This phase Ib trial studies the side effects and best dose of Hsp90 inhibitor XL888 when given together with pembrolizumab in treating patients with advanced gastrointestinal cancer that has spread to other places in the body. Hsp90 inhibitor XL888 may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Monoclonal antibodies, such as pembrolizumab, may block tumor growth in different ways by targeting certain cells. Giving Hsp90 inhibitor XL888 with pembrolizumab may work better in treating patients with gastrointestinal cancer.
I. Determine the recommended phase II dose for the combination of Hsp90 inhibitor XL888 (XL888) and pembrolizumab.
I. Define the toxicity profile of the combination of XL888 and pembrolizumab.
II. Evaluate the activity of the combination of XL888 and pembrolizumab in previously treated patients with gastrointestinal tumors.
I. Evaluate the effect of the combination on the immune profile in the serum and in tumor biopsies.
OUTLINE: This is a dose-escalation study of Hsp90 inhibitor XL888.
Patients receive pembrolizumab intravenously (IV) over 30 minutes on day 1 and Hsp90 inhibitor XL888 orally (PO) on day 1, 4, 8, 11, 15, and 18. Courses repeat every 21 days in the absence of disease progression or unacceptable toxicity.
After completion of study treatment, patients are followed up at 30 days and periodically thereafter.