Molecular Cancer Therapeutics

Our medical research library holds 33 studies published in Molecular Cancer Therapeutics (2008–2026). Each entry links to the study's record on PubMed and, where there is one, to the publisher's page and a free full text. 33 have an abstract, the authors' own summary as PubMed records it: open "Abstract" to read it.

About the journal

• Publisher: American Association for Cancer Research, Inc
• Published: 2001 to the present, United States
• Language: English
• ISSN: 1535-7163 (print), 1538-8514 (electronic)
• Its record in the NLM Catalog

2020s

• JNJ-79032421, a Novel Membrane-Restricted Mesothelin-Targeting T Cell-Engaging Bispecific Antibody for the Treatment of Mesothelin-Positive Cancers. K. Smans, T. Nesspor, S. De Breucker, et al. 2026;25(10):1585-1598. PubMed · Publisher · Free full text

  Abstract

  Mesothelin (MSLN) is a cell membrane-anchored glycoprotein overexpressed in several cancers, including pancreatic cancer, ovarian cancer, and mesothelioma. MSLN is protease-cleaved at the membrane proximal region, releasing shed MSLN (sMSLN) into the tumor microenvironment, leaving behind a membrane-bound stub. sMSLN in the tumor microenvironment is hypothesized to create a "sink" that could limit tumor binding of MSLN-targeted anticancer therapies. We describe JNJ-79032421, a bispecific antibody (BsAb) targeting cluster of differentiation (CD) 3 on T cells and the membrane-restricted, non-shed region of full-length MSLN on cancer cells. Crystal structure analysis confirmed JNJ-79032421 binding to the membrane-restricted, non-shed C-terminal region of MSLN. Using Western blotting, enzyme-linked immunosorbent assay (ELISA), fluorescence-activated cell sorting (FACS), and immunohistochemistry (IHC), elevated levels of sMSLN were detected in blood, serosal fluids, and tumor tissue of patients and tended to increase with MSLN tumor expression. Binding and cytotoxicity of JNJ-79032421 against cancer cell lines were unaffected by the presence of sMSLN. In cancer cell lines and cell line-derived and patient-derived xenograft mouse models, increasing levels of MSLN expression led to increased JNJ-79032421 potency. In contrast, MSLNxCD3 BsAbs, binding of which is non-membrane-restricted, demonstrated a loss of cytotoxicity in the presence of sMSLN. This "sink" effect was most pronounced for high-affinity non-membrane-restricted BsAbs. Increases in CD45+ and CD8+ T-cell infiltration, as well as CD8+ T-cell activation, observed in xenograft tumor tissues were time-dependent and JNJ-79032421 dose-dependent. Overall, these data suggest that JNJ-79032421 may offer meaningful clinical activity by avoiding binding to sMSLN.

  ©2026 The Authors; Published by the American Association for Cancer Research.

• Co-Targeting BCL-xL with MCL-1 Induces Lethal Mitochondrial Dysfunction in Diffuse Mesothelioma. Y. Xu, C.G. Medina, D.R. Surman, et al. 2025;24(10):1640-1652. PubMed · Publisher · Free full text

  Abstract

  Diffuse mesothelioma is a rare but highly aggressive and treatment-resistant neoplasm with low survival rates. Effective therapeutic strategies are limited, and resistance to treatment is a major obstacle. Myeloid cell leukemia (MCL)-1 and B-cell leukemia (BCL)-xL are antiapoptotic B-cell lymphoma 2 (Bcl-2) family proteins that block cell-intrinsic apoptosis through interactions on the mitochondrial outer membrane which contribute to therapeutic resistance. We investigated whether B-cell homology domain3 profiles were consistent between intra-patient fresh tumor sample, patient-derived cells, and patient-derived xenografts (PDX) by B-cell homology domain-3 profiling; we observed striking consistency which enabled cross-model comparisons. Next, we co-targeted BCL-xl and MCL-1 and noted that the combination synergistically reduced cell viability and increased apoptosis. Mechanistically, BCL-xL inhibition affected the cells through both the canonical and the emerging noncanonical apoptotic pathways. BCL-xL induced mitochondrial depolarization which resulted in MCL-1 cellular dependency, rendering cells highly sensitive to MCL-1 inhibition. Next, we co-targeted BCL-xL and MCL-1 in vivo which induced synthetic lethality in PDX models within hours, implying that this approach is not a safe strategy for clinical development. However, targeting MCL-1, which exerts its antiapoptotic activity without non-apoptotic on-target effects, decreased the mitochondrial threshold for apoptosis and enhanced chemosensitivity without toxicity in PDX models. Our findings suggest that targeting the mitochondria via MCL-1 enhances the efficacy of chemotherapy but co-targeting two proteins in the Bcl-2 pathways results in synergistic lethality. These results will help define a safe clinical strategy to utilize Bcl-2-targeted therapy to undermine therapeutic resistance in patients with diffuse mesothelioma.

  ©2025 American Association for Cancer Research.

• Effects of Combined Therapeutic Targeting of AXL and ATR on Pleural Mesothelioma Cells. S. Hirai, T. Yamada, Y. Katayama, et al. 2024;23(2):212-222. PubMed · Publisher · Free full text

  Abstract

  Few treatment options exist for pleural mesothelioma (PM), which is a progressive malignant tumor. However, the efficacy of molecular-targeted monotherapy is limited, and further therapeutic strategies are warranted to treat PM. Recently, the cancer cell-cycle checkpoint inhibitors have attracted attention because they disrupt cell-cycle regulation. Here, we aimed to establish a novel combinational therapeutic strategy to inhibit the cell-cycle checkpoint kinase, ATR in PM cells. The siRNA screening assay showed that anexelekto (AXL) knockdown enhanced cell growth inhibition when exposed to ATR inhibitors, demonstrating the synergistic effects of the ATR and AXL combination in some PM cells. The AXL and ATR inhibitor combination increased cell apoptosis via the Bim protein and suppressed cell migration when compared with each monotherapy. The combined therapeutic targeting of AXL and ATR significantly delayed regrowth compared with monotherapy. Thus, optimal AXL and ATR inhibition may potentially improve the PM outcome.

  ©2023 The Authors; Published by the American Association for Cancer Research.

• Development of Highly Effective Anti-Mesothelin hYP218 Chimeric Antigen Receptor T Cells With Increased Tumor Infiltration and Persistence for Treating Solid Tumors. S. Tomar, J. Zhang, M. Khanal, et al. 2022;21(7):1195-1206. PubMed · Publisher · Free full text

  Abstract

  Mesothelin targeting CAR T cells have limited activity in patients. In this study, we sought to determine if efficacy of anti-mesothelin CAR T cells is dependent on the mesothelin epitopes that are recognized by them. To do so, we developed hYP218 (against membrane-proximal epitope) and SS1 (against membrane-distal epitope) CAR T cells. Their efficacy was assessed in vitro using mesothelin-positive tumor cell lines and in vivo in NSG mice with mesothelin-expressing ovarian cancer (OVCAR-8), pancreatic cancer (KLM-1), and mesothelioma patient-derived (NCI-Meso63) tumor xenografts. Persistence and tumor infiltration of CAR T cells was determined using flow cytometry. hYP218 CAR T cells killed cancer cells more efficiently than SS1 CAR T cells, with a two- to fourfold lower ET50 value (effector-to-target ratio for 50% killing of tumor cells). In mice with established tumors, single intravenous administration of hYP218 CAR T cells lead to improved tumor response and survival compared with SS1 CAR T cells, with complete regression of OVCAR-8 and NCI-Meso63 tumors. Compared with SS1 CAR T cells, there was increased peripheral blood expansion, persistence, and tumor infiltration of hYP218 CAR T cells in the KLM-1 tumor model. Persistence of hYP218 CAR T cells in treated mice led to antitumor immunity when rechallenged with KLM-1 tumor cells. Our results show that hYP218 CAR T cells, targeting mesothelin epitope close to cell membrane, are very effective against mesothelin-positive tumors and are associated with increased persistence and tumor infiltration. These results support its clinical development to treat patients with mesothelin-expressing cancers.

  ©2022 The Authors; Published by the American Association for Cancer Research.

• BRCA1/MAD2L1 Deficiency Disrupts the Spindle Assembly Checkpoint to Confer Vinorelbine Resistance in Mesothelioma. S. Busacca, L. O'Regan, A. Singh, et al. 2021;20(2):379-388. PubMed · Publisher

  Abstract

  Mesothelioma is a universally lethal cancer lacking effective therapy. The spindle poison vinorelbine exhibits clinical activity in the relapsed setting, and in preclinical models requires BRCA1 to initiate apoptosis. However, the mechanisms underlying this regulation and the clinical implications have not been explored. Here, we show that BRCA1 silencing abrogated vinorelbine-induced cell-cycle arrest, recruitment of BUBR1 to kinetochores, and apoptosis. BRCA1 silencing led to codepletion of MAD2L1 at the mRNA and protein levels consistent with its status as a transcriptional target of BRCA1 Silencing of MAD2L1 phenocopied BRCA1 and was sufficient to confer resistance to vinorelbine. This was recapitulated in cell lines selected for resistance to vinorelbine, which acquired loss of both BRCA1 and MAD2L1 expression. Following ex vivo vinorelbine in 20 primary tumor explants, apoptotic response rate was 59% in BRCA1/MAD2L1-positive explants compared with 0% in BRCA1/MAD2L1-negative explants. In 48 patients, BRCA1 and/or MAD2L1 loss of expression was not prognostic; however, in a subset of patients treated with vinorelbine, survival was shorter for patients lacking BRCA1/MAD2L1 expression compared with double-positive patients (5.9 vs. 36.7 months, P = 0.03). Our data implicate BRCA1/MAD2L1 loss as a putative predictive marker of resistance to vinorelbine in mesothelioma and warrant prospective clinical evaluation.

  ©2020 American Association for Cancer Research.

• Novel Humanized Mesothelin-Expressing Genetically Engineered Mouse Models Underscore Challenges in Delivery of Complex Therapeutics to Pancreatic Cancers. B. Hagerty, T.N. O'Sullivan, X. Zhang, et al. 2021;20(10):2082-2092. PubMed · Publisher · Free full text

  Abstract

  Antibody-based therapies designed for human use frequently fail to cross-react with the murine isoform of their target. Because of this problem, preclinical studies of antibody-based mesothelin (Msl)-targeted therapeutics in immunocompetent systems have been limited by the lack of suitable mouse models. Here, we describe two immunocompetent humanized mesothelin transgenic mouse lines that can act as tolerant hosts for C57Bl/6-syngeneic cell lines expressing the human isoform of mesothelin. Thyroid peroxidase (TPO) mice have thyroid-restricted human mesothelin expression. Mesothelin (Msl) mice express human mesothelin in the typical serosal membrane distribution and can additionally be utilized to assess on-target, off-tumor toxicity of human mesothelin-targeted therapeutics. Both transgenic strains shed human mesothelin into the serum like human mesothelioma and patients with ovarian cancer, and serum human mesothelin can be used as a blood-based surrogate of tumor burden. Using these models, we examined the on-target toxicity and antitumor activity of human mesothelin-targeted recombinant immunotoxins. We found that immunotoxin treatment causes acute and chronic histologic changes to serosal membranes in Msl mice, while human mesothelin-expressing thyroid follicular cells in TPO mice are resistant to immunotoxin despite excellent drug delivery. Furthermore, poor delivery of immunotoxin to syngeneic orthotopic human mesothelin-expressing pancreatic adenocarcinoma limits antitumor activity both alone and in combination with immune checkpoint inhibition. In summary, we have developed two high-fidelity, immunocompetent murine models for human cancer that allow for rigorous preclinical evaluation of human mesothelin-targeted therapeutics.

  ©2021 American Association for Cancer Research.

• Therapeutic Synergy in Esophageal Cancer and Mesothelioma Is Predicted by Dynamic BH3 Profiling. D.R. Surman, Y. Xu, M.J. Lee, et al. 2021;20(8):1469-1480. PubMed · Publisher · Free full text

  Abstract

  Approximately 20,000 patients per year are diagnosed with esophageal adenocarcinoma (EAC) and malignant pleural mesothelioma (MPM); fewer than 20% survive 5 years. Effective therapeutic strategies are limited although patients receive a combination of chemotherapeutics. These tumors harbor thousands of mutations that contribute to tumor development. Downstream of oncogenic driving mutations, altered tumor mitochondria promote resistance to apoptosis. Dynamic Bcl-2 homology-3 profiling (DBP) is a functional assay of live cells that identifies the mitochondrial proteins responsible for resistance to apoptosis. We hypothesized that DBP will predict which protein to target to overcome resistance thereby enhancing combinatorial therapy.DBP predicted that targeting either Mcl-1 or Bcl-xL increases the efficacy of the chemotherapeutic agent, cisplatin, whereas targeting Bcl-2 does not. We performed these assays by treating EAC and MPM cells with a combination of Bcl-2 homology-3 (BH3) mimetics and cisplatin. Following treatments, we performed efficacy assessments including apoptosis assays, IC50 calculations, and generation of a combinatorial index. DBP confirmed that targeting mitochondria with BH3 mimetics alters the threshold of apoptosis. These apoptotic effects were abolished when the mitochondrial pathway was disrupted. We validated our findings by developing knockdown models of antiapoptotic proteins Mcl-1, Bcl-xL, and the mitochondrial effector proteins Bax/Bak. Knockdown of Mcl-1 or Bcl-xL recapitulated the results of BH3 mimetics. In addition, we report an approach for BH3 profiling directly from patient tumor samples. We demonstrate that the DBP assay on living tumor cells measures the dynamic changes of resistance mechanisms, assesses response to combinatorial therapy, and provides results in a clinically feasible time frame.

  ©2021 The Authors; Published by the American Association for Cancer Research.

• CRISPR Screening Identifies WEE1 as a Combination Target for Standard Chemotherapy in Malignant Pleural Mesothelioma. D. Xu, S.Q. Liang, H. Yang, et al. 2020;19(2):661-672. Case report PubMed · Publisher

  Abstract

  Malignant pleural mesothelioma (MPM) is an aggressive cancer with dismal prognosis, largely due to poor response rates to and rapid relapse after first-line pemetrexed (MTA)/cisplatin chemotherapy. A better understanding of the molecular mechanisms underlying chemotherapy sensitivity and duration represents a significant but still unmet clinical need. In this study, we reported on a kinome CRISPR/Cas9 knockout screen that identified several G2-M checkpoint kinases, including WEE1, whose loss of function sensitizes MPM cells to standard chemotherapy. We further showed that deregulation of the G2-M checkpoint contributes to chemotherapy resistance, and that WEE1 inhibition synergizes with cisplatin/MTA, leading to enhanced MPM cell death in vitro and potent antitumor effects in vivo Mechanistically, WEE1 blockage overrides chemotherapy-induced G2-M cell-cycle arrest and promotes premature mitotic entry, which causes DNA damage accumulation and ultimately apoptosis. Our results suggest a new therapeutic combination for MPM, and support the application of CRISPR/Cas9-based functional genomics in identifying novel therapeutic targets to potentiate existing cancer therapies.

  ©2019 American Association for Cancer Research.

• Functional Genomic Screen in Mesothelioma Reveals that Loss of Function of BRCA1-Associated Protein 1 Induces Chemoresistance to Ribonucleotide Reductase Inhibition. A. Okonska, S. Bühler, V. Rao, et al. 2020;19(2):552-563. PubMed · Publisher

  Abstract

  Loss of function of BRCA1-associated protein 1 (BAP1) is observed in about 50% of malignant pleural mesothelioma (MPM) cases. The aim of this study was to investigate whether this aspect could be exploited for targeted therapy. A genetically engineered model was established expressing either functional or nonfunctional BAP1, and whole-genome siRNA synthetic lethality screens were performed assessing differentially impaired survival between the two cell lines. The whole-genome siRNA screen unexpectedly revealed 11 hits (FDR < 0.05) that were more cytotoxic to BAP1-proficient cells. Two actionable targets, ribonucleotide reductase (RNR) catalytic subunit M1 (RRM1) and RNR regulatory subunit M2 (RRM2), were validated. In line with the screen results, primary mesothelioma (BAP1 +/-) overexpressing BAP1 C91A (catalytically dead mutant) was more resistant to RNR inhibition, while BAP1 knockdown in the BAP1-proficient cell lines rescued the cells from their vulnerability to RNR depletion. Gemcitabine and hydroxyurea were more cytotoxic in BAP1-proficient cell line-derived spheroids compared with BAP1 deficient. Upregulation of RRM2 upon gemcitabine and hydroxyurea treatment was more profound in BAP1 mut/del cell lines. Increased lethality mediated by RNR inhibition was observed in NCI-H2452 cells reconstituted with BAP1-WT but not with BAP1 C91A. Upregulation of RRM2 in NCI-H2452-BAP1 WT spheroids was modest compared with control or C91A mutant. Together, we found that BAP1 is involved in the regulation of RNR levels during replication stress. Our observations reveal a potential clinical application where BAP1 status could serve as predictive or stratification biomarker for RNR inhibition-based therapy in MPM.

  ©2019 American Association for Cancer Research.

• Targeting Multiple EGFR-expressing Tumors with a Highly Potent Tumor-selective Antibody-Drug Conjugate. M.G. Anderson, H.D. Falls, M.J. Mitten, et al. 2020;19(10):2117-2125. PubMed · Publisher

  Abstract

  ABBV-321 (serclutamab talirine), a next-generation EGFR-targeted antibody-drug conjugate (ADC) incorporates a potent pyrrolobenzodiazepine (PBD) dimer toxin conjugated to the EGFR-targeting ABT-806 affinity-matured AM1 antibody. ABBV-321 follows the development of related EGFR-targeted ADCs including depatuxizumab mafodotin (depatux-m, ABT-414), ABT-806 conjugated to monomethyl auristatin F (MMAF), and ABBV-221 (losatuxizumab vedotin), AM1 antibody conjugated to monomethyl auristatin E (MMAE). The distinct tumor selectivity of ABBV-321 differentiates it from many previous highly active antibody PBD conjugates that lack a therapeutic window. Potency of the PBD dimer, combined with increased binding of AM1 to EGFR-positive tumor cells, opens the possibility to target a wide array of tumors beyond those with high levels of EGFR overexpression or amplification, including those insensitive to auristatin-based ADCs. ABBV-321 exhibits potent antitumor activity in cellular and in vivo studies including xenograft cell line and patient-derived xenograft glioblastoma, colorectal, lung, head and neck, and malignant mesothelioma tumor models that are less sensitive to depatux-m or ABBV-221. Combination studies with ABBV-321 and depatux-m suggest a promising treatment option permitting suboptimal, and potentially better tolerated, doses of both ADCs while providing improved potency. Collectively, these data suggest that ABBV-321 may offer an extended breadth of efficacy relative to other EGFR ADCs while extending utility to multiple EGFR-expressing tumor indications. Despite its highly potent PBD dimer payload, the tumor selectivity of ABBV-321, coupled with its pharmacology, toxicology, and pharmacokinetic profiles, support continuation of ongoing phase I clinical trials in patients with advanced EGFR-expressing malignancies.

  ©2020 American Association for Cancer Research.

2010s

• Loss of NF2 Induces TGFβ Receptor 1-mediated Noncanonical and Oncogenic TGFβ Signaling: Implication of the Therapeutic Effect of TGFβ Receptor 1 Inhibitor on NF2 Syndrome. J.H. Cho, A.Y. Oh, S. Park, et al. 2018;17(11):2271-2284. PubMed · Publisher

  Abstract

  Neurofibromatosis type 2 (NF2) syndrome is a very rare human genetic disease, and there has been no proper treatment for it until now. In our recent study, it has been reported that the loss of NF2 activates MAPK signaling through reduction of RKIP in a mesothelioma model. Here, we show that loss of NF2 induces reduction of the TGFβ receptor 2 (TβR2) expression, and an overwhelming expression of TGFβ receptor 1 (TβR1) is activated by physical stimuli such as pressure or heavy materials. Activated TβR1 induces the phosphorylation and degradation of RKIP. RKIP reduction consequently results in MAPK activation as well as Snail-mediated p53 suppression and occurrence of EMT in NF2-deficient cells by physical stimuli. Thus, TβR1 kinase inhibitors restore cell differentiation and induce growth suppression in NF2-deficient Schwannoma cell line and MEF. Moreover, TEW7197, a specific TβR1 kinase inhibitor, reduces tumor formation in the NF2-model mouse (Postn-Cre;NF2f/f). Gene expression profiling reveals that TEW7197 treatment induces the expression of lipid metabolism-related gene set, such as NF2-restored cells in HEI-193 (NF2-deficient Schwannoma). Our results indicate that reduction or deletion of TβR2 or NF2 induces the TβR1-mediated oncogenic pathway, and therefore inhibition of the unbalanced TGFβ signaling is a putative strategy for NF2-related cancers (NF2 syndrome and mesothelioma) and TβR2-mutated advanced cancers. Mol Cancer Ther; 17(11); 2271-84. ©2018 AACR.

  ©2018 American Association for Cancer Research.

• Combined Inhibition of NEDD8-Activating Enzyme and mTOR Suppresses NF2 Loss-Driven Tumorigenesis. J. Cooper, Q. Xu, L. Zhou, et al. 2017;16(8):1693-1704. PubMed · Publisher · Free full text

  Abstract

  Inactivation of NF2/Merlin causes the autosomal-dominant cancer predisposition syndrome familial neurofibromatosis type 2 (NF2) and contributes to the development of malignant pleural mesothelioma (MPM). To develop a targeted therapy for NF2-mutant tumors, we have exploited the recent realization that Merlin loss drives tumorigenesis by activating the E3 ubiquitin ligase CRL4DCAF1, thereby inhibiting the Hippo pathway component Lats. Here, we show that MLN4924, a NEDD8-activating enzyme (NAE) inhibitor, suppresses CRL4DCAF1 and attenuates activation of YAP in NF2-mutant tumor cells. In addition, MLN4924 sensitizes MPM to traditional chemotherapy, presumably as a result of collateral inhibition of cullin-RING ubiquitin ligases (CRL) involved in DNA repair. However, even in combination with chemotherapy, MLN4924 does not exhibit significant preclinical activity. Further analysis revealed that depletion of DCAF1 or treatment with MLN4924 does not affect mTOR hyperactivation in NF2-mutant tumor cells, suggesting that loss of Merlin activates mTOR independently of CRL4DCAF1 Intriguingly, combining MLN4924 with the mTOR/PI3K inhibitor GDC-0980 suppresses the growth of NF2-mutant tumor cells in vitro as well as in mouse and patient-derived xenografts. These results provide preclinical rationale for the use of NAE inhibitors in combination with mTOR/PI3K inhibitors in NF2-mutant tumors. Mol Cancer Ther; 16(8); 1693-704. ©2017 AACR.

  ©2017 American Association for Cancer Research.

• Preclinical Efficacy of an Antibody-Drug Conjugate Targeting Mesothelin Correlates with Quantitative 89Zr-ImmunoPET. A.G. Terwisscha van Scheltinga, A. Ogasawara, G. Pacheco, et al. 2017;16(1):134-142. PubMed · Publisher

  Abstract

  Antibody-drug conjugates (ADC) use monoclonal antibodies (mAb) as vehicles to deliver potent cytotoxic drugs selectively to tumor cells expressing the target. Molecular imaging with zirconium-89 (89Zr)-labeled mAbs recapitulates similar targeting biology and might help predict the efficacy of these ADCs. An anti-mesothelin antibody (AMA, MMOT0530A) was used to make comparisons between its efficacy as an ADC and its tumor uptake as measured by 89Zr immunoPET imaging. Mesothelin-targeted tumor growth inhibition by monomethyl auristatin E (MMAE), ADC AMA-MMAE (DMOT4039A), was measured in mice bearing xenografts of ovarian cancer OVCAR-3×2.1, pancreatic cancers Capan-2, HPAC, AsPC-1, and HPAF-II, or mesothelioma MSTO-211H. Ex vivo analysis of mesothelin expression was performed using immunohistochemistry. AMA-MMAE showed the greatest growth inhibition in OVCAR-3×2.1, Capan-2, and HPAC tumors, which showed target-specific tumor uptake of 89Zr-AMA. The less responsive xenografts (AsPC-1, HPAF-II, and MSTO-211H) did not show 89Zr-AMA uptake despite confirmed mesothelin expression. ImmunoPET can demonstrate the necessary delivery, binding, and internalization of an ADC antibody in vivo and this correlates with the efficacy of mesothelin-targeted ADC in tumors vulnerable to the cytotoxic drug delivered. Mol Cancer Ther; 16(1); 134-42. ©2016 AACR.

  ©2016 American Association for Cancer Research.

• Antagonizing the Hedgehog Pathway with Vismodegib Impairs Malignant Pleural Mesothelioma Growth In Vivo by Affecting Stroma. M. Meerang, K. Bérard, E. Felley-Bosco, et al. 2016;15(5):1095-105. PubMed · Publisher

  Abstract

  An autocrine-driven upregulation of the Hedgehog (Hh) signaling pathway has been described in malignant pleural mesothelioma (MPM), in which the ligand, desert Hh (DHH), was produced from tumor cells. However, our investigation revealed that the Hh pathway is activated in both tumor and stroma of MPM tumor specimens and an orthotopic immunocompetent rat MPM model. This was demonstrated by positive immunohistochemical staining of Glioma-associated oncogene 1 (GLI1) and Patched1 (PTCH1) in both tumor and stromal fractions. DHH was predominantly expressed in the tumor fractions. To further investigate the role of the Hh pathway in MPM stroma, we antagonized Hh signaling in the rat model of MPM using a Hh antagonist, vismodegib, (100 mg/kg orally). Daily treatment with vismodegib efficiently downregulated Hh target genes Gli1, Hedgehog Interacting Protein (Hhip), and Ptch1, and caused a significant reduction of tumor volume and tumor growth delay. Immunohistochemical analyses revealed that vismodegib treatment primarily downregulated GLI1 and HHIP in the stromal compartment along with a reduced expression of previously described fibroblast Hh-responsive genes such as Fibronectin (Fn1) and Vegfa Primary cells isolated from the rat model cultured in 3% O2 continued to express Dhh but did not respond to vismodegib in vitro However, culture supernatant from these cells stimulated Gli1, Ptch1, and Fn1 expression in mouse embryonic fibroblasts, which was suppressed by vismodegib. Our study provides new evidence regarding the role of Hh signaling in MPM stroma in the maintenance of tumor growth, emphasizing Hh signaling as a treatment target for MPM. Mol Cancer Ther; 15(5); 1095-105. ©2016 AACR.

  ©2016 American Association for Cancer Research.

• Genomic Landscape of Malignant Mesotheliomas. S. Kato, B.N. Tomson, T.P. Buys, et al. 2016;15(10):2498-2507. PubMed · Publisher

  Abstract

  Understanding the genomic landscape of malignant mesothelioma may identify novel molecular drivers of this ultra-rare disease, which can lead to an expanded roster of targeted therapies and clinical trial options for patients with mesothelioma. We examined the molecular profiles of 42 patients with malignant mesothelioma (including pleural, peritoneal, and pericardial) that were referred by clinicians to be tested in a Clinical Laboratory Improvement Amendments (CLIA) laboratory using next-generation sequencing (NGS; 182 or 236 genes). Among 42 patients, there were 116 alterations, with 92 being distinct. The number of genomic alterations per patient ranged from 1 to 5 (median = 3). No two patients had identical molecular portfolios. The most common aberrations were in BAP1 (BRCA1-associated protein 1; 47.6% [20/42]), NF2 (38.1% [16/42]), and CDKN2A/B (loss) (35.7% [15/42]). BAP1 alterations and CDKN2A/B loss were associated with pleural mesothelioma (OR 3.4, P = 0.059 [BAP1] [trend]; OR 5.8, P = 0.01 [CDKN2A/B]). All 42 patients had a molecular abnormality that was potentially actionable (median = three actionable alterations per patient; range, 1 to 5), and, in 40 patients (95.2%), a drug approved by the FDA was applicable. In conclusion, each individual with malignant mesothelioma harbored a unique set of genomic aberrations, suggesting that NGS-based profiling of patients will be needed if patients are to be optimally matched to cognate treatments. All 42 patients had at least one alteration that was, in theory, pharmacologically tractable. Mol Cancer Ther; 15(10); 2498-507. ©2016 AACR.

  ©2016 American Association for Cancer Research.

• Trabectedin Is Active against Malignant Pleural Mesothelioma Cell and Xenograft Models and Synergizes with Chemotherapy and Bcl-2 Inhibition In Vitro. M.A. Hoda, C. Pirker, Y. Dong, et al. 2016;15(10):2357-2369. PubMed · Publisher

  Abstract

  Malignant pleural mesothelioma (MPM) is characterized by widespread resistance to systemic therapy. Trabectedin is an antineoplastic agent targeting both the malignant cells and the tumor microenvironment that has been approved for the treatment of advanced soft tissue sarcoma and ovarian cancer. In this preclinical study, we evaluated the antineoplastic potential of trabectedin as a single agent and in drug combination approaches in human MPM. Therefore, we utilized an extended panel of MPM cell lines (n = 6) and primary cell cultures from surgical MPM specimens (n = 13), as well as nonmalignant pleural tissue samples (n = 2). Trabectedin exerted a dose-dependent cytotoxic effect in all MPM cell cultures in vitro when growing as adherent monolayers or nonadherent spheroids with IC50 values ≤ 2.6 nmol/L. Nonmalignant mesothelial cells were significantly less responsive. The strong antimesothelioma activity was based on cell-cycle perturbation and apoptosis induction. The activity of trabectedin against MPM cells was synergistically enhanced by coadministration of cisplatin, a drug routinely used for systemic MPM treatment. Comparison of gene expression signatures indicated an inverse correlation between trabectedin response and bcl-2 expression. Accordingly, bcl-2 inhibitors (Obatoclax, ABT-199) markedly synergized with trabectedin paralleled by deregulated expression of the bcl-2 family members bcl-2, bim, bax, Mcl-1, and bcl-xL as a consequence of trabectedin exposure. In addition, trabectedin exerted significant antitumor activity against an intraperitoneal MPM xenograft model. Together, these data suggest that trabectedin exerts strong activity in MPM and synergizes with chemotherapy and experimental bcl-2 inhibitors in vitro Thus, it represents a promising new therapeutic option for MPM. Mol Cancer Ther; 15(10); 2357-69. ©2016 AACR.

  ©2016 American Association for Cancer Research.

• CD30 is a potential therapeutic target in malignant mesothelioma. S. Dabir, A. Kresak, M. Yang, et al. 2015;14(3):740-6. PubMed · Publisher · Free full text

  Abstract

  CD30 is a cytokine receptor belonging to the TNF superfamily (TNFRSF8) that acts as a regulator of apoptosis. The presence of CD30 antigen is important in the diagnosis of Hodgkin disease and anaplastic large cell lymphoma. There have been sporadic reports of CD30 expression in nonlymphoid tumors, including malignant mesothelioma. Given the remarkable success of brentuximab vedotin, an antibody-drug conjugate directed against CD30 antigen, in lymphoid malignancies, we undertook a study to examine the incidence of CD30 in mesothelioma and to investigate the ability to target CD30 antigen in mesothelioma. Mesothelioma tumor specimens (N = 83) were examined for CD30 expression by IHC. Positive CD30 expression was noted in 13 mesothelioma specimens, primarily those of epithelial histology. There was no significant correlation of CD30 positivity with tumor grade, stage, or survival. Examination of four mesothelioma cell lines (H28, H2052, H2452, and 211H) for CD30 expression by both FACS analysis and confocal microscopy showed that CD30 antigen localized to the cell membrane. Brentuximab vedotin treatment of cultured mesothelioma cells produced a dose-dependent decrease in cell growth and viability at clinically relevant concentrations. Our studies validate the presence of CD30 antigen in a subgroup of epithelial-type mesothelioma tumors and indicate that selected mesothelioma patients may derive benefit from brentuximab vedotin treatment.

  ©2015 American Association for Cancer Research.

• Recombinant Immunotoxin with T-cell Epitope Mutations That Greatly Reduce Immunogenicity for Treatment of Mesothelin-Expressing Tumors. R. Mazor, J. Zhang, L. Xiang, et al. 2015;14(12):2789-96. PubMed · Publisher · Free full text

  Abstract

  SS1P is a recombinant immunotoxin (RIT) that targets mesothelin. It consists of an antimesothelin Fv fused to a portion of Pseudomonas exotoxin A. In clinical studies, it has produced dramatic responses in patients with advanced mesothelioma, when combined with immunosuppressive therapy so that several treatment cycles could be given. Otherwise its activity is limited by its immunogenicity. In this work, we describe the development and characterization of LMB-T20, a highly potent RIT targeted at mesothelin-expressing cancers with low immunogenicity due to removal of its eight T-cell epitopes. LMB-T20 was more active than SS1P when tested on four different mesothelin-expressing cell lines as well as on cells obtained from patients with mesothelioma. It also has potent antitumor activity in mice, and has reduced immunogenicity as measured by cytokine secretion assays. In conclusion, LMB-T20 is a favorable candidate for evaluation in clinical trials due to its reduced immunogenicity and excellent activity.

  ©2015 American Association for Cancer Research.

• Activation of Nrf2 pathways correlates with resistance of NSCLC cell lines to CBP501 in vitro. N. Mine, S. Yamamoto, D.W. Kufe, et al. 2014;13(9):2215-25. PubMed · Publisher

  Abstract

  CBP501 is an anticancer drug candidate that was investigated in two randomized phase II clinical trials for patients with nonsquamous non-small cell lung cancer (NSCLC) and malignant pleural mesothelioma (MPM). CBP501 has been shown to have two mechanisms of action, namely calmodulin modulation and G2 checkpoint abrogation. Here, we searched for a biomarker to predict sensitivity to CBP501. Twenty-eight NSCLC cell lines were classified into two subgroups, CBP501-sensitive and -insensitive, by quantitatively analyzing the cis-diamminedichloro-platinum (II) (CDDP)-enhancing activity of CBP501 through treatments with short-term (1 hour) coexposure to CDDP and CBP501 or to either alone. Microarray analysis was performed on these cell lines to identify gene expression patterns that correlated with CBP501 sensitivity. We found that multiple nuclear factor erythroid-2-related factor 2 (Nrf2) target genes showed high expression in CBP501-insensitive cell lines. Western blot and immunocytochemical analysis for Nrf2 in NSCLC cell lines also indicated higher protein level in CBP501-insensitive cell lines. Moreover, CBP501 sensitivity is modulated by silencing or sulforaphane-induced overexpression of Nrf2. These results indicate that Nrf2 transcription factor is a potential candidate as a biomarker for resistance to CBP501. This study might help to identify those subpopulations of patients who would respond well to the CBP501 and CDDP combination treatment of NSCLC.

  ©2014 American Association for Cancer Research.

• An antimesothelin-monomethyl auristatin e conjugate with potent antitumor activity in ovarian, pancreatic, and mesothelioma models. S.J. Scales, N. Gupta, G. Pacheco, et al. 2014;13(11):2630-40. PubMed · Publisher

  Abstract

  Mesothelin (MSLN) is an attractive target for antibody-drug conjugate therapy because it is highly expressed in various epithelial cancers, with normal expression limited to nondividing mesothelia. We generated novel antimesothelin antibodies and conjugated an internalizing one (7D9) to the microtubule-disrupting drugs monomethyl auristatin E (MMAE) and MMAF, finding the most effective to be MMAE with a lysosomal protease-cleavable valine-citrulline linker. The humanized (h7D9.v3) version, αMSLN-MMAE, specifically targeted mesothelin-expressing cells and inhibited their proliferation with an IC50 of 0.3 nmol/L. Because the antitumor activity of an antimesothelin immunotoxin (SS1P) in transfected mesothelin models did not translate to the clinic, we carefully selected in vivo efficacy models endogenously expressing clinically relevant levels of mesothelin, after scoring mesothelin levels in ovarian, pancreatic, and mesothelioma tumors by immunohistochemistry. We found that endogenous mesothelin in cancer cells is upregulated in vivo and identified two suitable xenograft models for each of these three indications. A single dose of αMSLN-MMAE profoundly inhibited or regressed tumor growth in a dose-dependent manner in all six models, including two patient-derived tumor xenografts. The robust and durable efficacy of αMSLN-MMAE in preclinical models of ovarian, mesothelioma, and pancreatic cancers justifies the ongoing phase I clinical trial.

  ©2014 American Association for Cancer Research.

• Anetumab ravtansine: a novel mesothelin-targeting antibody-drug conjugate cures tumors with heterogeneous target expression favored by bystander effect. S. Golfier, C. Kopitz, A. Kahnert, et al. 2014;13(6):1537-48. PubMed · Publisher

  Abstract

  Mesothelin is a tumor differentiation antigen frequently overexpressed in tumors such as mesothelioma, ovarian, pancreatic, and lung adenocarcinomas while showing limited expression in nonmalignant tissues. Mesothelin is therefore an attractive target for cancer therapy using antibody-drug conjugates (ADC). This study describes the detailed characterization of anetumab ravtansine, here referred to as BAY 94-9343, a novel ADC consisting of a human anti-mesothelin antibody conjugated to the maytansinoid tubulin inhibitor DM4 via a disulfide-containing linker. Binding properties of the anti-mesothelin antibody were analyzed using surface plasmon resonance, immunohistochemistry, flow cytometry, and fluorescence microscopy. Effects of BAY 94-9343 on cell proliferation were first studied in vitro and subsequently in vivo using subcutaneous, orthotopic, and patient-derived xenograft tumor models. The antibody binds to human mesothelin with high affinity and selectivity, thereby inducing efficient antigen internalization. In vitro, BAY 94-9343 demonstrated potent and selective cytotoxicity of mesothelin-expressing cells with an IC(50) of 0.72 nmol/L, without affecting mesothelin-negative or nonproliferating cells. In vivo, BAY 94-9343 localized specifically to mesothelin-positive tumors and inhibited tumor growth in both subcutaneous and orthotopic xenograft models. In addition, BAY 94-9343 was able to induce a bystander effect on neighboring mesothelin-negative tumor cells. Antitumor efficacy of BAY 94-9343 correlated with the amount of mesothelin expressed and was generally superior to that of standard-of-care regimen resulting in complete tumor eradication in most of the models. BAY 94-9343 is a selective and highly potent ADC, and our data support its development for the treatment of patients with mesothelin-expressing tumors.

  ©2014 American Association for Cancer Research.

• Antitumor effects of immunotoxins are enhanced by lowering HCK or treatment with SRC kinase inhibitors. X.F. Liu, L. Xiang, D.J. FitzGerald, et al. 2014;13(1):82-9. PubMed · Publisher · Free full text

  Abstract

  Recombinant immunotoxins (RIT) are agents being developed for cancer treatment. They are composed of an Fv that binds to a cancer cell, fused to a 38-kDa fragment of Pseudomonas exotoxin A. SS1P is a RIT that targets mesothelin, a protein expressed on mesothelioma as well as pancreatic, ovarian, lung, and other cancers. Because the protein tyrosine kinase family regulates a variety of cellular processes and pathways, we hypothesized that tyrosine kinases might regulate susceptibility to immunotoxin killing. To investigate their role, we used siRNAs to lower the level of expression of the 88 known tyrosine kinases. We identified five tyrosine kinases, INSR, HCK, SRC, PDGFRβ, and BMX that enhance the activity of SS1P when their level of expression is lowered by siRNAs. We further investigated the Src family member HCK in this study. Knocking down of SRC slightly increased SS1P killing in A431/H9 cells, but knocking down HCK substantially enhanced killing by SS1P. We investigated the mechanism of enhancement and found that HCK knockdown enhanced SS1P cleavage by furin and lowered levels of Mcl-1 and raised Bax. We then found that Src inhibitors mimic the stimulatory effect of HCK knockdown; both SU6656 and SKI-606 (bosutinib) enhanced immunotoxin killing of mesothelin-expressing cells by SS1P and CD22-expressing cells by HA22 (moxetumomab pasudotox). SU6656 also enhanced the antitumor effects of SS1P and HA22 in mouse xenograft tumor models. Our data suggest that the combination of immunotoxin with tyrosine kinase inhibitors may be an effective way to treat some cancers.

• A human single-domain antibody elicits potent antitumor activity by targeting an epitope in mesothelin close to the cancer cell surface. Z. Tang, M. Feng, W. Gao, et al. 2013;12(4):416-26. PubMed · Publisher · Free full text

  Abstract

  Monoclonal antibodies against mesothelin are being evaluated for the treatment of mesothelioma and multiple forms of cancers, and show great promise for clinical development for solid cancers. Antibodies against mesothelin have been shown to act via immunotoxin-based inhibition of tumor growth and induction of antibody-dependent cell-mediated cytotoxicity (ADCC). However, complement-dependent cytotoxicity (CDC), considered an important additional mechanism of therapeutic antibodies against tumors, is inactive for such antibodies. Here, we used phage display antibody engineering technology and synthetic peptide screening to identify SD1, a human single-domain antibody to mesothelin. SD1 recognizes a conformational epitope at the C-terminal end (residues 539-588) of mesothelin close to the cell surface. To investigate SD1 as a potential therapeutic agent, we generated a recombinant human Fc (SD1-hFc) fusion protein. Interestingly, the SD1-hFc protein exhibits strong CDC activity, in addition to ADCC, against mesothelin-expressing tumor cells. Furthermore, it causes growth inhibition of human tumor xenografts in nude mice as a single agent. SD1 is the first human single-domain antibody targeting mesothelin-expressing tumors, shows potential as a cancer therapeutic candidate, and may improve current antibody therapy targeting mesothelin-expressing tumors.

• A recombinant immunotoxin against the tumor-associated antigen mesothelin reengineered for high activity, low off-target toxicity, and reduced antigenicity. J.E. Weldon, L. Xiang, J. Zhang, et al. 2013;12(1):48-57. PubMed · Publisher · Free full text

  Abstract

  SS1P is a recombinant immunotoxin (RIT) engineered for the targeted elimination of malignant cells that express the tumor-associated antigen mesothelin. It is composed of an antimesothelin antibody variable fragment (Fv) linked to a cytotoxic fragment of Pseudomonas exotoxin A (PE) that includes domains II and III of native PE. The clinical use of SS1P is limited by its propensity to induce neutralizing antibodies and to cause a dose-limiting capillary leak syndrome (CLS) in patients. In this article, we describe a reengineered SS1P with improved properties that overcome these deficits. The redesign of SS1P consists of (i) removing the bulk of PE domain II (residues 251-273 and 284-394 of native PE), leaving only an 11-residue furin cleavage site, (ii) adding a Gly-Gly-Ser peptide linker after the furin cleavage site, and (iii) replacing eight highly solvent-exposed residues in the catalytic domain of PE. The new molecule, SS1-LR/GGS/8M, has cytotoxic activity comparable with SS1P on several mesothelin-expressing cell lines and remarkably improved activity on primary cells from patients with mesothelioma. In a mouse xenograft tumor model, high doses of SS1-LR/GGS/8M elicit antitumor activity superior to the activity of SS1P at its maximum-tolerated dose. In addition, SS1-LR/GGS/8M has greatly decreased ability to cause CLS in a rat model and reduced antigenicity or reactivity with antibodies to the sera of patients previously treated with SS1P.

• Cyclooxygenase-2, epidermal growth factor receptor, and aromatase signaling in inflammation and mesothelioma. B. Nuvoli, R. Galati. 2013;12(6):844-52. Review PubMed · Publisher

  Abstract

  Malignant mesothelioma or mesothelioma is a rare form of cancer that develops from transformed cells originating in the mesothelium, the protective lining that covers many of the internal organs of the body. It is directly linked to asbestos exposure, which acts as a carcinogen by initiating the carcinogenic process. Because of their shape, asbestos fibers can cross the membrane barriers inside the body and cause inflammatory and fibrotic reactions. Such reactions are believed to be the mechanism by which asbestos fibers may trigger malignant mesothelioma in the pleural membrane around the lungs. Carcinogens are known to modulate the transcription factors, antiapoptotic proteins, proapoptotic proteins, protein kinases, cell-cycle proteins, cell adhesion molecules, COX-2, and growth factor signaling pathways. This article reviews recent studies regarding some malignant mesothelioma molecular targets not only for cancer prevention but also for cancer therapy.

  ©2013 AACR

• Efficacy of low-dose oral metronomic dosing of the prodrug of gemcitabine, LY2334737, in human tumor xenografts. S.E. Pratt, S. Durland-Busbice, R.L. Shepard, et al. 2013;12(4):481-90. PubMed · Publisher

  Abstract

  LY2334737, an oral prodrug of gemcitabine, is cleaved in vivo, releasing gemcitabine and valproic acid. Oral dosing of mice results in absorption of intact prodrug with slow systemic hydrolysis yielding higher plasma levels of LY2334737 than gemcitabine and prolonged gemcitabine exposure. Antitumor activity was evaluated in human colon and lung tumor xenograft models. The dose response for efficacy was examined using 3 metronomic schedules, once-a-day dosing for 14 doses, every other day for 7 doses, and once a day for 7 doses, 7 days rest, followed by an additional 7 days of once-a-day dosing. These schedules gave significant antitumor activity and were well tolerated. Oral gavage of 6 mg/kg LY2334737 daily for 21 days gave equivalent activity to i.v. 240 mg/kg gemcitabine. HCl administered once a week for 3 weeks to mice bearing a patient mesothelioma tumor PXF 1118 or a non-small cell lung cancer tumor LXFE 937. The LXFE 397 tumor possessed elevated expression of the equilibrative nucleoside transporter-1 (ENT1) important for gemcitabine uptake but not prodrug uptake and responded significantly better to treatment with LY2334737 than gemcitabine (P ≤ 0.001). In 3 colon xenografts, antitumor activity of LY2334737 plus a maximally tolerated dose of capecitabine, an oral prodrug of 5-fluorouracil, was significantly greater than either monotherapy. During treatment, the expression of carboxylesterase 2 (CES2) and concentrative nucleoside transporter-3 was induced in HCT-116 tumors; both are needed for the activity of the prodrugs. Thus, metronomic oral low-dose LY2334737 is efficacious, well tolerated, and easily combined with capecitabine for improved efficacy. Elevated CES2 or ENT1 expression may enhance LY2334737 tumor response.

• Synergistic anticancer activity of arsenic trioxide with erlotinib is based on inhibition of EGFR-mediated DNA double-strand break repair. K. Kryeziu, U. Jungwirth, M.A. Hoda, et al. 2013;12(6):1073-84. PubMed · Publisher

  Abstract

  Arsenic trioxide (ATO), one of the oldest remedies used in traditional medicine, was recently rediscovered as an anticancer drug and approved for treatment of relapsed acute promyelocytic leukemia. However, its activity against nonhematologic cancers is rather limited so far. Here, we show that inhibition of ATO-mediated EGF receptor (EGFR) activation can be used to potently sensitize diverse solid cancer types against ATO. Thus, combination of ATO and the EGFR inhibitor erlotinib exerted synergistic activity against multiple cancer cell lines. Subsequent analyses revealed that this effect was based on the blockade of ATO-induced EGFR phosphorylation leading to more pronounced G2-M arrest as well as enhanced and more rapid induction of apoptosis. Comparable ATO-sensitizing effects were also found with PI3K/AKT and mitogen-activated protein/extracellular signal-regulated kinase (MEK) inhibitors, suggesting an essential role of the EGFR-mediated downstream signaling pathway in cancer cell protection against ATO. H2AX staining and comet assay revealed that erlotinib significantly increases ATO-induced DNA double-strand breaks (DSB) well in accordance with a role of the EGFR signaling axis in DNA damage repair. Indeed, EGFR inhibition led to downregulation of several DNA DSB repair proteins such as Rad51 and Rad50 as well as reduced phosphorylation of BRCA1. Finally, the combination treatment of ATO and erlotinib was also distinctly superior to both monotreatments against the notoriously therapy-resistant human A549 lung cancer and the orthotopic p31 mesothelioma xenograft model in vivo. In conclusion, this study suggests that combination of ATO and EGFR inhibitors is a promising therapeutic strategy against various solid tumors harboring wild-type EGFR.

  ©2013 AACR

• Mesothelin-targeted agents in clinical trials and in preclinical development. R.J. Kelly, E. Sharon, I. Pastan, et al. 2012;11(3):517-25. Review PubMed · Publisher · Free full text

  Abstract

  Mesothelin is a tumor differentiation antigen that is highly expressed in several malignant diseases in humans, including malignant mesothelioma and pancreatic, ovarian, and lung adenocarcinomas. The limited expression of mesothelin on normal human tissues and its high expression in many common cancers make it an attractive candidate for cancer therapy. Several agents, including an immunotoxin, monoclonal antibody, antibody drug conjugate, and tumor vaccine, are in various stages of development to treat patients with mesothelin-expressing tumors. This review highlights ongoing clinical trials, as well as other approaches to exploit mesothelin for cancer therapy, that are in preclinical development.

• CBP501-calmodulin binding contributes to sensitizing tumor cells to cisplatin and bleomycin. N. Mine, S. Yamamoto, N. Saito, et al. 2011;10(10):1929-38. PubMed · Publisher

  Abstract

  CBP501 is an anticancer drug currently in randomized phase II clinical trials for patients with non-small cell lung cancer and malignant pleural mesothelioma. CBP501 was originally described as a unique G(2) checkpoint-directed agent that binds to 14-3-3, inhibiting the actions of Chk1, Chk2, mitogen-activated protein kinase-activated protein kinase 2, and C-Tak1. However, unlike a G(2) checkpoint inhibitor, CBP501 clearly enhances the accumulation of tumor cells at G(2)-M phase that is induced by cisplatin or bleomycin at low doses and short exposure. By contrast, CBP501 does not similarly affect the accumulation of tumor cells at G(2)-M that is induced by radiation, doxorubicin, or 5-fluorouracil treatment. Our recent findings point to an additional mechanism of action for CBP501. The enhanced accumulation of tumor cells at G(2)-M upon combined treatment with cisplatin and CBP501 results from an increase in intracellular platinum concentrations, which leads to increased binding of platinum to DNA. The observed CBP501-enhanced platinum accumulation is negated in the presence of excess Ca(2+). Some calmodulin inhibitors behave similarly to, although less potently than, CBP501. Furthermore, analysis by surface plasmon resonance reveals a direct, high-affinity molecular interaction between CBP501 and CaM (K(d) = 4.62 × 10(-8) mol/L) that is reversed by Ca(2+), whereas the K(d) for the complex between CBP501 and 14-3-3 is approximately 10-fold weaker and is Ca(2+) independent. We conclude that CaM inhibition contributes to CBP501's activity in sensitizing cancer cells to cisplatin or bleomycin. This article presents an additional mechanism of action which might explain the clinical activity of the CBP501-cisplatin combination.

• Genetically engineered oncolytic Newcastle disease virus effectively induces sustained remission of malignant pleural mesothelioma. G.R. Silberhumer, P. Brader, J. Wong, et al. 2010;9(10):2761-9. PubMed · Publisher · Free full text

  Abstract

  Malignant pleural mesothelioma is a highly aggressive tumor. Alternative treatment strategies such as oncolytic viral therapy may offer promising treatment options in the future. In this study, the oncolytic efficacy and induction of tumor remission by a genetically engineered Newcastle disease virus [NDV; NDV(F3aa)-GFP; GFP, green fluorescent protein] in malignant pleural mesothelioma is tested and monitored by bioluminescent tumor imaging. The efficacy of NDV(F3aa)-GFP was tested against several mesothelioma cell lines in vitro. Firefly luciferase-transduced MSTO-211H* orthotopic pleural mesothelioma tumor-bearing animals were treated with either single or multiple doses of NDV(F3aa)-GFP at different time points (days 1 and 10) after tumor implantation. Tumor burden was assessed by bioluminescence imaging. Mesothelioma cell lines exhibited dose-dependent susceptibility to NDV lysis in the following order of sensitivity: MSTO-211H > MSTO-211H* > H-2452 > VAMT > JMN. In vivo studies with MSTO-211H* cells showed complete response to viral therapy in 65% of the animals within 14 days after treatment initiation. Long-term survival in all of these animals was >50 days after tumor installation (control animals, <23 d). Multiple treatment compared with single treatment showed a significantly better response (P = 0.005). NDV seems to be an efficient viral oncolytic agent in the therapy of malignant pleural mesothelioma in an orthotopic pleural mesothelioma tumor model.

2000s

• A novel human monoclonal antibody that binds with high affinity to mesothelin-expressing cells and kills them by antibody-dependent cell-mediated cytotoxicity. Y. Feng, X. Xiao, Z. Zhu, et al. 2009;8(5):1113-8. PubMed · Publisher · Free full text

  Abstract

  Mesothelin is a potential new target for cancer immunotherapy because it is present at relatively low levels only in mesothelial cells of pleura, peritoneum, and pericardium of healthy people, but is significantly elevated in a number of tumors, including mesothelioma, ovarian, pancreatic, and lung cancers. However, all currently available antibodies against mesothelin are either murine or chimeric, which could limit their use because of increased likelihood of immunogenicity compared with fully human antibodies. Here, we report the identification and characterization of a novel fully human monoclonal antibody, m912, which was isolated from a human Fab library by panning against recombinant mesothelin. This antibody in scFv, Fab, and IgG1 formats bound specifically and with high affinity (equilibrium dissociation constant in the nmol/L range) to cell surface-associated human mesothelin and to recombinant mesothelin. It specifically lysed cancer cells engineered to express mesothelin in the presence of peripheral blood mononuclear cells isolated from healthy donors most likely by antibody-dependent cellular cytotoxicity. M912 is the first reported fully human monoclonal antibody to mesothelin, which has potential for cancer treatment and diagnosis.

• The HDAC inhibitor panobinostat (LBH589) inhibits mesothelioma and lung cancer cells in vitro and in vivo with particular efficacy for small cell lung cancer. M.C. Crisanti, A.F. Wallace, V. Kapoor, et al. 2009;8(8):2221-31. PubMed · Publisher · Free full text

  Abstract

  Lung cancer is the leading cause of cancer deaths in the United States. Current therapies are inadequate. Histone deacetylase inhibitors (HDACi) are a recently developed class of anticancer agents that cause increased acetylation of core histones and nonhistone proteins leading to modulation of gene expression and protein activity involved in cancer cell growth and survival pathways. We examined the efficacy of the HDACi panobinostat (LBH589) in a wide range of lung cancers and mesotheliomas. Panobinostat was cytotoxic in almost all 37 cancer cell lines tested. IC(50) and LD(50) values were in the low nmol/L range (4-470 nmol/L; median, 20 nmol/L). Small cell lung cancer (SCLC) cell lines were among the most sensitive lines, with LD(50) values consistently <25 nmol/L. In lung cancer and mesothelioma animal models, panobinostat significantly decreased tumor growth by an average of 62% when compared with vehicle control. Panobinostat was equally effective in immunocompetent and severe combined immunodeficiency mice, indicating that the inhibition of tumor growth by panobinostat was not due to direct immunologic effects. Panobinostat was, however, particularly effective in SCLC xenografts, and the addition of the chemotherapy agent etoposide augmented antitumor effects. Protein analysis of treated tumor biopsies revealed elevated amounts of cell cycle regulators such as p21 and proapoptosis factors, such as caspase 3 and 7 and cleaved poly[ADP-ribose] polymerase, coupled with decreased levels of antiapoptotic factors such as Bcl-2 and Bcl-X(L). These studies together suggest that panobinostat may be a useful adjunct in the treatment of thoracic malignancies, especially SCLC.

• A novel combination: ranpirnase and rosiglitazone induce a synergistic apoptotic effect by down-regulating Fra-1 and Survivin in cancer cells. M.E. Ramos-Nino, B. Littenberg. 2008;7(7):1871-9. PubMed · Publisher · Free full text

  Abstract

  Accumulating evidence supports the idea that two known phosphatidylinositol 3'-kinase (PI3K) downstream proteins, Fra-1 and Survivin, are potential targets for cancer therapy. Increased expression of Fra-1, a Fos family member of the transcription factor activator protein-1, has been implicated in both the maintenance and the progression of the transformed state of several cancer cells. In addition, high Survivin expression in tumors correlates with more aggressive behavior, lower response to chemotherapeutic drugs, and shortened survival time. Previously, we reported that, in malignant mesothelioma cells with increased PI3K activity, small-molecule inhibitors of the PI3K/AKT pathway acted cooperatively with the amphibian RNase chemotherapeutic drug ranpirnase to inhibit cell growth. Because the thiazolidinedione antidiabetic drug rosiglitazone targets the PI3K/AKT pathway, we investigated the effect of the combination of these two drugs in cell survival in several cancer cell lines. We show here that the combination of ranpirnase and rosiglitazone synergistically decreases cell viability and increases cell apoptosis in several cancer cell lines. Cell killing is associated with decreased Fra-1 and Survivin expression and knockdown of Fra-1 increases cell killing by ranpirnase in a dose-dependent manner but not by rosiglitazone. The drug combination does not have a synergistic effect on killing in Fra-1 knockdown cells, showing that Fra-1 modulation accounts in part for the synergism. The novel drug combination of ranpirnase and rosiglitazone is a promising combination to treat cancers with increased PI3K-dependent Fra-1 expression or Survivin.

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