Molecular Therapeutics Scientific Reports
Recent selected scientific progress and achievements are listed below, organized into the following categories:
- Synthesis and discovery of novel compounds and potential anticancer drugs
- Interrogation of cancer vulnerabilities
- Development of hypothesis-based cancer clinical trials
1. Synthesis and discovery of novel compounds and potential anticancer drugs
Natural product chemistry
Natural products provide a vast array of novel chemical scaffolds across a much larger chemical space than available from typical small molecule synthesis, and hence provide an opportunity to develop many novel anti-cancer drugs. In this regard, Dr. Jimmy Wu is performing total synthesis of natural products, and their derivatives that might have potential as novel anticancer agents. A collaboration between Drs. Wu and Eastman resulted in a 4-year grant from the American Cancer Society and the first total synthesis of nuphar alkaloids that are derived from water lilies (Kortokov et al 2015). These compounds rapidly induce apoptosis (~1 h) in vitro. The alkaloids have a dimeric structure, and the synthetic route involved condensing two monomers. It was found that the monomers are also extremely rapid inducers of apoptosis (Li et al 2016; Li et al 2017). The molecular target remains elusive. Recent results have shown that apoptosis is dependent on release of cytochrome c from mitochondria, but this release is independent of BAX and BAK and occurs while retaining mitochondrial membrane potential, suggesting a novel means to induce apoptosis. In an unexpected extension of research described below, Dr. Eastman discovered that the MCL1 inhibitor A1210477 elicited a similar off-target effect that also resulted in BAX/BAK independent apoptosis. Hence it is extremely interesting that analysis of two different compounds resulted in identification of a completely novel mechanism of apoptosis. In 2018, Dr. Wu obtained funding from the iTARGET COBRE grant, in collaboration with NCCC Cancer Mechanisms investigator Scott Gerber, PhD, to apply mass spectrometry approaches to the search for the target of these compounds.
Pectenotoxins are marine toxins, but are very labile in cell culture. Analysis of the NCI60 cell line database demonstrated a very similar profile of sensitivity as two other actin-targeting drugs, albeit pectenotoxin has much greater potency. The potential for pectenotoxin as a novel drug arises from the observation of 100-fold range of sensitivity in the NCI60 panel. Dr. Glenn Micalizio is attempting synthesis of this natural product, with the intent to create more stabile analogs. Dr. Eastman has been performing cytotoxicity assays while NCCC Cancer Mechanisms investigator Harry Higgs, PhD has been looking at inhibition of actin by the initially synthesized analogs (O’Rourke et al, 2017). This collaboration was funded by a 2-year grant from the Provost’s Office of Dartmouth College.
Enantiomeric steroids as a novel scaffold
New chemical methods generated by Dr. Micalizio led to the discovery of structurally unique enantiomeric steroidal agents that display potent growth inhibitory properties in a number of human tumor cell lines. Analogs have generated an early appreciation of structure–activity relationships associated with this novel compound ‘class’. The synthesis and cytotoxicity of these enantiomeric steroids was published in Nature Chemistry (Kim et al 2018). The translation of this program has involved a collaboration with Drs. Dale Mierke, Alan Eastman, and Scott Gerber, initially to synthesize novel CDK-targeting compounds. This collaboration resulted in pilot funding from the Munck-Pfefferkorn fund at Geisel with cost-sharing from NCCC. Ongoing studies are focusing on a lead compound (JA-1-58) that is cytotoxic at 1 µM but elicits unexpected characteristics in that it arrests cells in mitosis at pro-metaphase. A kinome screen identified CLK1/2/4 as the most sensitive kinases, yet cell based assays suggest that intracellular concentrations are insufficient to inhibit this target. Recognizing that it had structural similarities to 2-methoxyestradiol (2ME), they compared the two compounds and found that 2ME also arrested cells in prometaphase. 2ME was developed as an anticancer drug based on its perceived tubulin disrupting function, but failed clinically because of metabolic inactivation. This observation also led to analysis of estrogenic activity: JA-1-58 is slightly more selective as an agonist for ER-beta compared to ER-alpha. Ongoing research has identified a compound that is 10,000 fold more potent as an agonist of estrogen beta over alpha, whereas the best pharmaceutical compound has only 32-fold selectivity. Their potential for suppressing ER-beta expressing glioma is currently under investigation by Dr. Arti Gaur.
NMR-driven structural biology
Structural biology provides an alternative approach to generate novel compounds that bind a known target. Dr. Dale Mierke has been using his expertise in NMR to dissect the structures of critical regulators of apoptosis. For example, he has defined the interaction domains between the cellular FLICE inhibitory protein (cFLIP), an inhibitor of caspase 8 activation, with calmodulin (Gaidos et al 2015). He recently solved the structure of the DED domain of cFLIP and mapped the interaction interface with calmodulin and the DED domain of FADD (Panaitui, et al, Scientific Reports, submitted). Employing this structural insight, he is screening small libraries to inhibit these interactions, to identify important regulators of the pro-survival actions of cFLIP. A similar analysis of TRAIL receptors (DR4 and DR5) has identified domains of interaction with caspase 8. This led to the identification of a small molecule that binds caspase 8 and enhances its activation when combined with TRAIL (Bacur et al 2015). This approach provides insight into the structure-function relationship of caspase 8 homodimers as putative targets in cancer. A collaboration between Drs. Mark Spaller, Mierke and Mukhopadhyay (Mayo Clinic) has identified inhibitors of the GAIP-interacting protein C-terminus (GIPC) protein with GIPC as a potential target for pancreas adenocarcinoma as well as other cancers. They have previously demonstrated that peptides that specifically target of GIPC-interacting proteins, including IGF-1R or endoglin-1, can inhibit tumor growth and metastasis potential. They have solved the structure of the PDZ domain of GIPC (Barczewski, et al, Biochemistry submitted) B and have employed this information to develop inhibitors with enhanced physico-chemical properties. Dr. Mierke has recently developed a novel NMR-based ATPase assay that has been shown to be extremely efficient at identification of kinase inhibitors (Guo, et al. 2014a). Exploiting this assay to screen for GTP turnover, Drs. Mierke and Miller are screening for inhibitors of RAC1. This project supported by a Prouty pilot grant, has produced extremely potent inhibitors of both wild-type RAC1 as well as a mutant (P29S) that has been shown to be present in about 10% of breast cancers. These compounds are currently being examined in cell-based assays. These findings will form the basis of an R01 application to the NCI.
An alternative pathway amenable to structural biology and peptide inhibition is NFkB signaling by targeting the interactions between NEMO and IKKa/b. Dr. Maria Pellegrini, a new recruit to Molecular Therapeutics, has generated fragments of NEMO that contain the binding domain, and generated a crystal structure to help predict effective binding peptides (Guo et al 2014b). She is collaborating with Dr. Mierke to use an NMR-based screen of candidate peptides and small molecule libraries. The lead compounds will again be screened for cytotoxicity in Dr. Eastman’s laboratory using lymphoma and melanoma cells known to depend on NFkB for survival. Dr. Pellegrini obtained an RO3 grant for the initial development of this approach, and more recently this collaboration was awarded a grant from the Munck-Pfefferkorn fund at Geisel with cost-sharing from NCCC.
Autophagy as a target
The importance of mitochondrial degradation by autophagy (mitophagy) in cancer has become increasingly clear. However, a lack of a molecular understanding of this pathway has made it challenging to fully elucidate its role in cancer. Dr. Michael Ragusa is investigating the mechanisms of ubiquitin-independent mitophagy initiation. Dr. Ragusa obtained a Prouty Pilot grant from NCCC for structural studies of the receptors that initiate ubiquitin-independent mitophagy. This work, including collaboration with Dr. Pellegrini, resulted in the identification and structural characterization of a previously undescribed domain within the ubiquitin-independent mitophagy receptor Atg32 (Xia et al. 2017; Xia et al 2018 in press). This work was also critical in obtaining a project grant as part of the iTARGET COBRE and more recently provided a large portion of the preliminary data for a NIGMS R35 application which has just been funded. Dr. Ragusa continues to collaborate with Dr. Sanchez to determine if mitophagy receptors are potential anti-cancer targets.
2. Interrogation of cancer vulnerabilities
Epithelial to mesencyhmal transition (EMT)
Tumors frequently undergo EMT that leads to enhanced drug resistance and metastasis. Dr. Diwakar Pattabiraman has identified a novel mechanism that operates as a guardian of the epithelial state, which, when deregulated, paves the way for EMT and metastasis. The pathway involves cAMP-mediated signaling and downstream activation of PKA (Pattabiraman et al, 2016). Targeting this pathway can revert the EMT program, inhibit metastasis and resensitize tumors to chemotherapy. Another effort to derail the EMT program involves the identification of inhibitors of the association of Zeb1 and YAP, which have been shown to be key players in the progression of carcinomas. A Prouty funded collaboration with Dr. Mierke aims to disrupt this protein-protein interaction that is critical for cancer cells to initiate the metastatic cascade. They have begun with the overexpression and purification of the two regions of Zeb1 believed to be important in the interaction of the proteins. Using NMR, they will solve the structures of these protein domains and initiate screening to identify inhibitors of the association with YAP. Dr. Pattabiraman’s research program is geared towards using multiple approaches towards the inhibition of EMT, as a means of inducing differentiation therapy for breast cancers.
Cancer vulnerabilities in chromatin remodeling complexes
The SWI/SNF chromatin remodeling complex has various subunits that are frequently mutated in cancer. These mutations alter the enhancer binding properties of the complex, primarily through preferential binding to super-enhancers at the expensive of regular enhancers, and hence modifying gene expression profiles in tumors. The complex contains redundant subunits, such that loss of one subunit creates dependency on another. For example, loss of ARID1A creates dependency on ARID1B, while loss of SMARCA4 creates dependency on SMARCA2. Dr. Xiaofeng Wang, a new recruit from Dr. Charles Roberts’ laboratory proposes to investigate these tumor selective vulnerabilities as the basis for novel drug development. His current research is directed to elucidating the contribution of SMARCB1/SNF5 to the complex assembly and impact on gene targeting (Wang et al 2017), identifying novel SWI/SNF complex subtypes in various cancer types, as well as using genome-wide CRISPR-Cas9 screen to identify specific vulnerabilities. He has established a Prouty-funded collaboration with Dr. Scott Gerber to define the interacting proteins in novel Swi/Snf complexes by mass spectrometry.
Novel small molecules target cells with dysregulated Ras signaling due to NF1 loss or KRAS mutations
Combining human and yeast models and high-throughput chemical screens, Dr. Sanchez identified potential drugs targeting cancer cells in which NF1 loss drives tumor formation. This work, initially supported by an NCCC pilot grant, is funded by an interdisciplinary, multi-PI R01 that includes Drs. Lewis and NCCC investigators P. Jack Hoopes and Brian Pogue. The current goals are to identify the targets of the lead compounds using genetic, biochemical and proteome-wide approaches, and move them into in vivo models. This approach includes structure-activity relationship studies in collaboration with Dr. Wu. A collaboration with Dr. Gerber, and funded by a Prouty pilot grant, used thermal proteome profiling to identify 12 candidate cellular targets for one of the lead compounds that modulates mitochondrial dynamics (Allaway, R. J., et al., 2017). They followed up on three proteins SPRE, GSTM1 and PFKFB3. Small molecule inhibitors of GSTM1 and PFKB3 inhibited the growth of GBM cells. In addition, the PFKFB3 inhibitor, PFK15, recapitulated the phenotype observed with the lead compound Y100, including the mitochondrial phenotype possibly by reversing the Warburg effect to which tumor cells are addicted. The team is testing the efficacy of the lead compounds on neurological tumors driven by NF1 loss and other tumors driven by Ras dysregulation. For this, Dr. Kerrington Smith developed a bank of pancreatic cancer and GBM patient-derived xenografts (PDX). Up to 40% of GBM tumors have low to no NF1 protein, whereas only 15-18% have NF1 mutation. This indicates that genotype alone may not identify sensitive GBM tumors. In partnership with Dr. Casey Greene (UPENN), the team developed the first RNA-based classifier that identified tumors with low or no NF1 protein irrespective of NF1 mutation (Way, GP, et al 2017). More recently, the team used a machine learning approach that integrates bulk RNA sequencing, copy number aberrations and mutation data in RAS genes from PanCanAtlas and showed that this method can detect RAS activation. This pan-cancer RAS classifier identifies mutations that phenocopy RAS activation including NF1 mutation in brain malignancies and identified cell lines with wild-type RAS genes that were sensitive to MEK inhibitors. The best classifier will be used to predict response to their lead compounds (Way, GP, et al 2018).
Targeting anti-estrogen resistance in ER+ breast cancer
Dr. Todd Miller’s team screened a library of recombinant secreted microenvironmental proteins and found that fibroblast growth factor 2 (FGF2) is a potent mediator of resistance to anti-estrogens, mTORC1 inhibition, and PI3K inhibition in tissues associated with ER+ breast cancer. Phosphoproteomic analyses performed in partnership with Dr. Arminja Kettenbach identified ERK1/2 as a major output of FGF2 signaling, with consequent up-regulation of Cyclin D1 and down-regulation of BIM as mediators of drug resistance. FGF2-driven drug resistance in anti-estrogen-sensitive and -resistant models, including patient-derived xenografts, was reverted by neutralizing FGF2 or FGFRs. Statistical modeling by Dr. Eugene Demidenko revealed that FGF2-directed therapy synergized with anti-estrogen therapy in vivo. In collaboration with Dr. Chao Cheng, bioinformatic interrogation of a transcriptomic signature of FGF2 signaling in primary tumors independently predicted shorter recurrence-free survival. These findings delineate FGF2 signaling as a ligand-based drug resistance mechanism and highlight an underdeveloped aspect of precision oncology: characterizing and treating patients according to the constitution of their tumor microenvironment (Shee et al, 2018, J. Exp. Med.).
Dr. Miller’s team also established a novel platform for the study of dormant ER+ breast tumor cells and to test potential dormancy-targeted therapeutics in mice. They found that AMPK-mediated fatty acid oxidation drives the survival of ER+ breast cancer cells during estrogen deprivation therapy. Dr. Demidenko’s (CIR) statistical modeling of tumor growth data showed that treatment with the AMPK-activating diabetes drug metformin promoted survival of dormant tumor cells, while the AMPK inhibitor dorsomorphin and the fatty acid oxidation inhibitors etoxomir, perhexiline, and ranolazine induced tumor cell death (Hampsch et al, submitted). These findings have prompted development of a clinical trial by Drs. Miller and Gary Schwartz to test the safety and efficacy of the fatty acid oxidation inhibitor ranolazine (FDA-approved for angina) in combination with the anti-estrogen letrozole in patients with advanced ER+ breast cancer.
NOXA induction as a novel mechanism to inhibit MCL-1
The observation that microtubule disrupting agents such as vinca alkaloids can rapidly induce apoptosis in certain hematopoietic cell lines was first published by Dr. A. Eastman more than 15 years ago (Stadheim et al, 2001). This acute apoptosis has been shown to depend on the activation of c-Jun N-terminal kinase (JNK) and induction of the pro-apoptotic protein NOXA. This observation has now been translated into several clinical trials (see below). However, only a few leukemias (and not carcinomas) appear acutely sensitive to the monotherapy activity of microtubule disrupting agents. Dr. Eastman’s ongoing research has assessed the impact of a variety of putative BCL2 inhibitors (BH3 mimetics) on inhibition of BCL2 proteins. A comparison of multiple BH3 mimetics demonstrated that most actually work through inducing NOXA and not by directly inhibiting BCL2 proteins (Soderquist and Eastman 2016). One notable observation was that the putative BH3 mimetic gossypol (which in fact acts as an agonist of phospholipase A2) induces NOXA and can reverse the stroma-mediated resistance to the BCL2 inhibitor venetoclax (Soderquist et al 2013, 2014). Most recently, this research has been extended to carcinoma lines where AT-101 (the isomer of gossypol assessed clinically) has been shown to dramatically induce NOXA, and sensitize cells to other BCL2 inhibitors. In particular, AT-101 reduces the concentration of BCL-X inhibitors needed to kill cell lines, suggesting this combination might alleviate the neutropenia observed clinically with BCL-X inhibitors. Another BCL2 protein, Bfl-1, is up-regulated by NFkB, and this occurs frequently in melanoma, hence Dr. Eastman’s collaboration with Dr. Pellegrini to develop novel NFkB inhibitors.
Dietary fat remodels breast tumor structure, function, and gene expression
Current dogma asserts that (a) breast cancer cells rely on de novo synthesis of saturated fatty acids to facilitate proliferation, and (b) that tumor metabolism, including lipid synthesis and oxidation, is constitutively activated, and does not respond to dietary cues. Research in Dr. William Kinlaw’s laboratory contradicts these assertions (Kinlaw et al, 2016). Breast cancer cells avidly take up triglyceride-rich, very low-density lipoproteins (VLDL), using receptor-mediated endocytosis involving a specific heparan sulfate motif. Enforced overexpression of lipoprotein lipase grossly increased cellular lipid droplet accumulation, and cells responded with major alterations in expression of metabolism-related genes. The relevance of exogenous fat to breast cancer biology in vivo was assessed using human breast cancer xenografts (non-LPL-expressing, ER+ MCF7; or LPL-expressing, ER- MDA-MB-231) in mice fed diets with high or low saturated (SF) or polyunsaturated (PUF) fat. High SF stimulated tumor growth, but had minimal effects on plasma membrane phospholipid content and gene expression. In stark contrast, high PUF did not accelerate xenograft growth, but caused extensive remodeling of plasma membranes and significantly altered the expression of >5000 genes. Notably, PUF induced estrogen receptor 1 (ESR1) 38 fold, as well as transcription factors that drive the ESR1 gene (FOXA1, GATA3). Pathway and chromatin immunoprecipitation enrichment, in collaboration with Dr. Chao Cheng, showed induction of a large number of estrogen-responsive genes, confirming the functional significance of ESR1 induction. A related collaboration with Dr. Paul Baures (Keene State U) has generated a promising inhibitor of fatty acid synthase. The proapoptotic action of this compound is enhanced when lipid uptake is curtailed, indicating that targeting both pathways of lipid acquisition may be an effective therapeutic strategy. A collaboration with Dr. Lewis and the Clinical Pharmacology Shared Resource is investigating the in vivo pharmacokinetics of this compound as a precursor to assessing anticancer activity. Overall, the findings indicate that fat is taken up by breast cancer cells, and that exogenous fats differentially affect tumor structure and function, sharply contradicting current dogma in the field. Moreover, the unexpected linkage of dietary fat to ESR1 gene expression provides a potential mechanism for the association of fatty diets and obesity with breast cancer risk and prognosis.
Targeting obesity and cancer
Obesity is a known contributor to cancer, especially of the colon and breast, but pharmacologic and behavioral modification approaches for treatment are ineffectual. Dr. Craig Tomlinson has shown that the aryl hydrocarbon receptor (AHR) plays a key role in obesity. The AHR is a promiscuous, ligand-activated nuclear receptor primarily known for regulating genes involved in xenobiotic metabolism and T cell polarization. A collaborative study with Drs. Kinlaw and Demidenko demonstrated that Western diet-derived oxidized low density lipoproteins induced TLR2/4 signaling to initiate downstream signaling events through NF-κB that ultimately activated IDO1 in mouse models and a hepatocyte cell line. IDO1 metabolizes tryptophan to kynurenine (Kyn), a known AHR agonist. It is proposed that the sustained increases in Kyn-induced, AHR-mediated transcription, including the AHR-regulated Cyp1b1 gene, causes obesity. Loss of the Cyp1b1 gene in mice causes obesity resistance. Recently, they found that AHR inhibition both prevents and reverses diet-induced obesity in mice, and thus, the AHR may serve as a potent therapeutic target for the treatment of obesity (Moyer et al, 2016, 2017). A collaboration with Drs. Chamberlin and Demidenko resulted in a 2017-8 Synergy (CTSA) pilot grant to profile biomarkers in human adipose tissue and blood to determine whether AHR-based signaling in humans is similar to that of mice. The next step will be a Phase I clinical trial to test whether AHR antagonists can act as an effective therapy to reverse obesity in humans, and in turn, ameliorate obesity-associated diseases such as breast cancer. The link between breast cancer and AHR signaling is being further investigated in collaboration with Drs. Miller, Christensen, and Demidenko with funds from a 2018 Prouty pilot grant. They are testing the hypothesis that the AHR acts as a key signal transducer linking diet, gut microbiota, obesity, and breast tumor growth, and that inhibition of the AHR will ameliorate obesity and reduce tumor burden. The proposed studies will generate evidence describing a mechanistic link between diet, gut microbiota and breast cancer, and suggest potential therapeutic targets for cancer treatment.
3. Development of hypothesis-based cancer clinical trials
The Molecular Therapeutics Program continues to emphasize early-phase clinical trials as one of its major themes, with NCCC-initiated trials reflecting translation of research in the Molecular Therapeutics program. Program members have also focused on a variety of novel targeted therapies in cancer patients with hepatic or renal dysfunction, the effects of novel oncology therapeutics on the QTc interval, and combined modality therapies. To further enhance the translation of NCCC science, Drs. Eastman and Lewis have been major drivers of the Early-Phase Trials Cooperative Oncology Group (EPTCOG), whose mission is to develop teams of investigators to translate laboratory-based hypotheses into clinical trials. Examples of Dartmouth investigator-initiated trials, recently completed or ongoing, are described herein.
Biomarkers and therapeutic agents in high-grade gliomas
Dr. Arti Gaur, a new recruit to Molecular Therapeutics, is studying the molecular basis of gliomas with the aim of identifying a comprehensive panel of biomarkers to track disease and establish therapeutic agents and delivery mechanisms. Leveraging data obtained from an EPTCOG-funded study, Dr. Gaur received an Alliance Clinical Trials in Oncology Network award to establish a prospective, multi-center clinical trial to assess diagnostic and prognostic biomarkers, as well as biomarkers of treatment efficacy. Dr. Dragnev is the co-PI and Drs. Ronan and Tomlinson are co-investigators. Blood, tumor tissue and cerebrospinal fluid from consented patients are being assayed for expression of a panel of microRNAs and their targets. In addition to patients at NCCC, this clinical trial recently started recruiting patients at Tufts Medical Center, University of Vermont and Massachusetts General Hospital. Preliminary data demonstrate that a panel of microRNAs found in plasma correlates with tumor burden in glioma patients using as little as 20 µL of patient plasma collected pre- and post-surgical resection. This ongoing trial also provides a unique opportunity to rapidly test each patient’s tumor sample ex vivo for sensitivity to specific therapeutic agents, thus laying the foundation for translating specific anti-glioma therapies directly to the patient in the clinic. Additionally, Dr. Gaur in collaboration with Dr. Axel Scherer (Visiting Professor at Thayer) and Dr. Lewis is also developing innovative, in vivo wireless, nano scale, implantable devices for early detection of disease as well as regulated and targeted drug delivery. This collaboration was funded in 2017 by DARPA to assess whether the wireless diagnostic devices can detect a panel of biomarkers (physiological, metabolic, genomic and immune regulatory). Data generated by the EPTCOG funded study also established that anti-microRNA-10b treatment can ablate primary gliomas ex vivo. The wireless drug delivery system aims to develop spatially and temporally regulated anti-mir-10b treatment against gliomas. To further address in vivo drug delivery, Dr. Gaur recently received industry funding to study the pharmacokinetic and tissue distribution patterns of cell penetrating peptides and their anti-glioma conjugates in xenograft models of human gliomas.
The Chk1 inhibitor MK-8776 dramatically enhances sensitivity of tumors to gemcitabine
Combining DNA damaging agents with DNA checkpoint inhibitors is an emerging strategy to treat cancer. The combination of gemcitabine plus a Chk1 inhibitor (Chk1i) is particularly effective in preclinical models. Dr. Eastman has established that the underlying mechanism depends on Chk1i-mediated activation of dormant origins of replication, but as gemcitabine depletes deoxyribonucleotides, large regions of single-strand DNA result that exceed the protective capacity of the single-strand binding protein RPA, leading to nuclease attack and replication catastrophe. An important aspect of this drug combination is that greatest cell killing occurs when Chk1i is administered 24 h after gemcitabine. This schedule was first established in cell lines but was confirmed in xenograft models in collaboration with Drs. N. Khan and H. Hou. The primary rationale for this schedule is that gemcitabine arrests cells in S phase and, as more cells accumulate in S at 24 h, the addition of Chk1i at that time is more effective. This arrest was confirmed in the xenograft models and the schedule has been adopted in the majority of pharma-sponsored clinical trials with various Chk1i. Whether gemcitabine induces S phase arrest in human tumors in patients had not been previously established. Through collaboration with Drs. John Seigne and Lewis, a proof-of-concept clinical trial was performed to assess cell cycle perturbation in human bladder cancers. Tumor was obtained prior to and following intravenous 1000 mg/m2 gemcitabine administration in 6 patients, and strong S phase arrest was observed in all the tumors after 24 h (Montano et al, 2017). This study was funded by a multi-investigator grant from the NCCC/Hopeman Fund. While the development of MK-8776 has been shelved, they now have pilot funding from Sierra Oncology whose oral Chk1i, SRA737, is showing clinical promise.
The Wee1 inhibitor AZD1775
In contrast to Chk1i, which as a single agent is acutely cytotoxic to 15% of cell lines, Dr. Eastman has shown that the Wee1 inhibitor is effective on many more cell lines (Sakurikar et al, 2016). However, the underlying mechanism of action for both drugs is the activation of CDK2 in S phase cells. As an example of aligning pharmaceutical trials with our laboratory translational programs, Dr. Lewis has initiated a Phase I clinical pharmacology study with AZD1775 in patients with advanced solid tumors. This continues his interest in evaluating the effects of novel cancer therapeutics on drug metabolism and the cardiac action potential. This study investigates the hypothesis that (i) AZD1775 modulates the activity of CYP3A4/CYP1A2 and CYP2C19 and effects the pharmacokinetics of probe drug substrates for these drug metabolizing enzymes, and (ii) AZD1775 blocks the cardiac HERG channel, slowing the Ikr current and manifests as prolonging the cardiac QTc interval.
Novel, cell cycle-independent mechanisms of action of tubulin-targeting drugs
The ability of vinca alkaloids to induce acute, cell cycle phase independent, apoptosis is particularly evident in peripheral chronic lymphocytic leukemia (Bates et al 2013). The project, initially funded by an NCCC pilot grant, was converted into a 3-year grant from the Leukemia Lymphoma Society (PI Dr. Eastman). An important aspect of this grant was a proof-of-concept clinical trial whereby patients received vincristine, followed by analysis of NOXA and JNK in their peripheral CLL cells. Surprisingly, only marginal increase in JNK was observed but no induction of NOXA (Bates et al 2015). It was concluded that vincristine could not be administered at a sufficiently high dose to elicit these effects (it is limited by neurotoxicity). Ongoing research identified a novel colchicine-binding site drug BNC-105P that was far more potent than the vinca alkaloids (Bates et al 2016). Importantly, a phase I trial had already shown that BNC-105P could induce tubulin dissolution in circulating leukocytes at tolerated doses. Collaborating with Drs. Lewis (IND holder) and Lansigan, a Phase Ib clinical trial opened March 2018 (NCT03454165) to test the safety of the combination of BNC105P with ibrutinib and assess the molecular biomarkers that would indicate proof-of-concept of the tubulin targeted activity of BNC-105P. The first two CLL patient treated with BNC-105P are still receiving drug and are tolerating it well. This clinical trial is funded by grants from NCCC Hopeman foundation and EPTCOG.
Estrogen therapy for advanced ER+ breast cancer
Before anti-estrogens such as tamoxifen were developed to treat ER+ breast cancer, estrogen therapies were used; these therapies were effective to a similar extent for the treatment of metastatic ER+ breast cancer. Tumors frequently exhibit fluctuating sensitivities to both anti-estrogen and estrogen therapies. Dr. Miller has been leading an effort to understand mechanisms of sensitivity to estrogen therapy. In collaboration with Drs. Peter Kaufman and Gary Schwartz and the NCCC Comprehensive Breast Program, they initiated a “Phase II study of Pre-emptive OsciLLation of ER activitY levels through alternation of estradiol/anti-estrogen therapies prior to disease progression in ER+/HER2- metastatic breast cancer (POLLY)” (D14122). Seed funding for this trial was awarded by the NCCC Early-Phase Trials COG (EPTCOG). To support extensive preclinical and clinical studies emerging from this work, this team [including Drs. Kettenbach (proteomics), Cheng (bioinformatics), and Demidenko (biostatistics)] was subsequently awarded a Career Catalyst Research Grant from Susan G. Komen (CCR1533084), and an R01 grant from NCI (R01CA200994). The first POLLY patient attained a radiographic response to 17β-estradiol with a dramatic reduction in plasma CA15.3. After a year on study, a new lesion developed, which was biopsied and grafted into mice to attempt to make a PDX model. Six evaluable patients have been enrolled thus far (all at NCCC). The NCCC-initiated POLLY study is also open at Baystate Medical Center, MA, and under review by collaborators at Mayo Clinic and Pittsburgh.