Abstract: New thiol and disulfide-containing maytansinoids bearing a mono or di-alkyl substitution on the ?-carbon atom bearing the sulfur atom are disclosed. Also disclosed are methods for the synthesis of these new maytansinoids and methods for the linkage of these new maytansinoids to cell-binding agents. The maytansinoid-cell-binding agent conjugates are useful as therapeutic agents, which are delivered specifically to target cells and are cytotoxic. These conjugates display vastly improved therapeutic efficacy in animal tumor models compared to the previously described agents.

Abstract: New thiol and disulfide-containing maytansinoids bearing a mono or di-alkyl substitution on the ?-carbon atom bearing the sulfur atom are disclosed. Also disclosed are methods for the synthesis of these new maytansinoids and methods for the linkage of these new maytansinoids to cell-binding agents. The maytansinoid-cell-binding agent conjugates are useful as therapeutic agents, which are delivered specifically to target cells and are cytotoxic. These conjugates display vastly improved therapeutic efficacy in animal tumor models compared to the previously described agents.

Abstract: Charged or pro-charged cross-linking moieties and conjugates of cell binding agents and drugs comprising the charged or pro-charged cross-linking moieties and method of making the same.

Abstract: Disclosed is a method of preparing an amino acid ester of maytansinol by reacting maytansinol with an N-carboxyanhydride of an amino acid (NCA) in the presence of a drying agent. Also disclosed is an improved method of preparing an amino acid ester of maytansinol in which a nucleophile is added to the reaction mixture after completion of the reaction between maytansinol and an N-carboxyanhydride of an amino acid.

Abstract: The present invention discloses a method for targeting maytansinoids to a selected cell population, the method comprising contacting a cell population or tissue suspected of containing the selected cell population with a cell-binding agent maytansinoid conjugate, wherein one or more maytansinoids is covalently linked to the cell-binding agent via a non-cleavable linker and the cell-binding agent binds to cells of the selected cell population.

Abstract: New ansamitocin derivatives bearing a linking group are disclosed. Also disclosed are methods for the synthesis of these new ansamitocin derivatives and methods for their linkage to cell-binding agents. The ansamitocin derivative-cell-binding agent conjugates are useful as therapeutic agents, which are delivered specifically to target cells and are cytotoxic. These conjugates display vastly improved therapeutic efficacy in animal tumor models compared to the previously described agents.

Abstract: New thiol and disulfide-containing maytansinoids bearing a mono or di-alkyl substitution on the ?-carbon atom bearing the sulfur atom are disclosed. Also disclosed are methods for the synthesis of these new maytansinoids and methods for the linkage of these new maytansinoids to cell-binding agents. The maytansinoid-cell-binding agent conjugates are useful as therapeutic agents, which are delivered specifically to target cells and are cytotoxic. These conjugates display vastly improved therapeutic efficacy in animal tumor models compared to the previously described agents.

Abstract: Methods of killing or inhibiting tumors comprising of heterogeneous or mixed cell populations is described. The killing or inhibition of tumors is achieved by selectively targeting a unique ligand suspected of being expressed on a particular cell population to also kill a cell population lacking the unique ligand. These conjugates have therapeutic use as they are delivered to a specific cell population to kill these cells and the cytotoxic drug is released to kill non-targeted cells, thereby eliminating the tumor.

Abstract: The invention relates to novel cell-binding agent-cytotoxic agent conjugate having a peptide linkers and more specifically to conjugates of formula (I). The invention also provides novel cytotoxic agents of formula (II), linker compounds represented by formula (III), and drug-linker compounds represented by formula (IV). The invention further provides compositions and methods useful for inhibiting abnormal cell growth or treating a proliferative disorder in a mammal using the compounds or conjugates of the invention.

Abstract: New thiol and disulfide-containing maytansinoids bearing a mono or di-alkyl substitution on the ?-carbon atom bearing the sulfur atom are disclosed. Also disclosed are methods for the synthesis of these new maytansinoids and methods for the linkage of these new maytansinoids to cell-binding agents. The maytansinoid-cell-binding agent conjugates are useful as therapeutic agents, which are delivered specifically to target cells and are cytotoxic. These conjugates display vastly improved therapeutic efficacy in animal tumor models compared to the previously described agents.

Abstract: New thiol and disulfide-containing maytansinoids bearing a mono or di-alkyl substitution on the ?-carbon atom bearing the sulfur atom are disclosed. Also disclosed are methods for the synthesis of these new maytansinoids and methods for the linkage of these new maytansinoids to cell-binding agents. The maytansinoid-cell-binding agent conjugates are useful as therapeutic agents, which are delivered specifically to target cells and are cytotoxic. These conjugates display vastly improved therapeutic efficacy in animal tumor models compared to the previously described agents.

Abstract: New thiol and disulfide-containing maytansinoids bearing a mono or di-alkyl substitution on the ?-carbon atom bearing the sulfur atom are disclosed. Also disclosed are methods for the synthesis of these new maytansinoids and methods for the linkage of these new maytansinoids to cell-binding agents. The maytansinoid-cell-binding agent conjugates are useful as therapeutic agents, which are delivered specifically to target cells and are cytotoxic. These conjugates display vastly improved therapeutic efficacy in animal tumor models compared to the previously described agents.

Abstract: A process of the large-scale fermentation of a highly productive ansamitocin-producing strains. A method for isolating crude ansamitocins. A method for purifying ansamitocins.

Abstract: The present invention describes the preparation of maytansinol by methods that minimize processing steps, and reduce solvent volumes, making the process more efficient, and scaleable. This process comprises a step of converting bridged acetals of maytansinol to maytansinol. The simplified processing also aids in lowering the potential for human exposure to chemicals. Also provided is an isolated C3 to C9 bridged acetal of maytansinol.

Abstract: The present invention discloses a one-step process for the production of cytotoxic conjugates of maytansinoids and cell binding agents. Maytansinoids having a disulfide linker that bears a reactive moiety are linked to cell binding agents, such as antibodies, without prior modification of the cell binding agent. These conjugates are useful as therapeutic agents which are delivered specifically to target cells and are cytotoxic.

Abstract: Improved processes for the preparation and purification of maytansinoid esters, especially thiol and disulfide-containing maytansinoids are described. In one aspect the process comprises a process of making a maytansinoid ester comprising forming an anion of maytansinol or a maytansinoid bearing a free C-3 hydroxyl moiety and reacting the anion with an activated carboxyl compound to thereby produce the maytansinoid ester.

Abstract: New thiol and disulfide-containing maytansinoids bearing a mono or di-alkyl substitution on the ?-carbon atom bearing the sulfur atom are disclosed. Also disclosed are methods for the synthesis of these new maytansinoids and methods for the linkage of these new maytansinoids to cell-binding agents. The maytansinoid-cell-binding agent conjugates are useful as therapeutic agents, which are delivered specifically to target cells and are cytotoxic. These conjugates display vastly improved therapeutic efficacy in animal tumor models compared to the previously described agents.

Abstract: New thiol and disulfide-containing maytansinoids bearing a mono or di-alkyl substitution on the &agr;-carbon atom bearing the sulfur atom are disclosed. Also disclosed are methods for the synthesis of these new maytansinoids and methods for the linkage of these new maytansinoids to cell-binding agents. The maytansinoid-cell-binding agent conjugates are useful as therapeutic agents, which are delivered specifically to target cells and are cytotoxic. These conjugates display vastly improved therapeutic efficacy in animal tumor models compared to the previously described agents.

Abstract: The present invention discloses a one-step process for the production of cytotoxic conjugates of maytansinoids and cell binding agents. Maytansinoids having a disulfide linker that bears a reactive moiety are linked to cell binding agents, such as antibodies, without prior modification of the cell binding agent. These conjugates are useful as therapeutic agents which are delivered specifically to target cells and are cytotoxic.

Abstract: The present invention discloses a one-step process for the production of cytotoxic conjugates of maytansinoids and cell binding agents. Maytansinoids having a disulfide linker that bears a reactive moiety are linked to cell binding agents, such as antibodies, without prior modification of the cell binding agent. These conjugates are useful as therapeutic agents which are delivered specifically to target cells and are cytotoxic.