24 April 2020

A new drug was recently approved by the US Food and Drug Administration (FDA) for the treatment of metastatic breast cancer – breast cancer that has spread to other areas of the body, such as the bones, liver, lungs or brain. Sacituzumab govitecan (Trodelvy), which is given by intravenous infusion, was granted accelerated approval to treat metastatic triple negative breast cancer in patients who have already been on 2 prior treatments for their disease. 

Triple negative breast cancer accounts for approximately 15% of breast cancers. It is more common in younger patients, African Americans, and those with a BRCA1 gene mutation. It can be very challenging to treat since there is no specific cellular target, such as the estrogen receptor or Her2/neu protein. Patients with triple-negative breast cancer very commonly receive chemotherapy but the disease may come back or progress despite aggressive treatment.

Sacituzumab govitecan is an antibody-drug conjugate, which is an antibody that is combined with a chemotherapy drug. The antibody targets a protein (trophoblast cell surface antigen-2, or trop-2) on the surface of the cancer cell, and the chemotherapy drug causes breaks in the tumor cell DNA, which leads to cancer cell death. The FDA approval was based on a non-randomized (meaning all patients received the study drug) study of 108 patients who were experiencing disease progression despite receiving between 2 – 10 prior treatment regimens. Among the study participants, approximately 33% experienced a partial or complete tumor response to the medication. Median duration of treatment response was nearly 8 months. Severe adverse reactions included diarrhea, neutropenia (low white blood cell counts), anemia (low red blood cell counts), fatigue, nausea and vomiting. 2 patients stopped treatment due to side effects.

Any advance in the treatment of metastatic breast cancer is welcome news. It is hoped that as new drugs are developed, a longer-lasting response to therapy will be achieved. 

Additional Information:

14 July 2019

A study recently published in the journal Cancer* reports on disparities in triple negative breast cancer (TNBC). The researchers used the US cancer statistics database, and compared differences between TNBC and other breast cancer subtypes focusing on age, race / ethnicity, and stage at diagnosis. 

Between 2010 and 2014, approximately 1.15 million breast cancer cases were identified in the database. The mean age at diagnosis was 61.8, and 75% of patients were non-Hispanic white (NHW). 27.7% were diagnosed at stage III and 5% were diagnosed at stage IV. 

TNBC accounted for 8.4% of all breast cancer cases, but accounted for 21.4% of cases in non-Hispanic Black (NHB) women. Women diagnosed with TNBC had a lower mean age at diagnosis versus non-TNBC (59.3 versus 62.1). NHB women accounted for 11.8% of the study population, but 15.3% of TNBC cases. Women diagnosed with TNBC were also more likely to be younger than age 40 and diagnosed at Stage III or IV compared to those with other cancer subtypes. After controlling for late-stage diagnosis and age, NHB women had approximately twice the likelihood of diagnosis with TNBC compared with NHW women.

The researchers noted that their study validated previous literature, and had the advantage of being geographically very broad. Not discussed in this paper is the relationship of TNBC with genetic mutations, specifically mutations in the BRCA1 gene. Among patients with breast cancer, those who carry deleterious BRCA1 mutations are more likely to have TNBC versus BRCA2 carriers or non-carriers, and a diagnosis of TNBC should prompt genetic testing.

This study and others like it point to the need for more research on TNBC, and on breast cancer in black women. Dr. Lisa Newman, a breast surgical oncologist at Cornell, has published extensively on this topic. In this brief video, she notes that socioeconomic factors account for some of the disparities associated with breast cancer outcomes in black women. However, she also notes that there appears to be biologic differences between TNBC in black versus white women, which may also at least in part account for later stage at diagnosis and poorer prognosis.

*If you are not able to access the full study and would like a copy, please email me: contact at drattai dot com