A modified T lymphocyte for use in a method of treating a tumor or cancer in an individual comprising: a first polypeptide comprising a first extracellular antigen binding domain that binds a first antigen, and a first intracellular signaling domain, wherein said first polypeptide does not comprise a co-stimulatory domain, wherein said first intracellular signaling domain comprises a polypeptide sequence comprising an immunoreceptor tyrosine-based activation motif (ITAM), wherein said polypeptide sequence is preferably a CD3ζ signaling domain, and wherein said first antigen is: (i) an antigen on a cell of said tumor or cancer, wherein said cell of said tumor or cancer is preferably a cell in a solid tumor or cancer; or (ii) a tumor-associated antigen or a tumor-specific antigen; and a second polypeptide comprising a second extracellular antigen binding domain binding a second antigen, or a receptor that binds said second antigen; and a second intracellular signaling domain, wherein said second polypeptide comprises one or more co-stimulatory domains, wherein said second antigen is a vascular endothelial growth factor (VEGF), and wherein said one or more co-stimulatory domains comprise one or more of: a co-stimulatory CD27 polypeptide sequence, a co-stimulatory CD28 polypeptide sequence, a co-stimulatory OX40 polypeptide sequence, a co-stimulatory 4-1BB polypeptide sequence, and a co-stimulatory inducible T-cell costimulatory (ICOS) polypeptide sequence; and wherein said modified lymphocyte becomes maximally cytotoxic only when said first intracellular signaling domain and said second intracellular signaling domain are both activated by said first antigen and said second antigen, respectively. a first polypeptide comprising a first extracellular antigen binding domain that binds a first antigen, and a first intracellular signaling domain, wherein said first polypeptide does not comprise a co-stimulatory domain, wherein said first intracellular signaling domain comprises a polypeptide sequence comprising an immunoreceptor tyrosine-based activation motif (ITAM), wherein said polypeptide sequence is preferably a CD3ζ signaling domain, and wherein said first antigen is: (i) an antigen on a cell of said tumor or cancer, wherein said cell of said tumor or cancer is preferably a cell in a solid tumor or cancer; or (ii) a tumor-associated antigen or a tumor-specific antigen; and wherein said first intracellular signaling domain comprises a polypeptide sequence comprising an immunoreceptor tyrosine-based activation motif (ITAM), wherein said polypeptide sequence is preferably a CD3ζ signaling domain, and wherein said first antigen is: (i) an antigen on a cell of said tumor or cancer, wherein said cell of said tumor or cancer is preferably a cell in a solid tumor or cancer; or (ii) a tumor-associated antigen or a tumor-specific antigen; and (i) an antigen on a cell of said tumor or cancer, wherein said cell of said tumor or cancer is preferably a cell in a solid tumor or cancer; or (ii) a tumor-associated antigen or a tumor-specific antigen; and a second polypeptide comprising a second extracellular antigen binding domain binding a second antigen, or a receptor that binds said second antigen; and a second intracellular signaling domain, wherein said second polypeptide comprises one or more co-stimulatory domains, wherein said second antigen is a vascular endothelial growth factor (VEGF), and wherein said one or more co-stimulatory domains comprise one or more of: a co-stimulatory CD27 polypeptide sequence, a co-stimulatory CD28 polypeptide sequence, a co-stimulatory OX40 polypeptide sequence, a co-stimulatory 4-1BB polypeptide sequence, and a co-stimulatory inducible T-cell costimulatory (ICOS) polypeptide sequence; and wherein said second antigen is a vascular endothelial growth factor (VEGF), and wherein said one or more co-stimulatory domains comprise one or more of: a co-stimulatory CD27 polypeptide sequence, a co-stimulatory CD28 polypeptide sequence, a co-stimulatory OX40 polypeptide sequence, a co-stimulatory 4-1BB polypeptide sequence, and a co-stimulatory inducible T-cell costimulatory (ICOS) polypeptide sequence; and wherein said modified lymphocyte becomes maximally cytotoxic only when said first intracellular signaling domain and said second intracellular signaling domain are both activated by said first antigen and said second antigen, respectively.