Additional Study Information: The primary purposes of this research study are to learn the safety and tolerability of the investigational drug, XmAb23104, for up to eight dose levels; to see if XmAb23104 works in treating tumors like the one that you have, and to see if side effects from XmAb23104 occur in order to find the maximum tolerated dose or recommended dose for treating your type of tumor. XmAb23104 is an investigational drug that is designed to activate your own cells to kill your tumor. XmAb23104 is an investigational drug in this study because it has not been approved by the U.S. Food and Drug Administration (FDA), the health authority that gives approval for new medicines to be prescribed in the United States.