Tucatinib/Capecitabine/Trastuzumab Studied in HER2+ Breast Cancer With LMD

Debu Tripathy, MD, professor and chairman of the Department of Breast Medical Oncology, Division of Cancer Medicine, at The University of Texas MD Anderson Cancer Center, discusses the TBCRC049 study (NCT03501979) investigating the use of tucatinib (Tukysa), capecitabine (Xeloda), and trastuzumab (Herceptin) in the cerebral spinal fluid (CSF) of patients with HER2-positive breast cancer and leptomeningeal disease (LMD).

This trial looked at the concentration of this combination in the patients’ blood and CSF. These data were reported at the 2021 American Society of Clinical Oncology (ASCO) annual meeting. The primary end points of response rate and time to progression will be reported in the future since the study is still ongoing. Tripathy says the poster presented at ASCO covered the CSF concentrations for patients on this trial, specifically.

The data showed that patients achieved concentrations that were in the range of 0.5 nm/mL, which is an active range in in vitro studies, according to Tripathy. This concentration was maintained over time. Numbers such as these have not been seen over time with many agents. The concentrations ranged from 0.2 to 4.7 nm/mL. The CSF to plasma ratio ranged from 0.18 to 4.0 in cycles 1 and 2, with a median of 0.87. He says these ranges did not appear to fluctuate much over time.