Keytruda Promising in Advanced Breast Cancer with High Tumor Mutational Burden


by Dr. C.H. Weaver M.D. 6/2019

The American Society of Clinical Oncology’s (ASCO) Targeted Agent and Profiling Utilization Registry (TAPUR) clinical study has added the enrollment of additional patient groups and continues to grow with more than 500 participants and 16 therapies now available. The purpose of TAPUR is to help cancer patients who have exhausted standard options access targeted study drugs matched to the genomic profiles of their cancers and provide physicians assistance in interpreting genomic results and identifying potential treatment options. (1)

The TAPUR Study is designed to identify signals of activity of commercially available, targeted anticancer drugs in advanced cancer patients whose tumor harbors one or more genomic variants known to be a drug target. The TAPUR Study Data Safety and Monitoring Board (DSMB) has expanded enrollment of additional participants for the advanced breast cancer patients with a high tumor mutation burden treated with Keytruda (pembrolizumab).

Keytruda (pembrolizumab) is an immune checkpoint inhibitor and high tumor mutational burden (HTMB) is an emerging predictive biomarker for checkpoint inhibitor therapy. In a group of breast cancer patients with HTMB as defined by a Foundation One test or approved by the TAPUR Molecular Tumor Board Twenty-eight women with advanced metastatic breast cancer were treated with Keytruda every 3 weeks and found to have anti-tumor activity in heavily pre-treated patients with HTMB*.*

About Keytruda Checkpoint Inhibitors

Keytruda belongs to a class of medicines called “checkpoint inhibitors.” Checkpoint inhibitors are a novel precision cancer immunotherapy that helps to restore the body’s immune system in fighting cancer by releasing checkpoints that cancer uses to shut down the immune system. PD-1 and PD-L1 are proteins that inhibit certain types of immune responses, allowing cancer cells to evade detection and attack by certain immune cells in the body. A checkpoint inhibitor can block the PD-1 and PD-L1 pathway and enhance the ability of the immune system to fight cancer. By blocking the binding of the PD-L1 ligand these drugs restore an immune cells’ ability to recognize and fight the colon cancer cells.

TAPUR Study participants are enrolled into treatment groups based on tumor type (advanced solid tumors, multiple myeloma, or B cell non-Hodgkin lymphoma), genomic variant and study drug. Stage I enrolls up to 10 patients in a group and monitors their response to treatment for 16 weeks. If two or more patients have a successful response to treatment the group is expanded, and an additional 18 patients are enrolled.

Currently, 510 participants are enrolled in the TAPUR Study, which is available at 83 clinical sites in 20 states. Patients can also find study information such as general eligibility criteria, participating clinical sites, and contact information for the site study teams at

Watch a video overview of the TAPUR Study.


  1. Positive Findings from Two TAPUR™ Study Cohorts to Be Presented at 2019 ASCO® Annual Meeting