Intricacies in the Preparation of Patient Doses of [177Lu]Lu-Rituximab and [177Lu]Lu-Trastuzumab Using Low Specific Activity [177Lu]LuCl3: Methodological Aspects.

The development of humanized monoclonal antibodies (MAbs) with Lutetium-177 ([177Lu]Lu3+) has brought a paradigm shift in the arena of targeted therapy of various cancers. [177Lu]Lu-DOTA-Rituximab and [177Lu]Lu-DOTA-Trastuzumab have gained prominence due to their improved therapeutic efficacy in the treatment of lymphoma and breast cancer. The clinical dose formulation of these radiolabeled MAbs, using low specific activity [177Lu]LuCl3, requires extensive optimization of the radiolabeling protocol. The present study merits the development of a single protocol which has been optimized for conjugation of Rituximab and Trastuzumab with p-NCS-benzyl-DOTA and further radiolabeling these immunoconjugates (ICs) with low specific activity [177Lu]LuCl3. Herein, we report a consistent and reproducible protocol for clinical dose formulations of [177Lu]Lu-DOTA-Rituximab and [177Lu]Lu-DOTA-Trastuzumab (~9.25 GBq each, equivalent to ~2 patient doses) with radiochemical yield (RCY) between 84 and 86% and radiochemical purities (RCP) >99%. The in vitro stabilities of both these radioimmunoconjugates (RICs) were retained up to 120 h post-radiolabeling, upon storage with L-ascorbic acid as stabilizer (concentration: ~ 220-240 µg/37MBq) at -20 °C. The ready-to-use formulation of clinical doses[177Lu]Lu-DOTA-Rituximab and [177Lu]Lu-DOTA-Trastuzumab has been successfully achieved by employing a single optimized protocol. While [177Lu]Lu-DOTA-Rituximab has exhibited a high degree of localization in retroperitoneal nodal mass of refractory lymphoma patient, high uptake of [177Lu]Lu-DOTA-Trastuzumab has been observed in metastatic breast carcinoma patient with multiple skeletal metastases.

Antituberculosis activity of polyphenols of Areca catechu.

Background: Polyphenols have been studied for their potential involvement in the prevention of various chronic diseases as well as for their antimicrobial potential. The crude extracts of arecanut have been reported to have antiinfective properties. We aimed to explore the endosperm of Areca catechu (arecanut) for the extraction of polyphenol components and to study the antituberculosis activity of these polyphenol against Mycobacterium tuberculosis H37Rv. Method: A comparative extraction was performed using microwave and Soxlet apparatus. High performance liquid chromatography (HPLC) technique was used for the estimation of the extracted polyphenols. The minimum inhibitory concentration (MIC) values against M.tuberculosis H37Rv stain, Staphylococcus aureus and Escherichia coli were estimated by resazurin microtiter assay. Results: There was a 11-fold increase in the total phenolic content by microwave assisted extraction compared to the Soxhlet extraction. The powdered extract was found to be active with MIC value of 0.975 ± 0.02 µg/mL. Fractionation and HPLC-based estimation of the extract revealed catechin, epicatechin, and epigallocatechin gallate to be the polyphenol components in the ethanol fraction. Conclusions: The bioactivity of these polyphenols confirmed their presence and complementary effect in the extract form. Because the toxic alkaloid arecoline, known to be present in arecanut, did not show any activity individually, the bioactivity of the extract was attributed to the nontoxic polyphenols present. This extract also showed selective inhibition of M. tuberculosis over other gram positive and gram-negative bacteria, thereby establishing that arecanut is an exploitable selective source of polyphenols acting against M. tuberculosis.

Synthesis and mycobacterial evaluation of 5-substituted-6-acetyl-2-amino-7-methyl-5,8-dihydropyrido-[2,3-d]pyrimidin-4(3H)-one derivatives.

5-Substituted-6-acetyl-2-amino-7-methyl-5,8-dihydropyrido[2,3-d]pyrimidin-4(3H)-one derivatives were synthesized and evaluated against Mycobacterium tuberculosis H37Rv, Mycobacterium aurum, Escherichia coli, and Staphylococcus aureus as well as a human monocyte-derived macrophage (THP-1), and murine macrophage (RAW 264.7) cell lines to assess their antibacterial and cytotoxic potential, respectively. The compounds showed activity in the range of 1.95-125 µg/ml against M. tuberculosis but showed no activity against M. aurum, E. coli, and S. aureus, indicating selectivity towards slow-growing mycobacterial pathogens. The compounds exhibited very low to no cytotoxicity up to 500 µg/ml concentration against eukaryotic cell lines. The most potent molecule, 2l, showed a minimum inhibitory concentration of 1.95 µg/ml against M. tuberculosis H37Rv and a selectivity index of >250 against both the eukaryotic cell lines. Furthermore, 2l showed moderate inhibition of whole-cell mycobacterial drug-efflux pumps when compared to verapamil, a known potent inhibitor of efflux pumps. Thus, derivative 2l was identified as an antituberculosis hit molecule, which could be used to yield more potent lead molecules.

Design and synthesis of 5-(5-nitrothiophen-2-yl)-3-phenyl-4,5-dihydro-1H-pyrazole derivatives with improved solubility and potential antituberculosis activity.

We report the design-synthesis of several nitrothiophene containing molecules as antituberculosis agents. The molecules were designed on the basis of previously reported nitrofuran molecules in our laboratory, and the α,ß-unsaturated linker was modified to cyclized linker in order to overcome the challenge of low solubility and possible toxicity. The stereo-electronic properties such as HOMO, LUMO, and HOMO-LUMO gap along with other properties such as aqueous solvation energies and QPLogS values were studied. The designed molecules were synthesized and tested for in vitro antituberculosis activity, and some molecules were found to be highly active comparable to standard drugs. Further, the aqueous solubility was determined using visual inspection method and the designed molecules were found to be more soluble than their chalcone counterparts. Cytotoxicity studies were performed and the molecules were found to be non-cytotoxic. Electroanalytical studies proved nitro reduction as the mechanism of action for these molecules. Thus, this study provides potential nitrothiophene containing hits with improved solubility and reduced chances of toxicity.

Fragment Discovery for the Design of Nitrogen Heterocycles as Mycobacterium tuberculosis Dihydrofolate Reductase Inhibitors.

Fragment-based drug design was used to identify Mycobacterium tuberculosis (Mtb) dihydrofolate reductase (DHFR) inhibitors. Screening of ligands against the Mtb DHFR enzyme resulted in the identification of multiple fragment hits with IC50 values in the range of 38-90 µM versus Mtb DHFR and minimum inhibitory concentration (MIC) values in the range of 31.5-125 µg/mL. These fragment scaffolds would be useful for anti-tubercular drug design.

Rational drug design, synthesis and biological evaluation of dihydrofolate reductase inhibitors as antituberculosis agents.

BACKGROUND: A series of 2,4-diamino-s-triazines was designed, with potential for activity against Mycobacterium tuberculosis (Mtb) dihydrofolate reductase enzyme, on the basis of virtual screening results and structure-based drug design. RESULTS: The compounds were evaluated against Mtb (H37Rv) and their cytotoxicity was assessed using VERO cell lines. Of particular note, two compounds were found to have the most promising antituberculosis activity (6b minimum inhibitory concentration: 1.76 µM and 6i minimum inhibitory concentration: 1.57 µM) along with low cytotoxicity (CC50: >300 µM). The enzyme assay results of these two indicated significant inhibition of Mtb dihydrofolate reductase along with selectivity. Selected derivatives were tested against dormant tubercle bacilli in vivo and ex vivo indicating potential inhibition. CONCLUSION: This study provides promising antituberculosis dihydrofolate reductase inhibitors that can act as potential leads for further development.