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PURPOSE: PI3K/AKT/mTOR and RAS/RAF/MEK pathways are frequently dysregulated in colorectal cancer (CRC). We conducted a biomarker-driven trial of the combination of MK-2206, an allosteric AKT 1/2/3 inhibitor, and selumetinib, a MEK 1/2 inhibitor, in patients with CRC to evaluate inhibition of phosphorylated ERK (pERK) and AKT (pAKT) in paired tumor biopsies. PATIENTS AND METHODS: Adult patients with advanced CRC were enrolled in successive cohorts stratified by KRAS mutation status. Initially, 12 patients received oral MK-2206 90 mg weekly with oral selumetinib 75 mg daily in 28-day cycles. Following an interim analysis, the doses of MK-2206 and selumetinib were increased to 135 mg weekly and 100 mg daily, respectively. Paired tumor biopsies were evaluated for target modulation. RESULTS: Common toxicities were gastrointestinal, hepatic, dermatologic, and hematologic. Of 21 patients enrolled, there were no objective responses. Target modulation did not achieve the pre-specified criteria of dual 70 % inhibition of pERK and pAKT levels in paired tumor biopsies. CONCLUSION: Despite strong scientific rationale and preclinical data, clinical activity was not observed. The desired level of target inhibition was not achieved. Overlapping toxicities limited the ability to dose escalate to achieve exposures likely needed for clinical activity, highlighting the challenges in developing optimal combinations of targeted agents.

Mutations in IDH1 are highly prevalent in human glioma. First line treatment is radiotherapy, which many patients often forego to avoid treatment-associated morbidities. The high prevalence of IDH1 mutations in glioma highlights the need for brain-penetrant IDH1 mutant-selective inhibitors as an alternative therapeutic option. Here, we have explored the utility of such an inhibitor in IDH1 mutant patient-derived models to assess the potential therapeutic benefits associated with intracranial 2-HG inhibition. Treatment of mutant IDH1 cell line models led to a decrease in intracellular 2-HG levels both in vitro and in vivo. Interestingly, inhibition of 2-HG production had no effect on in vitro IDH1 mutant glioma cell proliferation. In contrast, IDH1 mutant-selective inhibitors provided considerable survival benefit in vivo. However, even with near complete inhibition of intratumoral 2-HG production, not all mutant glioma models responded to treatment. The results suggest that disruption of 2-HG production with brain-penetrant inhibitors in IDH1 mutant gliomas may have substantial patient benefit.

Defective genome maintenance mechanisms, involving DNA repair and cell-cycle checkpoint pathways, initiate genetic instability in many sporadic and hereditary cancers. The DNA damage effector Checkpoint kinase 1 (Chk1) is a critical component of DNA replication, intra-S phase, and G 2 /M phase checkpoints and a recently reported mitotic spindle-assembly checkpoint. Here, we report for the first time that haploinsufficiency of Chk1 in mice resulted in multiple mitotic defects and enhanced binucleation. We observed that Aurora B, a critical cytokinetic regulator and a recently identified Chk1 substrate, was mislocalized in mitotic Chk1 +/− mammary epithelia. Chk1 also exhibited distinct mitotic localization patterns and was active during unperturbed mitosis and cytokinesis in mammalian cells. Active Chk1 expression was not dependent on treatment with spindle poisons such as colcemid during mitosis and cytokinesis. Furthermore, two different complementary approaches demonstrated that abrogation of Chk1 in mitotic mammalian cells resulted in cytokinetic regression and binucleation, increased chromosome lagging and/or nondisjunction, and abnormal localization of Aurora B at late mitotic structures. Thus, Chk1 is a multifunctional kinase that serves as a nexus between the DNA damage response and the mitotic exit pathways during cell-cycle progression to prevent genomic instability and cancer.

This review summarizes recent studies which have provided new insight into the mechanisms by which the DNA damage response kinase, Chk1 inhibits the dual specificity phosphatase, Cdc25, and thereby regulates cell cycle progression. Recently, Chk1 has been shown to not only regulate Cdc25A degradation but also its ability to interact with various Cdk complexes through phosphorylation of the carboxy-terminus of the phosphatase. Surprisingly, these effects appear to be specific for Chk1, but not Chk2, which may explain the recently reported in vivo haploinsufficiency phenotype observed in the mammary gland using a Chk1 conditional mouse model.

MicroRNAs are abundant in animal genomes and have been predicted to have important roles in a broad range of gene expression programmes1,2. Despite this prominence, there is a dearth of functional knowledge regarding individual mammalian microRNAs. Using a loss-of-function allele in mice, we report here that the myeloid-specific microRNA-223 (miR-223) negatively regulates progenitor proliferation and granulocyte differentiation and activation. miR-223 (also called Mirn223) mutant mice have an expanded granulocytic compartment resulting from a cell-autonomous increase in the number of granulocyte progenitors. We show that Mef2c, a transcription factor that promotes myeloid progenitor proliferation, is a target of miR-223, and that genetic ablation of Mef2c suppresses progenitor expansion and corrects the neutrophilic phenotype in miR-223 null mice. In addition, granulocytes lacking miR-223 are hypermature, hypersensitive to activating stimuli and display increased fungicidal activity. As a consequence of this neutrophil hyperactivity, miR-223 mutant mice spontaneously develop inflammatory lung pathology and exhibit exaggerated tissue destruction after endotoxin challenge. Our data support a model in which miR-223 acts as a fine-tuner of granulocyte production and the inflammatory response.

Background: BIND-2206 Accurins are novel polymeric nanoparticles encapsulating MK-2206, a Merck AKT inhibitor in phase 2 trials. MK-2206 targets the phosphatidylinositol 3-kinase (PI3K) pathway via AKT inhibition and has demonstrated therapeutic efficacy in the treatment of cancer albeit with dose limiting toxicities. Accurins have shown promise for targeting oncology agents preferentially to tumors, while limiting systemic exposure. To determine if encapsulation of MK-2206 improves therapeutic index, studies were performed to evaluate pharmacokinetics (PK), pharmacodynamics (PD), tolerability and anti-tumor activity compared to parent MK-2206. Materials and Methods: PK of four Accurin formulations with varying in vitro drug release rates was evaluated. Based on these data, two lead Accurins (BIND-2206C and BIND-2206D) were selected for further characterization. Since AKT inhibitors are documented to induce hyperglycemia in mice, blood glucose levels were also evaluated after acute administration of BIND-2206 Accurins or parent MK-2206 as a measure of tolerability. Using a panel of human tumor xenografts (VCaP, SK-OV-3 and BT-474) anti-tumor activity of the Accurins was assessed in mice. When tumors were established mice were dosed orally with parent MK-2206 or intravenously with BIND-2206 Accurins two or three times per week on a three week cycle. Tumor volume was measured post treatment to determine anti-tumor activity. Following final drug administration, tumors were collected for PK and PD evaluation. Extent and duration of tumor target inhibition was evaluated by measuring pAKT and total AKT using a mesoscale discovery method and was correlated to tumor MK-2206 levels. Results: Accurins BIND-2206C and BIND-2206D significantly enhanced the PK profile of parent MK-2206 by increasing Cmax (33 fold) and AUC (222 fold) and decreasing clearance (38 fold) in mice. In addition, both BIND-2206 Accurins improved tolerability as demonstrated by no hyperglycemic response compared to a 300% increase in blood glucose in nude mice treated with parent MK-2206. In the VCaP human prostate cancer tumor model, BIND-2206C inhibited tumor growth by 88% and BIND-2206D induced 16% tumor regression showing significant enhancement of anti-tumor efficacy compared to 55% tumor growth inhibition achieved by parent MK-2206. This correlated with high tumor exposure at 72 hours and prolonged tumor PD at 96 hours post dose for both Accurins compared to parent MK-2206. A similar increase in tumor exposure and prolonged PD response resulted in enhanced anti-tumor efficacy for BIND-2206 Accurins in the SK-OV-3 human ovarian cancer tumor model. In the BT-474 HER2 over-expressing human breast cancer tumor model, BIND-2206 Accurins did not improve efficacy compared to parent drug, although there was significant and prolonged tumor PD correlating with enhanced tumor PK. This suggests that anti-tumor efficacy is model specific and a combination strategy in the BT-474 model may be advantageous. Conclusions: BIND-2206 Accurins showed differentiated PK, increased tumor exposure, prolonged duration of target inhibition, superior efficacy and enhanced tolerability compared to parent MK-2206. These data suggest that nanoparticle formulations of the AKT inhibitor, MK-2206, may provide improved tolerability and therapeutic efficacy in a clinical setting. Citation Format: Louise Cadzow, Michael H. Lam, Young Ho Song, Maria Figueiredo, Hong Wang, David De Witt, Vincenzo Pucci, Jan-Rung Mo, Eric Lewis-Clark, Heidi Ferguson, Marian Gindy, Susan Low, Steve Zale, Jeff Hrkach, Caroline McGregor, Brian J. Long. Accurins improve the pharmacokinetics, pharmacodynamics, tolerability and anti-tumor activity of the AKT inhibitor MK-2206. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C197.

Yuan-Yuan Zhao,1,* Ying Tian,1,* Jing Zhang,2,* Fei Xu,1 Yun-Peng Yang,1 Yan Huang,1 Hong-Yun Zhao,3 Jian-Wei Zhang,4 Cong Xue,1 Michael H Lam,5 Li Yan,5 Zhi-Huang Hu,1 Xiao-Xiao Dinglin,6 Li Zhang1,3 1Department of Medical Oncology, Sun Yat-SenUniversityCancerCenter, State Key Laboratory of Oncology in South China, and Collaborative Innovation Center for Cancer Medicine, Guangzhou, People’s Republic of China; 2Department of Medical Oncology, the First Affiliated Hospital of Guang Zhou Traditional Chinese Medicine University, Guangzhou, People’s Republic of China; 3National Anti-Cancer Drug Research Centre, Sun Yat-Sen University Cancer Center; State Key Laboratory of Oncology in South China, and Collaborative Innovation Center for Cancer Medicine, Guangzhou, People’s Republic of China; 4The Six Affiliated Hospital of SunYat-Sen University, Guangzhou, People’s Republic of China; 5Merck and Co Inc, North Wales, PA USA; 6SunYat-Sen Memorial Hospital, Guangzhou, People’s Republic of China *These authors contributed equally tothiswork Aim: Protein kinase B (AKT) signaling frequently is deregulated in human cancers and plays an important role in nasopharyngeal carcinoma (NPC). This preclinical study investigated the effect of MK-2206, a potent allosteric AKT inhibitor, on human NPC cells in vitro and in vivo. Methods: The effect of MK-2206on the growth and proliferation of CNE-1, CNE-2, HONE-1, and SUNE-1cells was assessed by Cell Counting Kit 8and colony formation assay. Flow cytometry was performed to analyze cell cycle and apoptosis. The effects of MK-2206on the AKT pathway were analyzed by Western blotting. Autophagy induction was evaluated via electron microscopy and Western blot. To test the effects of MK-2206in vivo, CNE-2cells were subcutaneously implanted into nude mice. Tumor-bearing mice were treated orally with MK-2206or placebo. Tumors were harvested for immunohistochemical analysis. Results: In vitro, MK-2206inhibited the four NPC cell line growths and reduced the sizes of the colonies in a dose-dependent manner. At 72and 96hours, the half maximal inhibitory concentration (IC50) values of MK-2206in CNE-1, CNE-2, and HONE-1cell lines were 3–5µM, whereas in SUNE-1, IC50was less than 1µM, and MK-2206induced cell cycle arrest at the G1phase. However, our study found no evidence of apoptosis. MK-2206induced autophagy in NPC cells, as evidenced by electron microscopy and Western blot, and inhibited the growth of tumors that were subcutaneously implanted in mice. Inhibition of downstream phosphorylation through the PRAS40and S6pathways seems to be the main mechanism for the MK-2206-induced growth inhibition.Conclusion: Our preclinical study suggests that MK-2206’s antiproliferative effect may be useful for NPC treatment; however, strategies for reinforcing this effect are needed to maximize clinical benefit. Keywords: AKT inhibitor, MK-2206, nasopharyngeal carcinoma&nbsp