Sergio Penco

SST0001, a Chemically Modified Heparin, Inhibits Myeloma Growth and Angiogenesis via Disruption of the Heparanase/Syndecan-1 Axis

Purpose: Heparanase promotes myeloma growth, dissemination, and angiogenesis through modulation of the tumor microenvironment, thus highlighting the potential of therapeutically targeting this enzyme. SST0001, a nonanticoagulant heparin with antiheparanase activity, was examined for its inhibition of myeloma tumor growth in vivo and for its mechanism of action. Experimental Design: The ability of SST0001 to inhibit growth of myeloma tumors was assessed using multiple animal models and a diverse panel of human and murine myeloma cell lines. To investigate the mechanism of action of SST0001, pharmacodynamic markers of angiogenesis, heparanase activity, and pathways downstream of heparanase were monitored. The potential use of SST0001 as part of a combination therapy was also evaluated in vivo. Results: SST0001 effectively inhibited myeloma growth in vivo, even when confronted with an aggressively growing tumor within human bone. In addition, SST0001 treatment causes changes within tumors consistent with the compounds ability to inhibit heparanase, including downregulation of HGF, VEGF, and MMP-9 expression and suppressed angiogenesis. SST0001 also diminishes heparanase-induced shedding of syndecan-1, a heparan sulfate proteoglycan known to be a potent promoter of myeloma growth. SST0001 inhibited the heparanase-mediated degradation of syndecan-1 heparan sulfate chains, thus confirming the antiheparanase activity of this compound. In combination with dexamethasone, SST0001 blocked tumor growth in vivo presumably through dual targeting of the tumor and its microenvironment. Conclusions: These results provide mechanistic insight into the antitumor action of SST0001 and validate its use as a novel therapeutic tool for treating multiple myeloma. Clin Cancer Res; 17(6); 1382–93. ©2011 AACR.

Design, synthesis, and evaluation of biphenyl-4-yl-acrylohydroxamic acid derivatives as histone deacetylase (HDAC) inhibitors

A series of hydroxamic acid-based histone deacetylase (HDAC) inhibitors were designed on the basis of a model of the HDAC2 binding site and synthesized. They are characterized by a cinnamic spacer, capped with a substituted phenyl group. Modifications of the spacer are also reported. In an in vitro assay with the isoenzyme HDAC2, a good correlation of the activity with the docking energy was found. In human ovarian carcinoma IGROV-1 cells, selected compounds produced significant acetylation of p53 and alpha-tubulin. Most compounds showed an antiproliferative activity comparable to that of SAHA. At equitoxic concentrations, the tested compounds were more effective than SAHA in inducing apoptotic cell death. Compounds selected for in vivo evaluation exhibited a significant antitumor activity on three tumor models at well tolerated doses, thus suggesting a good therapeutic index.

Novel tumor-targeted RGD peptide-camptothecin conjugates: synthesis and biological evaluation.

Five RGD peptide-camptothecin (CPT) conjugates were designed and synthesized with the purpose to improve the therapeutic index of this antitumoral drug family. New RGD cyclopeptides were selected on the basis of their high affinity to alpha(v) integrin receptors overexpressed by tumor cells and their metabolic stability. The conjugates can be divided in two groups: in the first the peptide was attached to the drug through an amide bond, in the second through a hydrazone bond. The main difference between the two spacers lies in their acid stability. Affinity to the receptors was maintained for all conjugates and their internalization into tumor cells was demonstrated. The first group conjugates showed lower in vitro and in vivo activity than the parent drug, probably due to the excessive stability of the amide bond, even inside the tumor cells. Conversely, the hydrazone conjugates exhibited in vitro tumor cell inhibition similar to the parent drug, indicating high conversion in the culture medium and/or inside the cells, but their poor solubility hampered in vivo experiments. On the basis of these results, information was acquired for additional development of derivatives with different linkers and better solubility for in vivo evaluation.

Antitumor efficacy of the heparanase inhibitor SST0001 alone and in combination with antiangiogenic agents in the treatment of human pediatric sarcoma models

The activity of heparanase is responsible for heparan sulfate cleavage, thus resulting in the release of heparan sulfate-bound growth factors. Since heparanase activity is upregulated in several tumor types and is implicated in the malignant behavior, the enzyme is regarded as a promising target for antitumor therapy. Based on previous evidence that the heparanase inhibitor SST0001, a non-anticoagulant N-acetylated glycol split heparin, is effective against an Ewings sarcoma model, the present study was performed to extend the preclinical evaluation of SST0001 to a panel of pediatric sarcoma models, representative of various tumor histotypes (soft tissue and bone sarcomas) and to further elucidate its mode of action. SST0001 treatment downregulated several angiogenic factors in the conditioned media of sarcoma cells, inhibited the pro-invasive effect of heparin-binding factors (VEGF, bFGF, HGF, PDGF), and abrogated PDGF receptor tyrosine phosphorylation. Subcutaneous administration of SST0001 was very effective, resulting in a significant growth inhibition (range, 64-95%) of all tested tumor xenografts. The efficacy of SST0001 was enhanced in combination with antiangiogenic agents (bevacizumab, sunitinib) as documented by the high rate of complete response. The synergistic effect of SST0001 in combination with antiangiogenic agents is consistent with the heparanase mode of action and with the relevant role of heparin-binding proangiogenic/growth factors in the malignant behavior of sarcoma cells.

Enol Carbamates as Inhibitors of Fatty Acid Amide Hydrolase (FAAH) Endowed with High Selectivity for FAAH over the Other Targets of the Endocannabinoid System

Enol Carbamates as Inhibitors of Fatty Acid Amide Hydrolase (FAAH) Endowed with High Selectivity for FAAH over the Other Targets of the Endocannabinoid System Sonia Gattinoni, Chiara De Simone, c] Sabrina Dallavalle, Filomena Fezza, c] Raffaella Nannei, Daniele Amadio, c] Patrizia Minetti, Gianandrea Quattrociocchi, Antonio Caprioli, Franco Borsini, Walter Cabri, Sergio Penco, Lucio Merlini,* and Mauro Maccarrone*

Azetidinones as zinc-binding groups to design selective HDAC8 inhibitors.

2‐Azetidinones, commonly known as β‐lactams, are well‐known heterocyclic compounds. Herein we described the synthesis and biological evaluation of a series of novel β‐lactams. In vitro inhibition assays against HDAC isoforms showed an interesting isoform‐selectivity of these compounds towards HDAC6 and HDAC8. The isoform selectivity changed in response to modification of the azetidinone‐ring nitrogen atom substituent. The presence of an N‐thiomethyl group is a prerequisite for the activity of these compounds in the micromolar range towards HDAC8.

Preclinical profile of antitumor activity of a novel hydrophilic camptothecin, ST1968

ST1968 is a novel hydrophilic camptothecin (CPT) derivative of the 7-oxyiminomethyl series. Because ST1968 retained ability to form remarkably stable cleavable complexes, this study was done to investigate its preclinical profile of antitumor activity in a large panel of human tumor models, including irinotecan-resistant tumors. Although less potent than SN38 in vitro, i.v. administered ST1968 caused a marked tumor inhibition, superior to that of irinotecan, in most tested models. ST1968 exhibited an impressive activity against several tumors including models of ovarian and colon carcinoma in which a high rate of cures was observed. In the most responsive tumors, complete and persistent tumor regressions were achieved even with low suboptimal doses. Even tumors derived from intrinsically resistant cells exhibited a significant responsiveness. Histologic analysis of treated tumors supports a contribution of both proapoptotic and antiangiogenic effects to ST1968 antitumor efficacy. A study done in yeast cells transformed with CPT-resistant mutant forms of topoisomerase I documented that, in contrast to other tested CPT, ST1968 was active against yeasts expressing the mutant K720E enzyme. Based on its outstanding efficacy superior to that of irinotecan and of its good therapeutic index, ST1968 has been selected for clinical development. [Mol Cancer Ther 2008;7(7):2051–9]

Synthesis, modeling, and RET protein kinase inhibitory activity of 3- and 4-substituted β-carbolin-1-ones

A series of beta-carbolin-2-ones and 3,10-dihydro-2H-azepino[3,4-b]indol-1-ones have been designed, synthesized, and evaluated as RET protein kinase inhibitors on the basis of their structural similarity with the prototype indolin-2-one RPI-1. Some beta-carbolin-2-ones (structure 2) showed an ability to inhibit RET enzymatic activity in vitro and proliferation of RETC634R oncogene-transformed NIH3T3 cells comparable to that of the reference compound. The docking analysis of the interaction of these compounds with the crystallographic structure of RET tyrosine kinase domain suggested a new binding interaction scheme different from the one proposed during their design. The rigid structure of the compounds of this series represents a new scaffold with potential advantages in the design of RET protein kinase inhibitors.

Novel cytotoxic 7-iminomethyl and 7-aminomethyl derivatives of camptothecin

A series of new 7-iminomethyl derivatives of camptothecin were obtained from camptothecin-7-aldehyde and aromatic, alicyclic and aliphatic amines. Their hydrogenation led to the corresponding amines. All the imines and the less polar amines showed a marked increase of the cytotoxic activity against H460 non-small lung carcinoma cell line, with respect to topotecan. The lipophilicity of the substituent in position 7 of camptothecin seems to play an important role for cytotoxic potency. The 7-phenyliminomethyl derivative showed efficacy comparable to topotecan in vivo against NSCLC H460 xenografted in athymic nude mice.

A new group of oxime carbamates as reversible inhibitors of fatty acid amide hydrolase.

A series of oxime carbamates have been identified as potent inhibitors of fatty acid amide hydrolase (FAAH), an important regulatory enzyme of the endocannabinoid signaling system. Kinetic analysis indicates that they behave as non-competitive, reversible inhibitors, and show remarkable selectivity for FAAH over the other components of the endocannabinoid system.