2.6In de authentieke Engelse versie van de beschrijving van het octrooi is onder meer het volgende opgenomen:
“[0002] Antifolates represent one of the most thoroughly studied classes of antineoplastic agents, with aminopterin initially demonstrating clinical activity approximately 50 years ago. Methotrexate was developed shortly thereafter, and today is a standard component of effective chemotherapeutic regimens for malignancies such as lymphoma, breast cancer, and head and neck cancer. (Bonnadonna G, Zambetti M, Valagussa P. Sequential or alternating doxorubicin and CMF regimens in breast cancer with more than three positive nodes: Ten year results. JAMA 1995;273(7):542-547; Bonnadonna G, Valagussa P, Moliterni A, Zambetti M, Brambilla C. Adjuvant cyclophosphamide, methotrexate, and fluorouracil in node-positive breast cancer: The results of 20 years of follow-up. N Engl J Med 1995;332(14):901-906; and Hong WK, Schaefer S, Issell B, et al A prospective randomized trial of methotrexate versus cisplatin in the treatment of recurrent squamous cell carcinoma of the head and neck. Cancer 1983;52:206-210.) Antifolates inhibit one or several key folate-requiring enzymes of the thymidine and purine biosynthetic pathways, in particular, thymidylate synthase (TS), dihydrofolate reductase (DHFR), and glycinamide ribonucleotide formyltransferase (GARFT), by competing with reduced folates for binding sites of these enzymes. (Shih C, Habeck LL, Mendelsohn LG, Chen VJ, Schultz RM. Multiple folate enzyme inhibition: Mechanism of a novel pytrolopyrimidine-based antifolate LY231514 (MTA). Advan Enzyme Regul, 1998; 38:135-152 and Shih C, Chen VJ, Gossett LS, et al. LY231514, a pyrrolo[2,3-d]pyrimidine-based antifolaten that inhibits multiple folate-requiring enzymes. Cancer Res 1997;57:1116-1123.) Several antifolate drugs are currently in development. Examples of antifolates that have thymidylate synthase inhibiting ("TSI") characteristics include 5-fluorouracil and Tomudex®. An example of an antifolate that has dihydrofolate reductase inhibiting ("DHFRI'') characteristic is Methotrexate®. An example of an antifolate that has glycinamide ribonucleotide formyltransferase inhibiting (''GARFTI") characteristics is Lometrexol. Many of these antifolate drugs inhibit more than one biosynthetic pathway.
For example Lometrexol is also an inhibitor of dihydrofolate reductase and pemetrexed disodium (Alimta®, Eli Lilly and Company, Indianapolis, IN) has demonstrated thymidylate synthase, dihydrofolate reductase, and glycinamide ribonucleotide formyltransferase inhibition.
[0005] Surprisingly and unexpectedly, we have now discovered that certain toxic effects such as mortality and nonhematologic events, such as skin rashes and fatigue, caused by antifolates, as a class, can be significantly reduced by the presence of a methylmalonic acid lowering agent as vitamin B12, without adverse adversely affecting therapeutic efficacy. The present invention thus generally relates to a use in the manufacture of a medicament for improving the therapeutic utility of antifolate drugs by administering to the host undergoing treatment with a methylmalonic acid lowering agent as vitamin B12. We have discovered that increased levels of methylmalonic acid is a predictor of toxic events in patients that receive an antifolate drug and that treatment for the increased methylmalonic acid, such as treatment with vitamin B12, reduces mortality and nonhematologic events, such as skin rashes and fatigue events previously associated with the antifolate drugs. Thus, the present invention generally relates to a use in the manufacture of a medicament for reducing the toxicity associated with the administration of an antifolate to a mammal by administering to said mammal an effective amount of said antifolate in combination with a methylmalonic acid lowering agent as vitamin B12.
[0006] Additionally, we have discovered that the combination of a methylmalonic acid lowering agent as vitamin B12 and folic acid synergistically reduces the toxic events associated with the administration of antifolate drugs. Although, the treatment and prevention of cardiovascular disease with folic acid in combination with vitamin B12 is known, the use of the combination for the treatment of toxicity associated with the administration of antifolate drugs was unknown heretofore.
[0010] The invention specifically provides the use of the antifolate pemetrexed disodium in the manufacture of a medicament for use in combination therapy for inhibiting tumor growth in mammals wherein said medicament is to be administered in combination with a methylmalonic acid lowering agent selected from vitamin B12 and pharmaceutical derivatives thereof.
[0022] The terms "antifolate" and ''antifolate drug' generally refer to a chemical compound which inhibits at least one key folate-requiring enzyme of the thymidine or purine biosynthetic pathways, preferably thymidylate synthase ("TS"), dihydrofolate reductase ("DHFR"), or glycinamide ribonucleotide formyltransferase ("GARFT"), by competing with reduced folates for binding sites of these enzymes. The "antifolate" or ''antifolate drug" for use in this invention is Pemetrexed Disodium (ALIMTA0), as manufactured by Eli Lilly & Co.”
[0035] The animals were maintained on sterilized standard lab chow ad libitum and sterilized water ad libitum. The human MX-1 tumor cells (5 x 106) obtained from donor tumors were implanted subcutaneously in a thigh of female nude mice 8- to 1 0-weeks old. Beginning on day 7 post tumor cell implantation, the animals were treated with pemetrexed disodium (ALIMTA®) (100 mg/kg or 150 mg/kg) once daily on days 7 through 11 and 14 through 18 by intraperitoneal injection alone or along with folic acid (6 mg/kg or 60 mg/kg) and/or vitamin B12 (165 mg/kg) by intraperitoneal injection on the same schedule.
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[0037] The human MX-1 breast carcinoma xenograft was responsive to treatment with pemetrexed disodium (ALIMTA®) with doses of 100 mg/kg and 150 mg/kg producing tumor growth delays of 17 days and 21 days, respectively. Folic acid was administered to the animals alone at two doses 6 mg/kg and 60 mg/kg on the same schedule as pemetrexed disodium (ALIMTA®) and produced tumor growth delays of 7 days and 12 days, respectively. Vitamin B12 administered alone at a dose of 165 mg/kg resulted in a tumor growth delay of 12 days. Combinations of pemetrexed disodium (ALIMTA®) at each of the two doses were administered along with each of the vitamins as simultaneous combination regimens. Administration of folic acid (6 mg/kg) along with pemetrexed disodium (ALlMTA®) did not alter the tumor growth delay produced from that obtained with pemetrexed disodium (ALlMTA®) alone. The addition of folic acid at the higher dose (60 mg/kg) along with each dose of pemetrexed disodium (ALIMTA®) resulted in small increases in tumor growth delay to 22 days and 23 days at the pemetrexed disodium (ALlMTA®) doses of 100 mg/kg and 150 mg/kg, respectively. The tumor growth delays with pemetrexed disodium (ALIMTA®) and vitamin B12 (165 mg/kg) treatment were 22 days and 24 days at pemetrexed disodium (ALIMTA®) doses of 100 mg/kg and 150 mg/kg, respectively. Body weight was used as a general measure of toxicity for each of the treatment regimens. The body weight loss pattern reflected the treatment regimens with weight decrease during the treatment times of days 7 through 11 and 14 through 18 with some weight recovery during the intervening two days. The weight loss due to pemetrexed disodium (ALIMTA®) was dose dependent but overall minor (3%). Folic acid alone at either 6 mg/kg or 60 mg/kg did not cause weight loss, in fact folic acid treated animals maintained weight and gained weight over the course of the experiment better than the control animals. The animals treated with pemetrexed disodium (ALIMTA) (100 mg/kg) and folic acid (60 mg/kg) gained weight (about 20%) over the course of the experiment.
[0038] Administration of vitaminB12 did not prevent weight gain in the animals over the time course of the experiment. The animals treated with pemetrexed disodium (ALlMTA®) (100 mg/kg) along with vitamin B12 gained weight while those treated with pemetrexed disodium (ALlMTA®) (150 mg/kg) along with vitamin B12 maintained weight over the course of the experiment.
[0039] In conclusion, administration of super-physiologic but non-toxic doses of the vitamins, folic acid and vitamin B12, did not alter the antitum or activity of pemetrexed disodium (ALIMTA®) in the human MX-1 breast carcinoma xenograft tumor in nude mice and did not increase the toxicity of pemetrexed disodium (ALIMTA®) as determined by body weight measurements of the animals.
[0045] In preparation for the foregoing clinical study, pilot studies in humans have established that vitamin B12 given to patients receiving pemetrexed disodium (ALIMTA®) has effected reduced side effects due to the pemetrexed disodium (ALIMTA®). (…)”.