Patients receive onalespib intravenously (IV) over 1 hour on days 1 and 4 (course 0 only). Patients then receive onalespib IV over 1 hour and CDKI AT7519 IV over 1 hour on days 1, 4, 8, and 11 (course 1 and subsequent courses thereafter). Courses repeat every 21 days (7 days for course 0 only) in the absence of disease progression or unacceptable toxicity.