Metastatic breast cancer most commonly presents as a distant recurrence of previously treated local disease. However, 6% to 18% of patients have no prior history of breast cancer and present with de novo metastatic disease.33,34 The most commonly involved distant organs are the skeletal bones, liver, lung, distant lymph node stations, and brain. Compared to other subtypes, HER2-positive tumors have an increased tendency to involve the central nervous system.35–38 Although metastatic HER2-positive breast cancer is not considered curable, significant improvement in survival has been achieved, and patients with metastatic disease have median survival approaching 5 years.39
Case Presentation 3
A 69-year-old woman with a history of breast cancer 4 years ago presents with new-onset back pain and unintentional weight loss. On exam, she is found to have palpable axillary adenopathy on the same side as her previous cancer. Her initial disease was stage IIB ER-positive and HER2-positive and was treated with chemotherapy, mastectomy, and anastrozole, which the patient is still taking. She undergoes CT scan of the chest, abdomen, and pelvis and radionucleotide bone scan, which show multiple liver and bony lesions suspicious for metastatic disease. Axillary lymph node biopsy confirms recurrent invasive carcinoma that is ER-positive and HER2-positive by IHC (3+).
What is the approach to management of a patient who presents with symptoms of recurrent HER2-positive disease?
This patient likely has metastatic breast cancer based on the imaging findings. In such cases, a biopsy of the recurrent disease should always be considered, if feasible, to confirm the diagnosis and rule out other etiologies such as different malignances and benign conditions. Hormone-receptor and HER2 testing should also be performed on recurrent disease, since a change in HER2 status can be seen in 15% to 33% of cases.40–42
Based on data from the phase 3 CLEOPATRA trial, first-line systemic regimens for patients with metastatic breast cancer that is positive for HER2 should consist of a combination of docetaxel, trastuzumab, and pertuzumab. Compared to placebo, adding pertuzumab yielded superior progression-free survival of 18.4 months (versus 12.4 months for placebo) and an unprecedented OS of 56.5 months (versus 40.8 for placebo).39 Weekly paclitaxel can replace docetaxel with comparable efficacy (Table 3).43
Patients can develop significant neuropathy as well as skin and nail changes after multiple cycles of taxane-based chemotherapy. Therefore, the taxane backbone may be dropped after 6 to 8 cycles, while patients continue the trastuzumab and pertuzumab combination until disease progression or unacceptable toxicity. Some patients may enjoy remarkable long-term survival on “maintenance” anti-HER2 therapy.44 Despite lack of high-level evidence, such as from large randomized trials, some experts recommend the addition of a hormone blocker after discontinuation of the taxane in ER-positive tumors.45
Premenopausal and perimenopausal women with hormone receptor–positive metastatic disease should be considered for simultaneous ovarian suppression. Ovarian suppression can be accomplished medically using a gonadotropin-releasing hormone agonist (goserelin) or surgically via salpingo-oophorectomy.46–48
Case 3 Conclusion
The patient receives 6 cycles of docetaxel, trastuzumab, and pertuzumab, after which the docetaxel is discontinued due to neuropathy while she continues the other 2 agents. After 26 months of disease control, the patient is found to have new liver metastatic lesions, indicating progression of disease.
What therapeutic options are available for this patient?
Patients whose disease progresses after receiving taxane- and trastuzumab-containing regimens are candidates to receive the novel antibody-drug conjugate ado-trastuzumab emtansine (T-DM1). Early progressors (ie, patients with early stage disease who have progression of disease while receiving adjuvant trastuzumab or within 6 months of completion of adjuvant trastuzumab) are also candidates for T-DM1. Treatment usually fits in the second line or beyond based on data from the EMILIA trial, which randomly assigned patients to receive either capecitabine plus lapatinib or T-DM1.49,50 Progression-free survival in the T-DM1 group was 9.6 months versus 6.4 months for the comparator. Improvement of 4 months in OS persisted with longer follow-up despite a crossover rate of 27%. Furthermore, a significantly higher objective response rate and fewer adverse effects were reported in the T-DM1 patients. Most patients included in the EMILIA trial were pertuzumab-naive. However, the benefit of T-DM1 appears to persist, albeit to a lesser extent, for pertuzumab-pretreated patients.51,52
Patients in whom treatment fails with 2 or more lines of therapy containing taxane-trastuzumab (with or without pertuzumab) and T-DM1 are candidates to receive a combination of capecitabine and lapatinib, a TKI, in the third line and beyond. Similarly, the combination of capecitabine with trastuzumab in the same settings appears to have equal efficacy.53,54 Trastuzumab may be continued beyond progression while changing the single-agent chemotherapy drug for subsequent lines of therapy, per ASCO guidelines,55 although improvement in OS has not been demonstrated beyond the third line in a large randomized trial (Table 3).
