Joyce O'Shaughnessy, MD: Efficacy Data Supporting the Use of Eribulin Mesylate

With regard to metastatic triple negative breast cancer, there have been a couple of studies that have looked into very large patient populations at the impact of eribulin on the disease. One of these studies was the EMBRACE trial, and this was for later-line therapy where patients had had two prior regiments, but not more than five prior regimens for their breast cancer. The patients in the EMBRACE trial were randomized to either eribulin or single-agent chemotherapy of the phyisician's choice. There was a survival advantage in the entire treated population in favor of eribulin. That led to FDA approval, and that became our standard third-line therapy because of that survival advantage.

Then there was another trial called Study 301, which moved eribulin up to the second-line setting in both estrogen-receptor positive and triple negative breast cancer. These patients were randomized between eribulin versus capecitabine. The study showed basically the same results with regard to progression-free survival and overall survival, even with the eribulin and capecitabine being very similar in efficacy.

Triple Negative Breast Cancer: Case 1

Christine H is a 54-year-old stay-at-home-mother who works part time as a real estate agent. Medical history is notable for hypertension (well controlled) and surgery for aortic aneurysm in 2011

In September 2013, she presented to her PCP with a right breast lump; mammogram showed a large primary breast mass and two enlarged axillary lymph nodes.

• She underwent an extent of disease evaluation, which consisted of a chest, abdomen, pelvis, and bone scan, which showed no evidence of distant metastases
• Ultrasound-guided core needle biopsy of the right breast mass revealed grade 3 invasive ductal carcinoma that was ER-, PgR-, and HER2- (triple-negative) with cytokeratin 5/6 staining and 50% Ki67 staining
• The patient proceeded to right breast mastectomy and axillary lymph node dissection in October 2013
• She had a 4.8cm invasive breast cancer and the axillary lymph node dissection showed 15 positive nodes
• She underwent adjuvant therapy with doxorubicin plus cyclophosphamide (4 cycles), followed up by paclitaxel (4 cycles) and post-mastectomy radiation

At her follow-up in May 2014, the patient showed progression of the right chest wall metastases, and several new liver lesions were detected.

• She underwent therapy with paclitaxel plus bevacizumab for 5 cycles and her disease stabilized

In December of 2014, she presented with increasing fatigue and chest pain on follow up and her CT scan was consistent with progression of the hepatic metastases, with several new lesions also noted in the lungs; her ECOG performance status (PS) at the time was 1.

• She underwent therapy with pegylated liposomal doxorubicin and had a partial response after 4 cycles of therapy. After 6 cycles of therapy, she experienced progression
• Her CBC, liver, and kidney function at the time of progression were within normal limits
• Her oncologist initiated therapy with eribulin mesylate (1.4 mg/m2 IV on days 1 and 8 of a 21-day cycle)
• She experienced a partial response. Dose was reduced to 1.1 mg/m2 after she developed grade 3 peripheral neuropathy
• Her condition improved at the reduced dose and she continues in remission after 4 cycles