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Team Science

Breast

Breast Parallel Session 1

5: Change in Biomarker Profile after neoadjuvant chemotherapy is especially common in patients with HER2+ breast cancer subtype

Friday, March 22, 2024
11:02am – 11:12am ET
Location: Georgia Ballroom
Disclosure(s):
Soumy Gottipati, BS: No financial relationships to disclose
Rita A. Mukhtar, MD: No financial relationships to disclose
Judy C. Boughey, MD: Cairns Surgical: Other (Ongoing); Eli Lilly: Research Grant (Ongoing); EndoMag: Speaker (Terminated); OncLive: Speaker (Ongoing); SymBioSis: Advisor (Ongoing); UptoDate: Royalties (Ongoing)
Julia Tchou, MD PhD: BD/Bard: Consultant (Ongoing)
Introduction:

Rates of pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) for breast cancer have improved in the modern era, especially among HER2+ and triple negative subtypes. With the introduction of pertuzumab and pembrolizumab in 2013 and 2020 respectively, the impact of these newer agents on pCR rates and biomarker profile change in those with residual disease is unclear. We aim to determine the pCR rate and biomarker profile changes after NAC in a large patient cohort treated in the modern era.


Methods:

Upon IRB approval, we identified 779 consecutive patients with non-metastatic breast cancer treated with NAC between 2016-2020 at two large academic institutions.  Of these, we evaluated the 283 cases with both pre-NAC biomarker profiles, and residual invasive disease that underwent repeat biomarker profile testing.  Pre-NAC biomarker profiles were grouped according to hormone receptor (HR) and HER2 status: HR+/HER2+, HR+/HER2-, HR-/HER2+, and HR-/HER2-.  Overall pCR rate was determined. Biomarker profile change rate for each group was calculated and compared across groups using Fisher-Irwin tests.


Results:

Of the 779 patient, 314 had complete pathologic response with a pCR rate of 40.3%. In the 465 patients with residual disease, biomarker re-testing was performed in 283 (60.8%) patients. These 283 patients comprised our study cohort. Overall, biomarker profile change was seen in 53 (18.7%) patients. The pre-NAC and post-NAC biomarker profile of our cohort is shown in Table. The biomarker profile change rate was 36.1%, 14.5%, 50.0%, and 9.2% in pre-NAC groups: HR+/HER2+, HR+/HER2-, HR-/HER2+, and HR-/HER2-, respectively. Biomarker profile change occurred most commonly in those with HER2+ disease (26 of 66, 39.4%), p=0.0003.


Conclusions:

To our knowledge, this is the largest contemporary patient cohort examining the rate of biomarker profile change after NAC. Biomarker changes in 18.7% of our study cohort confirms the need for biomarker retesting in those with residual disease, and especially among those with HER2+ tumors. Investigations on whether biomarker profile change after NAC is associated with differential outcomes or impact of adjuvant therapy is ongoing.

Learning Objectives:

  • • Upon completion, participants will understand that biomarker profile change after neoadjuvant chemotherapy is around 19%.
  • • Upon completion, participants will understand that biomarker profile change is most common in those with HER2+ breast cancer subtype at a rate of 30%.
  • • Upon completion, participants will understand that biomarker retesting is warranted in patients with residual disease.