Daniel Guthy

Identification and Characterization of NVP-BKM120, an Orally Available Pan-Class I PI3-Kinase Inhibitor

Following the discovery of NVP-BEZ235, our first dual pan-PI3K/mTOR clinical compound, we sought to identify additional phosphoinositide 3-kinase (PI3K) inhibitors from different chemical classes with a different selectivity profile. The key to achieve these objectives was to couple a structure-based design approach with intensive pharmacologic evaluation of selected compounds during the medicinal chemistry optimization process. Here, we report on the biologic characterization of the 2-morpholino pyrimidine derivative pan-PI3K inhibitor NVP-BKM120. This compound inhibits all four class I PI3K isoforms in biochemical assays with at least 50-fold selectivity against other protein kinases. The compound is also active against the most common somatic PI3Kα mutations but does not significantly inhibit the related class III (Vps34) and class IV (mTOR, DNA-PK) PI3K kinases. Consistent with its mechanism of action, NVP-BKM120 decreases the cellular levels of p-Akt in mechanistic models and relevant tumor cell lines, as well as downstream effectors in a concentration-dependent and pathway-specific manner. Tested in a panel of 353 cell lines, NVP-BKM120 exhibited preferential inhibition of tumor cells bearing PIK3CA mutations, in contrast to either KRAS or PTEN mutant models. NVP-BKM120 shows dose-dependent in vivo pharmacodynamic activity as measured by significant inhibition of p-Akt and tumor growth inhibition in mechanistic xenograft models. NVP-BKM120 behaves synergistically when combined with either targeted agents such as MEK or HER2 inhibitors or with cytotoxic agents such as docetaxel or temozolomide. The pharmacological, biologic, and preclinical safety profile of NVP-BKM120 supports its clinical development and the compound is undergoing phase II clinical trials in patients with cancer. Mol Cancer Ther; 11(2); 317–28. ©2011 AACR.

Characterization of the novel and specific PI3Kα inhibitor NVP-BYL719 and development of the patient stratification strategy for clinical trials.

Somatic PIK3CA mutations are frequently found in solid tumors, raising the hypothesis that selective inhibition of PI3Kα may have robust efficacy in PIK3CA-mutant cancers while sparing patients the side-effects associated with broader inhibition of the class I phosphoinositide 3-kinase (PI3K) family. Here, we report the biologic properties of the 2-aminothiazole derivative NVP-BYL719, a selective inhibitor of PI3Kα and its most common oncogenic mutant forms. The compound selectivity combined with excellent drug-like properties translates to dose- and time-dependent inhibition of PI3Kα signaling in vivo, resulting in robust therapeutic efficacy and tolerability in PIK3CA-dependent tumors. Novel targeted therapeutics such as NVP-BYL719, designed to modulate aberrant functions elicited by cancer-specific genetic alterations upon which the disease depends, require well-defined patient stratification strategies in order to maximize their therapeutic impact and benefit for the patients. Here, we also describe the application of the Cancer Cell Line Encyclopedia as a preclinical platform to refine the patient stratification strategy for NVP-BYL719 and found that PIK3CA mutation was the foremost positive predictor of sensitivity while revealing additional positive and negative associations such as PIK3CA amplification and PTEN mutation, respectively. These patient selection determinants are being assayed in the ongoing NVP-BYL719 clinical trials. Mol Cancer Ther; 13(5); 1117–29. ©2014 AACR.

Characterization of the Mechanism of Action of the Pan Class I PI3K Inhibitor NVP-BKM120 across a Broad Range of Concentrations

The pan-phosphoinositide 3-kinase (PI3K) inhibitor BKM120 was found, at high concentrations, to cause cell death in various cellular systems, irrespective of their level of PI3K addiction. Transcriptional and biochemical profiling studies were used to identify the origin of these unexpected and apparently PI3K-independent effects. At 5- to 10-fold, the concentration needed to half-maximally inhibit PI3K signaling. BKM120 treatment caused changes in expression of mitotic genes and the induction of a robust G2–M arrest. Tubulin polymerization assays and nuclear magnetic resonance-binding studies revealed that BKM120 inhibited microtubule dynamics upon direct binding to tubulin. To assess the contribution of this off-target activity vis-à-vis the antitumor activity of BKM120 in PI3K-dependent tumors, we used a mechanistic PI3K-α–dependent model. We observed that, in vivo, daily treatment of mice with doses of BKM120 up to 40 mg/kg led to tumor regressions with no increase in the mitotic index. Thus, strong antitumor activity can be achieved in PI3K-dependent models at exposures that are below those necessary to engage the off-target activity. In comparison, the clinical data indicate that it is unlikely that BKM120 will achieve exposures sufficient to significantly engage the off-target activity at tolerated doses and schedules. However, in preclinical settings, the consequences of the off-target activity start to manifest themselves at concentrations above 1 μmol/L in vitro and doses above 50 mg/kg in efficacy studies using subcutaneous tumor–bearing mice. Hence, careful concentration and dose range selection is required to ensure that any observation can be correctly attributed to BKM120 inhibition of PI3K. Mol Cancer Ther; 11(8); 1747–57. ©2012 AACR.

A distinct p53 target gene set predicts for response to the selective p53–HDM2 inhibitor NVP-CGM097

Biomarkers for patient selection are essential for the successful and rapid development of emerging targeted anti-cancer therapeutics. In this study, we report the discovery of a novel patient selection strategy for the p53–HDM2 inhibitor NVP-CGM097, currently under evaluation in clinical trials. By intersecting high-throughput cell line sensitivity data with genomic data, we have identified a gene expression signature consisting of 13 up-regulated genes that predicts for sensitivity to NVP-CGM097 in both cell lines and in patient-derived tumor xenograft models. Interestingly, these 13 genes are known p53 downstream target genes, suggesting that the identified gene signature reflects the presence of at least a partially activated p53 pathway in NVP-CGM097-sensitive tumors. Together, our findings provide evidence for the use of this newly identified predictive gene signature to refine the selection of patients with wild-type p53 tumors and increase the likelihood of response to treatment with p53–HDM2 inhibitors, such as NVP-CGM097. DOI: http://dx.doi.org/10.7554/eLife.06498.001

Bim and Mcl-1 exert key roles in regulating JAK2V617F cell survival

BackgroundThe JAK2V617F mutation plays a major role in the pathogenesis of myeloproliferative neoplasms and is found in the vast majority of patients suffering from polycythemia vera and in roughly every second patient suffering from essential thrombocythemia or from primary myelofibrosis. The V617F mutation is thought to provide hematopoietic stem cells and myeloid progenitors with a survival and proliferation advantage. It has previously been shown that activated JAK2 promotes cell survival by upregulating the anti-apoptotic STAT5 target gene Bcl-xL. In this study, we have investigated the role of additional apoptotic players, the pro-apoptotic protein Bim as well as the anti-apoptotic protein Mcl-1.MethodsPharmacological inhibition of JAK2/STAT5 signaling in JAK2V617F mutant SET-2 and MB-02 cells was used to study effects on signaling, cell proliferation and apoptosis by Western blot analysis, WST-1 proliferation assays and flow cytometry. Cells were transfected with siRNA oligos to deplete candidate pro- and anti-apoptotic proteins. Co-immunoprecipitation assays were performed to assess the impact of JAK2 inhibition on complexes of pro- and anti-apoptotic proteins.ResultsTreatment of JAK2V617F mutant cell lines with a JAK2 inhibitor was found to trigger Bim activation. Furthermore, Bim depletion by RNAi suppressed JAK2 inhibitor-induced cell death. Bim activation following JAK2 inhibition led to enhanced sequestration of Mcl-1, besides Bcl-xL. Importantly, Mcl-1 depletion by RNAi was sufficient to compromise JAK2V617F mutant cell viability and sensitized the cells to JAK2 inhibition.ConclusionsWe conclude that Bim and Mcl-1 have key opposing roles in regulating JAK2V617F cell survival and propose that inactivation of aberrant JAK2 signaling leads to changes in Bim complexes that trigger cell death. Thus, further preclinical evaluation of combinations of JAK2 inhibitors with Bcl-2 family antagonists that also tackle Mcl-1, besides Bcl-xL, is warranted to assess the therapeutic potential for the treatment of chronic myeloproliferative neoplasms.

Discovery of Novel Dot1L Inhibitors through a Structure-Based Fragmentation Approach.

Oncogenic MLL fusion proteins aberrantly recruit Dot1L, a histone methyltransferase, to ectopic loci, leading to local hypermethylation of H3K79 and misexpression of HoxA genes driving MLL-rearranged leukemias. Inhibition of the methyltransferase activity of Dot1L in this setting is predicted to reverse aberrant H3K79 methylation, leading to repression of leukemogenic genes and tumor growth inhibition. In the context of our Dot1L drug discovery program, high-throughput screening led to the identification of 2, a weak Dot1L inhibitor with an unprecedented, induced pocket binding mode. A medicinal chemistry campaign, strongly guided by structure-based consideration and ligand-based morphing, enabled the discovery of 12 and 13, potent, selective, and structurally completely novel Dot1L inhibitors.

Abstract 3748: NVP-BYL719, a novel PI3Kalpha selective inhibitor with all the characteristics required for clinical development as an anti-cancer agent

Most of the current oncology drug discovery and development work has shifted towards molecularly targeted therapies. A key focus has been on identifying inhibitors against components of pathways that drive tumor cell proliferation, survival, and metastasis such as the PI3K/mTOR pathway, reported to be implicated in many human cancers through various mechanisms, such as, somatic PIK3CA missense mutations that occur at high frequency. These mutations are largely point mutations predominantly clustered within three hotspots in the helical and kinase domains of p110α: E542K, E545K and H1047R, which represent about 80% of the mutations observed, and confirmed to be oncogenic gain-of-function mutations. Based on these findings cancer-specific mutants of p110α appear to be ideal targets for drug development and p110α specific inhibitors, such as NVP-BYL719, could then have potential anti-cancer activity without causing the potential side effects that could be expected from interference with other Class I PI3K isoforms or other members of the PIKK family. NVP-BYL719 is best described as a PI3Kalpha inhibitor as in biochemical assays, it inhibits p110α as well as p110α most common somatic mutations (IC 50 =5 nM) much more potently than p110α and ≤ and has weak or no activity against p110α, Vps34 and mTOR and is selective against a wide range of protein kinases (> 50-fold). The potency and selectivity profile of NVP-BYL719 is confirmed at the cellular level, is correlated with inhibition of various PI3K/Akt downstream signaling pathway components and is associated with anti-proliferation of breast cancer cell lines harboring PIK3CA mutations. In vivo, NVP-BYL719 shows dose and time-dependent inhibition of the PI3K/Akt pathway which correlates with compound exposure and is associated with good tolerability and significant dose-dependent anti-tumor efficacy in PIK3CA mutant tumor xenograft models in rodents. Moreover, plasma insulin levels are significantly increased while blood glucose levels remained normal at all tested doses and time points indicating on-target effects of NVP-BYL719 on the regulation of metabolism. Overall, as a PI3Kalpha inhibitor, NVP-BYL719 has good drug-like and pharmacological properties and presents all the characteristics required for its ongoing Phase I clinical development in adult patients with advanced solid malignancies whose tumors have an alteration of the PIK3CA gene. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3748. doi:1538-7445.AM2012-3748

Maximizing the Efficacy of MAPK-Targeted Treatment in PTENLOF/BRAFMUT Melanoma through PI3K and IGF1R Inhibition

The introduction of MAPK pathway inhibitors paved the road for significant advancements in the treatment of BRAF-mutant (BRAF(MUT)) melanoma. However, even BRAF/MEK inhibitor combination therapy has failed to offer a curative treatment option, most likely because these pathways constitute a codependent signaling network. Concomitant PTEN loss of function (PTEN(LOF)) occurs in approximately 40% of BRAF(MUT) melanomas. In this study, we sought to identify the nodes of the PTEN/PI3K pathway that would be amenable to combined therapy with MAPK pathway inhibitors for the treatment of PTEN(LOF)/BRAF(MUT) melanoma. Large-scale compound sensitivity profiling revealed that PTEN(LOF) melanoma cell lines were sensitive to PI3Kβ inhibitors, albeit only partially. An unbiased shRNA screen (7,500 genes and 20 shRNAs/genes) across 11 cell lines in the presence of a PI3Kβ inhibitor identified an adaptive response involving the IGF1R-PI3Kα axis. Combined inhibition of the MAPK pathway, PI3Kβ, and PI3Kα or insulin-like growth factor receptor 1 (IGF1R) synergistically sustained pathway blockade, induced apoptosis, and inhibited tumor growth in PTEN(LOF)/BRAF(MUT) melanoma models. Notably, combined treatment with the IGF1R inhibitor, but not the PI3Kα inhibitor, failed to elevate glucose or insulin signaling. Taken together, our findings provide a strong rationale for testing combinations of panPI3K, PI3Kβ + IGF1R, and MAPK pathway inhibitors in PTEN(LOF)/BRAF(MUT) melanoma patients to achieve maximal response.

Antibody-based arrays in disease proteomics

License. The full terms of the License are available at http://creativecommons.org/licenses/by-nc/3.0/. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. Permissions beyond the scope of the License are administered by Dove Medical Press Limited. Information on how to request permission may be found at: http://www.dovepress.com/permissions.php Antibody Technology Journal 2015:5 15–25 Antibody Technology Journal Dovepress

Abstract 2909: A gene signature composed of 13 p53 target genes predicts for response to NVP-CGM097, a novel p53-Mdm2 inhibitor, in cell lines and in human primary tumor xenograft models

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Patient selection biomarkers are essential for the successful and rapid development of emerging targeted anti-cancer therapeutics. In this study we have identified a novel patient selection strategy for NVP-CGM097, a p53-Mdm2 inhibitor currently in a Phase I clinical trial ([NCT01760525][1]). We have analyzed the sensitivity of over 500 cell lines from the “Cancer Cell Line Encyclopedia” to the p53-Mdm2 inhibitor in cell viability assays, and intersected response data with information on gene expression and genomic alterations. This analysis has led to the identification of a gene signature consisting of 13 genes, as a predictor for sensitivity to NVP-CGM097. Interestingly, these 13 genes are known p53 downstream target genes, supporting the hypothesis that the identified gene signature is reflective of the p53 pathway functionality in sensitive cell lines. We show the performance of the signature as ROC and Precision-Recall curves in cell lines as well as in a number of human primary tumor xenografts, both unselected as well as pre-selected for p53 wild-type status. Work is now ongoing to validate this gene signature using baseline tumor biopsy samples and RECIST-based efficacy readouts in the current Phase I clinical trial. Citation Format: Sebastien Jeay, Swann Gaulis, Stephane Ferretti, Genevieve Albrecht, Louise Barys, Daniel Guthy, Ensar Halilovic, Moriko Ito, Masato Murakami, Astrid Pornon, Stephan Ruetz, Kavitha Venkatesan, Jianjun Yu, Michael Jensen, Marion Wiesmann, Jens Wuerthner, Diana Graus-Porta. A gene signature composed of 13 p53 target genes predicts for response to NVP-CGM097, a novel p53-Mdm2 inhibitor, in cell lines and in human primary tumor xenograft models. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2909. doi:10.1158/1538-7445.AM2014-2909 [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT01760525&atom=%2Fcanres%2F74%2F19_Supplement%2F2909.atom