Conjugate having cytotoxicity and process for the preparation thereof

Claim 2

A conjugate having cytotoxicity prepared by covalently binding a serum albumin having a cytotoxic substance linked thereto to an immunoglobulin, or its fragment, which is able to selectively bind to a particular antigen of a cell to be killed.

Claim 3

The conjugate having cytotoxocity according to Claim 1, wherein said serum albumin is a human or bovine serum albumin.

Claim 4

The conjugate having cytotoxicity according to Claim 1 and Claim 2, wherein the conjugate is expressed by the following formula (I) wherein Ab indicates an immunoglobulin or its fragment, Aℓ a serum albumin, and Cy a cytotoxic substance respectively. S 1 and NH indicate a sulfur atom and an imino group in the serum albumin respectively. B 1 indicates a divalent organic group. m indicates an integer 1 to 30 and n an integer 1 to 10 respectively.

Claim 5

The conjugate having cytotoxicity according to any one of Claims 1, 2, and 3, wherein the conjugate is expressed by the following formula (II) wherein definitions of Ab, Aℓ, Cy, S 1 , NH, m, and n are the same as those given in case of formula (I). S 2 indicates a sulfur atom. B 2 , B s , and B 4 are divalent organic groups. t 2 and t 3 are indentical with or different from each other, being 0 or 1.

Claim 6

The conjugate having cytotoxicity according to any one of Claims 1, 2, and 3, wherein the conjugate is expressed by the following formula (III) wherein definitions of Ab, Aℓ, Cy, S 1 , NH, m and n are the same as those given in case of formula (I). B 4 indicates a divalent organic group.

Claim 7

A process for the preparation of a conjugate having cytotoxicity expressed by the following formula (II-1) wherein definitions of Ab, Aℓ, cy, S 1 , NH, m, and n are the same as those given in case of formula (I); S 2 , B 2 , and t 2 are as defined in case of formula (II): characterized by reacting a serum albumin expressed by the following formula (V) having an active disulfide group having a cytotoxic substance linked thereto wherein Aℓ, Cy, S 1 , NH, and m are as defined with regard to the formula (I) and X indicates a group which is capable of forming an active disulfide linkage with a neighboring sulfur atom: with an immunoglobulin or its fragment expressed by the following formula (IV) having a generated or introduced thiol group wherein Ab is as defined with regard to the fomula (I); definitions of S 2 , B 2 , and t 2 are the same as those given in case of formula (II); and n' is an integer 1 to 10.

Claim 8

A process for the preparation of a conjugate having cytotoxicity expressed by the following formula (II-1) wherein definitions of Ab, Aℓ, cy, S 1 , NH, m, and n are the same as those given in case of formula (I); S 2 , B 2 , and t 2 are as defined in case of formula (II): characterized by reacting a serum albumin expressed by the following formula (V) having an active disulfide group having a cytotoxic substance linked thereto wherein Aℓ, Cy, S 1 , NH, and m are as defined with regard to the formula (I) and X indicates a group which is capable of forming an active disulfide linkage with a neighboring sulfur atom: with an immunoglobulin or its fragment expressed by the following formula (IV) having a generated or introduced thiol group wherein Ab is as defined with regard to the fomula (I); definitions of S 2 , B 2 , and t 2 are the same as those given in case of formula (II); and n' is an integer 1 to 10.

Claim 9

A process for the preparation of conjugate having cytotoxicity expressed by the aforementioned formula (II-I) characterized by reacting a serum albumin expressed by the following formula (VII) having a cytotoxic substance linked thereto wherein Aℓ, Cy S 1 , NH, and m are as defined with regard to the formula (I): with an immunoglobulin or its fragment expressed by the following formula (V I ) having an induced or introduced active disulfide group wherein Ab is as defined with regard to the formula (I); S 2, B 2 , and t 2 are as defined in case of formula (II); n' is as defined in case of formula (IV); and X is as defined with regard to the formula (V).

Claim 10

A process for the preparation of conjugate having cytotoxicity expressed by the aforementioned formula (II-I) characterized by reacting a serum albumin expressed by the following formula (VII) having a cytotoxic substance linked thereto wherein Aℓ, Cy S 1 , NH, and m are as defined with regard to the formula (I): with an immunoglobulin or its fragment expressed by the following formula (V I ) having an induced or introduced active disulfide group wherein Ab is as defined with regard to the formula (I); S 2, B 2 , and t 2 are as defined in case of formula (II); n' is as defined in case of formula (IV); and X is as defined with regard to the formula (V).

Claim 11

A process for the preparation of a conjugate having cutotoxicity expressed by the following formula (II-2) wherein Ab, Aℓ, Cy, S 1 , NH, m and n are as defined with regard to the formula (I); S 2 , B 2 , B 3 , and t 2 are as defined in case of formula (II): characterized by binding a serum albumin, which has cytotoxic substance linked thereto, expressed by the above-mentioned formula (VII), to an immunoglobulin or its fragment, which has a generated or introduced thiol group, expressed by the above- mentioned formula (IV) with the use of a cross-linking agent having two functional groups which are capable of reacting with a thiol group.

Claim 12

A process for the preparation of a conjugate having cutotoxicity expressed by the following formula (II-2) wherein Ab, Aℓ, Cy, S 1 , NH, m and n are as defined with regard to the formula (I); S 2 , B 2 , B 3 , and t 2 are as defined in case of formula (II): characterized by binding a serum albumin, which has cytotoxic substance linked thereto, expressed by the above-mentioned formula (VII), to an immunoglobulin or its fragment, which has a generated or introduced thiol group, expressed by the above- mentioned formula (IV) with the use of a cross-linking agent having two functional groups which are capable of reacting with a thiol group.

Claim 13

A process for the preparation of a conjugate having cytotoxicity expressed by the aforementioned formula (III) characterized by reacting a serum albumin, which has a cytotoxic substance linked thereto, expressed by the abovementioned formula (VII) with an immunoglobulin or its fragment, which has an introduced maleimide group, expressed wherein Ab is as defined with regard to the formula (I); n' is as defined in case of formula (IV); and B 4 is as defined in case of formula (III).

Claim 14

A process for the preparation of a conjugate having cytotoxicity expressed by the aforementioned formula (III) characterized by reacting a serum albumin, which has a cytotoxic substance linked thereto, expressed by the abovementioned formula (VII) with an immunoglobulin or its fragment, which has an introduced maleimide group, expressed wherein Ab is as defined with regard to the formula (I); n' is as defined in case of formula (IV); and B 4 is as defined in case of formula (III).