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COMBINATION OF PARA-AMINOHIPPURIC ACID (PAH) AND RADIOLABELED COMPLEXES FOR TREATING CANCER

20230414796 ยท 2023-12-28

    Inventors

    Cpc classification

    International classification

    Abstract

    The present invention provides a combination comprising (a) a radiolabeled complex comprising a radionuclide and a targeting molecule linked to a chelating agent, and (b) para-aminohippuric acid (PAH) or a salt or derivate thereof for the treatment of cancer. Moreover, a pharmaceutical composition comprising (a) a radiolabeled complex comprising a radionuclide and a targeting molecule linked to a chelating agent, and (b) para-aminohippuric acid (PAH) or a salt or derivate thereof is provided for the treatment of cancer. The radiolabeled complex and PAH may be used in a combination therapy for the treatment of cancer.

    Claims

    1. A combination of (a) a radiolabeled complex comprising (i) a radionuclide and (ii) a targeting molecule linked to a chelating agent; and (b) para-aminohippuric acid (PAH), or a salt or carboxylic acid derivative thereof; for use in the treatment of cancer.

    2. The combination for use according to claim 1, wherein the targeting molecule is selected from peptides, peptidomimetics, antibody fragments, antibody mimetics, small molecules, and knottings.

    3. The combination for use according to claim 1 or 2, wherein the targeting molecule is selected from somatostatin analogues, PSMA-inhibitors, gastrin analogues, integrin binding molecules and folate.

    4. The combination for use according to any one of the previous claims, wherein the targeting molecule binds to PSMA or a somatostatin receptor (SSTR), in particular SSTR-2.

    5. The combination for use according to any one of the previous claims, wherein the targeting molecule is selected from the group consisting of Tyr3-octeotride, Tyr3-octreotate, JR11, PSMA-11, Sargastrin, RGD and folate.

    6. The combination for use according to any one of the previous claims, wherein the targeting molecule is octreotide, preferably Tyr3-octeotride.

    7. The combination for use according to any one of the previous claims, wherein the chelating agent is a macrocyclic chelator, preferably selected from the group consisting of DOTA, HBED-CC, NOTA, NODAGA, DOTAGA, DOTAM, TRAP, NOPO, PCTA, DFO, DTPA, DO3AP, DO3AP.sup.PrA, DO3AP.sup.ABn, and HYNIC or derivatives thereof.

    8. The combination for use according to any one of the previous claims, wherein the chelating agent is DOTA.

    9. The combination for use according to any one of the previous claims, wherein the radiolabeled complex comprises or consists of (i) the radionuclide and (ii) DOTATOC or DOTATATE.

    10. The combination for use according to any one of the previous claims, wherein the radionuclide is selected from the group consisting of .sup.94Tc, .sup.99mTc, .sup.90In, .sup.111In, .sup.67Ga, .sup.68Ga, .sup.86Y .sup.90Y, .sup.177Lu, .sup.161Tb, .sup.186Re, .sup.188Re .sup.64Cu, .sup.67Cu, .sup.55Co, .sup.57Co, .sup.43Sc, .sup.44Sc, .sup.47Sc, .sup.225Ac, .sup.213Bi, .sup.212Bi, .sup.212Pb, .sup.227Th, .sup.153Sm, .sup.166Ho, .sup.166Dy, .sup.18F and .sup.131I, preferably selected from the group consisting of .sup.90In, .sup.111In, .sup.67Ga, .sup.68Ga, .sup.86Y, .sup.90Y .sup.177Lu, .sup.161Tb, .sup.64Cu, .sup.67Cu, .sup.55Co, .sup.57Co, .sup.43Sc, .sup.44Sc, .sup.47Sc, .sup.225Ac, .sup.213Bi, .sup.212Bi, .sup.212Pb, .sup.153Sm, .sup.166Ho, .sup.225Ac and .sup.166Dy.

    11. The combination for use according to any one of the previous claims, wherein the radionuclide is selected from the group consisting of .sup.177Lu, .sup.68Ga .sup.111In, .sup.90Y, .sup.99mTc, .sup.223Ac and .sup.161Tb, more preferably .sup.177Lu, .sup.223Ac and .sup.68Ga, or selected from a tri-valent radionuclide, preferably selected from the group consisting of .sup.177Lu, .sup.90Y, .sup.67Ga, .sup.68Ga, .sup.111In, .sup.225Ac, .sup.161Tb, .sup.44Sc and .sup.47Sc.

    12. The combination for use according to any one of the previous claims, wherein the radionuclide is .sup.177Lu (Lutetium-177).

    13. The combination for use according to any one of the previous claims, wherein the radiolabeled complex is selected from [.sup.177Lu-DOTA.sup.-Tyr3]-octreotide, .sup.177Lu-DOTA-JA11, .sup.177Lu-DOTA-RGD, .sup.177Lu-DOTA-Sargastrin, and .sup.177Lu-PSMA I&T.

    14. The combination for use according to any one of the previous claims, wherein the radiolabeled complex is .sup.177Lu-DOTATOC.

    15. The combination for use according to any one of the previous claims, wherein the combination comprises (a) the radiolabeled complex; and (b) para-aminohippuric acid (PAH).

    16. The combination for use according to any one of claims 1-14, wherein the combination comprises (a) the radiolabeled complex; and (b) a salt of para-aminohippuric acid (PAH).

    17. The combination for use according to claim 16, wherein the salt of PAH is sodium para-aminohippurate.

    18. The combination for use according to any one of claims 1-14, wherein the combination comprises (a) the radiolabeled complex; and (b) a carboxylic acid derivative of para-aminohippuric acid (PAH).

    19. The combination for use according to any one of the previous claims, wherein PAH or the salt or carboxylic acid derivate thereof is administered in a concentration of 5 mg to 500 mg per kilogram of body weight.

    20. The combination for use according to any one of the previous claims, wherein (a) the radiolabeled complex and (b) PAH or the salt or carboxylic acid derivate thereof are administered in a ratio from 1/240000 to 1/8000 (w/w).

    21. The combination for use according to any one of the previous claims, wherein (a) the radiolabeled complex and (b) PAH or the salt or carboxylic acid derivate thereof are administered on the same day.

    22. The combination for use according to any one of the previous claims, wherein (a) the radiolabeled complex and (b) PAH or the salt or carboxylic acid derivate thereof are administered at about the same time.

    23. The combination for use according to any one of the previous claims, wherein (a) the radiolabeled complex and (b) PAH or the salt or carboxylic acid derivate thereof are administered via the same route of administration.

    24. The combination for use according to any one of the previous claims, wherein (a) the radiolabeled complex and (b) PAH or the salt or carboxylic acid derivate thereof are administered systemically.

    25. The combination for use according to any one of the previous claims, wherein (a) the radiolabeled complex and (b) PAH or the salt or carboxylic acid derivate thereof are administered in the same composition.

    26. The combination for use according to any one of claims 1 to 24, wherein (a) the radiolabeled complex and (b) PAH or the salt or carboxylic acid derivate thereof are administered in distinct compositions by intravenous administration.

    27. The combination for use according to claim 26, wherein (a) the radiolabeled complex is administered continuously for 10 to 20 min and (b) PAH or the salt or carboxylic acid derivate thereof is administered continuously for a period of 50 to 90 min.

    28. The combination for use according to claim 26 or 27, wherein administration of (a) the radiolabeld complex starts 5 to 15 min after the start of the administration of (b) PAH or the salt or carboxylic acid derivate thereof.

    29. The combination for use according to any one of the previous claims, wherein the radiolabeled complex is administered once.

    30. The combination for use according to any one of the previous claims, wherein the cancer is selected from neuroendocrine tumors, prostate cancer, pancreatic cancer, renal cancer, bladder cancer, medullar thyroid carcinomas, small cell lung cancers, stromal ovarian carcinomas, ductal pancreatic adenocarcinoma, insulinomas, gastrinomas, and breast cancer.

    31. The combination for use according to claim 30, wherein the cancer is selected from neuroendocrine tumors, prostate cancer, small cell lung cancer, and breast cancer, in particular neuroendocrine tumors.

    32. The combination for use according to any one of the previous claims, wherein the subject in need of the treatment is a human cancer patient.

    33. A kit comprising (a) a radiolabeled complex comprising (i) a radionuclide and (ii) a targeting molecule linked to a chelating agent; and (b) para-aminohippuric acid (PAH), or a salt or carboxylic acid derivative thereof; for use in the treatment of cancer.

    34. The kit for use according to claim 33, wherein the radiolabelled complex is as defined in any one of claims 2-14.

    35. The kit for use according to claim 33 or 34, wherein the para-aminohippuric acid (PAH), or the salt or carboxylic acid derivative thereof is as defined in any one of claims 15-19.

    36. The kit for use according to any one of claims 33-35, wherein the kit comprises an instruction leaflet, package insert or label, preferably with directions to administer (a) the radiolabeled complex and/or (b) PAH or the salt or carboxylic acid derivate thereof as defined in any one of claims 19-32.

    37. A pharmaceutical composition comprising (a) a radiolabeled complex comprising (i) a radionuclide and (ii) a targeting molecule linked to a chelating agent; and (b) para-aminohippuric acid (PAH), or a salt or carboxylic acid derivative thereof; for use in the treatment of cancer.

    38. The pharmaceutical composition for use according to claim 37 further comprising a pharmaceutically acceptable excipient, diluent or carrier.

    39. The pharmaceutical composition for use according to claim 37 or 38, wherein the composition is an aqueous solution.

    40. The pharmaceutical composition for use according to any one of claims 37-39, wherein the radiolabelled complex is as defined in any one of claims 2-14.

    41. The pharmaceutical composition for use according to any one of claims 37-40, wherein the para-aminohippuric acid (PAH), or the salt or carboxylic acid derivative thereof is as defined in any one of claims 15-19.

    42. The pharmaceutical composition for use according to any one of claims 37-41, wherein the composition is administered as defined in any one of claims 19-32.

    43. Para-aminohippuric acid (PAH), or the salt or carboxylic acid derivative thereof, for use in the treatment of cancer, wherein PAH, or the salt or carboxylic acid derivative thereof, is administered in combination with a radiolabelled complex comprising (i) a radionuclide and (ii) a targeting molecule linked to a chelating agent.

    44. Para-aminohippuric acid (PAH), or the salt or carboxylic acid derivative thereof, for use according to claim 43, wherein the radiolabelled complex is as defined in any one of claims 2-14.

    45. Para-aminohippuric acid (PAH), or the salt or carboxylic acid derivative thereof, for use according to claim 43 or 44, wherein the para-aminohippuric acid (PAH), or the salt or carboxylic acid derivative thereof is as defined in any one of claims 15-19.

    46. Para-aminohippuric acid (PAH), or the salt or carboxylic acid derivative thereof, for use according to any one of claims 43-45, wherein (a) the radiolabeled complex and/or (b) PAH or the salt or carboxylic acid derivate thereof is administered as defined in any one of claims 19-32.

    47. A method for treating cancer or initiating, enhancing or prolonging an anti-tumor-response in a subject in need thereof comprising administering to the subject (a) a radiolabeled complex comprising (i) a radionuclide and (ii) a targeting molecule linked to a chelating agent; and (b) para-aminohippuric acid (PAH), or a salt or carboxylic acid derivative thereof.

    48. The method according to claim 47, wherein the radiolabelled complex is as defined in any one of claims 2-14.

    49. The method according to claim 47 or 48, wherein the para-aminohippuric acid (PAH), or the salt or carboxylic acid derivative thereof is as defined in any one of claims 15-19.

    50. The method according to any one of claims 47-49, wherein (a) the radiolabeled complex and/or (b) PAH or the salt or carboxylic acid derivate thereof is administered as defined in any one of claims 19-32.

    51. The method according to any one of claims 42-45 comprising administration of a pharmaceutical composition as defined in any one of claims 37-42.

    52. A combination therapy for the treatment of cancer comprising combined administration of (a) a radiolabeled complex comprising (i) a radionuclide and (ii) a targeting molecule linked to a chelating agent; and (b) para-aminohippuric acid (PAH), or a salt or carboxylic acid derivative thereof.

    53. The combination therapy according to claim 52, wherein the radiolabelled complex is as defined in any one of claims 2-14.

    54. The combination therapy according to claim 52 or 53, wherein the para-aminohippuric acid (PAH), or the salt or carboxylic acid derivative thereof is as defined in any one of claims 15-19.

    55. The combination therapy according to any one of claims 52-54, wherein (a) the radiolabeled complex and/or (b) PAH or the salt or carboxylic acid derivate thereof is administered as defined in any one of claims 19-32.

    56. The combination therapy according to any one of claims 52-55 comprising administration of a pharmaceutical composition as defined in any one of claims 37-42.

    Description

    BRIEF DESCRIPTION OF THE FIGURES

    [0213] In the following a brief description of the appended figures will be given. The figures are intended to illustrate the present invention in more detail. However, they are not intended to limit the subject matter of the invention in any way.

    [0214] FIG. 1 shows for Example 1 the experimental design. Mice were assigned to three distinct groups receiving either vehicle only (NaCl 0.9%; Group 0), .sup.177Lu-DOTATOC alone (no PAH; Group 1.1), or .sup.177Lu-DOTATOC combined with PAH (Group 1.2) on day 7 after inoculation with tumor cells.

    [0215] FIG. 2 shows for Example 1 the tumor growth of the three experimental groups Group 0 (control), Group 1.1 (NaCl) and Group 1.2 (PAH) over the 57-day observation period after treatment.

    [0216] FIG. 3 shows for Example 1 the body weight ratios of the three experimental groups Group 0 (Control group), Group 1.1 (177Lu-DOTATOC/NaCl 0.9%) and Group 1.2 (177Lu-DOTATOC/PA); (weight at different time points compared to initial body weight at day 0).

    [0217] FIG. 4 shows for Example 1 the results of a linear regression analysis performed for the tumor volume plotted against the actual tumor weight for each individual tumor (n=36; 2 tumors/mouse).

    [0218] FIG. 5 shows for Example 1 the survival rates of the distinct experimental groups Group 0 (Control), Group 1.1 (177Lu-DOTATOC+NaCl) and Group 1.2 (177Lu-DOTATOC+PAH).

    [0219] FIG. 6 shows for Example 2 the tumor growth of the three experimental groups Group 1 (177Lu-DOTATOC/NaCl 0.9%), Group 2 (177Lu-DOTATOC/PA) and Group 3 (Control groupNaCl 0.9%) over the 46-day observation period after treatment.

    [0220] FIG. 7 shows for Example 2 the body weight ratios of the three experimental groups Group 1 (177Lu-DOTATOC/NaCl 0.9%), Group 2 (177Lu-DOTATOC/PA) and Group 3 (Control groupNaCl 0.9%); (weight at different time points compared to initial body weight at day 0).

    [0221] FIG. 8 shows for Example 2 the results of a linear regression analysis performed for the tumor volume plotted against the actual tumor weight for each individual tumor.

    [0222] FIG. 9 shows for Example 2 the survival rates of the distinct experimental groups Group 1 (177Lu-DOTATOC/NaCl 0.9%), Group 2 (177Lu-DOTATOC/PA) and Group 3 (Control groupNaCl 0.9%).

    EXAMPLES

    [0223] In the following, particular examples illustrating various embodiments and aspects of the invention are presented. However, the present invention shall not to be limited in scope by the specific embodiments described herein. The following preparations and examples are given to enable those skilled in the art to more clearly understand and to practice the present invention. The present invention, however, is not limited in scope by the exemplified embodiments, which are intended as illustrations of single aspects of the invention only, and methods which are functionally equivalent are within the scope of the invention. Indeed, various modifications of the invention in addition to those described herein will become readily apparent to those skilled in the art from the foregoing description, accompanying figures and the examples below. All such modifications fall within the scope of the appended claims.

    Example 1: Combination of PAH and a Radiolabeled Complex in a Mouse Tumor Model

    [0224] To investigate the effects of a combination of para-aminohippuric acid (PAH) and a radiolabeled complex, an in vivo tumor model, namely, the AR42J pancreatic tumor-bearing nude mouse model, was used. As radiolabeled compound, a .sup.177Lu-labelled compound, .sup.177Lu-DOTATOC, was used.

    [0225] Briefly, CD1 nude mice (Crl: CD1-Foxn1.sup.nu; 8 weeks at beginning of experiment) were used. For the preparation of the AR42J xenograft tumor, AR42J cell line (rat pancreatic acinar cells) were cultured at 37 C. and 5% CO.sub.2 in Ham's F-12K medium (Gibco, Ref 21127022) supplemented with inactivated 20% FBS (Sigma Aldrich, Ref F7524). Subcultivation was performed every seven days by trypsinization and aliquoted in new flasks. A suspension of AR42J cells at 5010.sup.6 cells/mL was prepared in Ham's F-12K medium (without fetal bovine serum). Mice were inoculated subcutaneously in the both right and left flanks with 510.sup.6 cells in 100 L of Ham's F-12K medium. After inoculation, tumor growth was controlled by visual observation and palpation until the dosing day (7 days post-inoculation). Only animals showing apparent nodules were included in the experiment.

    [0226] For the experiment, 18 tumor-bearing mice were assigned to three distinct experimental groups as shown in Table 1 below:

    TABLE-US-00001 TABLE 1 Group 1.1 1.2 0 .sup.177Lu-DOTATOC + + PAH + Number of mice 6 6 6

    [0227] The experimental design is shown in FIG. 1. At day 7 after inoculation with the tumor cells mice received a single intravenous injection as indicated in Table 1, i.e. either with vehicle (0.9% NaCl; Group 0), or with 40 MBq .sup.177Lu-DOTATOC, alone (in 0.9% NaCl; Group 1.1) or in combination with PAH (in 20% PAH solution (Merck Sharp & Dohme Corp); Group 1.2) 10 min prior to dosing of .sup.177Lu-DOTATOC, mice of groups 1.1 and 1.2 were injected intraperitoneally with 50 L saline or PAH, respectively.

    [0228] Body weight and tumor volume were evaluated every two to three days for a period of 57 days after treatment (or until the tumor size limit was reached). The tumor volume was determined by measuring the length, the width and the depth of the tumor with a digital caliper. Tumor volume was calculated by using the following formula:


    Tumor volume=(lengthwidthdepth)0.5

    [0229] The mice were monitored until the individual tumor size reached 1500 mm.sup.3. When this experimental endpoint was reached or after a 57 days period following treatment, mice were euthanized. Mean tumor volume and body weight of AR42J xenograft CD1 nude mice were calculated for each treatment group throughout the duration of the study.

    [0230] The mean values of the tumor volume and the body weight of mice with respective standard errors (SD) for each treatment group throughout the duration of the study are shown in Table 2 and Table 3 below:

    TABLE-US-00002 TABLE 2 Tumor volume (mean SD mm.sup.3) Days post-dosing Group 0 Group 1.1 Group 1.2 0 0 0 0 0 0 0 (n = 6) (n = 6) (n = 6) 1 0 0 0 0 0 0 4 1 2 0 0 0 0 6 2 3 0 0 0 0 8 22 42 0 0 0 0 11 60 72 0 0 0 0 13 128 153 0 0 0 0 15 242 244 0 0 0 0 18 443 418 2 6 0 0 20 629 544 10 22 13 31 22 661 551 33 47 20 33 (n = 5) 25 673 621 122 120 76 96 (n = 3) 27 535 415 175 182 106 140 (n = 2) 29 724 624 251 233 159 206 32 777 805 516 347 322 360 (n = 1) 34 847 829 709 466 466 527 36 786 338 457 547 (n = 4) (n = 5) 39 1192 486 500 705 (n = 4) 41 1265 199 138 157 (n = 2) (n = 3) 43 215 241 46 395 411 48 534 516 50 690 655 53 673 22 (n = 1) 55 820 101 57 1010 98

    TABLE-US-00003 TABLE 3 Body weight (mean SD % ID/g) Days post-dosing Group 0 Group 1.1 Group 1.2 0 27.3 2.2 25.0 0.8 27.0 3.1 (n = 6) (n = 6) (n = 6) 1 27.1 2.1 24.7 1.1 26.7 3.3 4 27.4 1.7 25.4 0.8 26.7 3.3 6 27.9 1.8 25.9 0.9 27.8 3.3 8 27.8 1.9 25.8 0.8 28.0 3.2 11 28.4 1.9 25.9 0.9 28.1 3.3 13 28.8 1.9 25.9 1.1 28.4 3.1 15 29.0 1.9 25.9 1.1 28.2 3.1 18 30.2 2.4 26.0 0.9 28.6 2.9 20 30.4 2.7 26.1 0.9 28.6 2.8 22 31.3 2.4 26.3 0.9 28.7 2.7 (n = 5) 25 31.7 2.4 26.2 1.0 28.6 2.5 (n = 3) 27 31.5 0.7 27.0 1.2 29.5 2.5 (n = 2) 29 31.9 1.4 26.9 0.9 29.5 2.3 32 31.7 2.2 28.1 1.3 30.5 2.1 34 32.8 2.1 29.0 1.4 31.1 2.1 (n = 1) 36 28.4 0.8 31.6 2.0 (n = 4) (n = 5) 39 29.5 0.9 31.9 3.0 (n = 4) 41 30.6 0.4 31.4 3.0 (n = 2) (n = 3) 43 31.1 2.8 46 31.8 3.2 48 33.0 3.5 50 33.3 4.1 53 29.6 (n = 1) 55 30.6 57 30.6

    [0231] The tumor growth curve and the body weight ratios of mice (weight at different time points compared to initial body weight at DO) are shown in FIGS. 2 and 3, respectively. As mice exhibiting a tumor size >1500 mm.sup.3 were taken out of the experiment, the average tumor volume shown in the curves was affected accordingly.

    [0232] FIG. 2 shows a significant tumor growth delay of 10 days when mice were injected with .sup.177Lu-DOTATOC compared to the control group. The treatment with .sup.177Lu-DOTATOC suppressed tumor growth successfully for 20 days, revealing a substantial tumor growth inhibition. Furthermore, an even slower resumption of tumor growth was observed after treatment with .sup.177Lu-DOTATOC combined with PAH as compared to treatment with .sup.177Lu-DOTATOC alone.

    [0233] FIG. 3 reveals that the average weight of AR42J xenograft CD1 nude mice treated with radiolabeled DOTATOC increased similarly to that the untreated tumor-bearing control mice. Thus, mice treated with radiolabeled DOTATOC as well as untreated control mice maintained a healthy physical appearance throughout the study period.

    [0234] The tumor volume was then plotted against actual tumor weight for each individual tumor (n=36; 2 tumors/mouse) and a linear regression analysis was performed. The results are shown in FIG. 4. In FIG. 4, the linear regression analysis demonstrated that the correlation between tumor volume and weight was highly significant (r.sup.2=0.9598). Thus, these data established that the formula for estimating tumor volume reflected the actual tumor size accurately.

    [0235] FIG. 5 shows the survival curves for each treatment group. For each group, the median survival time (MST) to reach the maximum tumor size of 1500 mm.sup.3 was calculated. The median survival time was 23 days for the control group (Group 0) versus 39 days for Group 1.1 (.sup.177Lu-DOTATOC alone) and 44.5 days Group 1.2 (.sup.177Lu-DOTATOC in combination with PAH).

    [0236] In summary, while administration of the radiolabeled complex alone decreased/delayed tumor growth and increased the survival times of tumor-bearing mice, combined administration of the radiolabeled complex and PAH even further decreased/delayed tumor growth and increased the survival times of tumor-bearing mice.

    Example 2: Combination of PAH and a Radiolabeled Complex in a Mouse Tumor Model

    [0237] This study was performed to confirm the effects observed in Example 1 for a combination of para-aminohippuric acid (PAH) and a radiolabeled complex, in an in vivo tumor model, namely, the AR42J pancreatic tumor-bearing nude mouse model. Similarly as in Example 1, .sup.177Lu-DOTATOC was used as radiolabeled compound.

    [0238] Briefly, SWISS nude mice (Crl: NU(Ico)-Foxn1.sup.nu; 8 weeks at beginning of experiment) were used. For the preparation of the AR42J xenograft tumor, AR42J cell line (rat pancreatic acinar cells) were cultured at 37 C. and 5% CO.sub.2 in Ham's F-12K medium (Gibco, Ref 21127022) supplemented with inactivated 20% FBS (Sigma Aldrich, Ref F7524). Subcultivation was performed every seven days by trypsinization and aliquoted in new flasks. A suspension of AR42J cells at 5010.sup.6 cells/mL was prepared in Ham's F-12K medium (without fetal bovine serum). Mice were inoculated subcutaneously in the right flank with 510.sup.6 cells in 100 L of Ham's F-12K medium. After inoculation, tumor growth was controlled by visual observation and palpation until the dosing day (7 days post-inoculation). Only animals showing apparent nodules were included in the experiment.

    [0239] For the experiment, 36 tumor-bearing mice were assigned to three distinct experimental groups as shown in Table 4 below:

    TABLE-US-00004 TABLE 4 Group 1 2 3 .sup.177Lu-DOTATOC + + PAH + Number of mice 12 12 12

    [0240] The experimental design essentially corresponds to Example 1, as shown in FIG. 1. At day 7 after inoculation with tumor cells, mice received a single intravenous injection as indicated in Table 1, i.e. either with vehicle (0.9% NaCl; Group 3), or with 41-42 MBq .sup.177Lu-DOTATOC, alone (in 0.9% NaCl; Group 1) or in combination with PAH (in 20% PAH solution (Merck Sharp & Dohme Corp); Group 2). 10 min prior to dosing of .sup.177Lu-DOTATOC, mice of groups 1 and 2 were injected intraperitoneally with 50 L saline or PAH, respectively.

    [0241] Body weight and tumor volume were evaluated every two to three days for a period of 46 days after treatment (or until the tumor size limit was reached). The tumor volume was determined by measuring the length, the width and the depth of the tumor with a digital caliper. Tumor volume was calculated by using the following formula:


    Tumor volume=(lengthwidthdepth)0.5

    [0242] The mice were monitored until the individual tumor size reached 1500 mm.sup.3. When this experimental endpoint was reached or after a 46 days period following treatment, mice were euthanized. Mean tumor volume and body weight of AR42J xenograft SWISS mice were calculated for each treatment group throughout the duration of the study.

    [0243] The mean values of the tumor volume and the body weight of mice with respective standard errors (SD) for each treatment group throughout the duration of the study are shown in Table 5 and Table 6 below:

    TABLE-US-00005 TABLE 5 Tumor volume (mean SD mm.sup.3) Days post-dosing Group 3 Group 1 Group 2 1 0 0 0 0 0 0 (n = 12) (n = 12) (n = 12) 4 8 27 0 0 0 0 6 40 75 0 0 0 0 8 90 94 0 0 0 0 11 371 288 0 0 0 0 13 659 445 0 0 0 0 15 892 409 0 0 0 0 (n = 11) 18 1216 483 29 37 38 58 (n = 9) 20 951 380 59 48 79 93 (n = 4) 22 1181 570 147 130 169 194 25 965 87 410 255 342 356 (n = 2) 27 1137 104 674 362 604 548 29 1362 246 1033 461 793 605 (n = 11) (n = 11) 32 1238 1285 458 714 504 (n = 1) (n = 7) (n = 8) 34 1663 1396 408 920 620 (n = 4) (n = 7) 36 1425 419 779 516 (n = 2) (n = 5) 39 1567 822 311 (n = 1) (n = 4) 41 1186 468 43 1346 222 (n = 2) 46 1892 (n = 1)

    TABLE-US-00006 TABLE 6 Body weight (mean SD g) Days post-dosing Group 3 Group 1 Group 2 1 21.0 1.2 24.3 1.7 23.8 2.1 (n = 12) (n = 12) (n = 12) 4 22.1 1.1 24.3 1.6 23.5 2.2 6 22.1 1.1 24.5 1.9 23.8 2.2 8 22.6 0.9 24.9 1.9 24.4 2.2 11 23.1 1.0 24.8 1.9 24.4 2.1 13 23.6 1.1 24.8 1.9 24.6 1.9 15 23.9 1.4 24.7 1.9 24.6 2.0 (n = 11) 18 24.9 1.6 24.9 1.9 24.8 2.1 (n = 9) 20 25.4 1.9 25.2 1.8 24.8 2.2 (n = 4) 22 26.0 1.7 25.6 1.8 25.2 2.5 25 25.7 1.3 26.2 1.9 25.6 2.6 (n = 2) 27 26.3 1.1 26.8 1.8 26.4 2.6 29 27.0 1.2 26.9 1.9 26.6 2.7 (n = 11) (n = 11) 32 28.6 27.5 2.0 26.7 2.5 (n = 1) (n = 7) (n = 8) 34 29.5 28.1 1.1 27.4 2.8 (n = 4) (n = 7) 36 28.3 1.1 26.6 1.5 (n = 2) (n = 5) 39 29.6 27.6 2.0 (n = 1) (n = 4) 41 28.4 2.1 43 27.7 2.7 (n = 2) 46 27.5 (n = 1)

    [0244] The tumor growth curve and the body weight ratios of mice (weight at different time points compared to initial body weight at DO) are shown in FIGS. 6 and 7, respectively. As mice exhibiting a tumor size >1500 mm.sup.3 were taken out of the experiment, the average tumor volume shown in the curves was affected accordingly.

    [0245] FIG. 6 shows a significant tumor growth delay of about 14 days when mice were injected with .sup.177Lu-DOTATOC compared to the control group. The treatment with .sup.177Lu-DOTATOC suppressed tumor growth successfully for 15 days, revealing a substantial tumor growth inhibition. An even slower tumor growth was observed after treatment with .sup.177Lu-DOTATOC combined with PAH as compared to treatment with .sup.177Lu-DOTATOC alone.

    [0246] FIG. 7 reveals that no significant weight loss was observed regardless of the treatment administered to the mice suggesting a low radiotoxicity elicited by radiolabeled compound. However, the average weight of AR42J xenograft mice treated with the radiolabeled compound increased slightly more slowly than the tumor-bearing control mice. Independent of the combination with PAH, mice treated .sup.177Lu-DOTATOC showed the same weight gain throughout the experiment. Thus, mice treated with radiolabeled DOTATOC as well as untreated control mice maintained a healthy physical appearance throughout the study period.

    [0247] In FIG. 8, the linear regression analysis demonstrated that the correlation between tumor volume and weight was highly significant (r.sup.2=0.9101). Thus, these data established that the formula for estimating tumor volume reflected the actual tumor size accurately.

    [0248] FIG. 9 shows the survival curves for each treatment group. As expected, the control group had to be euthanized earlier due the faster tumor growth than the two groups treated with radiolabeled DOTATOC. Similarly as in Example 1, survival time was prolonged when .sup.177Lu-DOTATOC was combined with PAH as compared to .sup.177Lu-DOTATOC alone.

    [0249] Accordingly Example 2 confirmed the results of Example 1, namely, that combined administration of the radiolabeled complex and PAH even further decreased/delayed tumor growth and increased the survival times of tumor-bearing mice.