Synthesis of a covalent gemcitabine-(carbamate)-[anti-HER2/neu] immunochemotherapeutic and its cytotoxic anti-neoplastic activity against chemotherapeutic-resistant SKBr-3 mammary carcinoma

Synthesis of a Covalent Epirubicin-(C3-amide)-Anti-HER2/neuImmunochemotherapeutic Utilizing a UV-Photoactivated Anthracycline Intermediate

“…The lack of a requirement for protein thiolation is in obvious contrast to most other synthesis regimens that utilize heterobifunctional reactants similar to SMCC, 7,107-109 EMCH, 9,10,26 or PMPI 30,[110][111][112] that contain a sulfhydryl-reactive moiety. Pre-thiolation of immunoglobulin, F(ab') 2 , Fab, or other biological proteins is usually required due to the relatively low number of nonsterically hindered sulfhydryl groups in the form of reduced cysteine amino acid residues (e.g., R-SH) available within their amino acid sequence.…”

“…7). 7,[26][27][28][29][30]35,40 Discussion A small spectrum of molecular platforms has been applied to facilitate selective ''targeted'' delivery of a variety of biological agents and conventional chemotherapeutics that can exert significant cytotoxic anti-neoplastic properties. Biological agents utilized in this regard include various immunotoxin preparations synthesized to enhance selective ''targeted'' delivery of Pseudomonas exotoxin, 64 84 and monomethyl auristatin E. [86][87][88][89] Several different chemical characteristics of the anthracycline class of chemotherapeutics can be utilized to develop multiple molecular designs and synthesis strategies allowing their covalent incorporation into immunoglobulin fractions or receptor ligands applying a variety of organic chemistry reactions.…”

“…The epirubicin-(anti-HER2/neu) molarincorporation-index of 40% (39.65%) was comparable to analogous levels calculated when using the heterobifunctional reactants, succinimidyl-4-(N-maleimidomethyl)-cyclohexane-1-carboxylate (SMCC), 7 EMCH, 26 or N-[p-maleimidophenyl]-isocyanate (PMPI). 30 In contrast to SMCC, 7,107-109 EMCH, 9,10,26 and PMPI, 30,110-112 succinimidyl 4,4-azipentanoate is technically a homobifunctional reactant when it is applied under two separate conditions that both promoted covalent bond formation at primary amine groups. In this context, the NHS-ester group creates a covalent bond with amines in aqueous buffer or organic solvent systems in the presences of a proton donor (triethylamine) while the photoactivated diazirine group forms covalent bonds with amines in response to UV light exposure.…”

“…Increasing the number of available reduced sulfhydryl groups can be achieved by the application of 1,4-dithiothreitol which reduces intramolecular cystine-cystine bonds 28,31,32 and similar disulfide structures 113 (DTT: R-CH 2 -S-S-CH 2 -R / 2 R-CH 2 -SH). The actual synthetic introduction of ''new'' or additional reduced sulfhydryl groups at the e-amine of lysine amino acid residues is possible with reactions that utilize 2-iminothiolane (2-IT), 2,6,26,30,114 mercaptosuccinimide, 115 or N-succinimidyl-S-acetylthioacetate (SATA). 7,114,116 Alternatively, carboxyl groups on molecules like heparin and hyaluronic acid can be thiolated with 3,3¢dithiobis(propanoic)-hydrazide 113,117 or divinylsulfone, 92,118 for hydroxyl groups of molecules with a cholesterol-like core.…”

“…Monoclonal immunoglobulin fractions are frequently utilized for specific recognition and physical binding to antigens or receptor complexes uniquely overexpressed on the exterior surface membrane of neoplastic cell populations. 7,[26][27][28][29][30] Doxorubicin 28,29,[31][32][33] has been the most common anthracycline to date utilized to synthesize covalent immunochemotherapeutics in addition to the relatively limited utilization of daunorubicin [34][35][36] and epirubicin.…”