GEMCITABINE INORGANIC-ORGANIC HYBRID NANOPARTICLES

Abstract

The present invention relates to an inorganic-organic hybrid compound as ionic compound, composed of an inorganic metal cation selected from [ZrO].sup.2+, and of an organic active ingredient anion selected from gemcitabine monophosphate or gemcitabine triphosphate.

Claims

1. An inorganic-organic hybrid compound as ionic compound, comprising the cation [ZrO].sup.2+ and an organic active ingredient anion selected from gemcitabine monophosphate or gemcitabine triphosphate.

2. The inorganic-organic hybrid compound as claimed in claim 1, which has a particle diameter in the range from 1 to 100 nm.

3. The inorganic-organic hybrid compound as claimed in claim 1, said compound being [ZrO].sup.2+[GMP].sup.2 or [ZrO].sup.2+.sub.3[GTP].sup.3.sub.2.

4. The inorganic-organic hybrid compound as claimed in claim 1, which is in X-ray-amorphous form.

5. The inorganic-organic hybrid compound as claimed in claim 1, further comprising a fluorescent dye anion which carries a phosphate, phosphonate, sulfate, sulfonate, carbonate, or carboxylate group as functional group.

6. The inorganic-organic hybrid compound as claimed in claim 5, the organic fluorescent dye anion being derived from fluorescent dyes selected from the group consisting of 1,1-diethyl-2,2-cyanine iodide, 1,2-diphenylacetylene, 1,4-diphenylbutadiene, 1,6-diphenylhexatriene, 2,5-diphenyloxazole, 2-methylbenzoxazole, 4,6-diamidino-2-phenylindole (DAPI), 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM), 4-dimethylamino-4-nitrostilbene, 5,10,15-triphenylcorrole, 5,10,15-tris(pentafluorophenyl)corrole, 5,10-diarylchlorin, 5,10-diarylcopper chlorin, 5,10-diarylcopper oxochlorin, 5,10-diarylmagnesium oxochlorin, 5,10-diaryloxochlorin, 5,10-diarylzinc chlorin, 5,10-diarylzinc oxochlorin, 7-benzylamino-4-nitrobenz-2-oxa-1,3-diazole, 7-methoxycoumarin-4-acetic acid, 9,10-bis(phenylethynyl)anthracene, 9,10-diphenylanthracene, acridine orange, acridine yellow, adenine, anthracene, anthraquinone, auramine O, azobenzene, bacteriochlorophyll A, benzoquinone, beta-carotene, bilirubin, biliverdin dimethyl ester, biphenyl, bis(5-mesityldipyrrinato)zinc, bis(5-phenyldipyrrinato)zinc, boron subphthalocyanine chloride, chlorin E6, chlorophyll A, chlorophyll B, cis-stilbene, coumarin and its derivatives, cresyl violet perchlorate, cryptocyanine, crystal violet, cytosine, dansylglycine, diprotonated tetraphenylporphyrin, eosine and its derivatives, ethyl (p-dimethylamino)benzoate, ferrocene, fluorescein and its derivatives, as for example methylfluorescein, resorufin, amaranth, aluminum(III)-phthalocyanine chloride tetrasulfonic acid, trypan blue, guanine, hematin, histidine, Hoechst 33258, indocarbocyanine and its derivatives, lucifer yellow CH, magnesium octaethylporphyrin, magnesium phthalocyanine, magnesium tetramesitylporphyrin, magnesium tetraphenylporphyrin, malachite green, merocyanine, N, N-difluoroboryl-1,9-dimethyl-5-(4-iodophenyl)dipyrrin, N, N-difluoroboryl-1,9-dimethyl-5-[(4-(2-trimethylsilylethynyl), N,N-difluoroboryl-1,9-dimethyl-5-phenyldipyrrin, tetraphenylporphyrin, naphthalene, nile blue, nile red, octaethylporphyrin, oxacarbocyanine and its derivatives, oxazine and its derivatives, p-quaterphenyl, p-terphenyl, perylene and its derivatives, phenol, phenylalanine, phenyldipyrrin, pheophorbide, phthalocyanine, pinacyanol iodide, piroxicam, porphin, proflavin, protoporphyrin IX dimethyl ester, pyrene, pyropheophorbide and its derivatives, pyrrol, quinine, rhodamine and its derivatives, riboflavin, bengal red, squarylium dye III, TBP beta-octa(COOBu)-Fb, TBP beta-octa(COOBu)-Pd, TBP beta-octa(COOBu)-Zn, TBP meso-tetraphenyl-beta-octa(COOMe)-Fb, TBP meso-tetraphenyl-beta-octa(COOMe)-Pd, TBP meso-tetraphenyl-beta-octa(COOMe)-Zn, TCPH meso-tetra(4-COOMe-phenyl)-Fb, TCPH meso-tetra(4-COOMe-phenyl)-Pd, TCPH meso-tetra(4-COOMe-phenyl)-Zn, tetra-tert-butylazaporphin, tetra-tert-butylnaphthalocyanine, tetrakis(2,6-dichlorophenyl)porphyrin, tetrakis(o-aminophenyl)porphyrin, tetramesitylporphyrin, tetraphenylporphyrin, tetraphenylsapphyrin, thiacarbocyanine and its derivatives, thymine, trans-stilbene, tris(2,2-bipyridyl)ruthenium(II), tryptophan, thyrosine, uracil, vitamin B12, zinc octaethylporphyrin, phthalocyanine and its derivatives, porphyrin and its derivatives, including tetra(o-amidophosphonatophenyl)porphyrin, and umbelliferone, where the organic fluorescent dyes which do not as such have a phosphate, phosphonate, sulfate, sulfonate, carbonate, or carboxylate group have been modified with at least one of these functional groups.

7. The inorganic-organic hybrid compound as claimed in claim 1, which is doped with a lanthanoid selected from Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu, with a transition metal selected from Cr, Mn, Cu, Zn, Y, Ag, or Cd, with a main group element selected from Sn, Sb, Pb, or Bi, or with a complex anion selected from [VO.sub.4].sup.3, [MoO.sub.4].sup.3 or [WO.sub.4].sup.3.

8. The inorganic-organic hybrid compound as claimed in claim 1, which is further functionalized with an antibody, peptide or oligonucleotide.

9. The inorganic-organic hybrid compound as claimed in claim 1, which is cetuximab-functionalized.

10. The inorganic-organic hybrid compound as claimed in claim 1, which is glucose-coated.

11. A method of treating pancreatic ductal adenocarcinoma (PDAC) by administering the inorganic-organic hybrid compound of claim 1.

12. The method of claim 11, wherein the inorganic-organic hybrid compound has a particle diameter in the range from 1 to 100 nm.

13. The method of claim 11, wherein the inorganic-organic hybrid compound is [ZrO].sup.2+[GMP].sup.2 or [ZrO].sup.2+.sub.3[GTP].sup.3.sub.2.

14. The method of claim 11, wherein the inorganic-organic hybrid compound is in X-ray-amorphous form.

15. The method of claim 11, wherein the inorganic-organic hybrid compound further comprises a fluorescent dye anion which carries a phosphate, phosphonate, sulfate, sulfonate, carbonate, or carboxylate group as functional group.

16. The method of claim 15, wherein the fluorescent dye anion is derived from fluorescent dyes selected from the group consisting of 1,1-diethyl-2,2-cyanine iodide, 1,2-diphenylacetylene, 1,4-diphenylbutadiene, 1,6-diphenylhexatriene, 2,5-diphenyloxazole, 2-methylbenzoxazole, 4,6-diamidino-2-phenylindole (DAPI), 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM), 4-dimethylamino-4-nitrostilbene, 5,10,15-triphenylcorrole, 5,10,15-tris(pentafluorophenyl)corrole, 5,10-diarylchlorin, 5,10-diarylcopper chlorin, 5,10-diarylcopper oxochlorin, 5,10-diarylmagnesium oxochlorin, 5,10-diaryloxochlorin, 5,10-diarylzinc chlorin, 5,10-diarylzinc oxochlorin, 7-benzylamino-4-nitrobenz-2-oxa-1,3-diazole, 7-methoxycoumarin-4-acetic acid, 9,10-bis(phenylethynyl)anthracene, 9,10-diphenylanthracene, acridine orange, acridine yellow, adenine, anthracene, anthraquinone, auramine O, azobenzene, bacteriochlorophyll A, benzoquinone, beta-carotene, bilirubin, biliverdin dimethyl ester, biphenyl, bis(5-mesityldipyrrinato)zinc, bis(5-phenyldipyrrinato)zinc, boron subphthalocyanine chloride, chlorin E6, chlorophyll A, chlorophyll B, cis-stilbene, coumarin and its derivatives, cresyl violet perchlorate, cryptocyanine, crystal violet, cytosine, dansylglycine, diprotonated tetraphenylporphyrin, eosine and its derivatives, ethyl (p-dimethylamino)benzoate, ferrocene, fluorescein and its derivatives, as for example methylfluorescein, resorufin, amaranth, aluminum(III)-phthalocyanine chloride tetrasulfonic acid, trypan blue, guanine, hematin, histidine, Hoechst 33258, indocarbocyanine and its derivatives, lucifer yellow CH, magnesium octaethylporphyrin, magnesium phthalocyanine, magnesium tetramesitylporphyrin, magnesium tetraphenylporphyrin, malachite green, merocyanine, N, N-difluoroboryl-1,9-dimethyl-5-(4-iodophenyl)dipyrrin, N,N-difluoroboryl-1,9-dimethyl-5-[(4-(2-trimethylsilylethynyl), N,N-difluoroboryl-1,9-dimethyl-5-phenyldipyrrin, tetraphenylporphyrin, naphthalene, nile blue, nile red, octaethylporphyrin, oxacarbocyanine and its derivatives, oxazine and its derivatives, p-quaterphenyl, p-terphenyl, perylene and its derivatives, phenol, phenylalanine, phenyldipyrrin, pheophorbide, phthalocyanine, pinacyanol iodide, piroxicam, porphin, proflavin, protoporphyrin IX dimethyl ester, pyrene, pyropheophorbide and its derivatives, pyrrol, quinine, rhodamine and its derivatives, riboflavin, bengal red, squarylium dye III, TBP beta-octa(COOBu)-Fb, TBP beta-octa(COOBu)-Pd, TBP beta-octa(COOBu)-Zn, TBP meso-tetraphenyl-beta-octa(COOMe)-Fb, TBP meso-tetraphenyl-beta-octa(COOMe)-Pd, TBP meso-tetraphenyl-beta-octa(COOMe)-Zn, TCPH meso-tetra(4-COOMe-phenyl)-Fb, TCPH meso-tetra(4-COOMe-phenyl)-Pd, TCPH meso-tetra(4-COOMe-phenyl)-Zn, tetra-tert-butylazaporphin, tetra-tert-butylnaphthalocyanine, tetrakis(2,6-dichlorophenyl)porphyrin, tetrakis(o-aminophenyl)porphyrin, tetramesitylporphyrin, tetraphenylporphyrin, tetraphenylsapphyrin, thiacarbocyanine and its derivatives, thymine, trans-stilbene, tris(2,2-bipyridyl)ruthenium(II), tryptophan, thyrosine, uracil, vitamin B12, zinc octaethylporphyrin, phthalocyanine and its derivatives, porphyrin and its derivatives, including tetra(o-amidophosphonatophenyl)porphyrin, and umbelliferone, where the organic fluorescent dyes which do not as such have a phosphate, phosphonate, sulfate, sulfonate, carbonate, or carboxylate group have been modified with at least one of these functional groups.

17. The method of claim 11, wherein the inorganic-organic hybrid compound is doped with a lanthanoid selected from Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu, with a transition metal selected from Cr, Mn, Cu, Zn, Y, Ag, or Cd, with a main group element selected from Sn, Sb, Pb, or Bi, or with a complex anion selected from [VO.sub.4].sup.3, [MoO4].sup.3 or [WO.sub.4].sup.3.

18. The method of claim 11, wherein the inorganic-organic hybrid compound is further functionalized with an antibody, peptide, or oligonucleotide.

19. The method of claim 11, wherein the inorganic-organic hybrid compound is cetuximab-functionalized.

20. The method of claim 11, wherein the inorganic-organic hybrid compound is glucose-coated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 shows the synthesis and characterization of [ZrO].sup.2+[GMP].sup.2 IOH-NPs: a) Scheme illustrating the aqueous synthesis, b) particle size distribution according to DLS and SEM with photo of aqueous suspension, c) SEM images at different levels of magnification, d) FT-IR spectra (with H2(GMP) as a reference), e) zeta potential, including surface-functionalized [ZrO].sup.2+[GMP].sup.2@[ZrO].sup.2+[G6P].sup.2 and [ZrO].sup.2+[GMP].sup.2@CTX IOH-NPs (G6P: glucose-6-phosphate; CTX: cetuximab), f) scheme of IOH-NPs with designation used for in vitro/in vivo studies.

[0037] FIG. 2 shows a schematic representation of the protocol for establishing GEM-resistant PDAC cell-lines, here KPC and AsPC-1 cells. Initially, native KPC or AsPC-1 cells were cultured in a medium with stepwise increases in GEM (Gemcitabine) concentration during the adaptation phase, until resistance was achieved at a final concentration of 1000 nM (consolidation phase). After acquiring GEM resistance, the pancreatic ductal adenocarcinoma (PDAC) cells were maintained in a medium containing 700 nM GEM to ensure the stability of the GEM-resistant phenotype.

[0038] FIG. 3 shows the anti-tumor efficacy of GMP-IOH-NPs in GEM-Resistant KPC - PDAC cells in comparison to native KPC cells. Cell viability of KPC-Native cells (left graph) and KPC-Resistant cells (right graph) after 6 days of treatment with Free GEM (blue line), Ref-IOH-NP (red line), and GMP-IOH-NPs (green line). Cell viability was assessed using the luminescent CellTiter-Glo assay, and results are presented as the percentage of viable cells normalized to untreated (unstimulated) cells. Data is presented as meanSEM. Two-way ANOVA, followed by Dunnett's multiple comparisons was performed from triplicates of three independent experiments (**p0.01).

[0039] FIG. 4 shows the anti-tumor efficacy of GMP-IOH-NPs and GTP-IOH-NPs in human GEM-Resistant AsPC-1 PDAC cells in comparison to Native AsPC-1 cells. Cell viability of AsPC-1 Native cells (upper graphs) after 6 days of treatment with Free GEM (blue line), GMP-IOH-NPs (green line, left graph) and GTP-IOH-NP (green line, right graph). Cell viability of AsPC-1 Resistant cells (lower graph) after 6 days in response to treatment with Free GEM (blue line), GMP-IOH-NPs (green line) and GTP-IOH-NP (red line). Cell viability was assessed using the luminescent CellTiter-Glo assay, and results are presented as the percentage of viable cells normalized to unstimulated (untreated) cells. Data is presented as meanSEM. Two-way ANOVA, followed by Dunnett's multiple comparisons was performed from triplicates of three independent experiments. Statistical differences as free GEM vs. GMP-IOH-NP; free GEM vs. GTP-IOH-NP; and GMP-IOH-NP vs. GTP-IOH-NP are calculated from all values of all concentrations in the range of 1000 to 2000 nM (***p0.001, ****p<0.0001).

DETAILED DESCRIPTION

[0040] Provided is an inorganic-organic hybrid compound as ionic compound, composed of an inorganic metal cation selected from [ZrO].sup.2+, and of an organic active ingredient anion selected from gemcitabine monophosphate or gemcitabine triphosphate.

[0041] Inorganic-organic hybrid nanoparticles (IOH-NPs) are characterized by a saline composition with an inorganic cation and a drug anion, which is functionalized by phosphate, sulfonate, or carboxylate groups (see B. L. Neumeier, M. Khorenko, F. Alves, O. Goldmann, J. Napp, U. Schepers, H. M. Reichardt, C. Feldmann, ChemNanoMat 2019, 5, 24-45). Specifically, the concept of IOH-NPs comprises a simple synthesis in water, an extraordinary high drug load (>60 % of total nanoparticle mass), an uncomplex composition and structure of the nanocarriers, and a high adaptability of the IOH-NPs to use various drugs. Previous studies with antibiotic or anti-inflammatory drugs have already pointed to the feasibility of the material concept. Here, gemcitabine monophosphate (GMP) is used as chemotherapeutic anion for the first time. Zirconyl ([ZrO].sup.2+) is used as inorganic cation to make the drug insoluble in water and to obtain IOH-NPs with a saline composition [ZrO].sup.2+GMP].sup.2 (FIG. 1).

[0042] In detail, [ZrO].sup.2+[GMP].sup.2 IOH-NPs were synthesized by injection of aqueous ZrOCl.sub.28H2O into an aqueous solution of H.sub.2(GMP) (FIG. 1a), which, after purification, results in colloidally highly stable suspensions (5 mg/mL) that do not show any sedimentation over several weeks (FIG. 1b). Particle size, size distribution and zeta-potential analysis were examined by dynamic light scattering (DLS) and scanning electron microscopy (SEM). Accordingly, a hydrodynamic diameter of 6916 nm (DLS) and a diameter of 294 nm (SEM) were obtained with negative surface charging (356 mV) (FIG. 1b,c,e), which is also causative for the colloidal stability. The chemical composition of the [ZrO].sup.2+[GMP].sup.2 IOH-NPs was validated by different methods, including X-ray diffraction (XRD), energy-dispersive electron spectroscopy (EDXS), Fourier-transform infrared (FT-IR) spectroscopy, elemental analysis (EA, C/H/N/S analysis), and total organics combustion/thermogravimetry (TG) (FIG. 1d). Whereas the presence of zirconium and GMP were qualitatively confirmed by EDXS and FT-IR, the [ZrO].sup.2+:[GMP].sup.2 ratio and the overall composition were quantified by EA and TG. In sum, the composition [ZrO].sup.2+[GMP].sup.2 with a GMP-load of 76 % of the total IOH-NP mass (24 % due to [ZrO].sup.2+ as inorganic cation) was confirmed.

[0043] Here, it should be noticed that IOH-NPs with gemcitabine triphosphate (GTP) as the drug anion ([ZrO].sup.2+.sub.3[GTP].sup.3.sub.2 IOH-NPs) can be realized similarly, showing comparable properties as [ZrO].sup.2+[GMP].sup.2 IOH-NPs.

[0044] In addition to [ZrO].sup.2+[GMP].sup.2 IOH-NPs as active drug-loaded nanocarrier, [ZrO].sup.2+[CMP].sup.2 IOH-NPs (CMP: cytidine monophosphate) were prepared as GEM-free reference via a similar synthesis protocol. In difference to GMP, CMP does not contain fluorine in 2,2-position of the ribose unit, so that the DNA reproduction is not blocked. Beside the cytostatic activity, [ZrO].sup.2+[GMP].sup.2 and [ZrO].sup.2+[CMP].sup.2 IOH-NPs exhibit similar properties (size, composition, etc.) within the significance of the analytical characterization. Therefore, GEM-free [ZrO].sup.2+[CMP]2- IOH-NPs were used (with similar concentration as [ZrO].sup.2+[GMP].sup.2) as negative control without any cytostatic effect. Moreover, solutions of H.sub.2(GMP) and free GEM were used (with similar GMP concentration as in [ZrO].sup.2+[GMP].sub.2) as positive control.

As a Summary of All Investigations Carried out With the Present Ioh-nps, the Following Has Been

[0045] revealed.

[0046] Efficient uptake of GMP-IOH-NPs has been shown into tumor cells in vitro. Fluorescence labelling of the IOH-NP allowed to assess their cell-uptake, biodistribution and tumor specific delivery. In this regard, multiscale imaging allows to the monitor biodistribution and tumor accumulation from in vivo via tissue to cellular levels by tracking the IOH-NPs, which is an essential key to understand the pharmacokinetic processes and to define an optimal application route.

[0047] Multiscale fluorescence microscopy confirmed the uptake of the IOH-NPs in tumor cells via endocytosis, followed by intracellular trafficking via endocytic pathways. Although the endosomal escape mechanisms for cytosol delivery of IOH-NPs or already released GMP within endosomal vesicles are not yet sufficiently defined, GMP is finally delivered from the endosomes/lysosomes to the cytosol as demonstrated by their antitumor efficacy. Notably, the uptake of GMP-IOH-NPs is independent of the activity of the human equilibrative nucleoside transporter (hENT1), which is responsible for the transport of free GEM into cells. As a result, IOH-NPs overcome the often occurring chemoresistance of GEM due to a downregulation of hENT1. Most probably, GMP-IOH-NPs are also independent of dCK for GEM activation since the GMP-IOH-NPs already contain phosphorylated GMP. In orthotopic PDAC mouse models, a high accumulation of GMP-IOH-NPs in primary tumor lesions as well as at metastatic sites is verified, which is highly beneficial in treating PDAC since more than half of the patients exhibit metastasis at the time of diagnosis. GMP-IOH-NPs are delivered to tumor cells, protecting GEM during the delivery process by preventing the metabolic inactivation of GEM by enzymes present in the circulation and liver. The treatment with GMP-IOH-NPs is well tolerated and results in a higher anti-tumor efficacy compared to free GEM, which was enhanced even further applying cetuximab-functionalized GMP-CTX-IOH-NPs.

[0048] By minimizing undesired side effects, overcoming chemoresistance, preventing GEM inactivation by delivering already phosphorylated GEM to tumor sites with GMP-IOH-NPs, we could address most of the disadvantageous associated with current GEM-based PDAC therapy. Associating the results to therapy efficacy will further support the design of the IOH-NPs as drug-delivery system with a high chance to further improve treatment efficacy. Together with maximizing therapeutic benefits by high drug load, advantageous biodistribution, characterized by almost no liver accumulation but tumor-specific delivery after intraperiotenal application, and the option of long-term GEM treatment by circumventing the mechanisms of chemoresistance, we anticipate GMP-IOH-NPs to have a high chance of improving the quzality of life and survival of PDAC patients.

EXAMPLES

[0049] Synthesis of Inorganic-organic Hybrid Nanoparticles [ZrO].sup.2+[GMP].sup.2IOH-NPs (designated as GMP-IOH-NPs in in vitro/in vivo studies). The synthesis of [ZrO].sup.2+[GMP].sup.2 IOH-NPs is characterized by a straightforward water-based precipitation at room temperature. Accordingly, a concentrated aqueous solution of ZrOCl.sub.28H2O was injected with vigorous stirring into an aqueous solution of H.sub.2(GMP). Following the LaMer-Dinegar model of particle nucleation and particle growth, a high supersaturation is induced by the injection, which induces rapid nucleation, and thus, the formation of uniform nanoparticles.

[0050] For the synthesis of [ZrO].sup.2+[GMP].sup.2 IOH-NPs, 100 L of an aqueous solution of ZrOCl.sub.28H.sub.2O (14.6 mg, 45.5 mol, 99.9 %, Sigma Aldrich, Germany) were injected into 10 mL of an aqueous solution of gemictabine monophosphate (GMP, 17.2 mg, 50 mol, 97 %, Toronto Research Chemicals, Canada). After 2 min of intense stirring, the IOH-NPs were separated by centrifugation (25.000 rpm, 15 min) and twice purified by redispersion/centrifugation in/from H.sub.2O. For further use, the [ZrO].sup.2+[GMP].sup.2 IOH-NPs were dispersed in demineralized water or dried to powder samples. After purification and redispersion, colorless suspensions of [ZrO].sup.2+[GMP].sup.2 were obtained, which are colloidally stable over several weeks.

[0051] [Zro].sup.2+.sub.3[GTP].sup.3.sub.2 IOH-NPs (designated As GTP-IOH-NPs in in vitro studies). for the synthesis of [ZrO].sup.2+.sub.3[GTP].sup.3.sub.2 IOH-NPs, 100 L of an aqueous solution of ZrOCl.sub.28H.sub.2O (14.6 mg, 45.5 mol, 99.9 %, Sigma Aldrich, Germany) were injected into 10 mL of an aqueous solution of sodium gemictabine triphosphate (GTP, 18.2 mg, 50 mol, 95 %, Jena Biosciences, Germany). After 2 min of intense stirring, the IOH-NPs were separated by centrifugation (25.000 rpm, 15 min) and twice purified by redispersion/centrifugation in/from H.sub.2O. For further use, the [ZrO].sup.2+3[GTP].sup.3.sub.2 IOH-NPs were dispersed in demineralized water or dried to powder samples. After purification and redispersion, colorless suspensions of [ZrO].sup.2+.sub.3[GTP].sup.3.sub.2 IOH-NPs were obtained, which are colloidally stable over several weeks. [ZrO].sup.2+[CMP].sup.2 IOH-NPs (designated as Ref-IOH-NPs in in vitro/in vivo studies). Since cytidine monophosphate (CMP, C.sub.9H.sub.12N.sub.3O.sub.8P) has a similar structure as gemcitabine monophosphate (GMP, C.sub.9H.sub.10N.sub.3O.sub.7F.sub.2P) but without any therapeutic activity, [ZrO].sup.2+[CMP].sup.2 IOH-NPs were prepared as negative-control nanoparticles for biological studies. Since GMP is very expensive but chemically similar to CMP, moreover, [ZrO].sup.2+[CMP].sup.2 IOH-NPs were used to characterize many properties of the IOH-NPs. [ZrO].sup.2+[CMP]2-IOH-NPs were prepared by dissolving 36.7 mg (0.1 mmol) of cytidine monophosphate sodium salt (Na.sub.2(CMP), 97 %, Biosynthesis, United Kingdom) in 50 mL of demineralized water. Thereafter, 0.5 mL of an aqueous solution containing 29.3 mg (0.09 mmol) of ZrOCl.sub.28H.sub.2O (99.9 %, Sigma Aldrich, Germany) were injected, which results in an instantaneous nucleation of IOH-NPs. After 2 min of intense stirring, the as-prepared IOH-NPs were separated via centrifugation (25.000 rpm, 15 min) and twice purified by redispersion/centrifugation in/from H.sub.2O. For further use, the [ZrO].sup.2+[CMP].sup.2 IOH-NPs were dispersed in demineralized water or dried to powder samples.

[0052] Fluorescence labelling. For biological studies on cellular uptake and efficacy, the IOH-NPs were fluorescence-labelled by addition of small amounts of the fluorescent dye DY-549P1-dUTP (DUT549, Dyomics, Germany) for in vitro studies and the fluorescent dye DY-647P1-dUTP (DUT647, Dyomics, Germany) for in vivo studies. To this concern, 25 nmol of DUT549 or DUT647 were added to the respective solution of [GMP].sup.2 or [CMP].sup.2 prior to initiating the nanoparticle nucleation by the injection of the ZrOCl.sub.28H.sub.2O solutions. In this way, fluorescent IOH-NPs with the composition [ZrO].sup.2+[(CMP).sub.>0.99(DUT).sub.<0.01].sup.2 or [ZrO].sup.2+[(GMP).sub.>0.99(DUT).sub.<0.01].sup.2 were formed. The fluorescence-labelled IOH-NPs show a pink (DUT549) or blue (DUT647) color, which is characteristic for the respective DUT dye.

[0053] Surface functionalization by glucose (designated as GMP-GLU-IOH-NPs in in vitro/in vivo studies). Surface functionalization with glucose was performed by coating the IOH-NPs with a layer of [ZrO].sup.2+[G6P].sup.2 (G6P: glucose-6-phosphate, C.sub.6H.sub.11O.sub.9P). To this concern, [ZrO].sup.2+[GMP].sup.2 or [ZrO].sup.2+[CMP].sup.2 IOH-NPs were prepared as described. Subsequent to synthesis, they exhibit a negative surface charge. In the following, an aqueous solution of 1 mL of ZrOCl.sub.28H.sub.2O (10.8 mg, 33.8mol, 99.9 %, Sigma Aldrich, Germany) was added to the [ZrO].sup.2+[GMP].sup.2/[ZrO].sup.2+[CMP].sup.2IOH-NP suspension and stirred for 1 h at room temperature. Thereafter, the suspension was centrifuged (25.000 rpm, 15 min) and redispersed to remove excess [ZrO].sup.2+, which could promote undesired additional particle nucleation instead of a growth of the preformed nanoparticles. Finally, 1 mL of an aqueous Na.sub.2(G6P) solution (10.6 mg, 37.5 mol, Sigma Aldrich, Germany) was added slowly at a defined flow rate (1 mL/h) using a syringe pump. The resulting nanoparticles were separated via centrifugation (25.000 rpm, 15 min) and purified by redispersion/centrifugation in/from H.sub.2O. For analytical characterization, the [ZrO].sup.2+[GMP].sup.2@[ZrO].sup.2+[G6P].sup.2 or [ZrO].sup.2+[CMP]2-@[ZrO].sup.2+[G6P]2-IOH-NPs IOH-NPs were dispersed in demineralized water or dried to powder samples.

[0054] Surface Functionalization With Cetuximab As Antibody (designated As GMP-CTX-IOH-NPs in in vitro/in vivo studies). The antibody cetuximab (CTX, Erbitux, solution for infusion, Merck, Germany) was used to functionalize the surface of the IOH-NPs by electrostatic adsorption. CTX at a concentration range of 0.1-0.5 mg/mL was added to an aqueous suspension of [ZrO].sup.2+[GMP].sup.2 or [ZrO].sup.2+[CMP].sup.2 IOH-NPs (1 mg/mL) and stirred for 1 h at room temperature. Thereafter, the IOH-NPs were separated by centrifugation. The CTX-functionalized IOH-NPs were resuspended in demineralized water for further characterization, while the supernatant after centrifugation was collected to measure the antibody concentration. Bradford assays were used to quantify the CTX concentration in the supernatant (Bradford reagent, Sigma Aldrich, Germany). The amount of the antibody on the IOH-NP surface was calculated by the initial amount minus the amount detected in the supernatant.

[0055] Subsequent to the surface functionalization, the ctx-functionalized IOH-NPs were collected by centrifugation and resuspended in water. The supernatant was separated and the microprotocol (1-10 g/mL protein) of the Bradford assay performed to measure the antibody concentration. The amount of CTX was adapted so that it was just detectable in the supernatant. As a result, a maximum amount of CTX was adsorbed on the IOH-NP surface. To this concern, 1 mL of the Bradford reagent (Sigma Aldrich, Germany) was mixed to 1 mL of the supernatant after CTX treatment and incubated for 15 minutes. Subsequently, the absorbance was measured at 595 nm with a UV 2700 spectrophotometer (Shimadzu, Japan). Finally, a calibration curve was used to determine the CTX amount.

[0056] Immunofluorescence assay. For the indirect fluorescence immunoassay, the as-prepared IOH-NPs were immobilized by passive adsorption at the bottom of a microtiter plate containing MaxiSorp (Thermo Fisher Scientific, Germany). To this concern, CTX-functionalized IOH-NP and the free CTX antibody control group were diluted in 50 mM of carbonate-bicarbonate buffer (pH=9.6) at different concentrations (1.2-600g/mL), under the assumption that 2 mg of IOH-NPs bear 2.8 mol CTX on the particle surface. 200 L of the dilutions were transferred in each well and incubated overnight at 4 C. Then, the supernatant was decanted and the wells were washed two times with 200 L PBS washing buffer (137 mM NaCl, 2.7 mM KCl, 10 mM Na.sub.2HPO.sub.4, KH.sub.2PO.sub.4, 0.05 % Tween, pH=7.4). The wells were then blocked with 200 L 5% BSA-solution in PBS buffer for 2 h and washed again two times with PBS washing buffer. Finally, 100 L of the FITC-labelled (FITC: fluorescein isothiocyanate) rabbit anti-human IgG antibody was added as the secondary antibody with a concentration of 2.5 g/mL. After an incubation time of 1 h, the wells were washed four times with 200 L of PBS washing buffer. Fluorescence measurements were performed on a Synergy H1 Hybrid Reader (Agilent Biotek, Germany) at an excitation wavelength of 490 nm and an emission wavelength of 530 nm.

[0057] In addition, the fluorescence immunoassay was extended to determine the biological activity in terms of receptor recognition of the antibody on the IOH-NP surface. For this purpose, the microtiter plate was first coated with streptavidin (STV) to subsequently immobilize the biotinylated hEGFR1. For this, 50 L of a 200 nM STV solution in PBS buffer (137 mM NaCl, 2.7 mM KCl, 10 mM Na.sub.2HPO.sub.4, KH.sub.2PO.sub.4, pH=7.4) was added to the wells of a microtiter plate and incubated at 4 C. on for 72 hours. Subsequently, each well of the microtiter plate was washed three times with 240 L of TBS buffer (20 mM Tris-Base, 150 mM NaCl, pH=7.35) and incubated with 200 L of a 5 % BSA-solution in PBS buffer for 2 h at 4 C. Then, the wells were washed three times with PBS washing buffer and 50 L of biotinylated hEGFR1 was added in each well at a concentration of 2 g/mL for receptor immobilisation through biotin-streptavidin binding. After 2 h incubation time, the wells were washed two times with TETBS buffer (20 mM Tris-Base, 150 mM NaCl, 5 mM EDTA, 0.05 % (v/v) Tween-20, pH=7.35) supplemented with 800 M d-biotin to block free STV binding sites. After a second washing step with PBS washing buffer, 200 L of CTX-functionalized IOH-NPs and the control groups (free CTX and Trastuzumab) were added in the wells and all parameters from the assay description above were retained.

[0058] Cytotoxic effects of GMP-NP on GEM resistant murine KPC cells and GMP-NP or GTP-NP on GEM resistant human AsPC-1 pancreatic cancer cells in comparison to control KPC and AsPC-1 pancreatic cancer cells.

[0059] In the course of the present invention, the inventors have assessed the cytotoxicity of gemcitabine monophosphate containing nanoparticles, GMP-IOH-NPs on GEM resistant murine KPC pancreatic cancer cells and the cytotoxicity of GMP-IOH-NPs and gemcitabine triphosphate containing nanoparticles, GTP-IOH-NPs, on human GEM resistant AsPC-1 pancreatic cancer cells, all in comparison to the treatment with free GEM.

[0060] In order to study the anti-tumor efficacy of GMP-IOH-NPs and GTP-IOH-NPs in comparison to the free GEM drug on GEM-chemo-resistant PDAC cells, the GEM-resistant murine PDAC cell line KPC and the GEM-resistant human PDAC cell line AsPC-1 were established using a two-step method adapted from Zhou J, Zhang L, Zheng H, et al. Identification of chemoresistance-related mRNAs based on gemcitabine-resistant pancreatic cancer cell lines. Cancer Med. 2020; 9:1115-1130. PMID: 31823522, as illustrated in FIG. 2.

[0061] In the adaptation stage, KPC or AsPC-1 cells were treated with GEM for 48 hours, with stepwise increases in concentration from 20 to 500 nM (20, 50, 100, 200 and 500 nM). After each dose-induced step, apoptotic cells were discarded, and surviving cells were expanded in GEM-free culture medium. This process was repeated three times. In the consolidation stage, cells were then exposed to a final GEM concentration of 1000 nM. Following the last round of treatment at this concentration, KPC as well as AsPC-1 cells acquired resistance to GEM. To maintain the GEM-resistant phenotype, cells were cultured in medium containing 700 nM GEM.

[0062] The native KPC cell line was provided by Prof. Volker Ellenrieder (Clinic for Gastroenterology, Gastrointestinal Oncology and Endocrinology, University Medical Center Gttingen, Germany). These cells were derived from KPC mice (Hingorani et al., 2005). KPC cells were cultured in Dulbecco's Modified Eagle Medium (DMEM; GIBCO) supplemented with 10 % fetal bovine serum (FBS; GIBCO), 1 % penicillin and streptomycin (pen/strep), and 1 % L-glutamine. Cells were cultivated at 37 C. under a humidified atmosphere of 5 % CO.sub.2.

[0063] The human AsPC-1 PDAC cell line was obtained from ATCC, USA (CRL-1682) and grown in RPMI 1640medium supplemented with 10 % fetal bovine serum (FBS) and GlutaMAX (Gibco, USA), 1 % penicillin and streptomycin (pen/strep) as described (Saccomano et al., 2016). Cells were cultivated at 37 C. under a humidified atmosphere of 5 % CO.sub.2.

[0064] CellTiter-Glo luminescent viability assay: KPC and AsPC-1 native cells (control) and KPC-GEM and AsPC-1-GEM resistant cells were seeded in a 96-well plate at a concentration of 10,000 cells per well. After overnight incubation, a single dose of increasing concentrations (1000 nM-2000 nM) of free GEM, or [ZrO].sup.2+[CMP].sup.2 IOH-NPs (CMP: cytidine monophosphate) used as GEM-free reference (Ref-IOH-NP), or gemcitabine monophosphate (GMP) containing GMP-IOH-NPs or gemcitabine triphosphate (GTP) containing GTP-IOH-NPs were added to the cells at the start of the experiment. GMP-IOH-NPs have a composition [ZrO].sup.2+[GMP].sup.2 with GMP as drug anion (76 % of total IOH-NP mass). GTP-IOH-NPs have a composition [ZrO].sup.2+.sub.3[GTP].sup.3.sub.2 with GTP as drug anion (75 % of total IOH-NP mass). The efficacy of the free chemotherapeutic drug gemcitabine or of the nanoparticles was normalized to an /stimulated/ untreated condition. Cell viability was assessed using the CellTiter-Glo assay (Promega, G8461). Following six days of drug treatment, after the supernatant aspiration, 80 L of CellTiter-Glo reagent diluted 1:5 with phosphate buffered saline (PBS) was added to each well. The plate was shaken for 2 minutes at room temperature to facilitate cell lysis, then incubated for an additional 10 minutes without shaking to stabilize the luminescence signal. Luminescence was measured using a CLARIOstar multimode plate reader (BMG LABTECH, Germany).

Results

[0065] Cytotoxic effects of GEM-NP on GEM resistant murine KPC cells in comparison to control KPC pancreatic cancer cells

[0066] To test the cytotoxic effect of GMP nanoparticles, GMP-IOH-NPs, on GEM-resistant cells, murine PDAC KPC cells were made resistant through dose-escalation GEM exposure.

[0067] To evaluate the cytotoxic effects of GMP-IOH-NPs on GEM-resistant KPC cells, both GEM-resistant and native KPC cells were incubated with increasing concentrations of GMP-IOH-NPs (1000 nM-2000 nM). The anti-tumor efficacy of these nanoparticles was compared to Ref-IOH-NP (negative control) and free GEM (positive control). The concentration-dependent efficacy on cell viability was measured as the percentage of live cells after 6 days of incubation by the CellTiter-Glo luminescent viability assay and normalized to unstimulated, untreated KPC cells.

[0068] The sensitivity of GEM to treat native KPC cells is shown in FIG. 3, left graph. High doses of GMP-IOH-NPs and free GEM, starting from 1000 nM, resulted in complete cell death of native KPC cells, indicating sensitivity of KPC native cells to both treatments.

[0069] The non-toxic effect of GEM in the resistant KPC cells was confirmed by their maintained viability in the presence of high doses of free GEM (FIG. 3, right graph). The viability of KPC cells remained unchanged with Ref-IOH-NP treatment, even at concentrations up to 2000 nM, indicating that these nanoparticles are non-toxic. However, we observed a statistically significant 20 % reduction in the viability of GEM-resistant KPC cells in response to treatment with 2000 nM GMP-IOH-NPs, compared to those treated with 2000 nM free GEM (FIG. 3, right graph).

[0070] These results demonstrate the advantage of GMP-IOH-NPs in the efficacy to treat GEM resistant murine KPC cells in comparison to no effect by applying standard free GEM therapy most likely by circumventing gemcitabine chemoresistance mechanisms in KPC PDAC cells (FIG. 3, right graph).

[0071] Cytotoxic effects of GEM-NP or GTP-NP on human AsPC-1 pancreatic cancer cells in comparison to control AsPC-1 pancreatic cancer cells

[0072] To test the cytotoxic effect of GMP/GTP nanoparticles, GMP-IOH-NPs and GTP-IOH-NPs, on GEM-resistant cells, human PDAC-AsPC-1 cells were made resistant through dose-escalation GEM exposure.

[0073] To evaluate the cytotoxic effects of GMP-IOH-NPs as well as GTP-IOH-NPs on GEM-resistant human AsPC-1 cells, both GEM-resistant and native AsPC-1 cells (controls) were incubated with increasing concentrations of GMP-IOH-NPs or GTP-IOH-NPs (1000 nM-2000 nM). The anti-tumor efficacy of these nanoparticles was compared to free GEM (positive control). The concentration-dependent efficacy on cell viability was measured as the percentage of live cells after 6 days of incubation by the CellTiter-Glo luminescent viability assay and normalized to non-treated (unstimulated) AsPC-1 cells.

[0074] The sensitivity of GEM or GMP-IOH-NPs to treat native AsPC-1 cells is shown in FIG. 4, upper graph, left panel, and the sensitivity of GEM or GTP-IOH-NPs to treat native AsPC-1 cells in FIG. 4, upper graph, right panel. The viability of AsPC-1 native cells remained unchanged with Ref-IOH-NP treatment, even at concentrations up to 2000 nM, indicating that these nanoparticles are non-toxic. High doses of GMP-IOH-NPs, GTP-IOH-NPs and free GEM, starting from 1000 nM, resulted in 50 % cell death of native AsPC-1 cells, indicating sensitivity of AsPC-1 native cells to these treatments (GMP-IOH-NPs, GTP-IOH-NPs and free GEM), and also demonstrating that AsPC-1 cells provide already GEM resistance to a certain amount under these conditions.

[0075] The non-toxic effect of GEM in the resistant AsPC-1 cells was confirmed by their maintained viability in the presence of high doses of free GEM (FIG. 4, lower graph, blue line). However, the inventors observed a statistically significant reduction in the viability of GEM-resistant AsPC-1 cells in response to different concentrations of treatment with GMP-IOH-NPs in the range of 1000 - 2000 nM (p0.001) and even more pronounced in response to different concentrations of GTP-IOH-NPs in the range of 1000-2000 nM (p0.0001), compared to those treated with free GEM in the range of 1000-2000 nM (FIG. 4, lower panel).

[0076] These results demonstrate the advantage of GMP-IOH-NPs in the efficacy to treat GEM resistant AsPC-1 cells, and show that GTP-IOH-NPs is even more potent, in comparison to no cytotoxic effect by applying standard free GEM therapy most likely by circumventing gemcitabine chemoresistance mechanisms in AsPC-1 cells (FIG. 4, lower panel).

[0077] In particular, the study demonstrates that GMP-IOH-NPs are still cytotoxic in GEM-resistant murine KPC cells in which free GEM application does not have any effect on tumor cell death anymore. Treatment with 2000 nM GMP-IOH-NPs resulted in a statistically significant 20% reduction in cell viability of GEM-resistant KPC cells compared to no effect in response to 2000 nM free GEM, underscoring the superior effectiveness of GMP-IOH-NPs to treat chemoresistant PDAC cells compared to free GEM by overcoming GEM resistance.

[0078] Furthermore, the study demonstrates that GMP-IOH-NPs and GTP-IOH-NPs (even more potent) are still cytotoxic in GEM-resistant AsPC-1 cells in which free GEM application does not have any effect on tumor cell death anymore. Treatment with different concentrations of GMP-IOH-NPs in the range of 1000 to 2000 nM resulted in a reduction in cell viability of GEM-resistant AsPC-1 cells compared to no effect in response to free GEM. This cytotoxic effect was even more potent when applying GTP-IOH-NPs in the range of 1000 to 2000 nM to GEM-resistant AsPC-1 cells underscoring the superior effectiveness of GMP-IOH-NPs and even more GTP-IOH-NPs to treat GEM-resistant PDAC cells compared to free GEM by overcoming GEM resistance.

[0079] Since the therapeutic efficacy of gemcitabine is limited by the innate and acquired resistance leading to treatment failure and recurrent disease in most PDAC patients, this novel drug-delivery system by GMP-IOH-NPs or GTP-IOH-NPs has a high chance to significantly improve current PDAC treatment and increase clinical responses of this deadly disease as well as patient outcome not only by selective delivery of extraordinarily high concentrations of already phosphorylated gemcitabine monophosphate (GMP) or gemcitabine triphosphate (GTP) to the primary tumor and metastatic sites and by reduced side effects, but also by being still cytotoxic in already GEM resistant PDAC cells or cells that have become resistant during GEM therapy, by circumventing chemoresistance mechanisms.

[0080] To sum up, GEM-IOH-NPs can overcome the often occurring chemoresistance of GEM in PDAC cells since [0081] the encapsulation of already phosphorylated gemcitabine in nanoparticles as GMP-IOH-NPs or as GTP-IOH-NPs enables intracellular GEM activation independent of the deoxycytidine kinase (dCK), an enzyme often inactivated in GEM-resistant PDAC cells, thereby circumventing GEM toxicity (Dash, et al 2024), and [0082] GMP-IOH-NPs and GTP-IOH-NPs are taken up by the tumor cells most likely via one of the endocytic pathways, independent of the activity of the human equilibrative nucleoside transporter (hENT1), which is responsible for the transport of free GEM into cells and often downregulated due to chemoresistance.