The present invention concerns compositions and methods of use of bispecific antibodies comprising at least one binding site for Trop-2 (EGP-1) and at least one binding site for CD3. The bispecific antibodies are of use for inducing an immune response against a Trop-2 expressing tumor, such as carcinoma of the esophagus, pancreas, lung, stomach, colon, rectum, urinary bladder, breast, ovary, uterus, kidney or prostate. The methods may comprising administering the bispecific antibody alone, or with one or more therapeutic agents such as antibody-drug conjugates, interferons (preferably interferon-α), and/or checkpoint inhibitor antibodies. The bispecific antibody is capable of targeting effector T cells, NK cells, monocytes or neutrophils to induce leukocyte-mediated cytotoxicity of Trop-2+ cancer cells. The cytotoxic immune response is enhanced by co-administration of interferon, checkpoint inhibitor antibody and/or ADC.