ASCO 2020: Metastatic Breast Cancer Updates

This year’s virtual meeting included clinical trial presentations focused on these cancers

Breast cancer metastasis is a complex process—and the leading cause of breast cancer deaths. At this year’s American Society of Clinical Oncology (ASCO) virtual annual meeting, researchers presented several studies that addressed the challenges of treating metastatic breast cancer. Below are key highlights:

Triple-negative breast cancer

The KEYNOTE-355 trial compared pembrolizumab (an anti PD-L1 checkpoint inhibitor) plus chemotherapy versus chemotherapy plus placebo as first-line therapy for patients with advanced (locally recurrent, inoperable, or metastatic) triple-negative breast cancer. The study investigators reported that women receiving pembrolizumab had improved survival rates compared to those with chemotherapy alone, particularly if their tumors had high amounts of the PD-L1 protein. In patients with high PD-L1, the median progression-free survival (PFS) was 9.7 months with pembrolizumab compared to 5.6 months with chemotherapy alone. 39 percent of women in the pembrolizumab group were progression free at 12 months compared to 23 percent of women in the chemotherapy alone group. Regardless of PD-L1 status, the median PFS was 7.5 months with pembrolizumab compared to 5.6 months without the anti-PD L1 therapy. Read more about the study here.

HER2-positive breast cancer with brain metastasis

BCRF investigator Dr. Nancy Lin presented results from the HER2CLIMB trial, a randomized phase II study in patients with advanced HER2-positive breast cancer (including patients with brain metastases). The study compared standard therapy (trastuzumab/Herceptin®) plus chemotherapy (capecitabine) to standard therapy plus tucatinib (Tukysa®), a small molecule HER2 inhibitor, in patients who had progressed on one or more HER2-targeted treatments.

The results of HER2CLIMB for the overall study population demonstrated significant improvement in PFS and overall survival in patients who received tucatinib compared with placebo, which led to its fast-tracked FDA approval. Reporting on an exploratory analysis of 291 patients with brain metastasis, Dr. Lin noted that the addition of tucatinib to standard therapy doubled the intracranial response rate, reduced the risk of central nervous system progression or death by two-thirds, and reduced the risk of death by nearly half. Tucatinib is the first tyrosine kinase inhibitor to demonstrate prolongation of overall survival in patients with brain metastasis. Read more about the study here.

Read the rest of BCRF’s 2020 ASCO annual meeting coverage here.