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Treatment Paradigms in HER2 Low and Ultralow MBC

CE / CME

Challenging Treatment Paradigms in HER2-Low and HER2-Ultralow MBC: Experts Examine the Evidence to Guide Individualized Clinical Decisions

Physicians: Maximum of 1.50 AMA PRA Category 1 Credits

ABIM MOC: maximum of 1.50 Medical Knowledge MOC points

Released: June 20, 2025

Expiration: December 19, 2025

Pretest

Progress
1 2 3
Course Completed
Please answer the questions below.
1.

Patient Case: 59-Yr-Old Patient With a Long History of Endocrine-Sensitive HER2-Low mBC 



  • 2010 Initial diagnosis: BCS, radiotherapy, and tamoxifen

  • 2016 Developed bone metastases: received AI + bisphosphonates

    • Histology: ER, 80%; PR, 70%; HER2 IHC, 1+; Ki-67, 20%



  • 2018 First visit at breast center for second opinion – SD

  • 2020 Progression of bone mets: started abemaciclib + fulvestrant

  • 2023 Disease progression in bone: started exemestane and everolimus (wild type for ESR1, PIK3CA, and gBRCA)

  • 2024 Disease progression in the liver: What to do now? 

When implementing the latest information on evaluation of HER2 status in patients with breast cancer, which the following patients with unresectable or metastatic breast cancer and a long history of endocrine-sensitive disease would you consider for treatment with trastuzumab deruxtecan (T-DXd)?

2.

Patient Case: 54-Yr-Old Math Teacher With HR+/HER2-Low Unresectable Breast Cancer 



  • Patient is a 54-yr-old high school math teacher with a history of HR+/HER2-low stage IV breast cancer

  • She was prescribed ET plus CDK4/6 inhibitor as adjuvant therapy

  • At a 6-mo follow-up visit, the patient reported new vision disturbances, dizziness, and disorientation

  • Brain magnetic MRI confirmed multiple CNS lesions (one 2-cm parietal and one 1-cm temporal lobe)

  • CT scan of the chest, abdomen, and pelvis also revealed innumerable liver lesions, and a bone scan shows bone metastases

  • Biopsy of liver metastasis shows ER+ (30%), HER2 1+ by IHC


Which of the following systemic treatment options would be optimal for a patient with CNS lesions, several liver lesions, and a bone scan showing bone metastases?

3.

In addition to explaining potential for ILD/ pneumonitis with T-DXd, which of the following strategies would you implement to overcome clinical challenges regarding nausea/vomiting with this agent?