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Breast Cancer Case Studies

Joyce O'Shaughnessy, MD: Different Mechanisms of Action in Eribulin

Joyce O'Shaughnessy, MD
Published Online:Feb 23, 2016
Christine is a 54-year-old stay-at-home-mother who works part time as a real estate agent. Her medical history is notable for hypertension (well controlled) and surgery for aortic aneurism in 2011.

Triple Negative Breast Cancer with Andrew Seidman, MD and Joyce O'Shaughnessy, MD: Case 1



Eribulin is a very non-cross-resistant agent, and that is because its mechanism of action is different than our other options, such as taxanes. It targets the microtubules, in that it stops the assembly of the leading edge of the microtubule. Taxanes attach all along the microtubules and stop their depolymerization, but eribulin stops the advancement and production of the microtubules.

Even if the cells have become resistant to the taxanes, they have not become resistant to eribulin. What I like about that is that eribulin targets the mitotic spindles, or the cell division rate, but also targets the invasiveness and the metastagenicity of the cancer. Cancer cells need advancing microtubules to accomplish invasion through the cytoplasmic microtubules. Eribulin gets the nuclear microtubules leading to cell division, as well as the cytoplasmic microtubules that lead to invasion and metastases.

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
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