Calicheamicin derivative-carrier conjugates

  • US 20040082764A1
  • Filed: 05/02/2003
  • Published: 04/29/2004
  • Est. Priority Date: 05/02/2002
  • Status: Active Grant
First Claim
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1. A method for preparing monomeric cytotoxic drug/carrier conjugates with reduced low conjugated fraction (LCF) having the formula, Pr(—

  • X—

    W)m wherein;

    Pr is a proteinaceous carrier, X is a linker that comprises a product of any reactive group that can react with a proteinaceous carrier, W is a cytotoxic drug;

    m is the average loading for a purified conjugation product such that the cytotoxic drug constitutes 7-9% of the conjugate by weight; and

    (—

    X—

    W)m is a cytotoxic drug derivative, said method comprising the steps of;

    (1) adding the cytotoxic drug derivative to the proteinaceous carrier wherein the cytotoxic drug derivative is 4.5-11% by weight of the proteinaceous carrier;

    (2) incubating the cytotoxic drug derivative and a proteinaceous carrier in a non-nucleophilic, protein-compatible, buffered solution having a pH in the range from about 7 to 9 to produce a monomeric cytotoxic drug/carrier conjugate, wherein the solution further comprises (a) an organic cosolvent, and (b) an additive comprising at least one C6-C18 carboxylic acid or its salt, and wherein the incubation is conducted at a temperature ranging from about 30°

    C. to about 35°

    C. for a period of time ranging from about 15 minutes to 24 hours; and

    (3) subjecting the conjugate produced in step (2) to a chromatographic separation process to separate monomeric cytotoxic drug derivative/proteinaceous carrier conjugates with a loading in the range of 4-10% by weight cytotoxic drug and with low conjugated fraction (LCF) below 10 percent from unconjugated proteinaceous carrier, cytotoxic drug derivative, and aggregated conjugates.

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