and ionising radiation also increased cytotoxic T lymphocyte‐mediated killing of tumour cells 171 . Ionising radiation increased tumour PD‐L1 expression and the combination of ionising radiation or AZD1775 with anti‐PD‐1 antibody induced tumour rejection in 27–33% of the treated mice, whereas the triple combination of ionising radiation, AZD1775 and anti‐PD‐1 antibody significantly delayed tumour growth and induced tumour rejection in 73% of mice, thus prolonging survival.…”

“…Ionising radiation increased tumour PD‐L1 expression and the combination of ionising radiation or AZD1775 with anti‐PD‐1 antibody induced tumour rejection in 27–33% of the treated mice, whereas the triple combination of ionising radiation, AZD1775 and anti‐PD‐1 antibody significantly delayed tumour growth and induced tumour rejection in 73% of mice, thus prolonging survival. This therapeutic effect is dependent on CD8 + T cells 171 . Cured mice were subsequently rechallenged with tumour cells and rejection of tumour cells was observed, suggesting that the triple combination also conferred immunological memory 171 .…”

“…This therapeutic effect is dependent on CD8 + T cells 171 . Cured mice were subsequently rechallenged with tumour cells and rejection of tumour cells was observed, suggesting that the triple combination also conferred immunological memory 171 . Another study using model antigen‐positive tumours also reported that antigen‐specific CD8 + TILs expressed higher levels of PD‐1 and treatment with AZD1775 or anti‐PD‐1 monotherapy induced tumour rejection in some mice but dual treatment with AZD1775 and anti‐PD‐1 antibody resulted in complete tumour rejection in all treated mice.…”

Advances in synthetic lethality for cancer therapy: cellular mechanism and clinical translation

“…AZD6738 increased cell proliferation, infiltration, and interferon-gamma (IFN-γ) production of tumor-infiltrating lymphocyte CD8 + T cells, resulting in decreased T cells and tumor-infiltrating lymphocyte Tregs in mice xenografts. Moreover, Patel et al [ 151 ] indicated that adavosertib and ionizing radiation combination therapy enhanced the sensitivity to T-lymphocyte, tumor-specific cytotoxicity, and programmed death-axis immune checkpoint blockade response in various cancers such as melanoma, lung carcinoma, and head and neck carcinoma in vitro and in vivo. The addition of adavosertib after ionizing radiation reversed the G2/M cell cycle checkpoint activation and led to cell death.…”

Pharmacological Inhibition of WEE1 Potentiates the Antitumoral Effect of the dl922-947 Oncolytic Virus in Malignant Mesothelioma Cell Lines

“…However, other mechanisms, such as DDR aberrations, nucleotide starvation, replicative stress, and, as more recently found, loss of the ATRX chromatin remodeler gene [ 36 ] and low phosphatase and tensin homolog (PTEN) expression [ 37 ], contribute to sensitize cancer cells to WEE1 inhibition, which, thus, proved monotherapy activity even in TP53 -wild-type cancer cells [ 29 , 30 , 38 ]. Moreover, WEE1 inhibition showed efficacy also in combination with inhibitors of other DDR factors, such as PARP [ 39 , 40 , 41 , 42 ], CHK1 [ 29 , 43 , 44 , 45 , 46 , 47 ], and ataxia telangiectasia and Rad3 related (ATR) kinase [ 48 , 49 , 50 ], and also when combined with different anticancer targeted agents [ 29 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 ] and immunotherapeutic approaches [ 29 , 62 , 63 , 64 ].…”