A pharmaceutical preparation comprising an anti-glypican-1 (anti-GPC1) antibody and/or an antigen-binding fragment thereof, for use in treating prostate, bladder, and/or pancreatic cancer in a subject, wherein: the antibody and/or fragment is conjugated to at least one cytotoxic agent that is toxic to a prostate, bladder, and/or pancreatic cancer cell in the subject; and the antibody and/or fragment comprises: (a) a heavy chain variable region comprising: a complementarity determining region 1 comprising or consisting of an amino acid sequence defined by positions 50-54 of SEQ ID NO: 3; a complementarity determining region 2 comprising or consisting of an amino acid sequence defined by positions 69-85 of SEQ ID NO: 3; a complementarity determining region 3 comprising or consisting of an amino acid sequence defined by positions 118-126 of SEQ ID NO: 3; and (b) a light chain variable region comprising: a complementarity determining region 1 comprising or consisting of an amino acid sequence defined by positions 44-54 of SEQ ID NO: 4; a complementarity determining region 2 comprising or consisting of an amino acid sequence defined by positions 70-76 of SEQ ID NO: 4; a complementarity determining region 3 comprising or consisting of an amino acid sequence defined by positions 109-117 of SEQ ID NO: 4; and the pharmaceutical preparation does not comprise an antibody with a light chain variable region comprising: a complementarity determining region 1 comprising or consisting of an amino acid sequence defined by positions 48-58 of SEQ ID NO: 11; a complementarity determining region 2 comprising or consisting of an amino acid sequence defined by positions 74-80 of SEQ ID NO: 11; a complementarity determining region 3 comprising or consisting of an amino acid sequence defined by positions 113-121 of SEQ ID NO: 11. the antibody and/or fragment is conjugated to at least one cytotoxic agent that is toxic to a prostate, bladder, and/or pancreatic cancer cell in the subject; and the antibody and/or fragment comprises: (a) a heavy chain variable region comprising: a complementarity determining region 1 comprising or consisting of an amino acid sequence defined by positions 50-54 of SEQ ID NO: 3; a complementarity determining region 2 comprising or consisting of an amino acid sequence defined by positions 69-85 of SEQ ID NO: 3; a complementarity determining region 3 comprising or consisting of an amino acid sequence defined by positions 118-126 of SEQ ID NO: 3; and (b) a light chain variable region comprising: a complementarity determining region 1 comprising or consisting of an amino acid sequence defined by positions 44-54 of SEQ ID NO: 4; a complementarity determining region 2 comprising or consisting of an amino acid sequence defined by positions 70-76 of SEQ ID NO: 4; a complementarity determining region 3 comprising or consisting of an amino acid sequence defined by positions 109-117 of SEQ ID NO: 4; and (a) a heavy chain variable region comprising: a complementarity determining region 1 comprising or consisting of an amino acid sequence defined by positions 50-54 of SEQ ID NO: 3; a complementarity determining region 2 comprising or consisting of an amino acid sequence defined by positions 69-85 of SEQ ID NO: 3; a complementarity determining region 3 comprising or consisting of an amino acid sequence defined by positions 118-126 of SEQ ID NO: 3; and a complementarity determining region 1 comprising or consisting of an amino acid sequence defined by positions 50-54 of SEQ ID NO: 3; a complementarity determining region 2 comprising or consisting of an amino acid sequence defined by positions 69-85 of SEQ ID NO: 3; a complementarity determining region 3 comprising or consisting of an amino acid sequence defined by positions 118-126 of SEQ ID NO: 3; and (b) a light chain variable region comprising: a complementarity determining region 1 comprising or consisting of an amino acid sequence defined by positions 44-54 of SEQ ID NO: 4; a complementarity determining region 2 comprising or consisting of an amino acid sequence defined by positions 70-76 of SEQ ID NO: 4; a complementarity determining region 3 comprising or consisting of an amino acid sequence defined by positions 109-117 of SEQ ID NO: 4; and a complementarity determining region 1 comprising or consisting of an amino acid sequence defined by positions 44-54 of SEQ ID NO: 4; a complementarity determining region 2 comprising or consisting of an amino acid sequence defined by positions 70-76 of SEQ ID NO: 4; a complementarity determining region 3 comprising or consisting of an amino acid sequence defined by positions 109-117 of SEQ ID NO: 4; and the pharmaceutical preparation does not comprise an antibody with a light chain variable region comprising: a complementarity determining region 1 comprising or consisting of an amino acid sequence defined by positions 48-58 of SEQ ID NO: 11; a complementarity determining region 2 comprising or consisting of an amino acid sequence defined by positions 74-80 of SEQ ID NO: 11; a complementarity determining region 3 comprising or consisting of an amino acid sequence defined by positions 113-121 of SEQ ID NO: 11. a complementarity determining region 1 comprising or consisting of an amino acid sequence defined by positions 48-58 of SEQ ID NO: 11; a complementarity determining region 2 comprising or consisting of an amino acid sequence defined by positions 74-80 of SEQ ID NO: 11; a complementarity determining region 3 comprising or consisting of an amino acid sequence defined by positions 113-121 of SEQ ID NO: 11.