Jack Henkin

Publications of Jack Henkin

• Therapies using anti-angiogenic peptide mimetics of thrombospondin-1.

  Authors: Jack Henkin, Olga V Volpert

  Expert opinion on therapeutic targets. 12/2011; 15(12):1369-86.

  INTRODUCTION: The role of hrombospondin-1 (TSP1) as a major endogenous angiogenesis inhibitor has been confirmed by numerous studies and subsequent mechanistic discoveries. It has yielded a new classINTRODUCTION: The role of hrombospondin-1 (TSP1) as a major endogenous angiogenesis inhibitor has been confirmed by numerous studies and subsequent mechanistic discoveries. It has yielded a new class of potential drugs against cancer and other angiogenesis-driven diseases. AREAS COVERED: An overview of TSP1 functions and molecular mechanisms, including regulation and signaling. Functions in endothelial and non-endothelial cells, with emphasis on the role of TSP1 in the regulation of angiogenesis and inflammation. The utility of duplicating these activities for drug discovery. Past and current literature on endogenous TSP1 and its role in the progression of cancer and non-cancerous pathological conditions is summarized, as well as the research undertaken to identify and optimize short bioactive peptides derived from the two TSP1 anti-angiogenic domains, which bind CD47 and CD36 cell surface receptors. Lastly, there is an overview of the efficacy of some of these peptides in pre-clinical and clinical models of angiogenesis-dependent disease. EXPERT OPINION: It is concluded that TSP1-derived peptides and peptide mimetics hold great promise as future agents for the treatment of cancer and other diseases driven by excessive angiogenesis. They may fulfill unmet medical needs including neovascular ocular disease and the diseases of the female reproductive tract including ovarian cancer.

• ABT-898 induces tumor regression and prolongs survival in a mouse model of epithelial ovarian cancer.

  Authors: Nicole Campbell, James Greenaway, Jack Henkin, Jim Petrik

  Molecular cancer therapeutics. 08/2011; 10(10):1876-85.

  Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy and is often not diagnosed until late stages due to its asymptomatic nature. Women diagnosed with EOC typically undergoEpithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy and is often not diagnosed until late stages due to its asymptomatic nature. Women diagnosed with EOC typically undergo surgical debulking followed by chemotherapy; however, disease recurrence often occurs. In this study, we evaluated the ability of the thrombospondin-1 mimetic peptide, ABT-898, to regress established, late-stage tumors in a mouse model of human EOC. Ovarian tumors were induced and ABT-898 treatment was initiated at time points that were representative of late stages of the disease to study tumor regression. ABT-898 induced tumor regression and reduced the morbidity of treated animals compared with controls. Analysis of tumors from ABT-898-treated animals showed reduced abnormal tumor vasculature, decreased expression of the proangiogenic compound VEGF, and reduced tumor tissue hypoxia. ABT-898 treatment initiated at late-stage disease also significantly prolonged disease-free survival compared with control animals. Results from this study show that ABT-898 is capable of regressing established ovarian tumors in an animal model of the disease. As most women are detected at advanced stage EOC, ABT-898 may improve our treatment of ovarian cancer.

• The thrombospondin-1 mimetic ABT-510 increases the uptake and effectiveness of cisplatin and paclitaxel in a mouse model of epithelial ovarian cancer.

  Authors: Nicole E Campbell, James Greenaway, Jack Henkin, Roger A Moorehead, Jim Petrik

  Neoplasia (New York, N.Y.). 03/2010; 12(3):275-83.

  Epithelial ovarian cancer (EOC) comprises approximately 90% of ovarian cancers and arises from the surface epithelium. Typical treatment of EOC involves cytoreductive surgery combined withEpithelial ovarian cancer (EOC) comprises approximately 90% of ovarian cancers and arises from the surface epithelium. Typical treatment of EOC involves cytoreductive surgery combined with chemotherapy. More recent therapies have targeted the tumor vasculature using antiangiogenic compounds such as thrombospondin-1 (TSP-1). TSP-1 mimetic peptides such as ABT-510 have been created and have been in various clinical trials. We have previously shown that ABT-510 reduces abnormal vasculature associated with tumor tissue and increases the presence of mature blood vessels. It has been hypothesized that treatment with antiangiogenic compounds would allow increased delivery of cytotoxic agents and enhance treatment. In this study, we evaluated the potential role of ABT-510 and various chemotherapeutics (cisplatin and paclitaxel) on tumor progression, angiogenesis, and the benefits of combinational treatments on tissue uptake and perfusion using an orthotopic syngeneic mouse model of EOC. Animals were treated with ABT-510 (100 mg/kg per day) alone or in combination with cisplatin (2 mg/kg per 3 days) or paclitaxel (10 mg/kg per 2 days) at 60 days after tumor induction. Radiolabeled and fluorescently labeled paclitaxel demonstrated a significant increase in tumor uptake after ABT-510 treatment. Combined treatment with ABT-510 and cisplatin or paclitaxel resulted in a significant increase in tumor cell and tumor endothelial cell apoptosis and a resultant decrease in ovarian tumor size. Combined treatment also regressed secondary lesions and eliminated the presence of abdominal ascites. The results from this study show that through vessel normalization, ABT-510 increases uptake of chemotherapy drugs and can induce regression of advanced ovarian cancer.

• Plasminogen Kringle 5 Induces Apoptosis of Brain Microvessel Endothelial Cells: Sensitization by Radiation and Requirement for GRP78 and LRP1.

  Authors: Braden C McFarland, Jerry Stewart, Amal Hamza, Robert Nordal, Donald J Davidson, Jack Henkin, Candece L Gladson

  Cancer research. 07/2009;

  Recombinant plasminogen kringle 5 (rK5) has been shown to induce apoptosis of dermal microvessel endothelial cells (MvEC) in a manner that requires glucose-regulated protein 78 (GRP78). As we areRecombinant plasminogen kringle 5 (rK5) has been shown to induce apoptosis of dermal microvessel endothelial cells (MvEC) in a manner that requires glucose-regulated protein 78 (GRP78). As we are interested in antiangiogenic therapy for glioblastoma tumors, and the effectiveness of antiangiogenic therapy can be enhanced when combined with radiation, we investigated the proapoptotic effects of rK5 combined with radiation on brain MvEC. We found that rK5 treatment of brain MvEC induced apoptosis in a dose- and time-dependent manner and that prior irradiation significantly sensitized (500-fold) the cells to rK5-induced apoptosis. The rK5-induced apoptosis of both unirradiated and irradiated MvEC required expression of GRP78 and the low-density lipoprotein receptor-related protein 1 (LRP1), a scavenger receptor, based on down-regulation studies with small interfering RNA, and blocking studies with either a GRP78 antibody or a competitive inhibitor of ligand binding to LRP1. Furthermore, p38 mitogen-activated protein kinase was found to be a necessary downstream effector for rK5-induced apoptosis. These data suggest that irradiation sensitizes brain MvEC to the rK5-induced apoptosis and that this signal requires LRP1 internalization of GRP78 and the activation of p38 mitogen-activated protein kinase. Our findings suggest that prior irradiation would have a dose-sparing effect on rK5 antiangiogenic therapy for brain tumors and further suggest that the effects of rK5 would be tumor specific, as the expression of GRP78 protein is up-regulated on the brain MvEC in glioblastoma tumor biopsies compared with the normal brain. [Cancer Res 2009;69(13):5537-45].

• ABT-510 induces tumor cell apoptosis and inhibits ovarian tumor growth in an orthotopic, syngeneic model of epithelial ovarian cancer.

  Authors: James Greenaway, Jack Henkin, Jack Lawler, Roger Moorehead, Jim Petrik

  Molecular cancer therapeutics. 02/2009; 8(1):64-74.

  Epithelial ovarian cancer (EOC) is the fifth most common cancer in women and is characterized by a low 5-year survival rate. One strategy that can potentially improve the overall survival rate inEpithelial ovarian cancer (EOC) is the fifth most common cancer in women and is characterized by a low 5-year survival rate. One strategy that can potentially improve the overall survival rate in ovarian cancer is the use of antitumor agents such as ABT-510. ABT-510 is a small mimetic peptide of the naturally occurring antiangiogenic compound thrombospondin-1 and has been shown to significantly reduce tumor growth and burden in preclinical mouse models and in naturally occurring tumors in dogs. This is the first evaluation of ABT-510 in a preclinical model of human EOC. Tumorigenic mouse surface epithelial cells were injected into the bursa of C57BL/6 mice that were treated with either 100 mg/kg ABT-510 or an equivalent amount of PBS. ABT-510 caused a significant reduction in tumor size, ascites fluid volume, and secondary lesion dissemination when compared with PBS controls. Analysis of the vasculature of ABT-510-treated mice revealed vascular remodeling with smaller diameter vessels and lower overall area, increased number of mature vessels, and decreased tissue hypoxia. Tumors of ABT-510-treated mice had a significantly higher proportion of apoptotic tumor cells compared with the PBS-treated controls. Immunoblot analysis of cell lysates revealed a reduction in vascular endothelial growth factor, vascular endothelial growth factor receptor-2, and proliferating cell nuclear antigen protein expression as well as expression of members of the phosphatidylinositol 3-kinase and mitogen-activated protein kinase survival pathways. In vitro, ABT-510 induced tumor cell apoptosis in mouse and human ovarian cancer cells. This study shows ABT-510 as a promising candidate for inhibiting tumor growth and ascites formation in human EOC. [Mol Cancer Ther 2009;8(1):64-74].

• ABT-510, a modified type 1 repeat peptide of thrombospondin, inhibits malignant glioma growth in vivo by inhibiting angiogenesis.

  Authors: Joshua C Anderson, J Robert Grammer, Wenquan Wang, L Burton Nabors, Jack Henkin, Jerry E Stewart, Candece L Gladson

  Cancer biology & therapy. 04/2007; 6(3):454-62.

  Anti-angiogenic therapies would be particularly beneficial in the treatment of malignant gliomas. Peptides derived from the second type 1 repeat (TSR) of thrombospondin-1 (TSP-1) have been shown toAnti-angiogenic therapies would be particularly beneficial in the treatment of malignant gliomas. Peptides derived from the second type 1 repeat (TSR) of thrombospondin-1 (TSP-1) have been shown to inhibit angiogenesis in non-glioma tumor models and a modified TSR peptide, ABT-510, has now entered into Phase II clinical trials of its efficacy in non-glioma tumors. As microvascular endothelial cells (MvEC) exhibit heterogeneity, we evaluated the ability of the modified TSR peptide (NAcSarGlyValDallolleThrNvalleArgProNHE, ABT-510) to inhibit malignant glioma growth in vivo and to induce apoptosis of brain microvessel endothelial cells (MvEC) propagated in vitro. We found that daily administration of ABT-510 until euthanasia (days 7 to 19), significantly inhibited the growth of human malignant astrocytoma tumors established in the brain of athymic nude mice. The microvessel density was significantly lower and the number of apoptotic MvEC was significantly higher (3-fold) in the tumors of the ABT-510-treated animals. Similar results were found using a model in which the established tumor is an intracerebral malignant glioma propagated in a syngeneic mouse model. ABT-510 treatment of primary human brain MvEC propagated as a monolayer resulted in induction of apoptosis in a dose- and time-dependent manner through a caspase-8-dependent mechanism. It also inhibited tubular morphogenesis of MvEC propagated in collagen gels in a dose- and caspase-8 dependent manner through a mechanism that requires the TSP-1 receptor (CD36) on the MvEC. These findings indicate that ABT-510 should be evaluated as a therapeutic option for patients with malignant glioma.

• Thrombospondin-1 peptide ABT-510 combined with valproic acid is an effective antiangiogenesis strategy in neuroblastoma.

  Authors: Qiwei Yang, Yufeng Tian, Shuqing Liu, Rana Zeine, Alexandre Chlenski, Helen R Salwen, Jack Henkin, Susan L Cohn

  Cancer research. 03/2007; 67(4):1716-24.

  In the pediatric cancer neuroblastoma, clinically aggressive disease is associated with increased levels of angiogenesis stimulators and high vascular index. We and others have hypothesized thatIn the pediatric cancer neuroblastoma, clinically aggressive disease is associated with increased levels of angiogenesis stimulators and high vascular index. We and others have hypothesized that blocking angiogenesis may be effective treatment for this pediatric malignancy. However, little is known about the efficacy of antiangiogenic agents in pediatric malignancies. Recently, promising results have been reported in an adult phase I study of ABT-510, a peptide derivative of the natural angiogenic inhibitor thrombospondin-1. Histone deacetylase inhibitors, such as valproic acid (VPA), have also been shown to have antiangiogenic activity in several cancer models. In this study, we evaluated the effects of ABT-510 and VPA on neuroblastoma tumor growth and angiogenesis. Although only VPA was capable of blocking the proliferation of neuroblastoma cells and inducing neuroblastoma cell apoptosis in vitro, treatment with VPA or ABT-510 alone significantly suppressed the growth of neuroblastoma xenografts established from two different MYCN-amplified cell lines. Combination therapy more effectively inhibited the growth of small neuroblastoma xenografts than single-agent treatment, and in animals with large xenografts, total cessation of tumor growth was achieved with this treatment approach. The microvascular density was significantly reduced in the xenografts treated with combination therapy compared with controls or tumors treated with single agents. In addition, the number of structurally abnormal vessels was reduced, suggesting that these agents may "normalize" the tumor vasculature. Our results indicate that ABT-510 combined with VPA may be an effective antiangiogenic treatment strategy for children with high-risk neuroblastoma.

• Preclinical evaluation of antiangiogenic thrombospondin-1 peptide mimetics, ABT-526 and ABT-510, in companion dogs with naturally occurring cancers.

  Authors: Anthony Rusk, Evelyn McKeegan, Fortuna Haviv, Sandra Majest, Jack Henkin, Chand Khanna

  Clinical cancer research : an official journal of the American Association for Cancer Research. 12/2006; 12(24):7444-55.

  PURPOSE: The angiogenic phenotype of malignant cancers has been established as a target for cancer therapy. ABT-526 and ABT-510, two peptide mimetics of thrombospondin-1 (TSP-1), block angiogenesisPURPOSE: The angiogenic phenotype of malignant cancers has been established as a target for cancer therapy. ABT-526 and ABT-510, two peptide mimetics of thrombospondin-1 (TSP-1), block angiogenesis in vitro and in vivo and slow tumor growth in mice. To guide the clinical development of these drugs, translational studies in dogs with naturally occurring cancers were initiated. EXPERIMENTAL DESIGN: A prospective open-label trial using ABT-510 or ABT-526 in pet dogs with measurable malignant spontaneously arising tumors. Endpoints included safety, pharmacokinetics, antitumor activity, and preliminary assessment of changes in circulating endothelial cell populations. RESULTS: Two-hundred and forty-two dogs were sequentially entered to this open-label trial. The elimination half-life for ABT-510 and ABT-526 was 0.7 and 0.8 h, respectively (range, 0.5-1 h). No dose-limiting toxicities were seen in any dogs (N = 242). Forty-two dogs receiving peptide had objective responses (>50% reduction in tumor size; n = 6) or significant disease stabilization. Most objective responses were seen after 60 days of exposure to the TSP-1 peptide. Antitumor activity was similar for both peptides and was seen in several histologies, including mammary carcinoma, head and neck carcinoma, soft tissue sarcoma, cutaneous T-cell lymphoma, and non-Hodgkin's lymphoma. Assessment of circulating endothelial cell populations in a small subset of dogs suggested that effective exposure to TSP-1 peptides may be associated with reductions in circulating endothelial cells. CONCLUSIONS: These results support the safety and activity of ABT-526 and ABT-510 in dogs with naturally occurring malignant cancers. Data from this preclinical trial support the development of TSP-1 mimetic peptides as anticancer agents.

• Cooperative activity of cytotoxic chemotherapy with antiangiogenic thrombospondin-I peptides, ABT-526 in pet dogs with relapsed lymphoma.

  Authors: Anthony Rusk, Elizabeth Cozzi, Marty Stebbins, David Vail, Joanne Graham, Victor Valli, Jack Henkin, Rick Sharpee, Chand Khanna

  Clinical cancer research : an official journal of the American Association for Cancer Research. 12/2006; 12(24):7456-64.

  PURPOSE: Thrombospondin-I (TSP-I) is a natural antiangiogenic protein that enhances apoptosis of activated endothelial cells. A modified nonapeptide from TSP-I, ABT-526, has been found to be activePURPOSE: Thrombospondin-I (TSP-I) is a natural antiangiogenic protein that enhances apoptosis of activated endothelial cells. A modified nonapeptide from TSP-I, ABT-526, has been found to be active in mouse cancer models and in dogs with naturally occurring cancers. To further assist in the development of ABT-526, we report herein on its evaluation in combination with cytotoxic chemotherapy in pet dogs with relapsed non-Hodgkin's lymphoma (NHL). EXPERIMENTAL DESIGN: Ninety-four pet dogs with naturally occurring first-relapse NHL were entered into a prospective randomized placebo controlled double-blinded trial of ABT-526 plus CeeNu (Bristol-Myers Squibb, New York, NY) versus CeeNu alone. Endpoints included response rate, duration of response, time to progression, and incidence of toxicoses. RESULTS: No significant ABT-526-specific toxicities were seen. CeeNu-associated toxicities, including neutropenia, thrombocytopenia, gastroenteritis, and elevated alanine transaminase, were similar. No significant difference in objective response rate was seen (ABT-526 + CeeNu versus placebo + CeeNu, 23/49 versus 23/37; P > 0.25). Cooperative activity between ABT-526 and CeeNu chemotherapy was evident based on a significant increase in the median response duration of dogs receiving ABT-526 plus CeeNu compared with placebo plus CeeNu (35 versus 15 days; P < 0.05). The time to progression for responding cases was also significantly greater in dogs receiving ABT-526 plus CeeNu compared with placebo plus CeeNu (41 versus 21 days; P < 0.05). CONCLUSIONS: Results of this preclinical trial suggest that the activity of ABT-526 is sustained when combined with cytotoxic chemotherapy; furthermore, the activity seems to be associated with the maintenance of CeeNu-induced treatment responses. Further studies of TSP-I peptide antiangiogenic therapy in pet dogs and humans with NHL are warranted.

• Development of sulfonamide compounds as potent methionine aminopeptidase type II inhibitors with antiproliferative properties.

  Authors: Megumi Kawai, Nwe Y Bamaung, Steve D Fidanze, Scott A Erickson, Jason S Tedrow, William J Sanders, Anil Vasudevan, Chang Park, Charles Hutchins, Kenneth M Comess, Douglas Kalvin, Jieyi Wang, Qian Zhang, Pingping Lou, Lora Tucker-Garcia, Jennifer Bouska, Randy L Bell, Richard Lesniewski, Jack Henkin, George S Sheppard

  Bioorganic & medicinal chemistry letters. 08/2006; 16(13):3574-7.

  We have screened molecules for inhibition of MetAP2 as a novel approach toward antiangiogenesis and anticancer therapy using affinity selection/mass spectrometry (ASMS) employing MetAP2 loaded withWe have screened molecules for inhibition of MetAP2 as a novel approach toward antiangiogenesis and anticancer therapy using affinity selection/mass spectrometry (ASMS) employing MetAP2 loaded with Mn(2+) as the active site metal. After a series of anthranilic acid sulfonamides with micromolar affinities was identified, chemistry efforts were initiated. The micromolar hits were quickly improved to potent nanomolar inhibitors by chemical modifications guided by insights from X-ray crystallography.

• Discovery and optimization of anthranilic acid sulfonamides as inhibitors of methionine aminopeptidase-2: a structural basis for the reduction of albumin binding.

  Authors: George S Sheppard, Jieyi Wang, Megumi Kawai, Steve D Fidanze, Nwe Y Bamaung, Scott A Erickson, David M Barnes, Jason S Tedrow, Lawrence Kolaczkowski, Anil Vasudevan [......] Chang H Park, Ki H Kim, Andrew Petros, Edward Olejniczak, David Nettesheim, Phillip Hajduk, Jack Henkin, Richard Lesniewski, Steven K Davidsen, Randy L Bell

  Journal of medicinal chemistry. 07/2006; 49(13):3832-49.

  Methionine aminopeptidase-2 (MetAP2) is a novel target for cancer therapy. As part of an effort to discover orally active reversible inhibitors of MetAP2, a series of anthranilic acid sulfonamidesMethionine aminopeptidase-2 (MetAP2) is a novel target for cancer therapy. As part of an effort to discover orally active reversible inhibitors of MetAP2, a series of anthranilic acid sulfonamides with micromolar affinities for human MetAP2 were identified using affinity selection by mass spectrometry (ASMS) screening. These micromolar hits were rapidly improved to nanomolar leads on the basis of insights from protein crystallography; however, the compounds displayed extensive binding to human serum albumin and had limited activity in cellular assays. Modifications based on structural information on the binding of lead compounds to both MetAP2 and domain III of albumin allowed the identification of compounds with significant improvements in both parameters, which showed good cellular activity in both proliferation and methionine processing assays.

• Metronomic low-dose chemotherapy boosts CD95-dependent antiangiogenic effect of the thrombospondin peptide ABT-510: a complementation antiangiogenic strategy.

  Authors: Ronald Yap, Dorina Veliceasa, Urban Emmenegger, Robert S Kerbel, Laura M McKay, Jack Henkin, Olga V Volpert

  Clinical cancer research : an official journal of the American Association for Cancer Research. 10/2005; 11(18):6678-85.

  Blocking angiogenesis is a promising approach in cancer therapy. Natural inhibitors of angiogenesis and derivatives induce receptor-mediated signals, which often result in the endothelial cell death.Blocking angiogenesis is a promising approach in cancer therapy. Natural inhibitors of angiogenesis and derivatives induce receptor-mediated signals, which often result in the endothelial cell death. Low-dose chemotherapy, given at short regular intervals with no prolonged breaks (metronomic chemotherapy), also targets angiogenesis by obliterating proliferating endothelial cells and circulating endothelial cell precursors. ABT-510, a peptide derivative of thrombospondin, kills endothelial cell by increasing CD95L, a ligand for the CD95 death receptor. However, CD95 expression itself is unaffected by ABT-510 and limits its efficacy. We found that multiple chemotherapy agents, cyclophosphamide (cytoxan), cisplatin, and docetaxel, induced endothelial CD95 in vitro and in vivo at low doses that failed to kill endothelial cells (cytoxan > cisplatin > docetaxel). Thus, we concluded that some of these agents might complement each other and together block angiogenesis with maximal efficacy. As a proof of principle, we designed an antiangiogenic cocktail combining ABT-510 with cytoxan or cisplatin. Cyclophosphamide and cisplatin synergistically increased in vivo endothelial cell apoptosis and angiosuppression by ABT-510. This synergy required CD95, as it was reversible with the CD95 decoy receptor. In a mouse model, ABT-510 and cytoxan, applied together at low doses, acted in synergy to delay tumor take, to stabilize the growth of established tumors, and to cause a long-term progression delay of PC-3 prostate carcinoma. These antitumor effects were accompanied by major decreases in microvascular density and concomitant increases of the vascular CD95, CD95L, and apoptosis. Thus, our study shows a "complementation" design of an optimal cancer treatment with the antiangiogenic peptide and a metronomic chemotherapy.

• Kringle 5 of human plasminogen induces apoptosis of endothelial and tumor cells through surface-expressed glucose-regulated protein 78.

  Authors: Don J Davidson, Catherine Haskell, Sandy Majest, Abdullah Kherzai, David A Egan, Karl A Walter, Andrew Schneider, Earl F Gubbins, Larry Solomon, Zhebo Chen, Rick Lesniewski, Jack Henkin

  Cancer research. 07/2005; 65(11):4663-72.

  Kringle 5 (K5) of human plasminogen has been shown to inhibit angiogenesis by inducing the apoptosis of proliferating endothelial cells. Peptide regions around the lysine-binding pocket of K5 largelyKringle 5 (K5) of human plasminogen has been shown to inhibit angiogenesis by inducing the apoptosis of proliferating endothelial cells. Peptide regions around the lysine-binding pocket of K5 largely mediate these effects, particularly the peptide PRKLYDY, which we show to compete with K5 for the binding to endothelial cells. The cell surface binding site for K5 that mediates these effects has not been defined previously. Here, we report that glucose-regulated protein 78, exposed on cell surfaces of proliferating endothelial cells as well as on stressed tumor cells, plays a key role in the antiangiogenic and antitumor activity of K5. We also report that recombinant K5-induced apoptosis of stressed HT1080 fibrosarcoma cells involves enhanced activity of caspase-7, consistent with the disruption of glucose-regulated protein 78-procaspase-7 complexes. These results establish recombinant K5 as an inhibitor of a stress response pathway, which leads to both endothelial and tumor cell apoptosis.

• Thrombospondin-1 mimetic peptide inhibitors of angiogenesis and tumor growth: design, synthesis, and optimization of pharmacokinetics and biological activities.

  Authors: Fortuna Haviv, Michael F Bradley, Douglas M Kalvin, Andrew J Schneider, Donald J Davidson, Sandra M Majest, Laura M McKay, Catherine J Haskell, Randy L Bell, Bach Nguyen [......] Bruce W Surber, John T Uchic, James Ferrero, Yi-Chun Wang, Juan Leal, Rae D Record, Jason Hodde, Stephen F Badylak, Richard R Lesniewski, Jack Henkin

  Journal of medicinal chemistry. 05/2005; 48(8):2838-46.

  The heptapeptide 1, NAc-Gly-Val-DIle-Thr-Arg-Ile-ArgNHEt, a structurally modified fragment derived from the second type-1 repeat of thrombospondin-1 (TSP-1), is known to possess antiangiogenicThe heptapeptide 1, NAc-Gly-Val-DIle-Thr-Arg-Ile-ArgNHEt, a structurally modified fragment derived from the second type-1 repeat of thrombospondin-1 (TSP-1), is known to possess antiangiogenic activity. However, therapeutic utility could not be demonstrated because this peptide has a very short half-life in rodents. To optimize the PD/PK profile of 1, we initiated a systematic SAR study. The initial structural modifications were performed at positions 5 and 7 of peptide 1 and at the N- and C-termini. Out of several hundred peptides synthesized, the nonapeptide 5 (ABT-526) emerged as a promising lead. ABT-526 inhibited VEGF-induced HMVEC cell migration and tube formation in the nanomolar range and increased apoptosis of HUAEC cells. ABT-526 showed acceptable PK in rodents, dog, and monkey. ABT-526, when incorporated in an angiogenic pellet implanted in the rat cornea at 10 microM, reduced neovascularization by 92%. Substitution of DalloIle in place of DIle in ABT-526 provided nonapeptide 6 (ABT-510), which was 30-fold less active than ABT-526 in the EC migration but 20-fold more active in the tube formation assay. In comparison to ABT-526, ABT-510 has increased water solubility and slower clearance in dog and monkey. Radiolabeled ABT-510 demonstrated saturable binding to HMVEC cells at 0.02-20 nM concentrations and was displaceable by TSP-1. ABT-510 and ABT-526 were shown to significantly increase apoptosis of HUAEC cells. ABT-510 was effective in blocking neovascularization in the mouse Matrigel plug model and inhibited tumor growth in the mouse Lewis lung carcinoma model. Previous studies had shown that ABT-510 was effective in inhibiting the outgrowth of murine melanoma metastases in syngeneic mice and in blocking the growth of human bladder carcinoma implanted in nude mice. It had been also shown that ABT-510 could regress tumor lesions in pet dogs or cause unexpected stabilization of the disease in advanced canine cancer. ABT-526 and ABT-510 are the first compounds in the class of potent inhibitors of angiogenesis that mimic the antiangiogenic function of TSP-1. ABT-510 is currently in phase II clinical studies.

• Genetic heterogeneity of the vasculogenic phenotype parallels angiogenesis; Implications for cellular surrogate marker analysis of antiangiogenesis.

  Authors: Yuval Shaked, Francesco Bertolini, Shan Man, Michael S Rogers, Dave Cervi, Thomas Foutz, Kimberley Rawn, Daniel Voskas, Daniel J Dumont, Yaacov Ben-David, Jack Lawler, Jack Henkin, Jim Huber, Daniel J Hicklin, Robert J D'Amato, Robert S Kerbel

  Cancer cell. 02/2005; 7(1):101-11.

  Development of antiangiogenic therapies would be significantly facilitated by quantitative surrogate pharmacodynamic markers. Circulating peripheral blood endothelial cells (CECs) and/or theirDevelopment of antiangiogenic therapies would be significantly facilitated by quantitative surrogate pharmacodynamic markers. Circulating peripheral blood endothelial cells (CECs) and/or their putative progenitor subset (CEPs) have been proposed but not yet fully validated for this purpose. Herein, we provide such validation by showing a striking correlation between highly genetically heterogeneous bFGF- or VEGF-induced angiogenesis and intrinsic CEC or CEP levels measured by flow cytometry, among eight different inbred mouse strains. Moreover, studies using genetically altered mice showed that levels of these cells are affected by regulators of angiogenesis, including VEGF, Tie-2, and thrombospondin-1. Finally, treatment with a targeted VEGFR-2 antibody caused a dose-dependent reduction in viable CEPs that precisely paralleled its previously and empirically determined antitumor activity.

• Peroxisome proliferator-activated receptor gamma ligands improve the antitumor efficacy of thrombospondin peptide ABT510.

  Authors: Hanhua Huang, Steven C Campbell, Dhugal F Bedford, Thomas Nelius, Dorina Veliceasa, Emelyn H Shroff, Jack Henkin, Andrew Schneider, Noel Bouck, Olga V Volpert

  Molecular cancer research : MCR. 11/2004; 2(10):541-50.

  An expanding capillary network is critical for several pathologic conditions. In cancer, the decrease of antiangiogenic thrombospondin-1 (TSP1) often enables an angiogenic switch, which can beAn expanding capillary network is critical for several pathologic conditions. In cancer, the decrease of antiangiogenic thrombospondin-1 (TSP1) often enables an angiogenic switch, which can be reversed with exogenous TSP1 or its peptide derivative ABT510. TSP1 acts by inducing endothelial cell apoptosis via signaling cascade initiated at CD36, a TSP1 antiangiogenic receptor. Here, we show that the ligands of nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma), 15-deoxy-delta(12,14)-prostaglandin J2, troglitazone, and rosiglitazone increased PPARgamma and CD36 expression in endothelial cells and improved the efficacy of TSP1 and ABT510 in a CD36-dependent manner. The ABT510 and PPARgamma ligands cooperatively blocked angiogenic endothelial functions in vitro and neovascularization in vivo. In tumor xenografts, 15-deoxy-delta(12,14)-prostaglandin J2 and troglitazone synergistically improved antiangiogenic and antitumor effects of ABT510. Our data provide one mechanism for the in vivo angioinhibitory effect of PPARgamma ligands and show fine-tuning of the antiangiogenic efficacy via targeted up-regulation of the endothelial receptor.

• Lysyl 4-aminobenzoic acid derivatives as potent small molecule mimetics of plasminogen kringle 5.

  Authors: George S Sheppard, Megumi Kawai, Richard A Craig, Donald J Davidson, Sandra M Majest, Randy L Bell, Jack Henkin

  Bioorganic & medicinal chemistry letters. 03/2004; 14(4):965-6.

  Kringle 5, a proteolytic fragment of human plasminogen has been shown to potently inhibit angiogenesis. The tetrapeptide KLYD derived from kringle 5 has been shown to capture many activities ofKringle 5, a proteolytic fragment of human plasminogen has been shown to potently inhibit angiogenesis. The tetrapeptide KLYD derived from kringle 5 has been shown to capture many activities of kringle 5 in vitro. Further simplification has been achieved by replacement of the two central amino acids with a 4-aminobenzoic acid spacer group. Molecules displaying the required recognition groups on this core show similar in vitro properties to kringle 5, and are able to displace radiolabeled protein from a high affinity binding site on endothelial cells.

• 3-Amino-2-hydroxyamides and related compounds as inhibitors of methionine aminopeptidase-2.

  Authors: George S Sheppard, Jieyi Wang, Megumi Kawai, Nwe Y Bamaung, Richard A Craig, Scott A Erickson, Linda Lynch, Jyoti Patel, Fan Yang, Xenia B Searle, Pingping Lou, Chang Park, Ki H Kim, Jack Henkin, Richard Lesniewski

  Bioorganic & medicinal chemistry letters. 03/2004; 14(4):865-8.

  Substituted 3-amino-2-hydroxyamides and related hydroxyamides and acylhydrazines were identified as inhibitors of human methionine aminopeptidase-2 (MetAP2). Examination of substituents throughSubstituted 3-amino-2-hydroxyamides and related hydroxyamides and acylhydrazines were identified as inhibitors of human methionine aminopeptidase-2 (MetAP2). Examination of substituents through parallel synthesis and iterative structure-based design allowed the identification of potent inhibitors with good selectivity against MetAP1. Diacylhydrazine 3t (A-357300) was identified as an analogue displaying inhibition of methionine processing and cellular proliferation in human microvascular endothelial cells (HMVEC).

• Tumor suppression by a rationally designed reversible inhibitor of methionine aminopeptidase-2.

  Authors: Jieyi Wang, George S Sheppard, Pingping Lou, Megumi Kawai, Nwe BaMaung, Scott A Erickson, Lora Tucker-Garcia, Chang Park, Jennifer Bouska, Yi-Chun Wang, David Frost, Paul Tapang, Daniel H Albert, Sherry J Morgan, Michael Morowitz, Suzanne Shusterman, John M Maris, Rick Lesniewski, Jack Henkin

  Cancer research. 12/2003; 63(22):7861-9.

  Methionine aminopeptidase (MetAP)-2 has been suggested as a novel target for cancer therapy because the anticancer agent TNP-470 irreversibly inactivates the catalytic activity of this enzyme.Methionine aminopeptidase (MetAP)-2 has been suggested as a novel target for cancer therapy because the anticancer agent TNP-470 irreversibly inactivates the catalytic activity of this enzyme. However, the importance of MetAP2 in cell growth and tumor progression was uncertain because previous data were based on the chemically reactive TNP-470. Here we show that a rationally designed reversible MetAP2 inhibitor, A-357300, suppresses tumor growth preclinically without the toxicities observed with TNP-470. We have synthesized this bestatin-type MetAP2 inhibitor with the aid of crystal structures of the enzyme-inhibitor complexes and parallel synthesis. A-357300 induces cytostasis by cell cycle arrest at the G(1) phase selectively in endothelial cells and in a subset of tumor cells, but not in most primary cells of nonendothelial type. A-357300 inhibits angiogenesis both in vitro and in vivo and shows potent antitumor efficacy in carcinoma, sarcoma, and neuroblastoma murine models. These data affirm that MetAP2 plays a pivotal role in cell growth and establish that reversible MetAP2 inhibitors are promising novel cancer therapeutic agents.

• Contrasting effects of VEGF gene disruption in embryonic stem cell-derived versus oncogene-induced tumors.

  Authors: Alicia Viloria-Petit, Lucile Miquerol, Joanne L Yu, Marina Gertsenstein, Capucine Sheehan, Linda May, Jack Henkin, Corrinne Lobe, Andras Nagy, Robert S Kerbel, Janusz Rak

  The EMBO journal. 09/2003; 22(16):4091-102.

  Previous gene targeting studies have implicated an indispensable role of vascular endothelial growth factor (VEGF) in tumor angiogenesis, particularly in tumors of embryonal or endocrine origin. InPrevious gene targeting studies have implicated an indispensable role of vascular endothelial growth factor (VEGF) in tumor angiogenesis, particularly in tumors of embryonal or endocrine origin. In contrast, we report here that transformation of VEGF-deficient adult fibroblasts (MDF528) with ras or neu oncogenes gives rise to highly tumorigenic and angiogenic fibrosarcomas. These aggressive VEGF-null tumors (528ras, 528neu) originated from VEGF(-/-) embryonic stem cells, which themselves were tumorigenically deficient. We also report that VEGF production by tumor stroma has a modest role in oncogene-driven tumor angiogenesis. Both ras and neu oncogenes down-regulated at least two endogenous inhibitors of angiogenesis [pigment epithelium derived factor (PEDF) and thrombospondin 1 (TSP-1)]. This is functionally important as administration of an antiangiogenic TSP-1 peptide (ABT-526) markedly inhibited growth of VEGF(-/-) tumors, with some ingress of pericytes. These results provide the first definitive genetic demonstration of the dispensability of tumor cell-derived VEGF in certain cases of 'adult' tumor angiogenesis, and thus highlight the importance of considering VEGF-independent as well as VEGF-dependent pathways when attempting to block this process pharmacologically.