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Optimizing Tx of HRpos HER2neg MBC

CME

Optimizing Treatment for Patients With HR-Positive/HER2-Negative MBC

Physicians: Maximum of 0.50 AMA PRA Category 1 Credit™

Released: March 24, 2025

Expiration: September 23, 2025

Sara A. Hurvitz
Sara A. Hurvitz, MD, FACP
CME/CE Information

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Case Description: 56-Yr-Old Woman With De-Novo MBC

Here is a patient case to help put the above results into clinical context.

A 56-year-old woman presents with newly diagnosed HR-positive/HER2-negative de novo MBC involving the lungs and liver. She is symptomatic with upper quadrant pain and is short of breath when walking up 2 flights of stairs. She is also notably obese and has a history of nonalcoholic steatohepatitis (fatty liver) with chronic mild elevation in her liver transaminases. She has type 2 diabetes, for which she is taking metformin. She has a history of a left lower extremity deep vein thrombosis, which was diagnosed 2 years ago. Tumor genomic testing reveals a p53 mutation and an AKT1 mutation with no germline gene mutations. Her ECOG PS is 1. 

Evidence-based Optimal First-line Treatment With the Best Efficacy and Safety Outcomes for This 56-Year-Old Woman

I would recommend palbociclib plus anastrozole as the optimal treatment for this patient. This combination was associated with a significant improvement in PFS compared with an NSAI alone in PALOMA-2.9,23  A ribociclib-based treatment would not be optimal for this patient because she has a history of steatohepatitis with elevation in her liver transaminases, which may be worsened with the use of ribociclib.25

Abemaciclib plus tamoxifen would be suboptimal for this patient since she has a prior history of VTE, and in the MONARCH 3 trial, abemaciclib was associated with a risk of grade 3 or higher VTE in approximately 4% of patients.8,26 Treatment using paclitaxel (6 cycles) induction followed by anastrozole maintenance would not be an optimal choice for her either. This is because the PADMA trial, which evaluated induction chemotherapy followed by maintenance ET vs palbociclib plus ET in patients with previously untreated HR-positive, HER2-negative MBC, showed a statistically significant improvement in TTF and PFS with the use of a nonchemotherapy-based approach.28 Lastly, inavolisib in combination with palbociclib and fulvestrant is inappropriate for this patient because her disease does not harbor a PIK3CA mutation and her disease has not demonstrated endocrine resistance as her disease has never been previously treated with an AI or ET.15,29

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