Antitumor effect of a WEE1 inhibitor and potentiation of olaparib sensitivity by DNA damage response modulation in triple-negative breast cancer

Abstract

Due to its regulation of CDK1/2 phosphorylation, WEE1 plays essentially roles in the regulations of G2/M checkpoint and DNA damage response (DDR). WEE1 inhibition can increase genomic instability by inducing replication stress and G2/M checkpoint inactivation, which result in increased cellular sensitivity to DNA damaging agents. We considered an increase in genomic instability induced by WEE1 inhibition might be used to augment the effects of drugs targeting DNA repair protein. Typically, PARP inhibitors are effective in germline BRCA 1/2 mutated breast and ovarian cancer, but their applicabilities in triple-negative breast cancer (TNBC) are limited. This study was conducted to investigate the antitumor effects of the WEE1 inhibitor, AZD1775, and the mechanism responsible for its potentiation of sensitivity to olaparib (a PARP inhibitor) via the modulation of DDR in TNBC cells. Our results suggest that AZD1775 could be used to broaden the application range of olaparib in TNBC and provide a rationale for a clinical trial of combined olaparib and AZD1775 therapy. Triple-negative breast cancer (TNBC) is a breast cancer subtype that lacks estrogen receptor (ER) and progesterone receptor (PR) expression and does not exhibit human epidermal growth factor receptor 2 (HER2) amplification. TNBC accounts for 15-20% of all breast cancer cases and has more aggressive characteristics and higher rates of distant recurrence and shorter overall survivals than other breast cancer subtypes 1. TNBC is also a heterogeneous disease with various subtypes, and as a result, translational studies based on the use of agents that target specific subtypes are being actively pursued 2. However, the clinical applications of such agents are currently very limited, and thus, the systemic treatment of TNBCs is largely dependent on platinum containing, taxane, and anthracycline based chemotherapies. Unfortunately, durable responses to these treatments are limited by high resistance and recurrence rates and by adverse toxic effects. As a result, many research programs are being conducted to identify new targeting therapies effective in TNBC. As reported in the cancer genome atlas (TCGA) database, alterations of RB and CCND1 are present in 22% of TNBC cases, and TP53 mutations are detected in more than 80% 3. Thus, dysregulation of the G1 cell cycle checkpoint is common in TNBC, and this results in higher mutation burdens because of high proliferation rates and replication stress accumulation observed at higher Ki-67 levels, which in turn, cause genomic instability 4. Specifically, cell cycle checkpoint defects promote DNA replication and cell division, which result in damaged DNA accumulation and increase genetic instability 5. These features have been proposed under the concept of synthetic lethality to inhibit other cell cycle checkpoints that were normally maintained, leading to cell death due to increased genetic instability caused by abnormal cell cycle progression.

Safety, Antitumor Activity, and Biomarker Analysis in a Phase I Trial of the Once-daily Wee1 Inhibitor Adavosertib (AZD1775) in Patients with Advanced Solid Tumors

“…The single-agent anti-tumor activity of adavosertib has been shown in multiple cancer cell lines (7)(8)(9) and in both TP53-intact and -deficient human tumor xenograft models (7). Adavosertib potentiates the activity of other DNA damage-inducing agents in preclinical models (10)(11)(12)(13), which has prompted several recent clinical trials (14)(15)(16)(17)(18). Adavosertib also acts as a radiosensitizer, enhancing radiation-induced DNA damage in vivo (19).…”

Targeting WEE1 Inhibits Growth of Breast Cancer Cells That Are Resistant to Endocrine Therapy and CDK4/6 Inhibitors

“…Combination of AZD1775 with a DNA-damaging chemotherapy agent has shown increased efficacy of both drugs in various preclinical cancer models (28,(55)(56)(57). In breast cancer, targeting WEE1 with AZD1775 has been recently investigated by others as a promising strategy in combination therapeutic approaches in different subtypes of the disease, particularly in preclinical models of TNBC (28,30,(58)(59)(60). In HER2-positive breast cancer cells models, treatment with AZD1775 overcomes resistance to standard-of-care therapy trastuzumab, a monoclonal antibody that targets HER2 (43).…”

“…Particularly in breast cancer, Murrow et al used a RNAi screen of the human tyrosine kinome, to identify WEE1 as a potential therapeutic target in triple-negative breast cancer cells that lack ER, progesterone receptor [PR] or HER2 (27). In recent years, a number of preclinical studies have focused on understanding the functionality of WEE1 in breast cancer cells, particularly those with defective cell cycle regulation (28)(29)(30).…”

Multiplexed and reproducible high content screening of live and fixed cells using the Dye Drop method

“…Several additional drugs exhibited subtype specificity that matched their targeted clinical indication: relative to other subtypes, HR + cell lines were more sensitive to the AKT inhibitors AZD5363 and ipatasertib, and mTOR inhibitors everolimus, AZD2014 and LY302341; TNBC cell lines were more sensitive to the WEE1 inhibitor adavosertib, the ATR inhibitor AZD6738, and the PARP inhibitors rucaparib and olaparib. [45][46][47] One striking feature of these data is that NM lines were not more resistant overall than cancer lines; this was true of pre-clinical compounds and drugs approved by the FDA for treatment of breast cancer (Fig. 4c, in bold).…”