Biomarkers Fail to Predict Platinum Chemo Response in TNBC

Share this content:
Biomarkers Fail to Predict Platinum Chemo Response in TNBC
Biomarkers Fail to Predict Platinum Chemo Response in TNBC

CHICAGO, IL—Established biomarkers failed to predict response to platinum in patients with metastatic triple-negative breast cancer (mTNBC), a study concluded at the 2014 American Society of Clinical Oncology (ASCO) Annual Meeting.

However, “homologous recombination deficiency [HRD] assays may identify sporadic TNBC tumors that are BRCA1/2-like and responsive to platinum chemotherapy,” said Steven J. Isakoff, MD, PhD, of Massachusetts General Hospital Cancer Center in Boston, MA.

Previously, a multicenter, single-arm, phase 2 study of single-agent platinum in 86 patients with mTNBC found that BRCA1/2 carriers (n=11) had an objective response rate (ORR) of 54.5% (95% CI: 23.4%-83.3%) versus 19.7% (95% CI: 10.9%-31.3%) in noncarriers (n=66; P= 0.022). In nine patients, BRCA1/2 status was unknown. Overall, ORR was 25.6% (95% CI: 16.8%-36.1%), and six long-term responders remain disease free at median follow-up of approximately 4 years, Dr. Isakoff reported.

However, although the BRCA1/2 germline mutation carriers had a significantly higher response rate, this was not found to predict either longer progression-free survival or overall survival.

RELATED: Breast Cancer Resource Center

In this analysis, the investigators explored biomarkers of response to platinum in that study, in which patients received cisplatin 75mg/m2 or carboplatin AUC 6 every 3 or 4 weeks, by physician choice. Co-primary endpoints were ORR in first- or second-line treatment of mTNBC and p63/p73 expression by reverse transcriptase polymerase chain reaction (RT-PCR) as a biomarker of response.

Among the 61 patients evaluable for p63/p73 expression by RT-PCR as a predictor of response, 28 (46%) had the prespecified p63/p73 ratio greater than or equal to 2, which did not predict response to platinum (ORR, 18% vs. 27% in p63/p73 ≥ 2 vs. < 2, respectively; P = 0.54). This study endpoint was not met.

When the p63/p73 ratio was evaluated in seven patients who had no prior treatment for TNBC, five had a complete or partial response and two had disease progression (P = 0.0308). These responses correlated with a higher p63/p73 ratio and supports results seen in neoadjuvant platinum therapy, he said.

Page 1 of 2

Related Resources

You must be a registered member of Cancer Therapy Advisor to post a comment.

Sign Up for Free e-newsletters

Regimen and Drug Listings


Bone Cancer Regimens Drugs
Brain Cancer Regimens Drugs
Breast Cancer Regimens Drugs
Endocrine Cancer Regimens Drugs
Gastrointestinal Cancer Regimens Drugs
Gynecologic Cancer Regimens Drugs
Head and Neck Cancer Regimens Drugs
Hematologic Cancer Regimens Drugs
Lung Cancer Regimens Drugs
Other Cancers Regimens
Prostate Cancer Regimens Drugs
Rare Cancers Regimens
Renal Cell Carcinoma Regimens Drugs
Skin Cancer Regimens Drugs
Urologic Cancers Regimens Drugs