Immunotherapy Trials Encouraging for Metastatic TNBC

The first triple negative breast cancer immunotherapy trial to date has yielded some hopeful results for metastatic TNBC, according to results presented at the 2017 American Society of Clinical Oncology Annual Meeting.

The checkpoint-blocking drug Keytruda shrank pre-treated tumors by more than 30 percent in 5 percent and stabilized disease in 21 percent of women in the group. All patients who saw their tumors shrink lived for at least another year. In comparison, the patients who did not experience tumor regression had lower survival rates. (Remember: This is metastatic TNBC, or stage 4, not earlier, or more treatable, forms, such as stages 1-3.)

The trial included two groups of patients with metastatic TNBC. The first consisted of 170 patients who had received earlier chemotherapy. The second group was previously untreated and had tumors expressing the checkpoint molecule PD-L1.

Both groups tolerated the treatment well, with 12 percent of patients in the first group, and 8 percent in the second group reporting side effects such as fatigue and nausea. Four percent of patients in the first group, but none in the second, stopped the treatment because of these effects.

SABCS: Managing Metastatic TNBC

Lisa Carey, M.D., of the University of North Carolina, provided an update on the management of metastatic triple-negative breast cancer at the 2013 San Antonio Breast Cancer Symposium today.  It was a clear overview of previous research, demonstrating that TNBC is a family of diseases, with varying subtypes that react differently to treatment. 

Some of her points:

• 49 percent of all TNBC cases are basal-like.

• 30 percent are claudin-low, a new subtype that researchers are just beginning to understand.

• Preclinical studies show that platinum drugs may be especially effective against basal-like TNBC.

• Conventional chemotherapy is effective against metastatic TNBC; however, as with all stage IV disease, the duration of response is often short. Several studies have found median survival after diagnosis of stage IV disease of approximately 1-2 years.

• PARP inhibitors are effective against BRCA-associated TNBC.

• Weekly paclitaxel was more effective than ixabepilone and less toxic than albumin-bound nab-paclitaxel in the CALGB 40502 study.

• Eribulin (a halichondrin B analogue) was effective in the EMBRACE study.

• A phase III comparison of eribulin and capecitabine may show a slight advantage for TNBC.

• Both eribulin and capecitabine are “reasonable choices” for TNBC. 

• Alternatives include anthracyclines, platinum drugs, gemcitabine, and doublet regimens.

• Bevacizamab (Avastin) plus chemo improved progression-free survival in metastatic TNBC but had zero effect on overall survival.  Researchers do not know why.

• Randomized clinical trials are ongoing.

• Androgen-fighting drugs may successfully fight androgen-sensitive subsets of TNBC, as demonstrated at last year's SABCS.

"To advance therapy in metastastic TNBC, we will need to better match the tumor to the target," she said.  TNBC may demonstrate that the old strategy of "one size fits all" treatment no longer works for any type of cancer.

Read more about TNBC in my book, Surviving Triple-Negative Breast Cancer.

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