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Background: BI 2536, a novel Polo-like kinase 1 inhibitor, was assessed in patients with unresectable advanced exocrine adenocarcinoma of the pancreas. Methods: The study employed a two-stage design. Randomised first-line patients received BI 2536 200 mg on day 1 ( n =43) or 60 mg on days 1–3 ( n =43) every 21 days. Recruitment of second-line patients was planned for a second stage dependent on an interim analysis demonstrating ⩾2 responses in the first 18 evaluable patients following 12 weeks of treatment and/or tumour control ⩾12 weeks in 5 patients per schedule. Primary end point was objective response rate (ORR). Results: By independent review, ORR was 2.3% (all partial) and 24.4% had stable disease as confirmed best response. The second stage was not initiated. Median overall and progression-free survivals were 149 (95% confidence interval (CI), 91–307) and 46 days (95% CI, 44–56). Most common drug-related adverse events were neutropenia (37.2%), leukopenia (29.1%), fatigue (29.1%) and nausea (22.1%); most common grade 3/4-related events were neutropenia (36.0%), leukopenia (27.9%) and thrombocytopenia (8.1%). Conclusion: Given the low ORR and poor survival, further development of BI 2536 monotherapy is not warranted in this population.

SummaryBackground Pharmacological inhibition of polo-like kinase 1 (PLK1) represents a new approach for the treatment of solid tumors. This study was aimed at determining the first cycle dose-limiting toxicities (DLTs) and related maximum tolerated dose (MTD) of NMS-1286937, a selective ATP-competitive PLK1-specific inhibitor. Secondary objectives included evaluation of its safety and pharmacokinetic (PK) profile in plasma, its antitumor activity, and its ability to modulate intracellular targets in biopsied tissue. Methods This was a Phase I, open-label, dose-escalation trial in patients with advanced/metastatic solid tumors. A treatment cycle comprised 5 days of oral administration followed by 16 days of rest, for a total of 21 days (3-week cycle). Results Nineteen of 21 enrolled patients with confirmed metastatic disease received study medication. No DLTs occurred at the first 3 dose levels (6, 12, and 24 mg/m2/day). At the subsequent dose level (48 mg/m2/day), 2 of 3 patients developed DLTs. An intermediate level of 36 mg/m2/day was therefore investigated. Four patients were treated and two DLTs were observed. After further cohort expansion, the MTD and recommended phase II dose (RP2D) were determined to be 24 mg/m2/day. Disease stabilization, observed in several patients, was the best treatment response observed. Hematological toxicity (mostly thrombocytopenia and neutropenia) was the major DLT. Systemic exposure to NMS-1286937 increased with dose and was comparable between two cycles of treatment following oral administration of the drug. Conclusions This study successfully identified the MTD and DLTs for NMS-1286937 and characterized its safety profile.

IntroductionPatients with head and neck squamous cell carcinoma with locally advanced disease often require multimodality treatment with surgery, radiotherapy and/or chemotherapy. Adjuvant radiotherapy with concurrent chemotherapy is offered to patients with high-risk pathological features postsurgery. While cure rates are improved, overall survival remains suboptimal and treatment has a significant negative impact on quality of life.Cell cycle checkpoint kinase inhibition is a promising method to selectively potentiate the therapeutic effects of chemoradiation. Our hypothesis is that combining chemoradiation with a WEE1 inhibitor will affect the biological response to DNA damage caused by cisplatin and radiation, thereby enhancing clinical outcomes, without increased toxicity. This trial explores the associated effect of WEE1 kinase inhibitor adavosertib (AZD1775).Methods and analysisThis phase I dose-finding, open-label, multicentre trial aims to determine the highest safe dose of AZD1775 in combination with cisplatin chemotherapy preoperatively (group A) as a window of opportunity trial, and in combination with postoperative cisplatin-based chemoradiation (group B).Modified time-to-event continual reassessment method will determine the recommended dose, recruiting up to 21 patients per group. Primary outcomes are recommended doses with predefined target dose-limiting toxicity probabilities of 25% monitored up to 42 days (group A), and 30% monitored up to 12 weeks (group B). Secondary outcomes are disease-free survival times (groups A and B). Exploratory objectives are evaluation of pharmacodynamic (PD) effects, identification and correlation of potential biomarkers with PD markers of DNA damage, determine rate of resection status and surgical complications for group A; and quality of life in group B.Ethics and disseminationResearch Ethics Committee, Edgbaston, West Midlands (REC reference 16/WM/0501) initial approval received on 18/01/2017. Results will be disseminated via peer-reviewed publication and presentation at international conferences.Trial registration number ISRCTN76291951 and NCT03028766.

Breast cancers (BC) carry a complex set of gene mutations that can influence their gene expression and clinical behavior. We aimed to identify genes driven by the TP53 mutation status and assess their clinical relevance in estrogen receptor (ER)-positive and ER-negative BC, and their potential as targets for patients with TP53 mutated tumors. Separate ROC analyses of each gene expression according to TP53 mutation status were performed. The prognostic value of genes with the highest AUC were assessed in a large dataset of untreated, and neoadjuvant chemotherapy treated patients. The mitotic checkpoint gene MPS1 was the most significant gene correlated with TP53 status, and the most significant prognostic marker in all ER-positive BC datasets. MPS1 retained its prognostic value independently from the type of treatment administered. The biological functions of MPS1 were investigated in different BC cell lines. We also assessed the effects of a potent small molecule inhibitor of MPS1, SP600125, alone and in combination with chemotherapy. Consistent with the gene expression profiling and siRNA assays, the inhibition of MPS1 by SP600125 led to a reduction in cell viability and a significant increase in cell death, selectively in TP53-mutated BC cells. Furthermore, the chemical inhibition of MPS1 sensitized BC cells to conventional chemotherapy, particularly taxanes. Our results collectively demonstrate that TP53-correlated kinase MPS1, is a potential therapeutic target in BC patients with TP53 mutated tumors, and that SP600125 warrant further development in future clinical trials. •TP53 status is associated with two sets of genes in ER+ and ER- breast tumors.•Genes associated with TP53 status were correlated to RFS in ER+ patients.•MPS1 was the most significant gene associated with TP53 status and poor prognosis.•MPS1 inhibition affected cell viability and apoptosis in TP53 mutated cells.•Targeting MPS1 by SP600125 sensitizes TP53 mutated cells to chemotherapy.

Purpose To support future dosing recommendations, the effect of food on the pharmacokinetics of adavosertib, a first-in-class, small-molecule reversible inhibitor of WEE1 kinase, was assessed in patients with advanced solid tumors.MethodsIn this Phase I, open-label, randomized, two-period, two-sequence crossover study, the pharmacokinetics of a single 300 mg adavosertib dose were investigated in fed versus fasted states.ResultsCompared with the fasted state, a high-fat, high-calorie meal (fed state) decreased adavosertib maximum plasma concentration (Cmax) by 16% and systemic exposure (area under the plasma concentration–time curve [AUC]) by 6%; AUC0–t decreased by 7% and time to maximum plasma concentration was delayed by 1.97 h (P = 0.0009). The 90% confidence interval of the geometric least-squares mean treatment ratio for AUC and AUC0–t was contained within the no-effect limits (0.8–1.25), while that of Cmax crossed the lower bound of the no-effect limits. Adverse events (AEs) related to adavosertib treatment were reported by 20 (64.5%) of the 31 patients treated in this study. Grade ≥ 3 AEs were reported by four (12.9%) patients (one in the fed state, three in the fasted state); two of these AEs were considered treatment-related by the investigator. Three serious AEs were reported in three (9.7%) patients; these were not considered treatment-related. No patients discontinued because of treatment-related AEs, and no new safety signals were reported.ConclusionA high-fat meal did not have a clinically relevant effect on the systemic exposure of adavosertib, suggesting that adavosertib can be administered without regard to meals.

Key Points Many cell cycle proteins are overexpressed or overactive in human cancers, in particular, D-type and E-type cyclins, cyclin-dependent kinases (CDK4, CDK6 and CDK2), Polo-like kinase 1 (PLK1) and Aurora kinases (Aurora A and Aurora B). In transgenic mice, overexpression of several of these cell cycle proteins induces or contributes to tumorigenesis, revealing their prominent oncogenic roles. Some of these cell cycle proteins are also required for tumorigenesis, and their ablation in mice impairs tumour formation induced by specific genetic lesions or by carcinogen treatment, as demonstrated for several cyclins (D1, D2 and D3) and CDKs (CDK4, CDK6, CDK2 and CDK1), as well as for checkpoint kinase 1 (CHK1). Importantly, in some cases the continued presence of a cell cycle protein has also been shown to be required for tumour maintenance and progression, for example, for cyclin D1, cyclin D3 and CDK4, thereby providing a clear rationale for targeting these proteins in cancer treatment. Kinases involved in cell cycle checkpoint function such as CHK1 and WEE1 also constitute potential therapeutic targets. Their inhibition compromises checkpoint function, causes excessive DNA damage and eventually leads to apoptosis, particularly in cells with compromised p53 function. CDK4/6-selective inhibitors, such as palbociclib, ribociclib and abemaciclib, have shown significant benefits in clinical studies, particularly in breast cancer, but also in non-small-cell lung cancer, melanoma and head and neck squamous cell carcinoma. Importantly, following demonstration of a substantial improvement in progression-free survival, combination of palbociclib and letrozole received accelerated approval for first-line treatment of patients with advanced ER + HER2 − breast cancer. Inhibitors of PLK1, such as rigosertib and volasertib, have also shown encouraging results in clinical phase II/III studies for patients with myelodysplastic syndromes and acute myelogenous leukaemia, respectively, and several phase III trials are currently ongoing. Compounds targeting Aurora A, particularly alisertib, have been extensively studied in preclinical models and demonstrated synergy with many other targeted therapies, leading to tumour regression in various cancer models. Moreover, clinical studies revealed encouraging activity of alisertib in peripheral T cell lymphoma, non-Hodgkin lymphoma, non-small-cell lung cancer and breast cancer. Proteins regulating cell cycle progression are involved in the formation of most cancer types. This Review discusses the role of cell cycle proteins in cancer, the rationale for targeting them in cancer treatment, results of clinical trials, as well as future therapeutic potential of various cell cycle inhibitors. Cancer is characterized by uncontrolled tumour cell proliferation resulting from aberrant activity of various cell cycle proteins. Therefore, cell cycle regulators are considered attractive targets in cancer therapy. Intriguingly, animal models demonstrate that some of these proteins are not essential for proliferation of non-transformed cells and development of most tissues. By contrast, many cancers are uniquely dependent on these proteins and hence are selectively sensitive to their inhibition. After decades of research on the physiological functions of cell cycle proteins and their relevance for cancer, this knowledge recently translated into the first approved cancer therapeutic targeting of a direct regulator of the cell cycle. In this Review, we focus on proteins that directly regulate cell cycle progression (such as cyclin-dependent kinases (CDKs)), as well as checkpoint kinases, Aurora kinases and Polo-like kinases (PLKs). We discuss the role of cell cycle proteins in cancer, the rationale for targeting them in cancer treatment and results of clinical trials, as well as the future therapeutic potential of various cell cycle inhibitors.

In the cell cycle, there are two checkpoint arrests that allow cells to repair damaged DNA in order to maintain genomic integrity. Many cancer cells have defective G1 checkpoint mechanisms, thus depending on the G2 checkpoint far more than normal cells. G2 checkpoint abrogation is therefore a promising concept to preferably damage cancerous cells over normal cells. The main factor influencing the decision to enter mitosis is a complex composed of Cdk1 and cyclin B. Cdk1/CycB is regulated by various feedback mechanisms, in particular inhibitory phosphorylations at Thr14 and Tyr15 of Cdk1. In fact, Cdk1/CycB activity is restricted by the balance between WEE family kinases and Cdc25 phosphatases. The WEE kinase family consists of three proteins: WEE1, PKMYT1, and the less important WEE1B. WEE1 exclusively mediates phosphorylation at Tyr15, whereas PKMYT1 is dual-specific for Tyr15 as well as Thr14. Inhibition by a small molecule inhibitor is therefore proposed to be a promising option since WEE kinases bind Cdk1, altering equilibria and thus affecting G2/M transition.

The inhibition of the DNA damage response (DDR) pathway in the treatment of cancer has recently gained interest, and different DDR inhibitors have been developed. Among them, the most promising ones target the WEE1 kinase family, which has a crucial role in cell cycle regulation and DNA damage identification and repair in both nonmalignant and cancer cells. This review recapitulates and discusses the most recent findings on the biological function of WEE1/PKMYT1 during the cell cycle and in the DNA damage repair, with a focus on their dual role as tumor suppressors in nonmalignant cells and pseudo-oncogenes in cancer cells. We here report the available data on the molecular and functional alterations of WEE1/PKMYT1 kinases in both hematological and solid tumors. Moreover, we summarize the preclinical information on 36 chemo/radiotherapy agents, and in particular their effect on cell cycle checkpoints and on the cellular WEE1/PKMYT1-dependent response. Finally, this review outlines the most important pre-clinical and clinical data available on the efficacy of WEE1/PKMYT1 inhibitors in monotherapy and in combination with chemo/radiotherapy agents or with other selective inhibitors currently used or under evaluation for the treatment of cancer patients.

Accurate repair of DNA double-stranded breaks by homologous recombination preserves genome integrity and inhibits tumorigenesis. Cyclic GMP–AMP synthase (cGAS) is a cytosolic DNA sensor that activates innate immunity by initiating the STING–IRF3–type I IFN signalling cascade 1 , 2 . Recognition of ruptured micronuclei by cGAS links genome instability to the innate immune response 3 , 4 , but the potential involvement of cGAS in DNA repair remains unknown. Here we demonstrate that cGAS inhibits homologous recombination in mouse and human models. DNA damage induces nuclear translocation of cGAS in a manner that is dependent on importin-α, and the phosphorylation of cGAS at tyrosine 215—mediated by B-lymphoid tyrosine kinase—facilitates the cytosolic retention of cGAS. In the nucleus, cGAS is recruited to double-stranded breaks and interacts with PARP1 via poly(ADP-ribose). The cGAS–PARP1 interaction impedes the formation of the PARP1–Timeless complex, and thereby suppresses homologous recombination. We show that knockdown of cGAS suppresses DNA damage and inhibits tumour growth both in vitro and in vivo. We conclude that nuclear cGAS suppresses homologous-recombination-mediated repair and promotes tumour growth, and that cGAS therefore represents a potential target for cancer prevention and therapy. DNA damage induces translocation of cyclic GMP–AMP synthase to the nucleus, where it suppresses homologous recombination by interfering with the formation of the PARP1–Timeless complex.

Background MRE11 is an important nuclease which functions in the end-resection step of homologous recombination (HR) repair of DNA double-strand breaks (DSBs). As MRE11-deficient ATLD cells exhibit hyper radio-sensitivity and impaired DSB repair, MRE11 inhibitors could possibly function as potent radio-sensitizers. Therefore, we investigated whether a bisbenzamidine derivative, pentamidine, which can inhibit endoexonuclease activity, might influence DSB-induced damage responses via inhibition of MRE11. Results We first clarified that pentamidine inhibited MRE11 nuclease activity and also reduced ATM kinase activity in vitro. Pentamidine increased the radio-sensitivity of HeLa cells, suggesting that this compound could possibly influence DNA damage response factors in vivo. Indeed, we found that pentamidine reduced the accumulation of γ-H2AX, NBS1 and phospho-ATM at the sites of DSBs. Furthermore, pentamidine decreased HR activity in vivo . Pentamidine was found to inhibit the acetylation of histone H2A which could contribute both to inhibition of IR-induced focus formation and HR repair. These results suggest that pentamidine might exert its effects by inhibiting histone acetyltransferases. We found that pentamidine repressed the activity of Tip60 acetyltransferase which is known to acetylate histone H2A and that knockdown of Tip60 by siRNA reduced HR activity. Conclusion These results indicate that inhibition of Tip60 as well as hMRE11 nuclease by pentamidine underlies the radiosensitizing effects of this compound making it an excellent sensitizer for radiotherapy or chemotherapy.