Predictors of Chemosensitivity in Triple Negative Breast Cancer Interview with:

Christos Hatzis, PhD Assistant Professor of Medicine Director of Bioinformatics, Breast Medical Oncology Yale Comprehensive Cancer Center Yale School of Medicine New Haven, CT

Dr. Christos Hatzis,

Christos Hatzis, PhD
Assistant Professor of Medicine
Director of Bioinformatics, Breast Medical Oncology
Yale Comprehensive Cancer Center
Yale School of Medicine
New Haven, CT What is the background for this study? What are the main findings?

Response: Triple negative breast cancer (TNBC) is a highly heterogeneous and aggressive disease, and although no effective targeted therapies are available to date, about one-third of patients with TNBC achieve pathologic complete response (pCR) from standard-of-care anthracycline/taxane (ACT) chemotherapy. The heterogeneity of these tumors, however, has hindered the discovery of effective biomarkers to identify such patients.

Identifying chemosensitive triple negative breast cancers could significantly impact
the survival of patients with these difficult to treat cancers until novel targeted
therapies become available. We hypothesized that genomic somatic aberrations may
provide important molecular clues about chemosensitivity in TNBC. Our study used
a carefully selected cohort of 29 uniformly treated TNBC patients who either achieved
pathologic complete response (pCR) or had extensive residual disease after neoadjuvant
anthracycline/taxane chemotherapy. What are the main findings?

Response: We sequenced the coding genomic DNA of TNBC tumors and compared the somatic mutations found in the two groups at the two extremes of the chemosensitivity spectrum.

Our analysis revealed that, although mutations in single genes were not individually predictive, TNBC tumors bearing mutations in genes involved in the androgen receptor
(AR) and FOXA1 pathways were much more sensitive to chemotherapy.
We also found that mutations that lowered the levels of functional BRCA1 or BRCA2 RNA
were associated with significantly better survival outcomes; we derived a BRCA
deficiency signature to define this new, highly chemosensitive subtype of TNBC.
BRCA-deficient TNBC tumors have a higher rate of clonal mutation burden, defined as
more clonal tumors with a higher number of mutations per clone, and are also associated
with a higher level of immune activation, which may explain their greater chemosensitivity. What should readers take away from your report?

Response: Mutations in the AR/FOXA1 pathway provide a novel marker for identifying chemosensitive TNBC patients who may benefit from current standard-of-care chemotherapy regimens.

The newly defined RNA-based BRCA-deficient subtype includes up to 50% of the
Triple negative breast cancer tumors that appear to be immune primed, and it would be of interest to investigate combinations of chemotherapy with immunotherapies, which could provide clinical benefit for these patients. Although our study showed concordant results in three different datasets, our key findings need to be further validated in a larger, prospectively designed study with archival samples. What recommendations do you have for future research as a result of this study?

Response: The comprehensive molecular analysis presented in this study directly links BRCA deficiency with increased clonal mutation burden and significantly enhanced chemosensitivity in Triple negative breast cancer and suggests that functional RNA-based BRCA deficiency needs to be further examined in TNBC. Our results suggest that the combination of immunotherapies with ACT chemotherapy or PARP inhibitors might be an effective strategy for treating BRCA-D tumors.

The strong connection of ACT chemosensitivity and immune activity with a new transcriptionally defined BRCA-D phenotype could help inform future therapeutic strategies for TNBC patients. Thank you for your contribution to the community.


Predictors of Chemosensitivity in Triple Negative Breast Cancer: An Integrated Genomic AnalysisTingting Jiang,Weiwei Shi,Vikram B. Wali,Lőrinc S. Pongor,Charles Li,Rosanna Lau,Balázs Győrffy,Richard P. Lifton,William F. Symmans,Lajos Pusztai,Christos Hatzis

PLOS Medicine Published: December 13, 2016

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.

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Last Updated on December 15, 2016 by Marie Benz MD FAAD