Chemistry: natural resins or derivatives; peptides or proteins; – Peptides of 3 to 100 amino acid residues – Calcitonin; related peptides
Reexamination Certificate
1998-08-20
2001-07-24
Borin, Michael (Department: 1631)
Chemistry: natural resins or derivatives; peptides or proteins;
Peptides of 3 to 100 amino acid residues
Calcitonin; related peptides
C530S318000, C514S011400, C514S808000, C930S060000, C930SDIG722
Reexamination Certificate
active
06265534
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to calcitonins and calcitonin derivatives having a hypocalcemic effect. Calcitonins and calcitonin derivatives of this type are employed in particular in the field of the pharmaceutical industry and in the field of medicine, for example for the treatment of osteoporosis, of Paget's disease or of hypercalcemia.
BACKGROUND OF THE INVENTION
Calcitonins are peptide hormones which consist of 32 amino acids. On account of their hypocalcemic effect and of the inhibition of bone destruction caused by them, they have great pharmacological importance. They are therapeutically employed for the treatment of osteoporosis, of Paget's disease or to hypercalcemia. Use is made here, in particular, of the calcitonins of man (hCt), of pig (pCt) or of ultimobranchial species, such as the salmon (sCt) or the eel (eCt).
The calcitonins or their derivatives of ultimobranchial species have a 20- to 50-fold higher activity in vivo than human calcitonin. Therefore these calcitonins are preferably employed for therapeutic purposes. The calcitonins of the ultimobranchial species differ considerably, however, in their amino acid sequence from the peptide of human calcitonin. For example, salmon calcitonin differs in 16 of the 32 amino acids from human calcitonin. Nevertheless, it is used to this day, since on account of its considerably higher activity the dosage for therapeutic purposes can be kept lower.
A disadvantage of calcitonins of ultimobranchial species, however, is that they cause an immune reaction in man on account of the amino acid differences. This high antigenicity leads to antibody formation against the particular calcitonin therapeutically employed, often even six months after the start of administration. This high antigenicity subsequently leads to secondary resistance and desensitization to the calcitonin employed. This necessitates, on the other hand, the administration of higher doses, which in turn lead to higher antibody formation and thus secondary resistance, and also to further side effects (contraindications).
Of the known calcitonins, further derivatives which are more active compared with the native form are known. For example, a replacement of three to five amino acid residues on the hydrophobic side of the potential &agr;-helical region (8-22) of hCt by leucines leads to more active calcitonin analogs. The activity of the calcitonin derivatives is in this case attributed to a close relationship between a potential amphiphilic &agr;-helical region between the amino acid residues 8 and 22 and the biological action of the molecule, on the other hand to the conformational flexibility and the spatial interactions of various molecular regions.
Apart from sCt and &agr;-aminosuberic acid-1,7-eCt, these analogs, however, up to now have no further clinical use for the treatment of the above mentioned diseases.
Since as a result of the high proteolytic degradation rate (in-vivo half-life) of the calcitonins therapeutically employed, at present comparatively high amounts have to be administered, this—as described above—in turn leading to rapid antibody formation (secondary resistance) and possible side effects (contraindications), the increase in the bioactivity or proteolysis resistance is ascribed great importance.
Conformationally stabilized analogs of hCt of this type having increased hypocalcemic action are disclosed in DE 44 31 121 A1. In this specification, hCt derivatives are described in which a 20-membered ring structure is produced by the introduction of a covalent lactam bridge between the amino acids in positions 17 and 21, for example by the amino acid in position 17 being aspartic acid and the amino acid in position 21 being lysine. These hCt analogs have an increased conformational stability and an increased hypocalcemic action.
This hypocalcemic action, however, is still not sufficient in order to make possible therapeutic use of these hCt analogs for the treatment of the diseases described above.
It is the object of the present invention to make available calcitonins or calcitonin derivatives which have an increased conformational stability and a high biological activity.
This object is achieved by the calcitonins and calcitonin derivatives as claimed in the precharacterizing clause of claim
1
in combination with its characterizing features.
DETAILED DESCRIPTION OF THE INVENTION
The calcitonins and calcitonin derivatives according to the invention have a bridge between the amino acids in the positions corresponding to the positions 17 and 21 of human calcitonin. In these positions, amino acids of this type are Incorporated such that as a result of the bridge a ring is formed which has 18 or 19 members. In contrast to the 20-membered ring structure known from the prior art, the calcitonins according to the invention are more stabilized with respect to their conformation, such that proteolytic degradation is retarded. Furthermore, these calcitonins and calcitonin derivatives according to the invention have a very high activity, as a result of which a low dosage is possible. Because the sequence is very similar to the human molecule, no immune reaction occurs (no secondary resistance). All in all, it was found that the ring contraction in comparison to the prior art leads to a very high activity, such that a 19-membered or 18-membered ring structure is suitable as a lead structure for further potent calcitonin analogs beyond those described in the examples.
Advantageous embodiments of the calcitonins and calcitonin derivatives according to the invention are described in the dependent claims.
The amino acids in the positions 17 and 21 can be bridged by suitable linkers or, with appropriate choice of the amino acid, via a lactam bridge. Calcitonins have particularly advantageous properties in which aspartic acid and omithine are present in the positions mentioned instead of asparagine and threonine in the human calcitonin. This calcitonin is 360-times more active than the original human calcitonin and still three times more active than calcitonin from salmon (sCt) in a mouse in-vivo test.
By means of the introduction of glutamic acid and &agr;,&ggr;-diaminobutyric acid instead of asparagine and threonine in the positions 17 and 21, a 19-membered ring and a highly active analog Is also produced.
A calcitonin derivative according to the invention having an 16-membered ring results by the replacement of the amino acids asparagine and threonine in the positions 17 and 21 by aspartic acid and &agr;,&ggr;-diaminobutyric acid, respectively. This calcitonin derivative is about 30 times more active than the original human calcitonin.
Several other highly active 19- or 18-membered ring containing analogs are also described in the invention including the following amino acid pairs in the positions 17 and 21 of calcitonin:1,3-diaminopropionic acid and 2-aminoadipic acid, or 1,3-diaminopropionic acid and 2-aminoadipic acid, or 1,3-diaminopropionic acid and 5-carboxymethylcystein, or 5-carboxymethylcyst in and 1,3-diaminopropionic acid, or 2-aminoadipic acid and serin, or serin and 2-aminoadipic acid, or glutamic acid and serin oder serin and glutamic acid.
The mentioned increase in the stability and activity due to the introduction of the 18-membered or 19-membered ring system according to the invention does not only result, however, in the case of human calcitonin, but also in the case of calcitonins of the pig or of the ultimobranchial species such as salmon or eel or their analogs known up to now. For example, the activity of a known highly active analog in which the positions 1 and 7 are replaced by an &agr;-aminosuberic acid reside can be further increased by the introduction of an 18-membered or 19-membered ring as described above. Even in the case of already-known analogs, an improvement in the stability and activity thus results due to the introduction of the 18- or 19-membered ring structure according to the Invention.
REFERENCES:
patent: 44 31 121 A1 (1996-05-01), None
Kapurniotu A. et al. J. Med. Chem., 38, 8
Bernhagen Jurgen
Brunner Herwig
Kapurniotu Afroditi
Barnes & Thornburg
Borin Michael
Fraunhofer-Gesellschaft zur Forderung der Angewandten Forschung
LandOfFree
Superpotent calcitonin analogs having greatly increased... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Superpotent calcitonin analogs having greatly increased..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Superpotent calcitonin analogs having greatly increased... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2566239