Ivan Spasojevic

Positions:

Associate Professor in Medicine

Medicine, Medical Oncology
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

Ph.D. 1999

Duke University

Grants:

Biomarker Studies for Novel Anti-Cancer Agents

Administered By
Medicine, Medical Oncology
Awarded By
National Institutes of Health
Role
Research Associate
Start Date
End Date

Development of CaMKK2 inhibitor drug for acute radiation syndrome

Administered By
Medicine, Hematologic Malignancies and Cellular Therapy
Awarded By
Columbia University
Role
Investigator
Start Date
End Date

Human EGFRvIII-specific BiTE for the treatment of Glioblastoma

Administered By
Neurosurgery
Awarded By
National Institutes of Health
Role
Investigator
Start Date
End Date

Measurement of oxidative stress biomarkers in human plasma and urine

Administered By
Duke Cancer Institute
Awarded By
University of California - Berkeley
Role
Principal Investigator
Start Date
End Date

Treatment of Neuropathic Pain after SCI with a Catalytic Oxidoreductant

Administered By
Anesthesiology
Awarded By
University of Alabama at Birmingham
Role
Co Investigator
Start Date
End Date

Publications:

Radiation-Mediated Tumor Growth Inhibition Is Significantly Enhanced with Redox-Active Compounds That Cycle with Ascorbate.

AIMS: We aim here to demonstrate that radiation (RT) enhances tumor sensitization by only those Mn complexes that are redox active and cycle with ascorbate (Asc), thereby producing H2O2 and utilizing it subsequently in protein S-glutathionylation in a glutathione peroxidase (GPx)-like manner. In turn, such compounds affect cellular redox environment, described by glutathione disulfide (GSSG)/glutathione (GSH) ratio, and tumor growth. To achieve our goal, we tested several Mn complexes of different chemical and physical properties in cellular and animal flank models of 4T1 breast cancer cell. Four other cancer cell lines were used to substantiate key findings. RESULTS: Joint administration of cationic Mn porphyrin (MnP)-based redox active compounds, MnTE-2-PyP5+ or MnTnBuOE-2-PyP5+ with RT and Asc contributes to high H2O2 production in cancer cells and tumor, which along with high MnP accumulation in cancer cells and tumor induces the largest suppression of cell viability and tumor growth, while increasing GSSG/GSH ratio and levels of total S-glutathionylated proteins. Redox-inert MnP, MnTBAP3- and two other different types of redox-active Mn complexes (EUK-8 and M40403) were neither efficacious in the cellular nor in the animal model. Such outcome is in accordance with their inability to catalyze Asc oxidation and mimic GPx. INNOVATION: We provided here the first evidence how structure-activity relationship between the catalytic potency and the redox properties of Mn complexes controls their ability to impact cellular redox environment and thus enhance the radiation and ascorbate-mediated tumor suppression. CONCLUSIONS: The interplay between the accumulation of cationic MnPs and their potency as catalysts for oxidation of Asc, protein cysteines, and GSH controls the magnitude of their anticancer therapeutic effects.
Authors
Tovmasyan, A; Bueno-Janice, JC; Jaramillo, MC; Sampaio, RS; Reboucas, JS; Kyui, N; Benov, L; Deng, B; Huang, T-T; Tome, ME; Spasojevic, I; Batinic-Haberle, I
MLA Citation
Tovmasyan, Artak, et al. “Radiation-Mediated Tumor Growth Inhibition Is Significantly Enhanced with Redox-Active Compounds That Cycle with Ascorbate.Antioxid Redox Signal, vol. 29, no. 13, Nov. 2018, pp. 1196–214. Pubmed, doi:10.1089/ars.2017.7218.
URI
https://scholars.duke.edu/individual/pub1302155
PMID
29390861
Source
pubmed
Published In
Antioxid Redox Signal
Volume
29
Published Date
Start Page
1196
End Page
1214
DOI
10.1089/ars.2017.7218

Challenges encountered during development of Mn porphyrin-based, potent redox-active drug and superoxide dismutase mimic, MnTnBuOE-2-PyP5+, and its alkoxyalkyl analogues.

We disclose here the studies that preceded and guided the preparation of the metal-based, redox-active therapeutic Mn(III) meso-tetrakis(N-n-butoxyethylpyridyl)porphyrin, MnTnBuOE-2-PyP5+ (BMX-001), which is currently in Phase I/II Clinical Trials at Duke University (USA) as a radioprotector of normal tissues in cancer patients. N-substituted pyridylporphyrins are ligands for Mn(III) complexes that are among the most potent superoxide dismutase mimics thus far synthesized. To advance their design, thereby improving their physical and chemical properties and bioavailability/toxicity profiles, we undertook a systematic study on placing oxygen atoms into N-alkylpyridyl chains via alkoxyalkylation reaction. For the first time we show here the unforeseen structural rearrangement that happens during the alkoxyalkylation reaction by the corresponding tosylates. Comprehensive experimental and computational approaches were employed to solve the rearrangement mechanism involved in quaternization of pyridyl nitrogens, which, instead of a single product, led to a variety of mixed N-alkoxyalkylated and N-alkylated pyridylporphyrins. The rearrangement mechanism involves the formation of an intermediate alkyl oxonium cation in a chain-length-dependent manner, which subsequently drives differential kinetics and thermodynamics of competing N-alkoxyalkylation versus in situ N-alkylation. The use of alkoxyalkyl tosylates, of different length of alkyl fragments adjacent to oxygen atom, allowed us to identify the set of alkyl fragments that would result in the synthesis of a single compound of high purity and excellent therapeutic potential.
Authors
Rajic, Z; Tovmasyan, A; de Santana, OL; Peixoto, IN; Spasojevic, I; do Monte, SA; Ventura, E; Rebouças, JS; Batinic-Haberle, I
MLA Citation
Rajic, Zrinka, et al. “Challenges encountered during development of Mn porphyrin-based, potent redox-active drug and superoxide dismutase mimic, MnTnBuOE-2-PyP5+, and its alkoxyalkyl analogues.J Inorg Biochem, vol. 169, Apr. 2017, pp. 50–60. Pubmed, doi:10.1016/j.jinorgbio.2017.01.003.
URI
https://scholars.duke.edu/individual/pub1176227
PMID
28131001
Source
pubmed
Published In
J Inorg Biochem
Volume
169
Published Date
Start Page
50
End Page
60
DOI
10.1016/j.jinorgbio.2017.01.003

An educational overview of the chemistry, biochemistry and therapeutic aspects of Mn porphyrins--From superoxide dismutation to H2O2-driven pathways.

Most of the SOD mimics thus far developed belong to the classes of Mn-(MnPs) and Fe porphyrins(FePs), Mn(III) salens, Mn(II) cyclic polyamines and metal salts. Due to their remarkable stability we have predominantly explored Mn porphyrins, aiming initially at mimicking kinetics and thermodynamics of the catalysis of O2(-) dismutation by SOD enzymes. Several MnPs are of potency similar to SOD enzymes. The in vivo bioavailability and toxicity of MnPs have been addressed also. Numerous in vitro and in vivo studies indicate their impressive therapeutic efficacy. Increasing insight into complex cellular redox biology has been accompanied by increasing awareness of complex redox chemistry of MnPs. During O2(-) dismutation process, the most powerful Mn porphyrin-based SOD mimics reduce and oxidize O2(-) with close to identical rate constants. MnPs reduce and oxidize other reactive species also (none of them specific to MnPs), acting as reductants (antioxidant) and pro-oxidants. Distinction must be made between the type of reactions of MnPs and the favorable therapeutic effects we observe; the latter may be of either anti- or pro-oxidative nature. H2O2/MnP mediated oxidation of protein thiols and its impact on cellular transcription seems to dominate redox biology of MnPs. It has been thus far demonstrated that the ability of MnPs to catalyze O2(-) dismutation parallels all other reactivities (such as ONOO(-) reduction) and in turn their therapeutic efficacies. Assuming that all diseases have in common the perturbation of cellular redox environment, developing SOD mimics still seems to be the appropriate strategy for the design of potent redox-active therapeutics.
Authors
Batinic-Haberle, I; Tovmasyan, A; Spasojevic, I
MLA Citation
Batinic-Haberle, Ines, et al. “An educational overview of the chemistry, biochemistry and therapeutic aspects of Mn porphyrins--From superoxide dismutation to H2O2-driven pathways.Redox Biol, vol. 5, Aug. 2015, pp. 43–65. Pubmed, doi:10.1016/j.redox.2015.01.017.
URI
https://scholars.duke.edu/individual/pub1062064
PMID
25827425
Source
pubmed
Published In
Redox Biology
Volume
5
Published Date
Start Page
43
End Page
65
DOI
10.1016/j.redox.2015.01.017

Differential coordination demands in Fe versus Mn water-soluble cationic metalloporphyrins translate into remarkably different aqueous redox chemistry and biology.

The different biological behavior of cationic Fe and Mn pyridylporphyrins in Escherichia coli and mouse studies prompted us to revisit and compare their chemistry. For that purpose, the series of ortho and meta isomers of Fe(III) meso-tetrakis-N-alkylpyridylporphyrins, alkyl being methyl to n-octyl, were synthesized and characterized by elemental analysis, UV/vis spectroscopy, mass spectrometry, lipophilicity, protonation equilibria of axial waters, metal-centered reduction potential, E(1/2) for M(III)P/M(II)P redox couple (M = Fe, Mn, P = porphyrin), kcat for the catalysis of O2(•-) dismutation, stability toward peroxide-driven porphyrin oxidative degradation (produced in the catalysis of ascorbate oxidation by MP), ability to affect growth of SOD-deficient E. coli, and toxicity to mice. Electron-deficiency of the metal site is modulated by the porphyrin ligand, which renders Fe(III) porphyrins ≥5 orders of magnitude more acidic than the analogous Mn(III) porphyrins, as revealed by the pKa1 of axially coordinated waters. The 5 log units difference in the acidity between the Mn and Fe sites in porphyrin translates into the predominance of tetracationic (OH)(H2O)FeP complexes relative to pentacationic (H2O)2MnP species at pH ∼7.8. This is additionally evidenced in large differences in the E(1/2) values of M(III)P/M(II)P redox couples. The presence of hydroxo ligand labilizes trans-axial water which results in higher reactivity of Fe relative to Mn center. The differences in the catalysis of O2(•-) dismutation (log kcat) between Fe and Mn porphyrins is modest, 2.5-5-fold, due to predominantly outer-sphere, with partial inner-sphere character of two reaction steps. However, the rate constant for the inner-sphere H2O2-based porphyrin oxidative degradation is 18-fold larger for (OH)(H2O)FeP than for (H2O)2MnP. The in vivo consequences of the differences between the Fe and Mn porphyrins were best demonstrated in SOD-deficient E. coli growth. On the basis of fairly similar log kcat(O2(•-)) values, a very similar effect on the growth of SOD-deficient E. coli was anticipated by both metalloporphyrins. Yet, while (H2O)2MnTE-2-PyP(5+) was fully efficacious at ≥20 μM, the Fe analogue (OH)(H2O)FeTE-2-PyP(4+) supported SOD-deficient E. coli growth at as much as 200-fold lower doses in the range of 0.1-1 μM. Moreover the pattern of SOD-deficient E. coli growth was different with Mn and Fe porphyrins. Such results suggested a different mode of action of these metalloporphyrins. Further exploration demonstrated that (1) 0.1 μM (OH)(H2O)FeTE-2-PyP(4+) provided similar growth stimulation as the 0.1 μM Fe salt, while the 20 μM Mn salt provides no protection to E. coli; and (2) 1 μM Fe porphyrin is fully degraded by 12 h in E. coli cytosol and growth medium, while Mn porphyrin is not. Stimulation of the aerobic growth of SOD-deficient E. coli by the Fe porphyrin is therefore due to iron acquisition. Our data suggest that in vivo, redox-driven degradation of Fe porphyrins resulting in Fe release plays a major role in their biological action. Possibly, iron reconstitutes enzymes bearing [4Fe-4S] clusters as active sites. Under the same experimental conditions, (OH)(H2O)FePs do not cause mouse arterial hypotension, whereas (H2O)2MnPs do, which greatly limits the application of Mn porphyrins in vivo.
Authors
Tovmasyan, A; Weitner, T; Sheng, H; Lu, M; Rajic, Z; Warner, DS; Spasojevic, I; Reboucas, JS; Benov, L; Batinic-Haberle, I
MLA Citation
Tovmasyan, Artak, et al. “Differential coordination demands in Fe versus Mn water-soluble cationic metalloporphyrins translate into remarkably different aqueous redox chemistry and biology.Inorg Chem, vol. 52, no. 10, May 2013, pp. 5677–91. Pubmed, doi:10.1021/ic3012519.
URI
https://scholars.duke.edu/individual/pub947892
PMID
23646875
Source
pubmed
Published In
Inorg Chem
Volume
52
Published Date
Start Page
5677
End Page
5691
DOI
10.1021/ic3012519

Erratum: Design of Mn porphyrins for treating oxidative stress injuries and their redox-based regulation of cellular transcriptional activities (Amino Acids DOI: 10.1007/s00726-010-0603-6)

Authors
Batinic-Haberle, I; Spasojevic, I; Tse, HM; Tovmasyan, A; Rajic, Z; Clair, DKS; Vujaskovic, Z; Dewhirst, MW; Piganelli, JD
MLA Citation
Batinic-Haberle, I., et al. “Erratum: Design of Mn porphyrins for treating oxidative stress injuries and their redox-based regulation of cellular transcriptional activities (Amino Acids DOI: 10.1007/s00726-010-0603-6).” Amino Acids, vol. 42, no. 1, Jan. 2012, pp. 115–16. Scopus, doi:10.1007/s00726-010-0821-y.
URI
https://scholars.duke.edu/individual/pub759451
Source
scopus
Published In
Amino Acids
Volume
42
Published Date
Start Page
115
End Page
116
DOI
10.1007/s00726-010-0821-y