Von Hippel-Lindau (VHL) gene mutations induce neural tissue hemangioblastomas, as well as highly vascularized clear cell renal cell carcinomas (ccRCCs). Pathological vessel remodeling arises from misregulation of HIFs and VEGF, among other genes. Variation in disease penetrance has long been recognized in relation to genotype. We show Vhl mutations also disrupt Notch signaling, causing mutation-specific vascular abnormalities, e.g., type 1 (null) vs. type 2B (murine G518A representing human R167Q). In conditional mutation retina vasculature, Vhl-null mutation (i.e., UBCCreER/+Vhlfl/fl) had little effect on initial vessel branching, but it severely reduced arterial and venous branching at later stages. Interestingly, this mutation accelerated arterial maturation, as observed in retina vessel morphology and aberrant α-smooth muscle actin localization, particularly in vascular pericytes. RNA sequencing analysis identified gene expression changes within several key pathways, including Notch and smooth muscle cell contractility. Notch inhibition failed to reverse later-stage branching defects but rescued the accelerated arterialization. Retinal vessels harboring the type 2B Vhl mutation (i.e., UBCCreER/+Vhlfl/2B) displayed stage-specific changes in vessel branching and an advanced progression toward an arterial phenotype. Disrupting Notch signaling in type 2B mutants increased both artery and vein branching and restored arterial maturation toward nonmutant levels. By revealing differential effects of the null and type 2B Vhl mutations on vessel branching and maturation, these data may provide insight into the variability of VHL-associated vascular changes — particularly the heterogeneity and aggressiveness in ccRCC vessel growth — and also suggest Notch pathway targets for treating VHL syndrome.
Alexandra Arreola, Laura Beth Payne, Morgan H. Julian, Aguirre A. de Cubas, Anthony B. Daniels, Sarah Taylor, Huaning Zhao, Jordan Darden, Victoria L. Bautch, W. Kimryn Rathmell, John C. Chappell
BACKGROUND. Constitutive activation of ERK1/2 occurs in various cancers, and its reactivation is a well-described resistance mechanism to MAPK inhibitors. ERK inhibitors may overcome the limitations of MAPK inhibitor blockade. The dual mechanism inhibitor SCH772984 has shown promising preclinical activity across various BRAFV600/RAS-mutant cancer cell lines and human cancer xenografts. METHODS. We have developed an orally bioavailable ERK inhibitor, MK-8353; conducted preclinical studies to demonstrate activity, pharmacodynamic endpoints, dosing, and schedule; completed a study in healthy volunteers (P07652); and subsequently performed a phase I clinical trial in patients with advanced solid tumors (MK-8353-001). In the P07652 study, MK-8353 was administered as a single dose in 10- to 400-mg dose cohorts, whereas in the MK-8353-001 study, MK-8353 was administered in 100- to 800-mg dose cohorts orally twice daily. Safety, tolerability, pharmacokinetics, pharmacodynamics, and antitumor activity were analyzed. RESULTS. MK-8353 exhibited comparable potency with SCH772984 across various preclinical cancer models. Forty-eight patients were enrolled in the P07652 study, and twenty-six patients were enrolled in the MK-8353-001 study. Adverse events included diarrhea (44%), fatigue (40%), nausea (32%), and rash (28%). Dose-limiting toxicity was observed in the 400-mg and 800-mg dose cohorts. Sufficient exposure to MK-8353 was noted that correlated with biological activity in preclinical data. Three of fifteen patients evaluable for treatment response in the MK-8353-001 study had partial response, all with BRAFV600-mutant melanomas. CONCLUSION. MK-8353 was well tolerated up to 400 mg twice daily and exhibited antitumor activity in patients with BRAFV600-mutant melanoma. However, antitumor activity was not particularly correlated with pharmacodynamic parameters. TRIAL REGISTRATION. ClinicalTrials.gov NCT01358331. FUNDING. Merck Sharp & Dohme Corp., a subsidiary of Merck & Co. Inc., and NIH (P01 CA168585 and R35 CA197633).
Stergios J. Moschos, Ryan J. Sullivan, Wen-Jen Hwu, Ramesh K. Ramanathan, Alex A. Adjei, Peter C. Fong, Ronnie Shapira-Frommer, Hussein A. Tawbi, Joseph Rubino, Thomas S. Rush III, Da Zhang, Nathan R. Miselis, Ahmed A. Samatar, Patrick Chun, Eric H. Rubin, James Schiller, Brian J. Long, Priya Dayananth, Donna Carr, Paul Kirschmeier, W. Robert Bishop, Yongqi Deng, Alan Cooper, Gerald W. Shipps, Blanca Homet Moreno, Lidia Robert, Antoni Ribas, Keith T. Flaherty
EBV infection is associated with a number of malignancies of clinical unmet need, including Hodgkin lymphoma, nasopharyngeal carcinoma, gastric cancer, and posttransplant lymphoproliferative disease (PTLD), all of which express the EBV protein latent membrane protein 2A (LMP2A), an antigen that is difficult to target by conventional antibody approaches. To overcome this, we utilized phage display technology and a structure-guided selection strategy to generate human T cell receptor–like (TCR-like) monoclonal antibodies with exquisite specificity for the LMP2A-derived nonamer peptide, C426LGGLLTMV434 (CLG), as presented on HLA-A*02:01. Our lead construct, clone 38, closely mimics the native binding mode of a TCR, recognizing residues at position P3–P8 of the CLG peptide. To enhance antitumor potency, we constructed dimeric T cell engaging bispecific antibodies (DiBsAb) of clone 38 and an affinity-matured version clone 38-2. Both DiBsAb showed potent antitumor properties in vitro and in immunodeficient mice implanted with EBV transformed B lymphoblastoid cell lines and human T cell effectors. Clone 38 DiBsAb showed a stronger safety profile compared with its affinity-matured variant, with no activity against EBV– tumor cell lines and a panel of normal tissues, and was less cross-reactive against HLA-A*02:01 cells pulsed with a panel of CLG-like peptides predicted from a proteomic analysis. Clone 38 was also shown to recognize the CLG peptide on other HLA-A*02 suballeles, including HLA-A*02:02, HLA-A*02:04, and HLA-A*02:06, allowing for its potential use in additional populations. Clone 38 DiBsAb is a lead candidate to treat EBV malignancies with one of the strongest safety profiles documented for TCR-like mAbs.
Mahiuddin Ahmed, Andres Lopez-Albaitero, Dmitry Pankov, Brian H. Santich, Hong Liu, Su Yan, Jingyi Xiang, Pei Wang, Aisha N. Hasan, Annamalai Selvakumar, Richard J. O’Reilly, Cheng Liu, Nai-Kong V. Cheung
Programmed cell death protein 1 (PD-1) inhibitors have efficacy in treating squamous cell carcinoma of the head and neck (SCCHN), but objective response rates are low. PD-1 ligand (PD-L1) expression alone is not considered a robust predictor of response and additional biomarkers are needed. This 3-year observational cohort followed 126 SCCHN patients treated with anti–PD-1/L1 therapy. Prior to treatment, 81 (64%) had targeted massively parallel tumor sequencing. Of these, 42 (52%) underwent fluorescence-activated cell sorting and PD-L1 immunohistochemistry for tumor immunoprofiling. Six (5%) complete responses (CRs) and 11 (9%) partial responses (PRs) were observed. Those treated with prior chemotherapy (98, 78%) versus only surgery and/or radiation had longer overall survival (OS) (10 vs. 3 months, P = 0.02). Smokers had a higher total mutational burden (TMB) (P = 0.01). Virus-positive patients had a lower TMB (P < 0.01) and improved OS (P = 0.02). Among virus-negative responders, NOTCH1 and SMARCA4 were more frequently mutated and frameshift events in tumor suppressor genes occurred more frequently (P = 0.03). Higher TMB and CD8+ T cell infiltrates predicted anti–PD-1/L1 benefit (P < 0.01, P < 0.01, respectively) among virus-negative tumors. TIM-3/LAG-3 coexpression with PD-1 was higher on T cells among nonresponders (P = 0.03 and 0.02, respectively). Somatic frameshift events in tumor suppressor genes and higher TMB among virus-negative SCCHN tumors predict anti–PD-1/L1 response.
Glenn J. Hanna, Patrick Lizotte, Megan Cavanaugh, Frank C. Kuo, Priyanka Shivdasani, Alexander Frieden, Nicole G. Chau, Jonathan D. Schoenfeld, Jochen H. Lorch, Ravindra Uppaluri, Laura E. MacConaill, Robert I. Haddad
Cancer stem cells (CSCs) — known to be resistant to genotoxic radiation and chemotherapy — are fundamental to therapy failure and cancer relapse. Here, we reveal that glioma CSCs are hypersensitive to radiation, but a temporal DNA repair mechanism converts the intrinsic sensitivity to genomic instability and treatment resistance. Transcriptome analysis identifies DNA-dependent protein kinase (DNA-PK) as a predominant DNA repair enzyme in CSCs. Notably, DNA-PK activity is suppressed after irradiation when ROS induce the dissociation of DNA-PKcs with Ku70/80, resulting in delayed DNA repair and radiosensitivity; subsequently, after ROS clearance, the accumulated DNA damage and robust activation of DNA-PK induce genomic instability, facilitated by Rad50-mediated cell-cycle arrest, leading to enhanced malignancy, CSC overgrowth, and radioresistance. Finally, we show a requisite in vivo role for DNA-PK in CSC-mediated radioresistance and glioma progression. These findings identify a time-sensitive mechanism controlling CSC resistance to DNA-damaging treatments and suggest DNA-PK/Rad50 as promising targets for CSC eradication.
Yanling Wang, Haineng Xu, Tianrun Liu, Menggui Huang, Param-Puneet Butter, Chunsheng Li, Lin Zhang, Gary D. Kao, Yanqing Gong, Amit Maity, Constantinos Koumenis, Yi Fan
Pancreatic cancer is characterized by nearly universal activating mutations in KRAS. Among other somatic mutations, TP53 is mutated in more than 75% of human pancreatic tumors. Genetically engineered mice have proven instrumental in studies of the contribution of individual genes to carcinogenesis. Oncogenic Kras mutations occur early during pancreatic carcinogenesis and are considered an initiating event. In contrast, mutations in p53 occur later during tumor progression. In our model, we recapitulated the order of mutations of the human disease, with p53 mutation following expression of oncogenic Kras. Further, using an inducible and reversible expression allele for mutant p53, we inactivated its expression at different stages of carcinogenesis. Notably, the function of mutant p53 changes at different stages of carcinogenesis. Our work establishes a requirement for mutant p53 for the formation and maintenance of pancreatic cancer precursor lesions. In tumors, mutant p53 becomes dispensable for growth. However, it maintains the altered metabolism that characterizes pancreatic cancer and mediates its malignant potential. Further, mutant p53 promotes epithelial-mesenchymal transition (EMT) and cancer cell invasion. This work generates new mouse models that mimic human pancreatic cancer and expands our understanding of the role of p53 mutation, common in the majority of human malignancies.
Heather K. Schofield, Jörg Zeller, Carlos Espinoza, Christopher J. Halbrook, Annachiara del Vecchio, Brian Magnuson, Tania Fabo, Ayse Ece Cali Daylan, Ilya Kovalenko, Ho-Joon Lee, Wei Yan, Ying Feng, Saadia A. Karim, Daniel M. Kremer, Chandan Kumar-Sinha, Costas A. Lyssiotis, Mats Ljungman, Jennifer P. Morton, Stefanie Galbán, Eric R. Fearon, Marina Pasca di Magliano
The production of the oncometabolite 2-hydroxyglutarate (2-HG) has been associated with c-MYC overexpression. c-MYC also regulates glutamine metabolism and drives progression of asymptomatic precursor plasma cell (PC) malignancies to symptomatic multiple myeloma (MM). However, the presence of 2-HG and its clinical significance in PC malignancies is unknown. By performing 13C stable isotope resolved metabolomics (SIRM) using U[13C6]Glucose and U[13C5]Glutamine in human myeloma cell lines (HMCLs), we show that 2-HG is produced in clonal PCs and is derived predominantly from glutamine anaplerosis into the TCA cycle. Furthermore, the 13C SIRM studies in HMCLs also demonstrate that glutamine is preferentially utilized by the TCA cycle compared with glucose. Finally, measuring the levels of 2-HG in the BM supernatant and peripheral blood plasma from patients with precursor PC malignancies such as smoldering MM (SMM) demonstrates that relatively elevated levels of 2-HG are associated with higher levels of c-MYC expression in the BM clonal PCs and with a subsequent shorter time to progression (TTP) to MM. Thus, measuring 2-HG levels in BM supernatant or peripheral blood plasma of SMM patients offers potential early identification of those patients at high risk of progression to MM, who could benefit from early therapeutic intervention.
Wilson I. Gonsalves, Vijay Ramakrishnan, Taro Hitosugi, Toshi Ghosh, Dragan Jevremovic, Tumpa Dutta, Dhananjay Sakrikar, Xuan-Mai Petterson, Linda Wellik, Shaji K. Kumar, K. Sreekumaran Nair
Anthracyclines such as doxorubicin are highly effective chemotherapy agents used to treat many common malignancies. However, their use is limited by cardiotoxicity. We previously identified visnagin as protecting against doxorubicin toxicity in cardiac but not tumor cells. In this study, we sought to develop more potent visnagin analogs in order to use these analogs as tools to clarify the mechanisms of visnagin-mediated cardioprotection. Structure-activity relationship studies were performed in a zebrafish model of doxorubicin cardiomyopathy. Movement of the 5-carbonyl to the 7 position and addition of short ester side chains led to development of visnagin analogs with 1,000-fold increased potency in zebrafish and 250-fold increased potency in mice. Using proteomics, we discovered that doxorubicin caused robust induction of Cytochrome P450 family 1 (CYP1) that was mitigated by visnagin and its potent analog 23. Treatment with structurally divergent CYP1 inhibitors, as well as knockdown of CYP1A, prevented doxorubicin cardiomyopathy in zebrafish. The identification of potent cardioprotective agents may facilitate the development of new therapeutic strategies for patients receiving cardiotoxic chemotherapy. Moreover, these studies support the idea that CYP1 is an important contributor to doxorubicin cardiotoxicity and suggest that modulation of this pathway could be beneficial in the clinical setting.
Aarti Asnani, Bahoui Zheng, Yan Liu, You Wang, Howard H. Chen, Anita Vohra, An Chi, Ivan Cornella-Taracido, Huijun Wang, Douglas G. Johns, David E. Sosnovik, Randall T. Peterson
Tumor microenvironments can promote stem cell maintenance, tumor growth, and therapeutic resistance, findings linked by the tumor-initiating cell hypothesis. Standard of care for glioblastoma (GBM) includes temozolomide chemotherapy, which is not curative, due, in part, to residual therapy-resistant brain tumor-initiating cells (BTICs). Temozolomide efficacy may be increased by targeting carbonic anhydrase 9 (CA9), a hypoxia-responsive gene important for maintaining the altered pH gradient of tumor cells. Using patient-derived GBM xenograft cells, we explored whether CA9 and CA12 inhibitor SLC-0111 could decrease GBM growth in combination with temozolomide or influence percentages of BTICs after chemotherapy. In multiple GBMs, SLC-0111 used concurrently with temozolomide reduced cell growth and induced cell cycle arrest via DNA damage in vitro. In addition, this treatment shifted tumor metabolism to a suppressed bioenergetic state in vivo. SLC-0111 also inhibited the enrichment of BTICs after temozolomide treatment determined via CD133 expression and neurosphere formation capacity. GBM xenografts treated with SLC-0111 in combination with temozolomide regressed significantly, and this effect was greater than that of temozolomide or SLC-0111 alone. We determined that SLC-0111 improves the efficacy of temozolomide to extend survival of GBM-bearing mice and should be explored as a treatment strategy in combination with current standard of care.
Nathaniel H. Boyd, Kiera Walker, Joshua Fried, James R. Hackney, Paul C. McDonald, Gloria A. Benavides, Raffaella Spina, Alessandra Audia, Sarah E. Scott, Catherine J. Libby, Anh Nhat Tran, Mark O. Bevensee, Corinne Griguer, Susan Nozell, G. Yancey Gillespie, Burt Nabors, Krishna P. Bhat, Eli E. Bar, Victor Darley-Usmar, Bo Xu, Emily Gordon, Sara J. Cooper, Shoukat Dedhar, Anita B. Hjelmeland
Primary myelofibrosis is a myeloproliferative neoplasm associated with significant morbidity and mortality, for which effective therapies are lacking. β-Arrestins are multifunctional adaptor proteins involved in developmental signaling pathways. One isoform, β-arrestin2 (βarr2), has been implicated in initiation and progression of chronic myeloid leukemia, another myeloproliferative neoplasm closely related to primary myelofibrosis. Accordingly, we investigated the relationship between βarr2 and primary myelofibrosis. In a murine model of MPLW515L-mutant primary myelofibrosis, mice transplanted with donor βarr2-knockout (βarr2–/–) hematopoietic stem cells infected with MPL-mutant retrovirus did not develop myelofibrosis, whereas controls uniformly succumbed to disease. Although transplanted βarr2–/– cells homed properly to marrow, they did not repopulate long-term due to increased apoptosis and decreased self-renewal of βarr2–/– cells. In order to assess the effect of acute loss of βarr2 in established primary myelofibrosis in vivo, we utilized a tamoxifen-induced Cre-conditional βarr2-knockout mouse. Mice that received Cre (+) donor cells and developed myelofibrosis had significantly improved survival compared with controls. These data indicate that lack of antiapoptotic βarr2 mediates marrow failure of murine hematopoietic stem cells overexpressing MPLW515L. They also indicate that βarr2 is necessary for progression of primary myelofibrosis, suggesting that it may serve as a novel therapeutic target in this disease.
Lindsay A.M. Rein, James W. Wisler, Jihee Kim, Barbara Theriot, LiYin Huang, Trevor Price, Haeyoon Yang, Minyong Chen, Wei Chen, Dorothy Sipkins, Yuri Fedoriw, Julia K.L. Walker, Richard T. Premont, Robert J. Lefkowitz
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